Crystal MultiCal BAR-PSI User Manual

PN: 1763 Rev A, 4/2004

Page 1 of 7

C R Y S T A L

engineering corporation

MultiCal

bar/PSI Pressure Module

PN: 1527, 206 bar/ 3000 PSI

INSTRUCTION SHEET

Introduction

The MulitCal™pressure modules can be used to measure almost any type of pneumatic
or hydraulic pressures, up to
3000 PSIG. It can also be used to
measure vacuum..

The module does not have a display.
Instead, the MultiCal converts
pressure (or vacuum) to milliVots.
The module must be used with
a device capable of measuring
milliVolts DC, such as a digital
multimeter (DMM).

The MultiCal is calibrated to convert
pressure units (bar or PSI) to 1 mV per pressure
unit. Vacuum readings will of course be negative.

Pressure is measured by connecting your pressure source to the 1/8” female NPT fitting
of the pressure transducer. Any gas or liquid compatible with 316 stainless steel may be
applied to the module as the pressure source.

The three-position switch acts as a power switch as well as selecting inches PSI or bar
scaling for the output. Also, the OFF position allows you to read the battery condition via the
external multimeter.

The module performs best when used with high accuracy multimeters. We recommend any
of the following meter:

Fluke 70 series, 80 series, Model 45

Any meter with 10MΩ or greater input impedance and 4mm banana jacks on 3/4” centers.

Typical uses. for the module are to calibrate pressure gauges and pressure transmitters.

When used with a high performance multimeter, the pressure adapter becomes more
than just a “digital pressure gauge.” For example, use the datalogging features built-in to

the Fluke 87 and you’ll have a system that can measure and record peak (high) pressures,
peak low and average pressures of varying or unstable pressure source.

L1B

PN: 1763 Rev A, 4/2004
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PRESSURE is Our BUSINESS

™

Use and Operation

The internal pressure sensor measures the difference between a sealed atmospheric
reference pressure, and the pressure (or vacuum) applied to the pressure port. The pressure
being measured can be either liquid or gaseous, providing it is compatible with the materials
listed in the specification section.

CAUTION:

THE SENSOR DIAPHRAGM IS VERY THIN AND CAN BE DAMAGED OR
DESTROYED BY SOLID OR SHARP OBJECTS. NEVER INSERT ANY OBJECT
INTO THE INLET OF THE TRANSDUCER FITTING. CLEANING OF THE SENSOR
MUST BE DONE WITH APPROPRIATE SOLVENTS, ONLY.

Teflon tape or other suitable sealing compound should be used with any fitting connected to

the 1/8” female NPT fitting.

Pressure Measurement

Follow this procedure to correctly use the MulitCal pressure module.

1. Plug the MultiCal into the retractile cord set and plug the cord set into the DV volts input
of the multimeter.

2. Set the multimeter to the mV (DC) range.

3. Check the battery condition: With the MultiCal still in the OFF position, the
multimeter must indicate a minumum reading of 100 mV. Readings less than 100
mV indicate the battery measurements are accurate, always check the battery condition
first, and replace the battery if necessary.

4. Turn on the MultiCal by sliding the switch to the range you intend to use.

5. “Zero” the MultiCal. With a small screwdriver adjust the small trimming potentiometer on
the end of the MultiCal until your meter reads precisely zero.

Prior to taking measurements, and recommended when changing scales, the module
should be “zeroed” at barometric pressure.

Some multimeters have a “relative” or “offset” button. This will have the same effect as
adjusting the zero knoob and accuracy of your measurements will not be degraded.
However, rezeroing the MultiCal will be required when changing scales.

Most multimeters “forget” the “relative” setting when changing from mV to any other scale,
even just to Volts. Some meters autorange from mV to Volts and then lose the “relative”
value. In these cases, the zero knob may be more convenient than the “relative” button on
the multimeter.

The zero reading may also shift when the MultiCal is shifted from a vertical to a
horizontal orientation. This is due to the oil filling that transmits the pressure signal from

the stainless diaphragm to the silicon sensor. The effect of the shift is not significant and can
be eliminated by any of the zero adjustment techniques noted above.

PN: 1763 Rev A, 4/2004

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C R Y S T A L

engineering corporation

6. Apply pressure to the MultiCal. If the meter reads overrange, change the multimeter
range to DC volts (instead of mV). Note: The decimal place will be for volts. Multiply the
reading by 1000. For example, 0.800 V would be 800 PSI.

Battery Replacement

1. Set the power switch to the OFF position.

2. Disconnect the MultiCal from the DMM and any pressure connections.

3. Turn the MultiCal so the power switch is facing down. Remove the single screw located
between the banana plugs.

4. Grasp the one case half in each hand. Pull the two halves apart, beginning at the end
with the banana plugs.

5. Remove and replace the battery.

6. Reassemble the MultiCal. To reassemble, mate the two case halves at the end opposite
the banana plugs, then “snap” the two halves together.

Specifications:

The following specifications apply at 23 ± 5 °C for 1 year after calibration and for use with
devices having 10MΩ input impedance. Accuracy specification requires the module to be
“zeroed” prior to taking reading.

Pressure

Range Accuracy

0 to 3000 PSI ± (0.1% of reading + 0.2 PSI)

0 to 206 PSI ± (0.1% of reading + 0.02 bar)

Vacuum

Range Accuracy

0 to -14.7 PSI ± (0.5% of reading + 0.2 PSI), typical

0 to -1 PSI ± (0.1% of reading + 0.2 bar), typical

Maximum Working Pressure: 3000 PSI

Burst Pressure: 5000 PSI

Operating Environment

Temperature Humidity

-10 to 10 °C Uncontrolled Humidity

10 to 30 °C 0 to 95% Relative Humidity

30 to 40 °C 0 to 75% Relative Humidity

40 to 50 °C 0 to 45% Relative Humidity

50 to 55 °C 0 to 35% Relative Humidity