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6.3
Ps1 and Ps2 CALIBRATION:
Step 1.
Connect the output of the Pressure Standard to the Ps1 and Ps2 ports on the 6600. The
pressure and vacuum sources are to be connected to the control mechanism of the Pressure
Standard.
Step 2.
Turn on the 6600 and allow it to warm up for about 30 minutes. Change the main
screen to the 3-output format. Change the Pt unit to “PtinHg” (Ptin) and Ps1 and Ps2 units to
“inHg”. Refer to section 3.2.3 on how to change units. During the warm-up period, purge
the system with Dry Air by cycling the pressure at the Ps1 and Ps2 ports between 38 inHg
absolute and 1 inHg absolute (or lower), at least three times.
During the warm-up period, ensure that the leaks in the system are within acceptable limits.
At 1 inHg absolute, the leak rate must not exceed 0.030 inHg/min. At 38 inHg absolute, the
leak rate must not exceed 0.010 inHg/min. To determine the leak rate, control the Pressure
Standard to the desired pressure, hold the pressure for 5 minutes to allow any temperature
effects to subside, then isolate the control mechanism from the Pressure Standard and
measure the leak rate. If the Pressure Standard is a Dead Weight Tester, the leak rate should
be low enough to ensure that the maximum allowable sink rate of the Dead Weight Tester is
not exceeded.
Towards the end of the warm-up period, perform a repeatability check at 38 inHg. Take the
pressure down to about 5 inHg and then back up to 38.000 inHg. Wait for 2 minutes, then
note the Actual value on Ps1 as “R1”. Again, take the pressure down to about 5 inHg and
then back up to 38.000 inHg. Wait for 2 minutes, then note the Actual value on Ps1 as “R2”.
The difference between “R1” and “R2” must not /- 0.002 inHg.
Step 3.
After the warm-up period is over, using the Pressure Standard, generate a pressure of
1.000 inHg absolute. Allow the pressure to be stable at 1.000 inHg for 2 minutes and note the
actual values for Ps1 and Ps2 on the 6600. These are the “As Found” readings for the Vacuum
Test Point (please see Fig. 6.1 below). They will indicate the zero drift since the previous
calibration.
Step 4.
Generate a pressure of 38.000 inHg absolute, allow the pressure to stabilize for 2
minutes and note the actual values for Ps1 and Ps2 on the 6600. These are the “As Found”
readings for the Full Scale Test Point (please see Fig. 6.1 below).They will indicate the zero
plus slope drift since the previous calibration. Leave the pressure at 38.000 inHg while you
perform the next step.
If you do not wish to make a calibration adjustment, but just want to verify the accuracy of the
6600, please skip to Step 10.
Step 5.
To make a calibration adjustment for the Ps1 and Ps2 outputs, on the 6600, move to
the the CALIBRATION screen using the NEXT SCREEN key and enter the password. The
calibration screen appears as follows:
Summary of Contents for 6600
Page 10: ...3 Figure 2 1 A...
Page 11: ...4 Figure 2 1 b...
Page 15: ...8 Figure 2 2...
Page 16: ...9 Figure 2 3...