ENMET MEDAIR 2200 - Manual (Page 15)

M ED A IR 2200 ENMET Corporation
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4.7 Fault Indications
4.7.1 Low Flow Indication
A flow sensor is used to furnish a low flow indication. When the sample air pressure drops below approximately 0.3
LPM, the fault light and audio alarm are activated, and the display flashes “Low Flow Alarm”.
4.7.2 Other Fault Indications
Other fault indications are associated with sensor zero and calibration activities, and are described in the maintenance
Section 5.0 of this manual.
4.8 Dew Point Sensor Response
It is a characteristic of the M ED A IR 2200 that it takes more time to extract moisture from a sample by passing dry air
through it, than it does to add moisture to a sample by passing moist air though it. Therefore, the time response of the
instrument to a step change from moist to dry air is slower, then the response to a step change from dry to moist air.
It is the nature of most materials to absorb and release moisture at different rates. In general, it typically takes longer
for a system to establish moisture equilibrium when going form a high to low humidity than it does to go from low to
high. The
M ED A IR 2200 is no different. It may take up to 12 hours to establish moisture equilibrium when the
instrument is first put on the air line if the Dew Point is less than 0
°F. The sensor T90 response time is 10 seconds for
a –40
° to +50°F step change and 240 seconds for a +50° to –40°F step change. The delivery apparatus such as
regulators, piping and tubing account for the additional response time of the instrument as a system.
4.9 Hydrocarbon Sensor Response
If a Hydrocarbon (HC) sensor is supplied with the M ED A IR 2200 instrument, it designed to detect hydrocarbon gases
and vapors with an ionization potential (IP) of 10.6 eV or less. Hydrocarbons with an IP of greater then 10.6 eV will
NOT be detected. Please see Appendix B for a list of common gases and vapors and their respective IP rating.
Unless otherwise noted Isobutylene is used as a calibration and reference gas.