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2
General Troubleshooting
Pressure Symptoms
This section describes unusual pressure readings and their possible causes. At
typical column flow rates (0.5 to 2.0 mL/minute), the foreline pressure will be
approximately 16 to 18 mTorr. The Quad pressure with collision cell gas on or off
will be approximately 1 × 10
from instrument to instrument so it is very important that you are familiar with
the pressures that are typical for your instrument at given carrier and collision
gas flows.
Table 2
Influence of carrier and collision cell gas flows on vacuum
Column flow
Rough Vac
(mL/min)
(mTorr)
0.7
1.25 E+02
1
1.30 E+02
1.2
1.34 E+02
2
1.48 E+02
3
1.63 E+02
Foreline pressure is too high
If the pressure you observe for a given column flow has increased over time,
check the following:
•
•
•
•
•
•
•
36
CC Gas On
N2 = 1 mL/min
He = 4 mL/min
Quad Vac
TOF Vac
(Torr)
(Torr)
3.50 E-05
2.61 E-07
3.49 E-05
2.61 E-07
3.49 E-05
2.61 E-07
3.51 E-05
2.61 E-07
3.52 E-05
2.61 E-07
Column (carrier gas) flow is too high
Collision cell gas flow is too high
Air leak (usually the side plate is not pushed in or vent valve is open)
Rotary foreline pump oil level is low or oil is contaminated
IDP foreline pump tip seal is worn down and needs replacing
Foreline hose is constricted
Foreline pump is not working correctly
7250 Accurate-Mass Q-TOF Troubleshooting and Maintenance Manual
-4
-4
to 2 × 10
Torr. These pressures can vary widely
Rough Vac
(mTorr)
2.70 E+01
3.61 E+01
4.13 E+01
6.18 E+01
8.45 E+01
CC Gas Off
Quad Vac
TOF Vac
(Torr)
(Torr)
5.78 E-07
1.58 E-07
6.21 E-07
1.58 E-07
6.55 E-07
1.58 E-07
8.09 E-07
1.59 E-07
9.99 E-07
1.60 E-07
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Table of Contents
Troubleshooting
