Table of Contents
Advertisement
4.19
Continued.
At 45-psig output pressure the rotameter float should not indicate greater than 50%
of full scale at any time since the rotameter is three atmospheres above ambient
and the actual flow is √4 times the indicated flow. Therefore, any flow reading
greater than 50% means that the flow capacity of the instrument is being exceeded
and the output purity is being jeopardized.
4.20
For the operator's convenience, listed in Section 4.21 is the multiplier for each
output pressure setting. Simply multiply the rotameter reading in LPM (determined
by the proper nomograph, Figure 17) using the multiplier from the listing for that
operating pressure.
4.21
T PRESSURE
60
55
50
45
40
35
30
25
20
15
10
5
4.22
The purpose of this exercise is to allow the operator to know the flow conditions but,
more importantly, TO AVOID EXCEEDING THE OUTPUT CAPACITY OF THE
PURE AIR GENERATOR AND JEOPARDIZING THE OUTPUT PURITY. Each
pure air generator has a maximum output rating and the operator should know this
before setting flows.
4.23
The pressure and flows at each of the using instruments should now be set
according to the recommendations of the manufacturer. If snubbers are present as
flow regulations devices, only proper pressure settings are required. If pressure
and flow settings are both required, set the pressure and then establish flows using
bubble towers or mass flow meters for accurate settings.
4.24
Any instrumentation which is sensitive to even slight variations in oxygen
concentration; e.g., flame ionization detectors used with total hydrocarbon
analyzers, gas chromatographs, flame photometric detectors, etc.; all require
incorporation of mixer-receivers, Figures 4, 7 and 8 (10).
FOR BENCH-MOUNTED AND RACK-MOUNTED UNITS UTILIZING THE
4.25
MULTIPLIER
2.24
2.16
2.08
2.00
1.91
1.82
1.73
1.63
1.53
1.415
1.29
1.155
9
Advertisement
Table of Contents
