Teledyne M300EM Particulate Filter, Pneumatic Sensors, Sample Pressure Sensor, Sample Flow Sensor

Theory of Operation Teledyne API – Technical Manual - Model 300E Family CO Analyzers

The actual flow rate of gas through the orifice (volume of gas per unit of time), depends on the size and shape of the aperture in the orifice. The larger the hole, the more the gas molecules move at the speed of sound and pass through the orifice. Because the flow rate of gas through the orifice is only related to the minimum 2:1 pressure differential and not absolute pressure, the flow rate of the gas is also unaffected by degradations in pump efficiency due to age.

The critical flow orifice used in the M300E/EM is designed to provide a flow rate of 800 cc/min.

11.4.2.PARTICULATE FILTER

The M300E/EM Analyzer comes equipped with a 47 mm diameter, Teflon, particulate filter with a 5 micron pore size. The filter is accessible through the front panel, which folds down to allow access, and should be changed according to the suggested maintenance schedule described in Table 12-1.

11.4.3.PNEUMATIC SENSORS

11.4.3.1.Sample Pressure Sensor

An absolute value pressure transducer plumbed to the outlet of the sample chamber is used to measure sample pressure. The output of the sensor is used to compensate the concentration measurement for changes in air pressure. This sensor is mounted to a printed circuit board with the Sample Flow Sensor on the sample chamber (see Section 11.4.3.2 and Figure 3-4

11.4.3.2.Sample Flow Sensor

A thermal-mass flow sensor is used to measure the sample flow through the analyzer. The sensor is calibrated at the factory with ambient air or N2, but can be calibrated to operate with samples consisting of other gases such as CO. This sensor is mounted to a printed circuit board with the Sample Pressure Sensor on the sample chamber (see Section 11.4.3.1 and Figure 3-4).).

236 04288D DCN5752