Sample System Volume And Flow Rates - Ametek 241CE II Operator's Manual

Sample System Volume and Flow Rates

3-40 | Model 241CE II Hydrocarbon Dewpoint Analyzer
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 Filter-
block Assembly and the used gas disposal location.
!
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
WARNING
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.
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 me-
tering 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 approximately 23 mL. The volume of the remainder of the sample
system can be estimated from the length and inner diameter of the Sam-
ple 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.
!
Do not exceed the pressure rating of the flow metering device.
WARNING
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/min SCFH
1.0 2
2.0 4
2.5 5
3.0 6
3.5 7
5.0 10
7.5 15
10.0 20