Crystal DTG - Manual (Page 2)

PN: 2646 REV B, 8/2002
Firmware Release 1.05
Page 2 of 8
PRESSURE is Our BUSINESS
TM
Operating Instructions
The DTG is shipped with batteries installed, so it’s ready to use. Press the power button and the
DTG will test all LCD segments. Continue pressing the power button for at least one second and
the DTG will start normal operation. (The one second delay avoids turning on the DTG by mistake.)
The DTG always resumes operation in the mode and the units of the pressure last used, and it
does not automatically rezero when turned on.
All DTGs are intended for gauge pressure measurement. That is, they indicate the difference
between applied pressure and ambient barometric pressure. The zero button can also be used
as a tare function, meaning it can be set to read zero pressure at for any pressure up to the full
scale of the gauge.
Connect the DTG to your system. Always use pipe thread tape or pipe thread sealant on the ¼
″
NPT fitting. To ensure safe and accurate operation, please read 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.
THIS GAUGE CAN DISPLAY ZERO PRESSURE WITH FULL SCALE PRESSURE APPLIED.
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 ⁄⁄⁄⁄⁄
16
″ ″ ″ ″ ″ NPT metal filter) INTO THE PROCESS
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/Tare
To make sure that the DTG is performing to it’s rated accuracy, the DTG 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 the DTG should return to a perfect zero
reading. (If it does not return to zero - check the filter - it may be blocked).
The DTG can zero (or “tare”) any applied pressure within it’s specified operating range.
This means that even if zero pressure is displayed, the actual gas or fluid pressure connected to
the DTG may be high enough to be dangerous if you were to disconnect the DTG without
relieving the pressure first.
Always check that the pressure has been equalized with
ambient pressure before disconnecting the DTG!
To zero or tare the DTG, you must press the Zero button for at least one second before it
responds. This is to avoid unintentional changes to the zero/tare setting.
Over-pressure Conditions
The DTG will read pressure up to approximately 110% of the rated pressure range, at which
point the display will start flashing and the readings will not be reliable. The zero function does
not affect the point at which the display starts flashing to indicate over-pressure, so depending
on the tare value it is possible that the display can start flashing without the maximum pressure
being displayed.
For instance, if a 100 PSI DTG is zeroed when 30 PSI is being applied, it will indicate that the
over-pressure condition has been reached at 80 PSI (i.e., 110% x 100 PSI – 30 PSI = 80 PSI).
Over-pressure can affect accuracy, but the effect is only temporary unless the sensor has been
destroyed. See Specifications on for maximum over-pressure.