Hazardous Area Operation
Purge Operation
A-10
Prima PRO & Sentinel PRO Mass Spectrometers User Guide
Thermo Fisher Scientific
Standard
High Pressure
Option*
Minimum Supply Pressure
4 bar
4 bar
Maximum Supply Pressure
6.9 bar
10 bar
Maximum Enclosure
Overpressure
15 mbar
25 mbar
Regulator Set Pressure
3.0 bar
3.0 bar
NOTE:
The High Pressure Option must be specified in the instrument order. A
Standard or High Pressure Option system can be operated at a higher line pressure,
provided that an additional regulator and pressure relief device (set to 6.9 bar or 10 bar
maximum respectively) are placed in the incoming air line.
All purge parameters are detailed on the instrument label and must
be adhered to. The parameters will have been set during factory
testing. The CDP flow rate should be sufficient to pressurise the
enclosure to a minimum of 1 mbar overpressure, but typically the
operating pressure is greater than this – the set point of the enclosure
pressure switch will have been adjusted to suit.
In the event of any problems (or suspected problems) with the purge
control equipment, or when certain part of that equipment is
replaced, it may be necessary to set or check any of the above
parameters. Before attempting this, suitable test equipment must be
available.
The requirements are as follows.
a.
Calibrated pressure gauge (0 to 20 mbar) for enclosure
pressure measurement. If such a gauge is not available, a
water manometer is acceptable (assume 10 mm of water
column is 1.0 mbar). The pressure can be measured at any
point on the main enclosure, but avoid points close to the air
inlet. There may be a spare blanked port that can be adapted
for this purpose.
b.
Calibrated flow meter for measurement of purge flow rates.
Additionally, a pressure gauge should be used to measure the
pressure at the flow meter inlet so the flow reading can be
corrected for pressure. The pressure correction is given by:
Flow = flow meter reading
(pressure reading (bar abs))
c.
Stopwatch for verifying purge timing.
Parameter
Measurement
