Option 3/2 Way Ball Valve /3Va And /3Va320; Figure 12 Calibration Gas Feeding - M&C SP Series Instruction Manual

Note
 The analysis system remains closed while calibration gas is being fed.
 The amount of calibration gas should be at least 25 % greater than the amount of sample gas drawn into the
analysis system in order to avoid mixing with the sample gas.
 This type of calibration gas feeding is not to be used in case of processes with over pressure. A built-in ball valve
in the probe entrance is recommended here. Basically, a smaller amount of calibration gas is needed in probes
with built-in ball valve as the probe is separated from the system on activating the ball valve and thus there is
no danger of mixing with the process gas.
 In order to close the probe the control grip has to be turned by hand to the right up to the stop.
Note
When feeding calibration gas via check valve /R at the probe, mixing with sample gas must be avoided. The
calibration gas flow should be at least 25 % higher than the flow of sample gas.
Figure 12 Calibration gas feeding
16.2.2

OPTION 3/2 WAY BALL VALVE /3VA AND /3VA320

With the 3/2 way ball-valve the two functions "backflush and calibration gas feed" can be carried out one after the
other. Only one function can be automated via the pneumatic drive.
This method of gas feed has the advantage that during backflushing the downstream analysis system is automati-
cally separated from the probe and during calibration gas feed, the probe is automatically separated from the pro-
cess and therefore a smaller amount of calibration gas is needed as no mixing with the process gas can occur.
During function blow back it is possible to feed test gas via an additional check valve /R at the same time (see also
Fig. 13).
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Feed the back purge gas as quick as possible and with a big nominal width in
order to avoid a loss of pressure in the feeding line during the back purge action.
In the case of negative pressure operation, it should be noted that false air would be drawn
in via the non-closed check valve /R at less than 300 mbar abs.
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