Special Scales Special calibrations can be performedby Lake Monitors to correct for the
following system characteristics: If a Lake monitor is installed in asystem where conditions differ from
the standard listed above, correc-
tion factors will need to be applied
to retain the design accuracy of the
monitor. The appropriate correc-
tion factor equations are detailed in
Chart 1 on the back of this page. To
assure the best monitoring accura-
cy, pressure and temperature meas-
urements should be taken directly
at the monitor’s inlet port. Lake products are designed forpneumatic systems where pressures
between 90-110 PSIG are used. In
these common applications, a Lake
monitor with a standard calibra-
tion can be read directly without
applying corrections. Correction Factors Standard Cubic Feet Lake’s monitors are calibrated tomeasure the flow of compressible
media (gases) in SCFM – standard
cubic feet per minute. A “standard”
cubic foot is defined as a cubic foot
of dry air at standard atmospheric
conditions: 70ºF and 14.7 PSIA (0
PSIG) measured at sea level. When a standard cubic foot of air iscompressed, its actual volume will
decrease proportionally as absolute
pressure increases. For example, a
standard cubic foot of air’s actual
volume will decrease by 50% and
density will increase by 100% as the
air is compressed from atmospheric
pressure 14.7 PSIA (0 PSIG) to 29.4
PSIA (14.7 PSIG). See FIGURE 1 on
back.There are three factors that affectthe
Flow meter Calibration: specific
gravity, pressure and temperature.
Lake Monitors are calibrated for air
(specific gravity of 1.0) at 70ºF and
100 PSIG. Most low pressure
rotameters are calibrated at 0 PSIG
and require corrections for use at
any other pressure. >
Lake MonitorsPneumatic Monitor Uses and Operating Theory Lake Monitors Pneumatic Monitor Uses and Operating Theory
Lake’s rugged, high pressure, pneumatic monitors are designed
for permanent installation in com-
pressed gas systems. These products
provide a low cost means to meas-
ure
industrial compressor volumetric outputs,
pneumatic tool consumptions and
other industrial gas flow rates.Lake Monitors operate using thevariable annular orifice method
with
compression spring return –
the identical method used in our
field proven liquid flow rate moni-
tors. The product’s follower, where
the measurement is indicated, is
magnetically coupled through a
high pressure casing to the moni-
tor’s internal orifice assembly.Benefits of these design featuresare: >
â—† high operating pressure >
â—† linear displacement of the follower with respect to flow rate >
â—† high turn-down ratios >
â—† measuring accuracy within
±4% of full-scale >
â—† system pressure >
â—† system temperature Lake Monitors are available in threestandard materials of construction: >
â—† operation in any mounting orientation >
â—† media specific gravity >
â—† various
measuring units (i.e.
LPM, LPS, m3/hr, etc.) >
â—† aluminum for standard moni-
toring applications to 600 PSIG >
â—† any combination of the above Consult Lake’s factory or your distributor for details and prices. >
â—† brass for media/material com-
patibility Selecting the Proper Monitor >
â—† stainless steel for compatibility
and operation to 1000 PSIG. Measuring ranges cover 1.5-12SCFM through 150-1300 SCFM.
Twenty-four port sizes from 1/8"
through 2" in NPT, SAE and BSP
can be ordered to meet specificplumbing requirements.Lake’spneumatic monitors are also avail-
able in alarm and transmitter con-
figurations for
electronic monitor-
ing applications. To order a pneumatic flow ratemonitor the following information
is required: â—† pipe size and port style â—† â—† media (air, nitrogen, argon,etc.) – for material compatibil-
ity and specific gravity consid-
erations approximate flow rangerequired >
1 â—† system pressure: nominal,maximum, minimum â—† system temperature >
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