Conditioning The Gas And Air Samples; Dry Reference Air; Pressure Requirements; Temperature Requirements - Ametek 388 Ranarex User Manual

Conditioning the Gas and Air Samples

The gas sample and the Reference air must be measured at the same tem-
perature, atmospheric pressure and humidity content to ensure accuracy. The
sampling system must condition the gas and air to meet these requirements.
Once these conditions are met, the analyzer and sampling system as a unit will
be self-compensating for all variations except the analysis and relative density
of the gas.

Dry Reference Air

The dry Reference air is provided by the Gravitometer's built-in Dryer which
uses Silica Gel as the desiccant.

Pressure Requirements

The gas sampling system must reduce the gas to barometric pressure to equal;
the pressure of the Reference air. The correct gas pressure corresponds to
a sample flow rate of 15–20 SCFH for the stationary Ranarex Gas Gravitom-
eter and 10–15 SCFH for the portable version. The flow rate is measured by a
rotameter. As an operating convenience, the Flow Scale is graduated in rela-
tive density units so that you can adjust the needle valve so the Gas Sample
Flowmeter reads the approximate relative density of the gas.

Temperature Requirements

Reference air is admitted to the Gravitometer at the ambient temperature of the
instrument. For the gas and air to be measured at the same temperature, the gas
must be heated or cooled to ambient temperature. This is especially important
if the gas pressure has been reduced more than 100 PSIG, or if the gas flows
through a temperature zone of more than -12 °C (10 °F) difference from the
ambient temperature of the Gravitometer. If the gas sample temperature must
be adjusted, the gas can be passed through a coiled 3-meter (10-foot) section of
metal tubing before entering the Gravitometer.
2-12 | 388 Ranarex Portable Gas Gravitometer – Chandler Engineering
The Silica Gel desiccant is normally blue in color and must be replaced
when the color has changed to pink.
The Gas Sample Flowmeter can be used with inlet pressures up to 20
PSIG. When the sample pressure is greater than 20 PSIG, you must
reduce to using an external pressure regulator.
PN RI-212, Rev. L