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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