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Porosity

  • How do you connect the earth when working under wharf jetty half kilometre from shore?

    Simply just drop the earth into the water, a trailing earth lead made from Stainless steel cable would be suitable. We have 10 & 15 meter trailing earth leads in stock and can also make them to any length required

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  • What is the function of PCWI Detectors?

    PCWI Detectors are test instruments that detect and indicate the location of pinholes and bare spots (Holidays) in non-conductive coatings, linings or films that have been applied for corrosion protection on metal and concrete surfaces.

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  • What types of non-conductive coatings are applied in corrosion prevention?

    Thin epoxies, vinyls, paints, polyethylene, rubber, porcelain, enamels etc, hot applied coal tar, asphalt, and heavy mastic materials. Most anti-corrosive coatings are of a dielectric material and in order to detect defects through these surfaces a suitable test voltage is applied.

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  • What is corrosion and how is it caused?

    Corrosion is the gradual wearing away to destruction of material. It can be caused by atmospheric exposure or by chemical reaction with corrosive agents – hence the necessity to apply complete sealing coatings to eliminate moisture permeable defects.

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  • When would a PCWI Detector be used?

    PCWI Detector would be used both pre and post installation by the contractor (manufacturer), to confirm the efficiency of his original sealing coat, and by the maintenance engineers in periodic examinations.

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  • In what industries is corrosion of major concern?

    Because corrosion is of serious concern over almost all aspects of industry, both operationally and cost-wise, a short list of major industries would include: Mining: Fabrication: Engineering and Construction: Paint Companies: Oils and Petrochemicals: Municipal and Government Authorities such as City Councils, Electricity, Water and Sewerage, Defence: and so on.

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  • How is the testing of coatings by PCWI Detectors cost effective?

    For newly constructed tanks, pipelines and other installations where corrosion prevention coatings have had to be applied, specifications will normally call for a specific coating to a specific thickness. With the use of a PCWI Detector in verification of the competency of the sealing coating, the contractor can be assured that his coatings responsibility has been met. In terms of cost effectiveness, with the low capital and operating costs of PCWI Detectors, the contractor will have substantial freedom from claims at a very low price. The approximate labour time in PCWI Detector checking should be no longer than the time taken for a single spray coating application by power equipment.

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  • On what principle do PCWI Detectors operate?

    The PCWI preferred principle employed for general application is a low frequency high voltage detector that delivers a stabilised pre-set pure DC output via a probe to an inspection electrode. As the electrode moves over the coating surface, if it encounters a pin hole or bare spot, a small current flows actuating a visible (non-hazardous) spark at the point of contact and a visible and audible alarm in the unit. A neon alarm in the probe handle provides 360° visibility to the user (DC15 and DC30 units only).

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  • How is the applied voltage pre-set?

    The voltage required is pre-set manually on the unit to a minimum level determined by the thickness of film of the coating product and its generic type ie: Rubber, Vinyl, Epoxy etc. Detailed instructions are set out in the unit Operator Handbook. It is important to follow these instructions in setting voltages as some surfaces have a much higher dielectric strength than others - consequently offering a high resistance to the conduction of electricity. Applied test voltages should only be sufficient to detect faults, otherwise overstressing of the dielectric strength may occur with possible surface rupturing.

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  • What are the minimum and maximum film thicknesses that can be tested with PCWI Detectors?

    This depends on the type of coating applied. Australian Standard AS3894.1-2002 states a minimum of 150µm - see Operator Handbook for coatings/voltages relationship. Refer to Operating Instructions.

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  • Do damp coatings or moist and humid conditions affect the operation of the PCWI Detector?

    As wet surfaces are generally conductive, this could affect the unit operationally. Atmospheric moisture is unlikely to do so. Some user preference exists for DC pulse units over direct DC units under wet operating conditions. This choice could be misleading, however, because the applied test voltage loss depends on the size of the electrode, the frequency of output, the depth of coating, and the possible conductivity of the moisture. These circumstances could cause the test voltage to drop to such an extent that there is insufficient test voltage to locate faults.
    Preferably use DC Pulsed Units on damp – contaminate and carbonised surface coatings.

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  • What checks are available on the functioning of the PCWI Detectors?

    A range of tests can be undertaken by employing the appropriate PCWI Detector Crest Meter. Details in Crest Meter brochure and Crest Meter Operator handbook. (ie: Voltage output and visual display; Continuity of leads etc.)

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  • Is it necessary to have a separate ground or earth lead?

    Yes! This is supplied as standard with all PCWI High Voltage Detectors. This is provided against the possible build up of static charge of the metal substrate should the substrate be above or potentially above the ground. To ensure an adequate test, it is essential that a positive earth return loop connection exists between the metal substrate and the Detector, and preferred also is an earth from the metal substrate to earth (ground) as well.

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  • What is the application for the two DC Compact Models & two Pulse Models?

    In all general corrosion inspection and detection applications where lengthy and varied conditions are met for this reason these models are harness mounted with the ability to be used with all electrodes, i.e. Brushes, Coils etc – Internal and External and an extensible wand at the same time maintaining user comfort

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  • Why are two models necessary?

    Most anti corrosion coatings or linings are made from dielectric material that can vary in their inherent electric strength offering greater or lesser resistance to the conduction of electricity. Applied test voltages should be adequate to detect faults in the particular coating but not to pose problems of possible rupture. The provision of a maximized voltage ie. 0.15 kV limits this possibility within the parameters of coating dielectric strength, type and depth; consequently the two models offer users a selection to meet their particular coating specification.

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  • What is the application for the Pulse P20/P40 models?

    The PCWI Pulsed Porosity Detectors are designed to test coatings that are conductive such as wet, chemically treated or high carbon coatings.

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  • What is the Wet/Dry control located in the battery compartment?

    This control allows the user to adjust the overall alarm sensitivity. The Pulse detector has an automatic alarm circuit which continually adjust for the coating being tested. If the coating being tested is too wet or conductive, the alarm may not be able to adjust correctly. It is then necessary to use the Wet/Dry control.

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  • It is noted that the PCWI High Voltage Detector employs wire brush inspection electrodes and not wet sponges. What are the advantages of the wire brush electrodes and the limitations of the wet sponge detectors?

    High voltage testers with wire brush electrodes are faster to use, larger areas can be covered and there is no contamination from the water.

    Wet Sponge (cellulose) electrodes are used in low-voltage detectors, having an output of less than 100VDC. The wet sponge method is not satisfactory for the detection of other than gross faults in thin film coatings, and is unsuitable for use where thicker coatings in excess of 150µm have been applied.

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  • The PCWI website shows maximum internal and external pipe-brushes at 20" (500mm). Can brushes of greater diameter be provided to complement the Detector?

    Brushes more than 20” (500mm) are large and difficult to handle. However, special large brushes can be made to order. Note: All coil sizes can be used in place of brushes where specification allows. Pipe joints and longitudinal welds should be tested with a brush.

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  • Under what conditions are Carbon filled silicone-rubber brush electrodes of advantage?

    These can provide longer life but may require the application of higher voltages. They do not lay flat, and the welded areas should be tested with a brass brush. They should not be used on heavily corroded surfaces and textured coatings.

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  • Are PCWI wire brushes interchangeable or compatible with competitive detectors and vice-versa?

    Yes, with suitable adaptors, which PCWI can manufacture to suit.

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  • Will wire brush electrodes ensure good inspection even in corners and around irregular shapes where pinholes or bare spots (holidays) are likely to occur?

    Yes! PCWI Detectors can accommodate a complete range of brushes (see Brochure for illustrations).

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  • It is stated that under practical conditions, it is impossible to obtain an absolutely uniform thickness of an applied coating to a metallic surface, due to unevenness, mill-scale or other surface blemishes. Using a “dry testing technique” by applying a high test-voltage to locate faults over the thickest section of the film, the thin areas of film could be ruptured due to excessive test voltage, even though these thinner film areas are perfectly homogeneous. Under these circumstances wet sponge testing utilising a low voltage can be effective - True or false?

    This is False! Rupturing will only occur if far too high a voltage is applied when testing. Passing the electrode over a test panel with similar (thinner) coating thickness will quickly determine whether the voltage is set to a level that will cause rupturing in the thinner areas.

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  • Can cable makers use the PCWI Detector for testing? Does this require a cable tester electrode box?

    Yes - this box can be made on special order.

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  • Can the PCWI Detector be used in the testing of flaws in Heavy-Duty glass?

    This depends on the thickness of the glass and the voltage required.

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  • Do the PCWI Detectors provide the same voltage automatically on various pipe diameters without resetting and what is the tolerance?

    Yes – the feedback circuit automatically adjusts for this.

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  • Does the PCWI Detector have earphones?

    Yes – Air operated.

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  • Can the PCWI Detector be operator belt mounted?

    No - the unit is supplied with an adjustable harness for waist, chest or shoulder mounting. The waist mounting is equivalent to a normal belt position.

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  • What are the important operational features of the PCWI High Voltage Units?

     •   Regulated test voltage
     •   Constant test current source
     •   Fully adjustable voltage output
     •   Fast testing speed
     •   Optional spare battery
     •   Battery over charge protection
     •   Wide electrodes with no output loss
     •   Air-operated earphones

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  • As Detectors are a working tool, what user comfort and safety is provided?

     •   Lightweight
     •   Fully adjustable shoulder & waist harness
     •   Clear digital display
     •   Sound and visual alarms
     •   Momentary “on” button – for safety (on DC detectors only)
     •   An Ergonomically designed probe handle

    (Refer to schematic drawings – features and user benefits)

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  • When passing brushes over inspection surfaces what scanning care should be taken?

    Multi cross directional scanning should be employed.

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  • How are the Detectors cleaned?

    By wiping with a mild detergent or isopropyl alcohol. Do not use solvents or aggressive chemicals, turpentine etc as the housing is PVC based.

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  • On what principle does the low voltage wet sponge unit operate?

    The low voltage instrument employs a cellulose sponge as an inspection electrode. When moistened with water, the electrode is moved over the coated surface under inspection: when the electrode passes a void or bare spot, moisture from the wet sponge (electrode) penetrates the coating making contact with the conductive substrate, resulting in a drop in electrical resistance. As a result, a small current flow activates an audible alarm enabling identification of the defect location.

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  • Is the applied voltage user selectable?

    Yes, each unit has three settings: 9, 67.5 and 90 volts.

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  • What are the important operational features of the Low Voltage Units?

     •   Digital Display of voltage
     •   Unique correction system to minimise output voltage drop during testing
     •   Selectable output voltage: 9, 67.5, 90V
     •   Battery condition displayed in volts
     •   Auto shut down after 20 minutes to save batteries (can be overridden)
     •   Earphones for uses in noisy environments
     •   Light weight – single hand operation
     •   Telescopic probe handle – to 1.2m
     •   Internally mounted 9v replaceable battery
     •   Wide sponge probe head - faster testing

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  • Will Wet Sponge electrodes ensure good inspection in corners and around irregular shapes?

    Yes. The flexibility of the sponge ensures good inspection.

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  • What user comfort and safety do low voltage units provide?

     •   Economically designed handle for easy use – single handed
     •   Large brush for faster testing
     •   Audible and visual alarm
     •   Seven metre earth lead & clip
     •   Belt/packet clip
     •   Weight 350gm (excl probe)

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  • Can Wet Sponge units be used in corrosive environments?

    Definitely not recommended.

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  • Does the PCWI Thin Film unit carry the CE marking?

    Yes: Together with other relevant International Standards. (see compliances)

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  • What is the function of the PCWI Compact Crest Meter?

    The Crest Meter has the following functions:
     •   To test the output of the PCWI Compact Detector and to verify the voltage on the visual display
     •   To test the continuity of the leads and to verify the voltage on the visual display
     •   To test the PCWI Compact Detector under load with an applied voltage - this test verifies all earth leads and connections, and partially loads the system
     •   To test the PCWI Compact Detector under full load. This test verifies all earth leads and connections, fully loads the system, indicates pull down voltage and displays actual test voltage. This test is as per Australian Standard 3894.1-2002 for setting test voltages

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  • What certification does the PCWI Compact Crest Meter carry?

    Certification is an option, however the Crest Meter can be supplied as checked against a NATA certified Crest Meter.

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  • What is the period of validity of the Test Certificate?

    Twelve Months - after which the unit should again be compared with a certified source.

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  • What certifications of compliance do PCWI Detectors carry?

    Australian Standard AS3894.1-2002. This standard sets the guidelines for equipment type, voltages for specific coating types and voltages applied. The Detectors also meets the EMC directive 89/336/EEC, amended 92/31/EEC & 93/68/EEC and carry the CE marking.

    However, due to the method of operation, PCWI Detectors will generate broadband RF emissions when a spark is produced at the probe, i.e.: when a defect in the coating is located. These emissions may interfere with the operation of sensitive electronic apparatus in the vicinity.

    In the extreme case of a continuous spark of length 5mm the magnitude of the emissions at a distance of 3m was found to be approximately 60dBµV/m from 30MHz to 1000MHz.

    It is therefore recommended that this equipment is not operated within 30m of known sensitive electronic equipment and that the user does not deliberately generate continuous sparks.

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  • Is AS3894.1-2002 accepted and/or would the Australian Standard comply with a relative International (ISO) Standard acceptable in other countries?

    We believe that AS3894.1 is the world leader in Porosity Standards and should satisfy all International criteria, as there is no equivalent International Standard for Porosity Detection.

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  • It is understood that the Australian Standard AS3894.1-2002 permits both DC high-voltage and DC pulse units for testing coatings of a depth thickness less than 500µm (micron)!

    The PCWI Detector has constant test voltage and current.

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Moisture

  • What does it mean by extra thick multi layer panels in your operating instructions? They are applying 15mm of glass resin flow-coat, then 20mm foam core and then 15mm of repeat of previous coating.

    We are referring to the different layers of material in a fibreglass (GRP) hull construction. Usually, a gel coat is applied to the outside layer of GRP to give a very smooth surface finish in contact with the water. Gel coatings tend to blister and lift if there is too much water in the fibreglass - a consequence of the process known as osmosis. The Aquant II will indicate the relative levels of moisture through multilayer materials to a nominal depth of 10-15mm. This gives the user relative information through the GRP and gel coat. When the field enhancer is fitted to the meter (the shoe like device in which the meter sits) the depth of penetration is compressed to a nominal 5mm. The user can investigate conditions at the gel coat fibreglass interface.

    MINI or pin type moisture meters. Measure conductance only, between the pins.

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  • Why does the Surveymaster provide widely differing results when using the pins versus search mode in a sub floor situation on particle board flooring and also timber bearers and joists?

    Search mode (Radio Frequency) utilises a 0-1000 relative scale; there are no units of measurement. Search mode gives relative information of the moisture condition from the surface to a nominal depth of 20mm (subject to the material being tested; perhaps slightly less than this in timber). The red-zone relative readings of 726 and 567 indicate that the material is damp beneath the surface. To quantify the actual moisture level in %mc (in wood) or in %WME (in materials other than wood) additional testing would be necessary, by using the Surveymaster together with the Deep Wall Probes or a Hammer Electrode (for wood only).

    Measure mode, using the pins (or accessories such Deep Wall Probes or Hammer Electrode) gives a precise and specific measurement of the actual %mc between the tips pf the electrode pins. The red zone readings of 28.9 and 22.1 indicate the actual %mc moisture level at the surface between the points of the pins.

    In essence, Search and Measure modes are complementary technologies. Search mode is used to detect, map and monitor the sub-surface condition in relative terms. Measure mode gives quantitative and precise measurement of the actual %mc in wood or %WME in materials other than wood. For further explanation of WME download these Equilibrium Moisure Content tables. When high Search mode readings are obtained it may often be necessary to take quantitative readings by using the Surveymaster in Measure mode.

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  • What is the difference between absolute humidity and mixing ratio?

    Absolute humidity:
    The mass of water vapour present in a unit volume of moist air of a given temperature and pressure. SI (metric) units are grams of water per cubic metre of air. Older references may be in terms of pounds per million cubic feet or in grains per cubic foot (One grain is approx equal to 0.0648gram).

    Mixing ratio:
    Mass of water vapour per unit mass of dry air with which it is associated. It is a dimensionless ratio but is often expressed in grams of water per kilogram of dry gas or in other units of mass. For low levels of moisture content, this may be expressed in parts per million by weight, ie mass of water vapour per million parts mass of dry gas (ppmw).

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  • Can the Aquant be used to measure moisture levels in fibreglass panels reinforced with a plywood core?

    The Aquant II should detect differences in moisture level through a GRP- Plywood-GRP sandwich. Effectiveness will be influenced by: Thickness and density of the GRP layer, density of the plywood and variability of the moisture level within the GRP and the plywood.

    Note: The Aquant is a moisture detector not a moisture meter. It is not calibrated to give actual %MC values.

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  • Is there some way of testing the search mode on the Aquant's (and other Protimeter moisture meters)?

    The Aquant is a moisture detector that highlights, in relative terms, areas of potential sub-surface (to a nominal depth of 20mm, depending on the material) moisture level concern. By contrast, moisture meters (pin-type devices) give a precise, repeatable and specific measurement (%mc in wood, %WME in other materials) between the contact points of the pin-electrodes. The two technologies – RF (Aquant) and pin-type moisture meters - perform different roles and give different perspectives. The technologies are complementary; it is a mistake to think of one technology being better than another.

    Focusing on the Aquant, it is designed for monitoring or highlighting sub-surface moisture levels in situations where it is impractical or undesirable to do invasive or destructive testing. The 0-1000 relative scale enables the user to monitor steady state conditions, or monitor changing conditions. The scale gives the user information on the moisture condition of the material: green zone (0-160) very dry, yellow (161-200) dry/marginal and red (201-1000) potentially damp through to wet. If material registers values in the green/yellow zones there is little to be learned from doing destructive tests with, say, a Mini and Deep Wall Probes because it is clear that the sub-surface material is dry. However, if the material registers red zone readings there may be value to the user in quantifying the sub-surface moisture condition in terms of %WME or ERH by using, say, a Mini with DWPs or a Hygromaster.

    Using the RF type instuments (Aquant, surveymaster MMS/MMS2) To obtain consistent readings in the RF modes the instruments must be held and used correctly. It is important for the user to hold the instrument more or less in the same way; wrap fingers fully around the handle of the instrument and avoid touching (the side of) the sensor pad when taking measurements. With the new style Aquants and MMS2, ensure that the flat pad is in 100% contact with the surface. With the older style Aquants, surveymasters and MMS, that have a curved RF sensor, hold the unit at about 30 degrees to the surface. Regarding wear of the sensor; advise your customers not to drag the instruments across surfaces. These instruments are designed to be placed in position and then lifted.

    RF Scale tolerance
    The 0-1000 relative scale is indicative, not a precise measurement of actual moisture level or content. An allowance of 30 points is acceptable between any two instruments in the range 0-200. So two instruments, one reading say 140 and the other reading 170 at the same measurement point, are within tolerance. A wider allowance (unspecified, but say 50 points) should be allowed for readings over 200.

    A better baseline reference to use is an area of solid wall and/or floor that you know is in a stable condition. To identify a suitable baseline I’d recommend using the average readings from, say 6, brand new instruments. Your hand is a good reference for full scale check; all units should read 999 or 1000. Having established a stable reference please check your customer’s instruments against this.

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  • Is there a recommended method for using the Aquant to test for moisture in ships hulls?

    Suggest taking a reference reading above the water line to establish the "norm" for the hull. Consider the difference between the "norm" and readings taken at critical points below the water line. A large difference suggests the hull may be saturated (assuming no water tank etc. directly behind the meter at that point). In essence the Aquant can only draw attention to potential problem areas. Readings in the bottom half of the Aquant scale are usually ok. Readings in the higher half should be scrutinised.

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  • Does the Aquant II react to anti-fouling paints (which often/usually) contain metallic compounds?

    It is a question of degree. If the paint is highly conductive it will cause the Aquant (and all other types of electrical moisture meter) to read high. Even if the paint is conductive the Aquant may still be usable as it is giving a relative reading. The difference between reference readings taken above the water line and those below is of most significance.

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  • How would the Aquant be used to measure moisture in radome structures (Radome – meaning dome or covering, protecting radar equipment)?

    The Aquant has a field reduction shoe that can be used which allows moisture assessment of the gel coat (outer 2-3mm) of a GRP composite structure. This is quite common in the marine world where one of the major hazards is what is known as osmosis (when the gel coat becomes semi porous and will lead to eventual breakdown of the structure/hull). This is probably needed for assessing radome structures. The field reduction facility would be necessary; as at full strength, it would also be looking at the honeycomb structure underneath the gel coat which by its nature will be full of air gaps etc, and such results would then be fairly meaningless.

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  • Can you measure moisture in bamboo?

    We have no calibration data for bamboo. For species that are not listed in our calibration table, we recommend using the A scale. This is the generic wood calibration that is common to all Protimeter moisture meters.

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  • Can a Surveymaster measure moisture in besser blocks?

    Because these are of an unknown mixture the Surveymaster would give “indication only".

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  • Can you measure moisture in cardboard?

    The Mini is used by the packaging industry to give relative measurement in cardboard and similar materials. The %WME value given by the meter tells you the moisture condition of the material - whether it is in a dry, borderline or damp state. Cardboard stored in a dry environment of say 40%rh would have a %WME value in the range of 8-10%WME. This is in the middle of the green zone of the instrument telling you that the material is in a safe air-dry condition. It will not deteriorate as a result of its moisture content. By contrast cardboard stored in an environment of say 85%rh would have a %WME value in the range of 19-21%WME, a damp condition where if maintained, deterioration would be expected. In summary, for cardboard the Mini is a simple and effective tool for monitoring and quality control applications where a relative reading is acceptable.

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  • Does the Surveymaster measure moisture in carpet?

    Best units for testing moisture in carpets are the pin-type (mini) meters. Search mode RF of the Surveymaster and Aquant are not effective for moisture measurement in carpet itself. Better for giving insight into conditions with solid walls/floors. The Surveymaster is the most versatile meter as it has both functions of RF and pins.

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  • Does a coating (paint) affect the moisture reading? How does this work?

    This depends on the paint system. If the paint is conductive (eg contains metal particles etc) then moisture meter readings may be affected, - other wise no. Suggest you discuss with your paint supplier.

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  • Does the Digital Mini measure moisture in coconut?

    This will record %mc values in wood species. If you have a species such as coconut which is not listed in the calibration tables we recommend you record scale A values, allowing a tolerance of ±2%. If more accurate values are required, the instrument should be calibrated with respect to oven dried samples.

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  • How do pin type moisture meters compare against meters which work on radio frequency (RF)?

    Measure mode with pins is a precise and specific measurement of the moisture level (in terms of % moisture content in wood or “wood moisture equivalent” WME in other materials) between the pin electrodes. If the pins are pushed just into the surface, then only the surface condition is being measured. By contrast, search mode RF is a moisture detection technique that identifies (in relative terms only) the presence of moisture measured from the surface to a nominal depth of 20mm (depends on the material).

    The two modes are not directly comparable because they are measuring different things. When both modes are used, two perspectives of the moisture level are gained that are complimentary; ie. surface and sub-surface conditions.

    The %WME and relative scales are not directly interchangeable. The reason for this is that there are too many variables that can affect the RF measurement (properties of the material, temperature, etc). That said, one can make the assumption that RF readings up to 200 are most likely to be equivalent to less than 20%WME. Relative values over 200 are likely to be equivalent to over 20%WME.

    Relative readings below 200 indicate the sub-surface is dry; there is little to be gained by drilling holes and using the deep wall probes to verify the level in %WME terms. But search mode readings over 200 are signalling that there may be an excessive moisture level present. If the user wishes to quantity this, then the Surveymaster should be used with the deep wall probes to quantify the sub-surface moisture level in terms of %WME.

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  • Customer asks one of our laboratory staff about using the Hygromaster in a concrete slab that is outdoors and is three months old. He took readings on a slab that was 15°C and getting readings of 76.9%rh and 78%rh. When he measured the same slab at a later date in the same locations at a slab temperatures of 6°C the readings were 90.6%rh and 90.9%rh. The probe was left in each sleeve for 30 minutes on each occasion. He asked why the high readings? Is it due to the colder slab temperature of 6°C?

    Initially let’s make two assumptions. In both cases the hygrostick used to take the measurements was correctly calibrated and was in equilibrium with the environment (the air in the hole) being measured. The saturation vapour pressure of water depends strongly on temperature. Near room temperature, the air’s capacity to hold water vapour doubles for every 10°C increase in temp. But at, say, -60°C the saturation vapour pressure doubles for only a 5°C increase in temp. (Source: A Guide to Measurement of Humidity, NPL). In short this means that the measured rh value will change significantly with temperature, even when the actual moisture level within the concrete and the air pocket itself are more or less constant. As the temperature falls, the rh value will rise and vice versa. So if the slab temp has fallen from 15°C to 6°C it is no surprise that the rh values have increased significantly.

    A thought regarding this situation. It is odd that there should be such a variance in the temperature of the slab. Generally speaking, slab temperatures tend to be pretty stable, varying by only a few degrees C irrespective of the external environment once below the surface. This is one of the reasons why rh measurement is considered a practical option for assessing the moisture condition of a slab. Any explanation on how/why the slab temperature varies so much? Is there a subfloor heating system installed?

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  • Is there a connection between condensation and dewpoint?

    In condensation, there is no explanation of dewpoint temperature. Dewpoint is the temperature at which moisture condenses. It is a function of ambient temperature and %rh and it varies if the %rh changes or ambient temperature changes or both change. Moisture condense on mirrors, walls etc when their surface temperatures fall below dewpoint. A simple example; when you take a cold bottle of beer out of the fridge, water droplets form on the glass. The reason – the temperature of the glass is below dewpoint temperature. The MMS enables the user to measure humidity, ambient temp, dewpoint and surface temperature for condensation investigation work. It even shows you the difference between surface temperature and dew point.

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    Answer 2
    The Surveymaster does not use “sonic” signals in search mode. It measures the dielectric capacitance of the material by using radio frequency (RF) signals.

    Answer 3
    Protimeter two-prong meters (Mini, Timbermaster, Surveymaster & MMS) are indeed calibrated for timber. However, these instruments are not designed solely for use in timber, they are designed for use in the whole range of non-conductive building materials. The point to note is that they only measure actual moisture in wood. In other materials they measure %WME values. This is very significant, because it means that the meters can be used to establish the moisture condition of the materials under investigation by using the wood calibration as a reference.

    Answer 4
    Hygroscopic salts, carbon and other conductors will cause high moisture meter readings. When this is suspected, instruments such as the MMS should be used in hygrometry mode to measure the ERH of the material under investigation.

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  • Will the Surveymaster measure moisture in corrugated cardboard?

    The SM will only work effectively when held directly against sold materials. It is designed not to bridge air gaps, which is why it does not register through corrugated cardboard.

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  • What is enthalpy?

    Enthalpy is a function of the gas temperature and pressure of the moisture content, since water absorbs energy in changing from condensed state to vapour. Useful concept in air conditioning whether it is important to know how much of the stored energy will be consumed or released when the temperature or water content is raised or lowered. Enthalpy of gas can be defined as the sum of “sensible” and “latent” heat for each component in the gas. Values of enthalpy are conventionally expressed relative to a datum point (ie. A zero or base line). For a dry gas, this is normally the heat content at 0°C. For water vapour, the enthalpy is usually expressed relative to the heat content of liquid water at 0.01°C. Expressed in terms of energy per quantity of dry gas ie. Kilojoules per kilogram (kJ kg).

    When we heat or cool air, we are heating or cooling the gases (called sensible heat) and we are heating or cooling the water vapour (called latent heat). The cooling process often removes water vapour form the air. This is commonly seen as water running from the amount of heat in a kilogram of air.

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  • Can the Balemaster be used to measure moisture in lucerne/hay, baled in high humidity conditions?

    Unit is calibrated for wheat and straw, but it is frequently used to take relative moisture measurement in other baled materials (e.g. hay, tobacco, cotton and hemp etc).

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  • Will the Balemaster probe have the ability to give a constant read out as you probe in and out of the bale?

    This is a crucial element in buying a probe to find possible "hot spots" or high moisture balls in bales for export.

    Unit will give a constant reading whilst it is on. In other words once switched on the display is active until the unit either switches off automatically (30 seconds or so, as I recall) or is switched off by the user. The measurement is made at the tip of the probe, not over the complete length of the probe. This means that you can take measurements at incremental increases in depth. If used in a methodical and consistent manner it should be possible to identify "hot spots” as required for this application.

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  • How many holes should you drill in concrete to put in the 70mm humidity sleeves?

    This depends on the recommendation of the standard your customer is applying (if any) and/or the level of rigor the client requires from the moisture measurement programme. So, not really possible for us to specify how many holes he should drill. That said, the goal is to drill sufficient holes to give a reasonably representative picture of the moisture level within the slab. That may depend on the layout; is it one large continuous area, or is it a fragmented area on different levels with areas in shade/sunlight and or areas that are in differing environments?

    If one large continuous area, in a more or less consistent and stable environment, then fewer holes will be required to obtain a representation than if the area is variable from place to place. Assuming it is one continuous area, and assuming that a hole pattern is not specified by a standard, then holes could be placed at regular intervals (spaced to the mutual agreement of the user and his client) parallel to the walls and, as a suggestion, diagonally across the area. This should give a reasonably representative picture, but in the end it is a judgment call as to where the sleeves are placed and how many are placed.

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  • I need to measure moisture in a laminate flooring which is made out of HDF (high density fibre board) and other layers to produce a hard wearing laminate floor. I need a unit to measure moisture within an installed floor that may be experiencing some problems - problems with our floors usually come down to customer wet mopping, spillage etc. I need an accurate way of testing floor without pulling floor up, how could I do this?

    Should be able to identify damp spots within the HDF floor using the RF search modes of the Aquant, Surveymaster and MMS. Readings are relative only but if moisture (from mopping etc) has penetrated the floor, it should be detectable with this method.

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  • Customer using a Surveymaster testing magnesite (20-25mm thick) on concrete. When they put the pins into the magnesite the SM shows dry. The magnesite has been removed at different places on the concrete and using search mode the meter shows wet. The concrete floor has been down for 30 years. They ask why the meter is giving two different readings?

    Surface readings (pin mode). Pins take a precise and specific measurement between the points of contact. Sub-surface readings (RF mode). Relative measurement is taken from the surface to a nominal depth (typically 20mm). Common for a moisture gradient to exist, even in material that may be old and stable. In essence, it is not uncommon for moisture level to increase with depth in material as there are numerous variables that affect moisture level/stability (e.g. type of material thickness, environment, whether or not concrete has been covered and so on). Possible that the magnesite layer has acted as a vapour check and kept moisture within the concrete.

    Note too that search mode RF measurements are relative not quantitate. Search mode is a moisture detection device designed to map extent of condition and to monitor levels in comparative terms. How “wet” is “wet”? Are the search mode readings just in the red zone (circa 200-250) or into the high hundreds?

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  • Does the Surveymaster measure moisture on marble & tile slabs?

    Does your want to know the %mc of the tiles themselves, or what the moisture level is behind the tiles? If behind, consider these as you would ceramic tiles. Provided the tiles are not too thick, the Surveymaster should give useful information. If within the tiles: We have no information on the Surveymaster performance in marble and granite tiles specifically. Assuming there are no conductors in these materials then the Surveymaster should work. However, as these materials are so dense they may not be capable of holding enough moisture to be detectable to the Surveymaster. Best advice we can offer is to try it out on samples that are known to have high and low moisture contents.

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  • Moist masonry wall covered with an impervious coating such as plastic epoxy paint. If you put the meter on the surface will it measure any surface moisture or just the masonry behind the paint?

    There are two measurement modes available with the Surveymaster:

    In REL/search mode, the instrument will detect any conductivity in the bulk material to a depth of at least 12mm but no more than 19mm. The measurement sees the moisture whether or not it has a route to the surface. This measurement mode will register any moisture in the depth range even it is behind a DPN or other impervious barrier.

    In WME/Pin mode the instrument primarily measures moisture in the direct line between the pins. It will not measure across gaps or through barriers. However, if both pins are pushed through the barrier – in this case the surface coatings of paint – the pins will be in direct contact with moisture behind and so the moisture will be included in the readings.

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  • Do the timber moisture meters work on MDF?

    The fact that timber instruments start measuring at 6-7% moisture content in timber does not preclude their use for other materials at lower moisture contents. Eg. In plaster board moisture content as low as 2% may be measured. Similarly, since we do not know exactly what the MDF consists of, the easiest way is to get a sample, which has a moisture content of 4% and see if one of our timber instruments work.

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  • What scale should I use when looking for Osmosis in GRP?

    Osmosis is quite common in the marine world. A major hazard is what is known as osmosis (when the gel coat becomes semi porous) and will lead to eventual breakdown of the structure should use the A scale. This scale is also used on the Mini, Surveymaster and MMS meters.

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  • I want to measure moisture up to 30% in plaster figures before they are painted. Will your timber moisture meters work?

    Yes, you should be able to use these to assess the moisture condition of plaster figures in the same way you would a wall Your customer could use the mini or similar to take relative readings. You would actually be measuring %WME values.

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  • Customer using a Timbermaster to measure blackbutt timber on a plywood sub floor and water under the flooring has caused the blackbutt to come off the sub floor. The blackbutt measures 13%-14% and the plywood measures 23%-25%. What should the plywood measure when dry? Also which scale should the customer be measuring the plywood with? Scale A?

    Wood, including ply, is in a safe air dry condition when the moisture content is 16% or lower (green zone on our Mini and Surveymaster instruments). The borderline or at-risk condition is 16-20%mc, indicated by the yellow zone. Damp wood has 20%mc or greater, in the red zone. If using a Timbermaster for plywood, the customer should use the A scale. This scale is also used on the Mini, Surveymaster and MMS meters.

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  • A polystyrene panel manufacturer wants to measure moisture in blocks of polystyrene that are up to 480mm thick by 2-3 meters wide by 3-5metres long. These blocks dry from the outside in and there and be a pocket in the centre not dry that does not show up until they are into fabrication. Could the Surveymaster with 240mm deep wall probes work?

    Deep wall probes may work. It depends if the levels of moisture within the panels are within the measuring range of the Mini or Surveymaster. It should be easy enough to establish this by trying it out on panels that are known to be acceptably dry and unacceptably wet.

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  • I asked you about polystyrene ten years ago and wondered if there have been any newer test methods? Would humidity now be more accurate?

    This really depends of the accuracy of measurement sought by the customer and the physical amount of water within the polystyrene itself. If customer is looking for simple moisture detection, then it may be that the radio frequency (RF detection devices (Aquant, Surveymaster and MMS) will be adequate as thickness of material (18-25mm) is not so great. Can the material be tested from both sides?

    But RF detection is relative measurement and can be affected by variables (temperature, inconsistency of the materials) etc). If a more precise measurement is required, I suspect %WME using deep wall probes will be more reliable and useful. Are you aware of the EIFS probe? This is used to push through polystyrene insulation widely used in low cost American houses external insulation finishing system. Same principle as deep wall probes but a lot more convenient to use. Humidity techniques, viable, I think but time consuming to get an equilibrium rh measurement.

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  • Can your Protimeter meters measure moisture in refractory bricks?

    The Surveymaster or Aquant using search mode are certainly an option for quick, sub-surface moisture level checking of refractory bricks. Point to note is that the scale of these instruments is a relative index only rather that an actual measurement of the bricks % moisture content (%mc)

    Is it important to know the actual %mc or to have an instrument that tells you in relative terms whether the bricks are in a dry, borderline or damp condition?

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  • What is the acceptable (maximum) moisture level for teak?

    Teak reads off scale F - we are reluctant to give people precise moisture content for individual types of timber and specific applications. We suggest they contact “The Timber Research Association" who would be able to give more expert advice.

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  • Moisture meters are usually used on lumber (such as air-dried or kiln-dried). We intend to use it on freshly cut logs to be used as a biomass fuel. Is the meter ok for this application? I have also read somewhere that for moisture beyond 30%, accurate readings are impossible because there is too much water in the wood. Your specs for the Timbermaster say its accuracy is ±1%. Does this accuracy only apply to moisture content <30% or does it also apply to MC up to 99%? What we are worried about is that we will be working on logs that are typically in the 60% MC range and will be dried to around 40% MC and does the accuracy of ±1% still apply? Eg: It might turn out that we get readings of 55% and in reality, the actual value lies between 50%-60% ±5%. Any explanation on this matter?

    The Timbermaster and other instruments only give a reliable measurement in wood up to fibre saturation; between 28-30%mc. Timbermaster scale extends to about 90, but measurements in the range 30-90 are relative only. You should not consider measurements in this range to accurately represent %mc, uncertainty could be ±10%mc.

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  • We intend to take deep measurements for MC. Other moisture meters are able to use alligator clips attached to nails hammered into the wood. Can we do this with the Timbermaster?

    Yes you could connect crocodile clips to nails driven into the wood. Also consider using the hammer electrode.

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  • Customer wants to inspect a tiled shower floor with a waterproof membrane under the tiles (he doesn’t know what type of membrane it is). If the shower is used say four hours before he does the inspection, will he be able to check whether the waterproof membrane has a leak through to the floor underneath or is ok?

    This is a hard one to call. If the tiles are assumed to be 100% non-porous, then a test after four hours should be fine provided all surface moisture has been dried off. However, tiles may not, in reality, be 100% non-porous. In other words, they may retain some residual moisture for considerable time as a consequence of normal use. Best advice is to look for variability in the readings rather than relying too much on the actual meter values. If readings are pretty much the same wherever they are taken, this would imply stable conditions. If there are significant differences in meter readings at different places, it may be indicative of areas where leaks have occurred through the tiles? Note that tile thickness influences the readings.

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  • Can your moisture meters be used measure moisture in vanilla beans (long brown bean)?

    It will depend on the moisture content range expected. If this needs measuring when growing prior to harvest then it would be unlikely any of our technologies would be able to cope. If we are measuring dried vanilla beans (pods) then depending on the actual levels involved maybe a mini could give guidance. Literally they need to try it or send us a well sealed sample for testing.

    Interesting customer reply:
    We are dealing with vanilla bean pods, about 16-22cm in length, that have been cured and sun-dried. We need to simply insert the two pins into the pod and obtain a moisture content reading. We need something that is relatively inexpensive, quick, reasonably accurate, portable and easy for the grower to use. We are dealing with uneducated, rural farmers, some of whom grow these crops 4-6 days trek from the nearest road, mainly in the Highlands of Papua New Guinea (PNG). We often do not even pay “cash money” for their crop, as they have no need for it (no banks, shops etc) nor have most of them ever seen notes/coins. We pay them in blankets, batteries, small radios, saws, knives, machetes, plastic bowls, and books and shoes for the kids. I will purchase a Mini for evaluation.

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  • Can the Mini or Surveymaster with deep wall probes measure moisture in vermiculite?

    Suggest a Mini with a deep wall probe for quick initial investigation. Then a Hygromaster could be used to measure the ERH if the material is of a compressed nature.

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  • If a subfloor has water pipes running through it and an MMS drill and plug test is being conducted, will the results be affected because of the water in the pipes?

    If measuring ERH values with the MMS, hygrostick and humidity sleeves then the measurement will not be affected by either the pipe material or the water within the pipe. Reason for this is that the hygrostick measures the relative humidity of the area in the hole rather than the concrete surrounding it. A word of caution! If the subfloor heating system is on then the temperature of the concrete floor will be fluctuating. This certainly would affect the ERH readings. The subfloor heating system should be switched off well in advance of taking measurements to ensure that the floor slab is at a constant normal temperature. By contrast, the MMS search mode (RF) readings could be affected. This would depend on the depth of the pipes below the surface and the diameter of the pipes etc. It should be easy to spot though. You would expect search mode readings to rise if directly over the pipe and to fall when moving to either side of the pipe.

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Coating Thickness Standards

  • What is the function of PCWI Calibration Standards?

    To check the accuracy and calibrate all coating thickness measuring gauges.

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  • What is the function of Coating Thickness Gauges?

    To check the thickness (depth) of Coatings applied on Ferrous or Non-Ferrous substrates for surface protection and appeal.

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  • How do PCWI Calibration Standards check the accuracy of Coating Thickness Gauges?

    Each Coating Standard consists of one Zero plate and four epoxy coated reference plates. The reference plates carry certified coating thicknesses that differ on each plate.

    The gauge under check is then used to relate the zero and reference plates against the gauge indicated readings – In this way arriving at agreement or variance.

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  • If variance shown from the standards how is re-calibration carried out?

    Coating Thickness Gauges carry adjustable calibration that can be used to bring the gauge readings in to conformity with the certified standards.

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  • Will this checking and calibration ensure the accuracy of the gauge?

    Yes – subject to the resolution tolerances within the instrument. A regular programme of checking and calibration is recommended.

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  • How is checking and calibration by PCWI Calibration Standard cost effective?

    To meet application and performance specifications the applicator (contractor) must rely on the accuracy and reproducibility of his Thickness Gauge readings. Regular checking and calibration to ensure this are critical.

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  • How many plates are on a Coating Thickness Standard?

    One zero plate and four coated plates, or one zero plate and two coated plates.

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  • What is the substrate material used?

    Ferrous – Steel, Non-Ferrous – Aluminium

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  • Is the substrate material the same on the one standard?

    Yes, the sets are entirely ferrous or non-ferrous.

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  • Why are four coated reference plates and one zero used?

    Coating Thickness Gauges are designed to be accurate through a wide range of thicknesses. To verify this it is advantageous to check and calibrate across the range.

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  • What are the specifications for PCWI’s plates?

    Plate size: 35 x 35 x 2mm (coatings up to 550µm), 43 x 43 x 2mm (coatings above 550µm)

    Base material: Steel (Ferrous), Aluminium (Non-Ferrous)

    Thickness material: Epoxy (up to 550µm), Acrylic (above 550µm)

    Resolution: 0.01µm

    Area of measurement: Centre single point of coated plate (not including the label)

    Weight: 211g (heavy duty example set)

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  • What are some example Coating Thickness Standard sets available?

    For Heavy Duty Coating: 0, 75, 150, 250, 500µm
    For Powder Coating: 0, 35, 75, 125, 175µm
    For Galvanising: 0, 50, 80, 125, 200µm
    For Plating & Anodising: 0, 10, 15, 20, 40µm
    For Ultra-high Builds: 0, 750, 1500, 2500, 5000µm

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  • Do PCWI manufacture different Standards?

    Yes, for some Companies we supply private label Coating Thickness Standards.

    There are set up costs involved in supplying private label Standards.

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  • Can I choose the coating thickness sizes I want?

    Yes, talk to one of our Professional Sales Team.

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  • How are the Standard sets packaged?

    All Standards are packaged in a durable plastic folder and then into a clear dust cover.

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  • Can the Standards be re-certified?

    Yes, we offer Certification to Class 1 or Class 2, this depends on the customer’s requirements, and the condition of the plates on the Standard when returned to PCWI.

    Class One Certification
    Coating Thickness Plates are measured with reference to the original specification

    Uncertainty of Measurement:
    Ferrous: ±0.25µm up to 6000µm, ±0.40µm from 6000µm up to 12500µm

    Non-Ferrous: ±0.30µm up to 6000µm, ±0.45µm from 6000µm up to 12500µm

    Class Two Certification
    Coating Thickness Plates are measured with reference to PCWI Internal Reference Standards

    Uncertainty of Measurement
    ±1.0µm +1% up to 50µm coating thickness.
    ±2.0µm +1% from 50µm to 1500µm
    ±(0.01mm + 1% of reading) 1500µm to 2500µm.
    ±(0.01mm + 3% of reading) 2500µm to 6000µm.

    Recommended Recalibration
    Australia: 12 months or customer specified recalibration period
    Overseas: Customer specified recalibration period

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  • Are replacement plates available if required?

    Yes, zero plates and reference plates are available- only necessary unless heavily scratched, dented or if the zero plate is corroded.

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  • What do the Coating Thickness Standards comply to?

    Australian Standard AS3894.3 – 2002

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  • What are the Calibration Certificates traceable to?

    Traceable to Australian National Standards via NATA Endorsed Test Reports traceable to NMIA. International Standards via NVLAP Certificates of Calibration traceable to NIST. The Mutual Recognition Agreements ensures acceptance of these reports as equivalent in each other’s economy.

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  • What industries typically use PCWI Calibration Standards?

    All Industries applying surface coatings when coating depth is critical and requires test measurement by gauges i.e. Automotive, Aviation, White goods, Coating Applicators, Maintenance and quality control engineers, Quality control inspectors, Coating thickness gauge manufacturers (private labelling available) etc.

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  • What advantages do PCWI Calibration Standards have over Certified Films?

    Films cannot be recertified, are expendable and relatively expensive. Technically, 3894.3 – 2002 does not recommend the use of films in the calibration of manual magnetic gauges, as films tested during the writing phase caused the magnet to lift off prematurely.

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