Enmet MEDAIR 2200 User Manual download pdf (Page 15)

2200 ENMET Corporation

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

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

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

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.

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Enmet MEDAIR 2200 User Manual Page 15