TESTING & MEASUREMENT
Holiday Detection with
the new PosiTest HHD
Coatings and linings 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.
DFT Instruments offers both a low voltage
pinhole detector and a high voltage holiday
detector. Instrument selection depends on the
thickness of the applied coating and the
chosen test method. The PosiTest LPD Low
voltage Pinhole Detector is ideal for finding
defects in coatings less than 500 microns
thick (20 mils) by using voltages below 100
volts through a moistened sponge. For
thicker coatings, the new PosiTest HHD
High-Voltage Holiday Detector is the simple,
durable, and accurate way to find defects in
the coating system. Instead of a moistened
sponge, a charged conductive brush or
spring electrode is used.
The lightweight and ergonomic PosiTest HHD
uses pulse DC technology, offering a
user-adjustable voltage range from 0.5 to 35
kV for detecting holidays, pinholes, and other
discontinuities in coatings up to 20 mm (780
mils). The versatile PosiTest HHD is ideal for
use with a wide range of quality electrodes,
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
— custom sizes are available upon request.
All connectors are manufactured from
stainless steel and aluminum to be corrosion
resistant, strong, and lightweight, with no
tools required for changing electrodes.
Alternatively, adaptors are available for
connecting Tinker and Rasor and PCWI
spring and brush electrodes. The PosiTest
HHD is directly compatible with DeFelsko
and SPY electrodes. The PosiTest HHD can
be used in stick configuration right out-of-the
box, or attach the optional wand accessory
to convert to a shoulder-carried configuration
for inspecting hard-to-reach areas.
The design and menu interface make holiday
detection easy. 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. The convenient
voltage calculator feature
makes conforming to ISO,
ASTM, NACE, and ACA
standards simple, by
automatically calculating a
test voltage without the
need for lookup tables or
complex math.
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 35 kV setting
and under maximum load,
the PosiTest HHD can last
through an 8-hour workday. The durable
PosiTest HHD features a shock-absorbent
housing purpose built for tough pipeline and
manufacturing environments. It weighs less
than four pounds and is designed to be
comfortably used all day.
More information, including a brief
overview video can be found at www.
dftinstruments.co.uk
50 JUNE 2020
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