EMDYNE, INC. GASMETER DETAILED DESCRIPTION
Precise gas volume measurements are commonly needed throughout research and industry. Traditional equipment
relied on precision graduated cylinder apparatus that, to achieve low pressure sensitivity, sometimes depended on a
liquid-mercury wetted counterbalanced piston. Moreover, the system relied upon a qualified observer to record all readings over
time. These were subject to the observer’s visual acuity and other variables.
Recent changes in environmental guidelines related to hazardous chemicals in the workplace, such as mercury (HG), have made
obsolete the above methods. A new approach has been developed over the last two decades that satisfies the need for precision gas
volume measurement without the previous hindrances. In addition, the new method permits a numerical report to be available to any
modern data logging system in the laboratory via an RS232 DTE serial port connection.
Temperature is one element that must be stabilized for any accurate measurement of gas volume to be achieved. The older method
mentioned above could achieve this only with the expense of a large temperature controlled chamber requiring extensive hardware
and electrical apparatus. The new method-- the Emdyne, Inc. Precision Gas Meter-- fulfills this need elegantly in a small
insulated section of it’s anodized aluminum housing. Within the 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. In addition, any
compounds that may condense to liquid, such as hydrogen sulfide (H2S), are phase limited to the gas regime. Temperature may be
set up to 180 F.
The left side of the unit contains the control electronics, power supply, computer interface board, temperature controller,
volume counter, pressure bar graph display, switches and indicators. Accessible via a screw- retained cover, as with the heat
bath side, the user can adjust calibration as required. A fuse on the rear panel protects the device and a nine- pin D connector
provides connection to the computer for data logging. The power input is universal for AC voltages from 90 to 240 volts.
Gas is introduced and exhausted via ¼ inch NPT 316 stainless ports located at the upper right side of the instrument’s front
panel. Very low pressure of about 1 inch water pressure is adequate to activate the collection function. This equals or betters
the traditional method mentioned above.