Crystal MultiCal Pressure Module - Manual (Page 5)

Operation  3
MultiCal H2O/PSI Pressure Module Manual
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PRESSURE MEASUREMENT
Follow this procedure to correctly use the MultiCal pressure module.
1 Plug the MultiCal directly into the voltage input terminals of the multimeter or with the patch cord set. The patch cord set consists of a 48" cord with double
banana plugs on each end and a double banana jack splice. Plug the splice into the MultiCal and the patch cord into the splice. Plug the other end of the
patch cord into the multimeter. Polarity is marked on the MultiCal and on the patch cord and splice.
2 Set the multimeter to the millivolt (DC) range.
3 Check the battery condition: With the MultiCal still in the OFF position, the multimeter must indicate a minimum reading of 100 mV. Readings less than 100
mV indicate the battery must be replaced. To be sure that your pressure 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. Without any pressure or vacuum applied to the module turn the knob opposite the banana plugs until your meter reads precisely zero.
Prior to taking measurements, and recommended when changing scales, the module should be "zeroed" at barometric pressure. Most multimeters "forget"
the "relative" setting when changing from mV to any other scale, even just to Volts. Some meters auto-range 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 multi-meter. The zero reading may also shift when the Multi-
Cal is shifted from a vertical to a horizontal orientation. This is due to the oil filling that transmits the pressure signal from the stainless steel diaphragm to
the silicon pressure sensor. The magnitude of the shift is typically 0.3 inH
2
O or less.
6 Apply pressure to the MultiCal. If the meter reads over-range, 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, 0.500 V would be 500 psi.
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BATTERY REPLACEMENT
1 Set the power switch to the OFF position.
2 Disconnect the MultiCal from the multimeter 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.