Manual

1. Introduction
1.1 Description
The Martel DPC Digital Pneumatic Calibrator improves upon traditional dial
gauge pneumatic calibrators. The Martel DPC improves accuracy, provides
digital accuracy of ±0.035% and also incorporates mA and V inputs, and a
built-in 24 volt loop power supply to simultaneously power a device while
reading the resultant current.
This equipment is designed primarily for field checking and calibration of
pneumatic controls, switches and instrumentation. In most cases, the
device being checked need not be removed from its mounting or operating
location.
The Martel DPC consists of a carrying case containing an aluminum panel
with the mounted digital pressure indicator, a selector valve, two precision
pressure regulators, an air filter and a connection block. A graphic flow
diagram on the panel shows clearly all connections between the various
units.
1.1.1 Selector Valve
The Martel DPC employs a differential pressure sensor. The low side of
the sensor is connected directly to port “S” on the calibrator. The high
side of the sensor can be pressurized directly via port P3, or through
the two regulators via ports Pl and P2. The selector valve permits only
one of the three pressure ports to be applied to the pressure
connection in the gauge. A fourth position permits venting pressure
from the gauge to atmosphere.
1.1.2 Air Filter
The air filter mounted under the panel is easily replaceable and
protects the various components if the air supply is of less than
instrument air quality. WARNING: TO AVOID POSSIBLE SEVERE
PERSONAL INJURY, DO NOT APPLY PRESSURE IN EXCESS OF 100
PSI TO THE FILTER.
1.1.3 Precision Pressure Regulators
The two precision pressure regulators accept supply air pressure up to
90 PSIG through the filter and regulate the output. These are used in
applying known pressures to pneumatic control devices.
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