PosiTest HHD C Compact Wand Style
Detects holidays using continuous DC
PosiTest HHD C Kit
Includes ALL features shown above plus...
Lightweight, one-piece ergonomic design provides comfortable all-day use, reducing operator...
DeFelsko PosiTest LPD Accessory Pack LPDACCPK
Includes adaptable sponge hardware and accessories to convert the PosiTest LPD Basic Kit into a PosiTest LPD Complete Kit in a hardshell carrying case.
Adaptable Sponge Hardware
Low voltage Pinhole Detector for Metal and Concrete Substrates
Detects holidays, pinholes and other discontinuities in coatings on metal and concrete substrates.
GroundSense visibly reassures the user that the...
Converts the PosiTest HHD to a wand-type instrument
*PosiTest HHD sold separately
Choose between 13 cm (5") and 50 cm (20") rods
Connect to spring and brush...
Flat Wire Brush Electrodes
HHD Flat Brush 51 mm/2" HHDFLTBRSH2
HHD Flat Brush 152 mm/6" HHDFLTBRSH6
HHD Flat Brush 203 mm/8" HHDFLTBRSH8
HHD Flat Brush 305 mm/12" ...
Rolling Spring Electrodes
Rolling Spring Coil for 4" pipe (102 mm) OD HHDSPRING4
Rolling Spring Coil for 6" pipe (152 mm) OD HHDSPRING6
Rolling Spring Coil for 8" pipe (203 mm) OD ...
High voltage Holiday Detector
Detects holidays, pinholes and other discontinuities using pulse DC
Lightweight, ergonomic design provides comfortable all-day use, reducing operator fatigue
Regulated pulse DC voltage...
After a protective coating has been applied, it is important to ensure there are no defects or discontinuities present that expose the substrate beneath. Small areas of thin or missing coating, called 'pinholes' or 'holidays', can become foci for corrosion and drastically reduce the life of a protective coating system. A pinhole or holiday detector is a non-destructive instrument used for detecting discontinuities in a coating system including holidays, pinholes, and cracks. Other names include porosity detector, continuity tester, holiday tester, spark tester, and jeep meter.
DeFelsko offers two types of porosity/pinhole detectors: low voltage (wet sponge tester) and high voltage (spark tester). Low voltage detectors, like the PosiTest LPD, are typically used on paint systems less than 500 µm (20 mils) thick. High voltage holiday testers, like the PosiTest HHD operate at voltages up to 35,000 V and are typically used on coatings at least 200 µm (8 mils) thick.
A holiday—pinhole, flaw, void, crack—is a discontinuity within a coating system where a small area of thin or missing coating exposes the substrate to the environment.
Due to a variety of potential errors in the application of a new protective coating, flaws—or holidays—can form. They can be invisible to the naked eye and are near-impossible to detect without proper instrumentation.
Holiday detection is a necessary step in identifying these areas of thin or missing coating. Porosity detectors are often used in applications where corrosion is difficult to monitor, or in aggressive service environments such as buried pipelines where performance of the protective coating is critical.
Outlined by standards organizations like AMPP (NACE), ASTM, and ISO, a holiday detector uses a charged electrode passed over a coating. When a holiday is encountered, current flows from the electrode into the conductive substrate below. The current returns to the detector through a ground wire, completing the circuit and triggering an alarm, alerting the inspector to the defect.
A wet sponge tester is another name for Low voltage Pinhole Detectors like the PosiTest LPD. By using a wet sponge to pass current through a grounded part, flaws and pinholes in the coating can be identified. They are typically used on paint systems less than 500 µm (20 mils) thick.
A holiday detector (porosity detector, continuity detector/tester, holiday tester) like the PosiTest HHD, is a non-destructive inspection instrument used for detecting discontinuities in a coating system, including holiday, pinholes, and cracks.
There are three main types of Pinhole/Holiday Detectors:
Low voltage Pinhole Detectors, such as the PosiTest LPD use a wet sponge to detect pinholes in coatings less than 500 microns (20 mils).
High voltage Pulse Holiday Detectors, such as the PosiTest HHD use pulse DC and either a spring or brush electrode to detect holidays in coatings greater than 200 µm (8 mils) thick. By using multiple pulses of high voltage every second, the unit is able to:
High voltage Continuous Holiday Detectors operate at the same voltage range as High voltage Pulse detectors, but do not feature the benefits of pulse technology.
The correct instrument will depend on the thickness of the coating being inspected and the specified standard. Both the PosiTest LPD and the PosiTest HHD work on non-conductive coatings over a conductive substrate (such as steel, aluminum, other metals, and concrete).
The PosiTest LPD has a voltage output of 9–90 V and is suitable for coatings less than 500 microns (20 mils).
The PosiTest HHD has a voltage output of 5–35,000 V and is suitable for coatings greater than 200 µm (8 mils).
There are many possible causes of porosity or holidays in a coating system. Some of the most common include:
Under-coating — If an insufficient build of coating is applied over a blasted surface, peaks in the substrate can protrude through the coating and remain exposed to the environment. Use a coating thickness gage, such as the PosiTector 6000 to ensure the proper coating thickness.
Over-coating — Due to the way in which a coating cures, with the outermost area drying and shrinking above the wet area below, cracks can form if too much coating is applied.
Improper coating technique – Poor spraying or brushing technique can leave voids or gaps in the coating.
Non-ideal viscosity — A coating with a viscosity that is too low can sag or curtain, resulting in areas of very low coating thickness. A coating with a viscosity that is too high may fail to cover the entire surface, leaving voids.
Introduction of too much air during paint mixing — Coatings with trapped gasses can cause pinholes (bubbling).
Surface preparation — Ensuring that the surface profile meets job specifications can reduce the likelihood that an error in a coating formulation/application will create a holiday.
Surface contamination — Grease, dirt, or other contaminants such as salt can repel a coating and prevent it from adhering to the contaminated area. Ensure the surface is adequately cleaned and free of salt contamination (PosiTector SST Soluble Salt Tester).
Environmental factors — Application of a coating under less-than-ideal environmental conditions, particularly when the dew point is within 3°C (5°F) of the substrate temperature, increases the chances of holidays forming. Use a PosiTector DPM Dew Point Meter to ensure proper environmental conditions.