Crystal MultiCal BAR-PSI User Manual

PN: 1763 Rev A, 4/2004

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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

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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.

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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

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Temperature derating:

Range Humidity

28 to 55 °C 0.016% x ( °C -28°)

18to 28 °C No Derating

0 to 18 °C 0.048% x (18° - °C)

-10 to 0 °C 0.264% x (9° - °C)

(Add to Basic Accuracy Specification, °C = ambient temperature)

Wetted Materials:

316 stainless steel

General

Weight 230 grams (8.1 oz) w/battery

Overall length 118 mm (4 5/8”)

Pressure Fitting 1/8” NPT

Battery NEDA #1604, 6F22, 006P

Battery Life 400 Hours typ. w/alkaline battery

Output 1mV/unit into 10 Mohm load

Storage -51 to 71 °C

MultiCal Calibration:

A calibration cycle of 1 year is recommended to maintain the MultiCal within specifications.
Recommended equipment is listed in Table 1.

Table 1 : Recommended Equipment

Instrument Minimum Specification Recommended Model

Pressure Standard ± 0.025% of Reading Pressurements

Dead weight gauge

Digital Voltmeter ± 0.025% of reading,

10 Mohm input impedance

Fluke 45

You do not need to use a reference multimeter if the MultiCal will be used with only one
multimeter. In those cases, your overall accuracy may be better if it is calibrated as a set with
the matching multimeter.

The recommended Digital Voltmeter listed in Table 1 has 10MΩ input impedance - as
do many handheld multimeters. Your reference multimeter should have the same input
impedance as the multimeters the module will be used with. In some cases this may mean
that the reference multimeter will need to have its input impedance lowered.

For example, a Flike 8840A is an excellent reference meter but has an input impedance Ω
10000MΩ. If the meters the module will be used with are Fluke 87s, connect a 10MΩ resistor
in parallel with the input to the 8840A.

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Procedure

1. Connect the MultiCal to the pressure calibration system and to the multimeter. Be sure

that the pressure calibration system and the connection to the MultiCal is leak free.

2. Allow the MultiCal to stabilize at room temperature, away from drafts, for at least 30
minutes before proceeding with calibration. Turn on the multimeter and allow it to warm
up per the multimeter operating instruction. Set the multimeter to the appropriate DC volt
or millivolt scale.

3. Verify the condition of the battery and replace the battery if necessary. Follow the
Battery Replacement procedure to disassemble the MultiCal, but do not remove the battery
or reassemble the MultiCal.

4. Set the switch on the MultiCal to the PSI position (switch in position closest to the
banana plugs). Allow the MultiCal to warm up for two minutes.

5. The FINE ZERO potentiometer (R1) should be set to the center of its rotational range.
Adjust the COARSE ZERO pot until the output is as close to zero as possible. Trim in the
final reading to 0 mV ±0.02 mV with the FINE ZERO potentiometer.

6. Check the PSI pressure points shown on Table 2. Adjust R12 if necessary to bring the
readings to within the tolerances shown on Table 2.

Figure 1: Potentiometer locations

7. Set the switch on the MultiCal to the PSI position. Vent the system and readjust zero if
necessary.

8. Test the MultiCal at the 206 bar point. The reading should be within the tolerance shown
in Table 2.

FINE ZERO

kPa

PSI

COARSE ZERO

-

LINEARITY

R1

R12
R15

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9. In the unlikely event that you are unable to adjust the MultiCal so that all of the points
meet the tolerances of Table 2, contact Customer Service for assistance. Do not readjust
linearity. The linearity adjustment is factory set and should never require readjustment,
unless the sensor is replaced.

Table 2: Readings in mV

True Pressure Acceptable Output (mV)

1500 PSI 1498.3 to 1501.7

3000 PSI 2996.8 to 3003.2

206 PSI 205.774 to 206.226

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C R Y S T A L

engineering corporation

Warranty

Crystal Engineering Corporation warrants MultiCals to be free from defects in material and
workmanship under normal use and service for one (1) year from date of purchase to the
original purchaser. It does not apply to batteries or when the product has been misused,
altered or damaged by accident or abnormal conditions of operation.

Crystal Engineering will, at our option, repair or replace the defective device free of charge
and the device will be returned, transportation prepaid. However, if we determine the failure
was caused by misuse, alteration, accident or abnormal condition of operation, you will be
billed for the repair.

CRYSTAL ENGINEERING CORPORATION MAKES NO WARRANTY OTHER THAN
THE LIMITED WARRANTY STATED ABOVE. ALL WARRANTIES, INCLUDING IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE,
ARE LIMITED TO A PERIOD OF ONE (1) YEAR FROM THE DATE OF PURCHASE.
CRYSTAL ENGINEERING SHALL NOT BE LIABLE FOR ANY SPECIAL, INCIDENTAL OR
CONSEQUENTIAL DAMAGES, WHETHER IN CONTRACT, TORT OR OTHERWISE.

Note (USA only): Some states do not allow limitations of implied warranties or the exclusion
of incidental or consequential damages, so the above limitations or exclusions may not apply
to you. This warranty gives you specific legal rights and you may have other rights which
vary from state to state.

How to Contact Us:

Phone. . . . . . . . [phone]

Toll-Free . . . . . [phone]

Fax. . . . . . . . . . [phone]

Email . . . . . . . . [e-mail]

Web . . . . . . . . . www.crystalengineering.net

If calling, have ready the model number, serial number, date of purchase and reason for
return. You will receive instructions for returning the device to Crystal Engineering.

Send your comments to: [e-mail]

© 2004, Crystal Engineering Corporation

720 Aerovista Place, Suite B

San Luis Obispo, CA 93401-8701