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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.

Pneumatic Flow Meter Uses and Theory - 13808 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 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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