What is a wet sponge detector?

A wet sponge detector is a non-destructive instrument for detecting discontinuities in a coating system including pinholes, cracks and fine spots. Other names: porosity detector, continuity tester, sponge tester… There are two types of pinhole detectors: low voltage (wet sponge) and high voltage (spark tester). Low voltage detectors, such as the PosiTest LPD, are typically used on coating systems less than 500 µm (20 mils) thick. High voltage spark testers operate at voltages up to 35,000V which can seriously harm the operator and damage the coating if the test is not performed correctly. They tend to be more expensive and more complex than low voltage wet sponge detectors.

What do you measure with a sponge detector?

A low voltage puncture test is performed by moving a wetted electrified sponge over a non-conductive coating applied to a conductive substrate. The instrument is "grounded" to the conductive substrate, typically by clamping on an uncoated area. When the coating is continuous and no defects are present, electricity cannot pass from the sponge to the substrate through the non-conductive coating. But when the electrified sponge encounters a defect in the coating, electricity is able to flow into the substrate and return to the instrument through the ground wire, completing the circuit and setting off the audible and visible alarms.

Why is porosity measurement important?

After a coating has been applied, it is important to ensure there are no blemishes or discontinuities present which expose the substrate underneath. Small areas of thin or missing coating, called “pinholes” or “porosity,” can become hot spots of corrosion and dramatically reduce the life of a protective coating system. They may be invisible to the naked eye. Porosity detectors are often used in applications where corrosion is difficult to control, or in aggressive operating environments where the performance of the protective coating is critical.

How does a low voltage pinhole detector measure coatings on concrete?

When measuring coating thickness, concrete is not considered a "conductive" substrate because it is much less conductive than metal. However, concrete is still slightly conductive and can carry enough current to allow low voltage puncture detectors to operate. Therefore, for the purpose of low voltage pinhole detection, concrete is considered a "conductive" substrate. The challenge in performing low voltage pinhole tests on concrete is to ensure that the instrument is properly grounded. If there is exposed rebar or metal protruding from concrete, this is the easiest solution. An alternative is to drive a metal rod (or piece of rebar) into the ground near the concrete to at least the depth of the slab, relying on the earth to conduct the electric current between the rod and slab.

How is the PosiTest LPD different from other wet sponge detectors?

The PosiTest LPD has been designed as a fully customizable unit and offers a number of features not typically found in other competitive instruments.

• Lightweight - weighs less than most competitive products, reducing muscle fatigue
• Ergonomic Design - While most other devices are box-shaped, the PosiTest LPD has been specially designed to fit comfortably in the hand with balanced weight distribution
• Easy to use - Bright LEDs and simple 3 button operation with graphic icons
• Calibrated voltage outputs (well regulated) that will not drop under load. The LPD PosiTest is more likely to detect small pinholes better than other devices.
• “GroundSense ™” visibly reassures the user by indicating that the instrument is properly grounded. Most competing devices would not alert if the ground connection was lost, resulting in undetected pinholes.
• Common wires and connectors that allow unprecedented compatibility and customization. Customers can extend the reach of the PosiTest LPD with their own extension poles and rods.
• All models include a hard case for easy transport of the instrument and all accessories.
• Includes long form calibration certificate traceable to NIST
• Two year warranty
• IP65 protection against dust and splash. No other device is rated so well.

What is a wetting agent used for?

Sometimes the pinholes are so tiny that water alone has difficulty reaching the conductive substrate underneath, especially on thick coatings, in which case the water has to penetrate deeper into a pinhole to reach the substrate. Then, inspectors will use a surfactant (wetting agent) to lower the surface tension of the water, allowing the solution to better penetrate the pinhole.

Is the PosiTest LPD compatible with PosiSoft solutions?

No. The PosiTest LPD does not record any data.

How is the PosiTest DPL calibrated?

Each PosiTest LPD is calibrated under all test voltages with a known electrical resistance load and voltmeter, each is traceable to a national metrology laboratory. A detailed calibration certificate containing the actual measured values is included with each instrument. No other device provides this level of certification.

Do your instruments require formal training to be used?

No. Our instruments are designed for ease of use, feature easy-to-use menus, comprehensive and quick instruction manuals and helpful videos.

Is the PosiTest LPD factory calibrated?

The PosiTest LPD arrives fully calibrated and ready to measure. A detailed calibration certificate traceable to NIST or PTB is included, which documents the actual readings taken by your instrument at our calibration lab on standards traceable to a national metrology institute. No other device provides this level of certification. Beware of "certificates" or "certificates of conformity" offered by competitors. These usually do not include the actual readings from the instrument and are often insufficient to meet common quality requirements.

Can I simply have my device recalibrated?

Yes, by simply contacting the LABOMAT after-sales service or by using the return form. An estimate will be drawn up to you as soon as possible. What test voltage should I use for my application? The PosiTest LPD low voltage wet sponge detector has four specific preset voltages. These voltages were chosen because they are specified in various international standards and / or they correspond to the operating voltages of other commercially available instruments. Most standards do not specify a specific voltage and instead allow a range of voltages - for example, NACE SP0188 specifies a range of 5 V to 90 V without any indication of the proper voltage setting for an application or coating thickness. given. At the time of this writing, we are only aware of two international standards that specify a specific voltage and sensitivity:

• ISO 8989, method A, vitreous enamels and porcelain - Low voltage test to detect and locate faults: 9 V, 90 kΩ
• ISO 14654 Epoxy coated steel for concrete reinforcement: 67.5 V, 80 kΩ In general, we have found that the parameters of 67.5 V, 80 kΩ (for metal substrates) or 67.5 V, 90 kΩ (for concrete substrates) are the most commonly accepted and used for the vast majority of applications.