Gas

Fixed

Adjustable

Sonic

Supply

Regulator

Regulator

Nozzle

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OR Porous Plug

Cal=Trak

DryCal

Stable Pressure

 

 

> 200 kPa

 

Figure 6 Alternative Setup for Piston Provers

Piston or Bell Prover

7.2Vacuum Comparison of Cal=Trak with Piston or Bell Provers

The Cal=Trak operates similarly in both pressure and suction applications. Sometimes, however, users wish to compare the Cal=Trak under suction (vacuum) conditions. With a piston or bell prover, the setup of Figure 7 can be used. Note that the inlet to the Cal=Trak is at atmospheric pressure.

The restrictor should be sized to provide a drop of at least 70 kPa (21 inches or 500 mm Hg). The purpose of the restrictor is to render the piston insertion pressure change (0.1 kPa) relatively insignificant, as in the similar pressure calibration methodology.

In volumetric, comparisons, it is important to compensate for the difference in outlet temperature from input temperature. Although the pressure is the same on each end, the restrictor and the pump affect the outlet temperature and flow must be normalized to the inlet (ambient) temperature.

Restrictor

Vacuum Pump

DryCal

Cal=Trak

Figure 7 Vacuum Setup for Piston or Bell Provers

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Image 13
Sierra SL-800 Vacuum Comparison of Cal=Trak with Piston or Bell Provers, Alternative Setup for Piston Provers