Measure Mode Pneumatics; Qc Reference; Test Port - Fluke RUSKA 7750i User Manual

RUSKA 7750i
Users Manual
The valves and transducers that make up the pneumatics module are shown in Figure 2-2.
In the sections that follow, the Zero, Isolation, Apply and Release valves are all 24-volt,
DC solenoid valves that are either open or closed depending on the ADTS's operational
mode. Their behavior is summarized in Table 2-2.
Valve
Ps Test
Ps Zero
Ps Vent
Ps Apply
Ps Release
Pt Test
Pt Equalize
Pt Apply
Pt Release

Measure Mode Pneumatics

Figures 2-2 and 2-3 summarize the Pneumatics of the ADTS.

Qc Reference

The Reference side of the true differential Qc sensor is internally tied to the test port of
the Ps sensor.
The Reference side of the Qc sensor is isolated from the Pt Test Port by a solenoid valve
that is closed during the ADTS's Measure and Control modes. When the user commands
the ADTS to perform the zeroing process, the solenoid automatically opens, and the
pressures on the Reference and Test Ports of the Qc sensor become equal. On the
permanent absolute Ps sensor, the Ps zeroing valve allows a vacuum to be pulled onto the
Ps test port allowing the instrument to zero at a low vacuum level.

Test Port

The Test Port connects the DUT to the Pneumatics Module. The RUSKA 7750i has two
test ports, one for the Ps and for the Pt channel. The Test Port is isolated from the DUT
by a normally closed solenoid valve that is open during the ADTS's Measure, Control
and Vent modes, and closed during the zeroing process.
Each Test Port is protected by a relief valve.
2-4
Table 2-2. Solenoid Valves States
Measure Mode
Open Open
Closed Closed
Closed Open
Closed Closed
Closed Closed
Open Open
Closed Open
Closed Closed
Closed Closed
Vent Control Mode
Open
Closed
Closed
Modulate
Modulate
Open
Closed
Modulate
Modulate
Zeroing
Closed
Open
Closed
Closed
Closed
Closed
Open
Closed
Closed