Teledyne 3000ZA - Trace oxygen analyzer - Manual (Page 74)

Appendix 3000ZA
Teledyne Analytical Instruments
A.5 Application Notes
3000 SERIES ANALYZERS
APPLICATION NOTES ON RESTRICTORS,
PRESSURES, AND FLOW RECOMMENDATIONS
The 3000 series analyzers require reasonably regulated sample
pressures. While the 3000 analyzers are not sensitive to variations of
incoming pressure (provided they are properly vented to atmospheric
pressure) the pressure must be maintained to provide a useable flow rate
through the analyzer. Any line attached to sample vent should be 1/4 or
larger in diameter.
FLOW RATE RECOMMENDATIONS:
A usable flow rate for a 3000 series analyzer is one which can be
measured on the flowmeter. This is basically 0.2 - 2.4 SLPM . The
optimum flow rate is 1 SLPM (mid scale). Note that response time is
dependent on flow rate; a low flow rate will result in slow response to
O
2
changes in the sample stream. The span flow rate should be the
approximately same as the sample flow rate.
RESTRICTION DEVICES:
For proper operation, all 3000 series analyzers require a flow
restriction device. This device is typically a restrictor or a valve. The
restriction device serves two functions in the sample path.
1. It is used to limit the flow rate of the sample through the
analyzer. A restrictor is chosen to operate over a range of
pressures and provide a useable flow rate over that range.
2. The restriction device provides a pressure drop. This device
is selected to provide the only significant pressure drop in the
sample path.
RESTRICTOR KIT
The current revision of the 3000 series analyzers are supplied with
a kit containing two restrictors and a union which are user installed.
These parts are supplied to give the end user more flexibility when
installing the analyzer. The restrictor kit is suitable for high and low