Lake Monitors Case Drain Monitor - Manual (Page 12)

Selecting the Proper Meter
To order a pneumatic flow meter the following information is required:
pipe size and port style
media (air, nitrogen, argon,etc.) – for material compatibility and
specific gravity considerations
approximate flow range required 1
system pressure: nominal, maximum, minimum
system temperature
Flow Range
1
Estimating the flow rate in a compressed gas system may seem
complicated, but with some research and a few simple equations
an educated guess can be made.
Two suggested methods are:
Method 1
A compressor is typically rated in SCFM output at a certain pressure
and efficiency. If the rating cannot be located or is unknown, an esti-
mate of compressor output can be obtained by the following formulas:
1-stage compressors:
motor HP/0.179 = SCFM @ 100 PSIG
2-stage compressors:
motor HP/0.164 = SCFM @ 100 PSIG
3-stage compressors:
motor HP/0.159 = SCFM @ 100 PSIG
Method 2
If all of the potential of a compressor is not being used (the unit
cycles on and off) or if flow rate in excess of compressor capacity is
being consumed (the compressor cannot meet the demand), a sum-
mation of machine usages can be totaled to determine the maximum
flow rate. Most machine tools that use compressed air specify the
maximum consumption of the tool.
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