Sample System Volume And Flow Rates - Ametek 241CE II User Manual

Sample System Volume and Flow Rates

The sample gas flow rate during the Purging/Hold Stage is controlled by the
pressure regulator. The regulator may be set for the desired gas flow rate by
temporarily installing a flow metering device (e.g., a rotameter – supplied by
the customer/end user) on the Vent Line between the Filterblock Assembly
and the used gas disposal location.
When determining the purge flow rate to use, the line pressure, purging time,
and sample system volume should all be considered.
The difference in pressure between the Measuring Cell and the flow metering
device must also be considered. The volume of the Measuring Cell is 7.3 mL;
the volume of the Measuring Cell, filter, and interconnecting line is approxi-
mately 23 mL. The volume of the remainder of the sample system can be
estimated from the length and inner diameter of the Sample Line. The volume
of 0.25-inch tubing having 0.035-inch wall thickness is 16.4 mL/m (5.0 mL/ft).
The maximum suggested purge flow rates for various sample gas pressures are
listed below.
PN 903-8797, Rev A
The rotameter can be a permanent installation if it is rated and ap-
proved for the pressure it will be exposed to when the Vent Line is
closed off. (Example, if the Vent Line is closed, the rotameter must be
able to withstand the pressure of the process line.)
If the rotameter being used cannot withstand the process gas line
pressure, it must be a temporary installation only; the rotameter must
be removed before running the analyzer under normal operating
conditions.
Do not exceed the pressure rating of the flow metering device.
Sample Gas Absolute Pressure
KPA PSI
700 100
2000 290
3000 435
4000 580
5000 725
7500 1088
10000 1450
13790 2000
Suggested Maximum Purge Flow Rate
L/minute SCFH
1.0
2.0
2.5
3.0
3.5
5.0 10
7.5 15
10.0 20
Installation and Start-Up
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