Videos & webinars

PosiTest HHD High voltage Holiday Detector - Testing Coatings for Pinholes and Voids

Products referenced in this video:

PosiTest HHD, PosiTest LPD, PosiTest HHD Verifier

Video Transcript

Introducing the new PosiTest HHD High-Voltage Holiday Detector from DeFelsko- the Measure of Quality

Coatings and linings are used across many industries to protect structural steel, concrete, and other materials from corrosion. To perform properly, they must be free of defects or discontinuities that expose the substrate beneath. Areas of thin or missing coating, called ‘pinholes’ or ‘holidays’, are often invisible to the naked eye, but can become foci for corrosion and drastically reduce the life of a protective coating system.

The instrument used to detect these defects depends on the thickness of the applied coating. The PosiTest LPD Low-voltage Pinhole Detector is ideal for finding defects in coatings less than 500 microns or 20 mils thick by emitting voltages below 100 volts through a moistened sponge.  

But for coatings in excess of 500 microns, a high-voltage detector is needed. Instead of a moistened sponge, a charged conductive brush or spring electrode is used.

The principle of operation for high-voltage holiday detectors is similar to low-voltage detectors. The charged electrode is passed over the coating, and when a holiday is encountered current flows from the electrode into the substrate below. The current returns to the detector through the ground wire, completing the circuit and triggering audible and visible alarms.

The PosiTest HHD High-Voltage Holiday Detector is the simple, durable, and accurate way to find defects, pinholes, and holidays in the coating system.

Its design and menu interface make holiday detection simple. To begin testing, simply attach the locking heavy-duty ground connector with a half turn, and find a suitable ground. Connecting to a bare area of the substrate is ideal, but the pulse technology in the PosiTest HHD allows a trailing ground wire to be used as long as the part, tank, or pipeline itself is grounded. Alternatively, a grounding mat can be used if the substrate is ungrounded.

A range of quality electrodes are available for the PosiTest HHD, including steel rolling springs for pipes up to 2.4 meters (8 feet) in diameter and a range of brushes up to 1.2 meters (4 feet) in length. All connectors are manufactured from stainless steel and aluminum to be corrosion resistant, strong, and lightweight, with no tools required for electrode changes. Adaptors are available for connecting Tinker & Rasor and PCWI spring and brush electrodes. The PosiTest HHD is directly compatible with DeFelsko and Spy electrodes. To attach the desired electrode, insert the rod until you hear a click. Then simply use the knurled thumbscrew to secure the electrode.

Conventional holiday detectors are available in two formats: an integral stick-type design, or shoulder-carried design with a wand attachment. The PosiTest HHD is both: it can be used in stick configuration out-of-the box, or attach the optional wand accessory to convert to a shoulder-carried configuration for inspecting tight areas.

Press the power button to turn the PosiTest HHD on. The set voltage is displayed in the large, backlit display, and the icon-based menu can be accessed at the touch of a button to change settings such as the test voltage and alarm modes. Once the test voltage has been verified begin testing by simultaneously pressing the power button and the trigger.

The PosiTest HHD uses pulsed DC technology to detect flaws. Instead of a continuous high-voltage output, the PosiTest HHD emits a precise pulse of high-voltage 30 times per second. This technology is much easier to ground, and safer, reducing the possibility of the exterior of the object becoming charged. The advanced circuitry is capable of maintaining a precise voltage output over the full range of 0.5-35 K-V in a single instrument. To alter the set voltage, simply choose the voltage selection menu option, and use the plus and minus buttons to adjust.

The PosiTest HHD conforms to ASTM, NACE, ISO, and ACA standards for holiday detection. The convenient voltage calculator feature makes following them easy, by automatically calculating a test voltage without the need for lookup tables or complex math.  Select the voltage calculator option from the menu and choose the desired test method. As the dry film thickness of the coating is adjusted, the proper test voltage is automatically calculated.

Lightweight, removable lithium-ion batteries provide lasting battery life. The smart battery technology features a built-in charge indicator, and lasts more than 40 hours on a single charge under typical conditions. Even at the 35kV setting and under maximum load, the PosiTest HHD can last through an 8-hour workday.

The PosiTest HHD is durable, featuring a shock-absorbent housing purpose built for tough pipeline and manufacturing environments. It weighs under four pounds and is designed to be comfortably used all day.

Despite its ergonomic, lightweight design, the PosiTest HHD has enough power to measure holidays using large diameter springs and wide brushes. Unlike some competitive models, the voltage won’t drop under load.

It has a built-in calibrated crest meter that constantly measures the voltage at the electrode while testing. The voltage on the screen is the actual voltage at the electrode, not the set voltage like on many competitive models. Included at no cost is a long form certificate of calibration documenting actual PosiTest HHD readings on traceable laboratory equipment, certifying that the PosiTest HHD is testing at the correct voltage.

For in-field verification, the PosiTest HHD Verifier is available to verify the accuracy of any DC or Pulse DC holiday detector, including the PosiTest HHD. Simply touch the PosiTest HHD Verifier to the electrode while it’s in use, and ensure that the voltage displayed on the Verifier matches the voltage displayed on the holiday detector. It’s that simple.

Ordering is easy. The PosiTest HHD kit includes the instrument, shoulder strap, 20” wand, battery pack, and charger. The kit is enclosed in a waterproof, dustproof, and crushproof Pelican Storm case that is guaranteed for life. Simply select your choice of electrode and the PosiTest HHD is ready to measure.

For over fifty years, DeFelsko has been a leader in inspection equipment, manufacturing simple, durable, and accurate gages. Backed by DeFelsko’s renowned quality, customer service and exceptional two-year warranty, the PosiTest HHD is the ideal choice for holiday detection.

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