Splitter Configurations 3
Installation and Operation Guide 33
Maximum and minimum flows
The maximum suggested flow for MSDs depends on the vacuum pump used.
For diffusion pump and standard turbo systems, the flow should not exceed
2 mL/min. For performance turbo systems, the flow should not exceed
4 mL/min. These flow limits restrict the column flows and split ratios that can
be used with MSDs.
Make sure that the flow through each restrictor tube is at least equal to the
suggested minimum flow in Table 4. Restrictors that fail this test will still
work, but peak broadening and/or tailing may result.
1 The makeup flow is listed in cell B 31 of the effluent splitter calculator. You
should have at least 0.5 mL/min for stable pressure regulation. Note that
this value will decrease as the oven temperature programs up.
2 Use the Column Pressure/Flow Calculator to determine the flow through each
restrictor at the maximum oven temperature of the method, add them and
subtract the calculated column flow at that temperature. This value should
be greater than 0.5 mL/min.
Table 4 Suggested minimum restrictor flows
Minimum carrier gas flow, mL/min
Restrictor internal
diameter, mm Helium Hydrogen Nitrogen Argon
0.10 0.400 0.500 0.125 0.110
0.18 0.720 0.900 0.225 0.198
0.20 0.800 1.000 0.250 0.220
0.25 1.000 1.250 0.313 0.275
0.32 1.280 1.600 0.400 0.352
0.45 1.800 2.250 0.563 0.495
0.53 2.120 2.650 0.663 0.583
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