Detailed Description


Precise gas volume measurements are commonly needed throughout research and industry. Prior measuring equipment relied on a precision graduated cylinder apparatus that, to achieve low pressure sensitivity, depended on a low friction liquid -mercury gasket used via a counterbalanced single piston suspension apparatus . This system relied upon a qualified observer to manually record readings during use. These readings were subject to the observer's visual acuity and other variables and total volume was limited to the volume of a single stroke of the piston.

Changes in environmental safety guidelines related to hazardous chemicals in the workplace, such as mercury (Hg), made obsolete the above method. A new motor-driven approach has been developed and refined by Emdyne, Inc, over the last three decades that satisfies the need for precision gas volume measurement without the previous disadvantages. This automated method outputs a numerical report for recording with modern data logging systems via an RS232 serial port connection.

Temperature is one variable that must be stabilized for accurate measurements of gas volume to be achieved. The older method mentioned above could achieve this only through the expense of a large temperature controlled chamber requiring extensive hardware and electrical apparatus. The Emdyne, Inc. Precision Gas Meter (PGM)-- fulfills this need efficiently in a compact, insulated section of it's anodized aluminum housing. Temperature control is available as an extra cost option.

Within the insulated temperature regulated chamber are located all of the stainless tubing, valves, fittings and the hard anodized cylinders and components that contact and collect the gas to be measured. Since all of these metal surfaces are maintained at the same temperature, volume errors are reduced.

The left section of the front panel contains the control electronics, power supply, temperature controller (if required), volume counter rate meter, pressure bar graph display, switches balance adjustments and indicators. The rate meter indicator provides the user calibration adjustment. A fuse (3A) on the rear panel protects the device and a nine- pin D connector provides connection to a computer for data logging. A two- pin connector provides output from an RTD temperature sensor in the collection chamber. A motor disable switch for leak checking is provided on the rear panel. The power input is universal for AC voltages from 90 to 240 volts.

Gas is introduced and exhausted via bulkhead 1/8 inch 316 stainless steel tubing fittings located at the upper right side of the instrument's front panel. Very low pressure of about 0.3 inches of water pressure is adequate to activate the collection function.  

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