Thermal Conductivity Analyzer | Model 212R |
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2.3.4 Installation of Cylinder Supplies.
The reference and standard gas cylinders should be installed as close to the analyzer as possible. Each cylinder should be provided with a dual stage, metallicdiaphragm,pressurereducingregulator. Wheninstallingtheregulators, crack the cylinder valve open so that gas is flowing. This procedure will prevent air from being entrapped in the regulator, and eliminate a common source of supportinggascontamination. Improperinstallationofacylinderregulatorcan appreciably change the composition of a standard gas. Air trapped in the regula- torwilldiffusebackintothecylinder,andtheimpurityconcentrationofthe composition will be altered. When dealing with the zero gas, the alteration of the compositioncanbesignificant.
Once installed, prior to use, the regulators for reference, span and zero gases must be purged by alteratively pressuring the first stage, with the second stage off, then bleeding out the first stage by opening the second stage, back and forth severaltimes.
Note: Make sure to close the cylinder prior to bleeding the first stage through the second.
2.3.5 Sample Pressure.
Thesamplepointshouldbeequippedwithametallicdiaphragmpressure regulator and the pressure reduced to between 10 and 50 psig. The regulator should be installed as close to the sample point as possible to minimize sample linelagtime.
2.3.6 Interconnecting Lines.
Theinletandventconnectionsareidentifiedontheanalyzeroutlinedia- gram. The connections are stainless steel 1/8" female pipe couplings that are braised into a gas connector bar mounted within the analyzer. The braised pipe coupling was selected as a transition so that the torque generated during installa- tion of the external system would beisolatedfrom the internal system. Bulkhead type fittings can be accidently twisted, and leaks promoted in hard to reach areas within the analyzer. TAI suggests that 1/4" tubing and adapter fittings be used throughouttheexternalsamplingandsupportinggassystem.
Teledyne Analytical Instruments | 11 |
