Retrotec DM32 - Manual (Page 56)

Page 56 of 94
©Retrotec Inc. 2014
7. Verify your gauge accuracy between factory calibrations
Recommended calibration interval for the DM32 series is 5 years. The question is when did the gauge go
out of calibration? Last week or last year?
What is needed is a quick field check to check your gauge regularly and before any important test.
Moreover, gauge calibration, where errors are typically a few %, are not as frequent a cause of problems
when compared to blocked, leaking or pinched tubes that happen more often and can yield errors of 10 to
90%. Sending your gauge in for calibration does not address those problems, but regularly carrying out this
field check will.
Here is how to check the tubes to be sure they are not blocked, pinched or leaking:
Checking each tube for blockage, leaks or pinching and checking gauge calibration should be done weekly.
It only takes a few seconds. Connect one tube between Channel A and B. If the pressure readings
displayed on [Channel A] and [Channel B] match within 2% both that tube and the gauge ports used are OK.
To perform a tubing check
1. Display pressure for [Channel B] (see section 3.3.9)
2. Tap [Settings][Baseline][Clear Baseline] to remove any captured Baseline
3. Tap [Settings][Time Averaging] and choose 5s
4. Connect a tube between Channel A and B on the gauge (e.g. yellow and red pressure tube
ports).
5. Check that the readings are within 2%
6. Repeat with each tube between other ports as shown in Figure 64
7. Connect the yellow tube from the yellow to the red port on the gauge which should be set to
Pressure on Channel B. If the readings are within two percent and don’t drop rapidly, you have
confirmed the yellow tube does not leak, the tube and gauge is not blocked and the gauge has
a 99.9% chance of being accurate. Disconnect the yellow and connect the Blue tube from Blue
to Green to check that tube and the negative side of the gauge. Disconnect the Blue and
connect the Green from the Green port to the Red Port to check that tube and the negative
versus positive calibration of the gauge.