External Leakage - Thermo Scientific Prima PRO User Manual

External Leakage

Thermo Fisher Scientific
Switch off all calibration and sample gases, and depressurise, the
lines.
Ensure the inlet is powered off, i.e. no valves selected. Connect
helium to each port on the calibration manifold in turn and pressurise
the line to normal operating pressure. Set the mass spectrometer to
monitor mass 4 and look for traces of helium. If the valve seat is
good there should be no increase in the signal level at mass 4.
To check the sample valves the inlet needs to be powered and any
external sample lines removed. Select an inlet and set the mass
spectrometer to mass 4 as above. Blank the selected inlet and then
connect the helium supply to the remaining, unselected, inlets in turn
and pressurise each to the normal operating pressure. A change in
mass 4 would indicate a cross seat leakage. Blank off one of the
tested inlets and select it through the system software. Connect the
helium to the previously blanked inlet to check it for cross seat
leakage.
To check the selector valve couple the helium to the
CALIBRATION INLET port on the solenoid inlet front panel while
the blanked sample inlet is still selected. Pressurise to normal
operating pressure and monitor for changes in mass 4 signal. Any
change would indicate a cross seat leakage of the selector valve into
the sample stream.
If there is a change in signal in any of the above tests, check that it is
reversible and repeatable, and check that the inlet is not being
pressurised beyond normal operating conditions. If a change is
confirmed, the valve may be faulty and require cleaning or
replacement. See Chapter
A leak of this type involves gas leaking into the atmosphere, and is
only likely to occur following disassembly of the system. The
significance of such a leak will depend on the nature of the gas
involved. External leakage may give rise to contamination of gas
samples with air, but is unlikely as the system normally runs at a
slight positive pressure.
Warning!
It is advisable to switch off the manifold heater before

performing work on the assembly.
The manifold heaters are Mains voltages rated and should be

isolated from the inlet control PCA. Switch off the mains
inlet breaker on the power distribution DIN rail assembly to
isolate the supply.
Prima PRO & Sentinel PRO Mass Spectrometers User Guide
Technical Description: Inlet
10.
Solenoid Inlet
C-35