Martel Electronics DPC-100 User Manual

DPC-30

DPC-100

Reference 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 PRES SURE 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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1.2 Unpacking

Remove the packing list and verify that all equipment has been received.
Upon receipt of shipment, inspect the container and equipment for any

signs of damage. Take particular note of any evidence of rough handling in
transit. Immediately report any damage to the shipping agent.

NOTE: THE CARRIER WILL NOT HONOR ANY CLAIMS UNLESS ALL
SHIPPING MATERIAL IS SAVED FOR THEIR EXAMINATION.

After examining and removing the contents, save packing material and
carton in the event reshipment is necessary. Check to see that the unit is
complete. Included with the calibrator should be a set of test leads, and an
AC adapter/charger.

Become familiar with the designation and polarities of the five jacks located
below the keypad of the calibrator.

2. Operation

2.1 Operating Safety Considerations

• All electrical connections are fused with a 1/8 Amp 2AG size fuse located
on the printed circuit board near the input jacks. These fuses can be
replaced in the field by removing the six(6) faceplate screws and
removing the faceplate to change the fuse in question.

• When using the internal 24 volt power supply to power a device under
test, be aware that the internal power supply is current limited to
approximately 25 mA.

• Do not subject the instrument to pressure beyond its range. This can
easily be controlled by properly setting the air regulator.

• Unless wide temperature changes are experienced, the effect of
temperature may be neglected. Do not use the instrument near a source
of heat or cold. Temperature allowance equals 0.01 percent of full scale
per 1° C change from calibration temperature of 23°C. Temperature
allowance represents the maximum possible error due to temperature.

• Compatible media is clean, dry air. Strong corrosive gases should be
avoided. DO NOT use for liquid service.

2.2 Operating Instructions

NOTE: BEFORE ANY PRESSURE MEASUREMENT CAN BE MADE, THE

CALIBRATOR MUST BE ZEROED OUT. THIS CAN BE DONE BY SETTING
THE SELECTOR VALVE TO THE “VENT” POSITION AND BY PRESSING
THE ZERO KEY. IT IS ADVISABLE TO DO THIS OFTEN TO ENSURE
ACCURATE CALIBRATIONS ARE BEING MADE.