A holiday detector is a non-destructive instrument for detecting discontinuities in a coating system including holidays, pinholes, and cracks. Other names include porosity detector, continuity tester, holiday tester, and leak detector.

There are two types of pinhole detectors: low voltage (wet sponge) and high voltage (spark tester). Low voltage detectors, like the PosiTest LPD, are typically used on coating systems less than 500 µm (20 mils) thick. High voltage spark testers, like the PosiTest HHD and the PosiTest HHD C operate at voltages up to 35,000V and are typically used on coatings more than 250 µm (10 mils) thick.

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 series 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 uses pulsed DC, has a voltage output of 500–35,000 V and is suitable for coatings greater than 200 µm (8 mils).

The PosiTest HHD C, uses continuous DC, has a voltage output of 500—30,000 V, and is suitable for coatings greater than 200 µm (8 mils).

When the electrode of a Pinhole/Holiday Detector is placed onto the coating, it puts an electrical load on the instrument. The Holiday Tester must compensate for this load by regulating its power output, to ensure that the voltage at the electrode remains at the set voltage. Many older or less expensive Holiday Testers do not have this functionality, meaning that the test voltage at the electrode could differ significantly from the set voltage and lead to invalid test results.

The PosiTest HHD series of High voltage Holiday Detectors and the PosiTest LPD Low voltage Pinhole Detector are factory calibrated and include a Certificate of Calibration traceable to NIST. They feature a built-in voltmeter that constantly monitors the voltage at the electrode. Auto-regulating circuitry inside the porosity detector adjusts the power output to ensure the correct test voltage throughout the measurement process.

A ‘stick type’ holiday detector is a standalone detector with internal battery power and electrodes that attach to the end of an electrode rod (stick). ‘Wand’ or ‘Belt-style’ detectors typically have a separate battery pack carried on the belt or shoulder strap and electrodes that attach to a handheld wand. The NEW PosiTest HHD C is a compact wand-style holiday detector that does not require a separate battery pack. The lithium ion batteries fit neatly within the handle.

The PosiTest HHD is the first combination stick type/wand type instrument on the market. With the optional handheld wand accessory, the PosiTest HHD converts into a wand-style instrument suitable for voltages less than 15k.

The PosiTest LPD Low voltage Pinhole Detector has four specific pre-set voltages. These voltages were chosen because they are specified in various international standards and/or they match 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 5V-90V with no guidance on the proper voltage setting for a given application or coating thickness.

At the time of writing, we are aware of only two international standards that specify a specific voltage and sensitivity:

• ISO 8289 Method A Vitreous and porcelain enamels — Low voltage test for detecting and locating defects: 9V, 90 kΩ
• ISO 14654 Epoxy-coated steel for the reinforcement of concrete: 67.5V, 80 kΩ

In general, we have found that settings of 67.5V, 80 kΩ (for metal substrates) or 67.5V, 90 kΩ (for concrete substrates) are most commonly accepted and used for the vast majority of applications.

To determine the correct voltage setting of the pinhole/holiday detector, consult the coating manufacturer’s technical data sheet and the appropriate standard.

The PosiTest HHD includes a voltage calculator feature—choose from one of 11 international standards, and input the coating thickness as determined by the PosiTector 6000 Coating Thickness Gage to automatically calculate the required test voltage.

The PosiTest HHD C also includes a voltage calculator feature, using an equation from the upcoming revision of ASTM and NACE standards. Simply enter the coating thickness as determined by the PosiTector 6000 Coating Thickness Gage to automatically calculate the required test voltage.

A low‐voltage pinhole test is performed by moving a moistened, electrified sponge over a non‐conductive coating applied to a conductive substrate. The instrument is‘grounded’ or ‘earthed’ to the conductive substrate, typically by clamping onto an uncoated area. When the coating is continuous and no defects are present, electricity is unable to pass from the sponge to the substrate through the non‐conductive coating. But when the electrified sponge encounters a flaw in the coating, electricity is able to flow into the substrate and travel back to the instrument through the ground wire, completing the circuit and setting off the audible and visible alarms.

A high-voltage holiday test is performed by moving a charged electrode over the coated surface. When a holiday is encountered, current flows from the electrode into the substrate. The current returns to the detector through the ground (earth) wire, completing the circuit and triggering audible and visible alarms. An integrated peak reading voltmeter measures and displays the output voltages on the display while in use.

For high voltage use, the most commonly used is a flat wire brush, also available are: rolling springs for pipe exteriors, fan brushes for hard to reach areas and conductive rubber probes to prevent scratches. Low voltage detectors use a wet sponge. These are available in rectangular and round pads and rollers (similar to paint rollers). Sponge sheets are also available to cut your own custom shapes.

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 strain and fatigue
• Ergonomic design ‐‐while most other devices are box‐shaped, the PosiTest LPD was specifically designed to fit comfortably in the hand with a balanced weight distribution
• Easy‐to‐use  – bright LEDs and simple 3‐button operation with graphic icons
• Calibrated (well‐regulated) voltage outputs that will not drop under load. The PosiTest LPD is more likely to find small pinholes than other devices.
• GroundSense™ visibly reassures the user that the instrument is properly grounded. Users of most competitive devices would not alert if the connection to ground is lost, resulting in undetected pinholes.
• Common threads and connectors that allow for unprecedented compatibility and customization. Customers can extend the reach of the PosiTest LPD with their own poles and extension rods.
• All models include a hard shell case to conveniently carry the instrument and all accessories.
• Includes Long Form Certificate of Calibration traceable to NIST
• Two year warranty
• IP65 ingress protection‐ dust and splash resistant. No other device is rated this highly.

When measuring coating thickness, concrete is not considered a ‘conductive’ substrate, as it is much less conductive than metal. However, concrete is still slightly conductive, and can carry enough current to allow low‐voltage pinhole detectors to function. Therefore, for the purposes of low‐voltage pinhole detection, concrete is considered a ‘conductive’ substrate.

The challenge when conducting low‐voltage pinhole testing on concrete is to ensure the instrument is properly grounded. If there is exposed rebar or metal protruding from the concrete, this is the easiest solution. An alternative is to drive a metal rod (or piece of rebar) into the ground nearby the concrete to at least the depth of the slab, relying on the earth to conduct the electric current between the rod and the slab.

After a protective coating has been applied, it is important to ensure that 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. They can be invisible to the naked eye. Porosity detectors are often used in applications where corrosion is difficult to monitor, or in aggressive service environments where performance of the protective coating is critical.

Sometimes pinholes are so miniscule that water has difficulty reaching the conductive substrate underneath, especially on thicker coatings when the water must penetrate further into a pinhole to reach the substrate. In these instances, inspectors will use a surfactant (wetting agent) to lower the surface tension of the water, allowing the solution to better penetrate the pinhole.

When measuring coating thickness, concrete is not considered a ‘conductive’ substrate, as it is much less conductive than metal. However, concrete is still slightly conductive, and can carry enough current to allow holiday detectors to function. Therefore, for the purposes of holiday detection, concrete is considered a ‘conductive’ substrate.

Yes. DeFelsko manufactures a wide variety of rolling spring and flat wire brush electrodes. Custom sizes are available upon request.

Flat brush and spring electrodes will be available in pre-stocked and custom lengths, in addition to the handheld rubber paddle and fan brush. DeFelsko plans to add additional types of electrodes in the future, based on demand. If you have a request for an electrode configuration not currently offered by DeFelsko, please let us know.

The PosiTest HHD series offers industry-standard connectors and adaptors for compatibility with nearly all existing electrodes including SPY, PCWI, Tinker & Rasor, and 266/280.

No. The PosiTest HHD series feature a built-in voltmeter (crest meter, jeep meter) with a traceable Long Form Certificate of Calibration. However, some standards call for a standalone voltmeter.

No. The PosiTest HHD and PosiTest HHD C do not record data and are not compatible with PosiSoft Software.

No. The PosiTest LPD does not record any data.

The cost to recertify is $95 and includes a Long Form Certificate of Calibration. Recertification usually takes one day.

Each PosiTest LPD is calibrated at all test voltages with a load of known electrical resistance and a voltmeter, each traceable to a National Metrology Lab. A Long Form Certificate of Calibration containing actual measured values is included with every instrument. No other device provides this level of Certification.

Both the PosiTest HHD and PosiTest HHD C are calibrated using instruments traceable to a National Metrology Lab. A Long Form Certificate of Calibration containing actual measure values is included with every instrument.

The PosiTest HHD and PosiTest HHD C may be shipped with two additional spare batteries (or sets of batteries for the HHD C) when charged to less than 30% of capacity. They can be shipped via surface and air transport on the major carriers (UPS, FedEx, and DHL) to all countries, subject to additional labelling requirements.

Note: When returning the PosiTest HHD for service or repair, DO NOT include any batteries.

Leak detection serves an important function in reducing the likelihood of costly leaks in construction, mining, and other water or liquid containment industries. Whether it’s a new roof, leach pad, processing pond, or a landfill—locating defects in geomembranes (and similar materials) help reduce potentially costly remediation and environmental damage.

The PosiTest HHD High voltage Holiday Detector series is offered in 2 configurations — stick-type with pulsed DC output or wand-style with continuous DC. Both models feature adjustable voltage, built-in certified voltmeters, and compatibility with nearly all existing (competitive) electrodes.

The PosiTest HHD stick-type detector uses pulsed DC to detect holidays and other discontinuities.

Features include:

• Ergonomic two-handed, stick-type detector for comfortable all day use
• Voltage calculator feature — choose from 11 international standards and input the coating thickness to calculate the required test voltage
• User adjustable voltage range from 0.5 to 35 kV
• Optional handheld wand accessory converts the detector into a wand configuration for testing hard-to-reach areas
• Pulse technology prevents buildup of charge on the surface and allows grounding using a ‘trailing lead’

The compact PosiTest HHD C wand-style detector uses continuous DC.

Features include:

• Lightweight, compact one-handed instrument eliminates operator fatigue
• Voltage calculator feature automatically calculates the required test voltage using an equation from the upcoming revision of ASTM and NACE standards
• User adjustable voltage range from 0.5 to 30 kV

The PosiTest HHD Verifier is a calibrated voltmeter (crest meter, jeep meter) ideal for verifying the operating voltage of ALL Pulse type holiday detectors in the range from 500 to 35,000 Volts.

The PosiTest HHD C Verifier is a calibrated voltmeter (crest meter, jeep meter) ideal for verifying the operating voltage of ALL Continuous type holiday detectors in the range from 500 to 30,000 Volts.