Retrotec DM-2 - Manual (Page 38)

Page 38 of 72
©Retrotec Inc. 2012
Figure 8: Gauge field check configuration: Cross gauge check
When performing a gauge calibration with two gauges, if one gauge is known
to be calibrated accurately, it can be used as a reference for the second gauge.
In that case, the measured pressure on the tested gauge should be within 2%
of the measured pressure on the calibrated gauge.
To perform a T-connection Fan Pressure check
1. Using a T-connection, connect a pressure tube to the Input port of
both Channel A and B as shown in Figure 9.
2. Create a Fan Pressure on the end of the pressure tube.
3. Both Channel A and B should display the same measured
pressure (or within 2%).
A similar procedure can be performed, by using a syringe to create a Fan Pressure. This can be done
with either one or multiple gauges.
Although the procedure with a syringe is fairly widely used, it is not recommended by Retrotec for the
following reasons:

Requires equipment that most people don’t have – an analog, magnehelic gauge.

Requires specific syringes (50 and 500 cc).

It's an awkward procedure.

Some part of the testing system of tubes and syringe will invariably be leaky and produce
inaccurate results.
To perform a syringe check (not as good as the cross-channel check)
1. Connect two gauges and a syringe following the set up in Figure 10.
2. Connect an analog, magnehelic gauge as shown.
3. Slowly pull air out of the syringe. Pressure readings on both gauges should increase.
4. Both gauges should display the same measured pressure.
5. Repeat steps 1 - 3 on the Input and Reference ports of both gauges.
Figure 9: Fan Pressure check
using a T-connection