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Increasing the temperature will cause the pressure readings to increase, while decreasing temperature
will cause the pressure readings to decrease. The instruments are initially adjusted at an ambient
temperature of approximately 22°C. This effect can be corrected by adjusting the low pressure reading at
the operating ambient temperature. The specified rate of change does not include any changes due to
thermal effects on the vacuum tube or actual changes in pressure that occur in a vacuum system during
temperature excursions.
1.6 Accessories
1.6.1 Installation Accessories
THI offers a complete line of system attachments that permit easy maintenance for contaminated
operations. Gauge tubes are offered with various system fittings to match almost any system
requirement. Additionally, THI’s complete line of quick disconnect attachments allows customers to install
these special fittings and easily replace sensors without vacuum sealant or Teflon® tape. For particularly
dirty systems, Hastings offers a particle dropout trap containing a series of nine separate baffles which
prevent solid contaminants from having a direct path to the sensor’s thermopile.
1.6.2 DV-6S: New DV-6 tube For Severe Environments
Hastings Instruments has developed a new gauge tube, the DV-6S, which is specifically designed for
outdoor use on cryogenic tanks including railcar and tanker truck applications. In addition to the DAVC,
the gauge tube is compatible with the hand-held HPM-4/6 and the analog VT-6.
The DV-6S is supplied with a protective cap. The O-ring-sealed cap protects the gauge tube pins from
moisture thus significantly reducing corrosion. A metal lanyard prevents cap loss. The tube is provided
with a standard 1/8” NPT fitting; however special fitting requests can often be met.
1.6.3 Calibration Reference Tubes
THI Reference Tubes employ the same metal thermopiles used in all THI Vacuum Gauge Tubes. The
thermopile is sealed in a glass capsule that has been evacuated, baked, outgassed, and then aged to
ensure long-term stability. The sealed capsule is then housed in a protective metal shell to provide a
rugged, trouble-free assembly.
Once assembled, the reference gauge tube is accurately calibrated to precisely simulate a gauge tube at
a given operating pressure. It provides quick and easy instrument re-calibration by merely plugging the
instrument and, in the case of the DAVC, adjusting the HTR potentiometer until the display reads the
exact pressure noted on the reference tube.
Reference Tubes for use with DAVC
Ref Tube (DV-6) for DAVC-6 Calibration
Ref Tube (DV-4D) for DAVC-4 Calibration
Ref Tube (DV-5) for DAVC-5 Calibration
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