Crystal 30 Series Digital Pressure Calibrator - Manual (Page 4)

Functions  2
30 Series Operation Manual
Functions
„„„„ „
OPERATING INSTRUCTIONS
To ensure safe and accurate operation, please be familiar with the following warnings:
!
WARNING: Severe injury or damage can occur through improper use of pressure instruments! Do not exceed recommended pressure limits of tubing
and fittings. Be certain all pressure connections are secured.
!
WARNING: This gauge can display zero pressure when connected to a source of pressure! Do not rely on the display indication before disconnecting - it
may not be indicating true pressure. Never disconnect pressure instrumentation without first relieving system pressure!
!
CAUTION: Never insert any object (other than the 1/8” NPT fitting) into the pressure connection! The sensor diaphragm is very thin and can be damaged
or destroyed by solid or sharp objects. Cleaning of the sensor must be done with appropriate solvents only.
Zero
To make sure that the calibrator is performing to its rated accuracy, it should be exercised and re-zeroed whenever exposed to changes in temperature (see
Specifications ). It’s also good practice to check zero as your final reading too, as these calibrators should return to a perfect zero reading. The 30 series does
not automatically re-zero when first turned on. The
(
zero
)
button can be used as a “tare” button because it will “zero out” any value the selected range is ca-
pable of displaying. The zero reading may also shift when the calibrator is moved 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”H
2
O or less.
Over-range Indication
Over-range conditions will be indicated regardless of the tare value. If the full scale rating of either the low or high pressure sensor are exceeded by 10% or
more, appropriate warning messages will be displayed. Also, if the milliamp input exceeds 55 mA a warning message will appear.
Model 33 Only: These messages will only appear if the parameter being measured is selected for display. For example, if the milliamp input is greater than
55 mA, but milliamps is not selected for display, no over-range warning will be indicated. (The milliamp input is protected by a semiconductor type fuse that
automatically resets once the fault condition is removed.)
Contrast button
The
(
contrast
)
button, left of the display, may never have to be pressed. It is provided to compensate in slight contrast changes with temperature and com-
ponent aging. Press the button and the contrast will increase. If you press the
(
contrast
)
button repeatedly enough times the display will jump to the least
contrast setting, allowing you to adjust it darker until you get the best contrast and legibility.