Glossary

impedance . . . . . . . . . . . . . . . the ratio of voltage to current at a specified frequency measured in Ohms, a resistor of the same value would act the same as the mea- sured circuit

in-hand micro-climate . . . . . . the warm and moist “climate” created when cupping the sensor in ones hand.

in-situ . . . . . . . . . . . . . . . . . . measurement with sensor located in the process stream intrinsically safe . . . . . . . . . . incapable of releasing enough electrical or thermal energy to cause

the ignition of flammable substances listed for a hazardous area classification

LBS H2O/mmscf. . . . . . . . . . see - pounds of water per million standard cubic feet

LCD . . . . . . . . . . . . . . . . . . . Liquid Crystal Display - a display that uses a special material (that is sensitive to electrical voltages) to affect the transmission or reflection of light

monograph . . . . . . . . . . . . . . a systematic learned exposition of a subject, e.g. a chart represent- ing dewpoint conversions for differing pressures.

National Electrical Code . . . . a set of US standards related to accepted practices for electrical wir- ing

NFPA. . . . . . . . . . . . . . . . . . . National Fire Protection Agency (issuer of the National Electrical Code (NEC))

NIST . . . . . . . . . . . . . . . . . . . National Institute of Standards and Technology

NPT . . . . . . . . . . . . . . . . . . . . National (American Standard) Pipe Taper; an ASTM (American Society for Testing and Materials) standard of tube fittings with tapered threads

parity . . . . . . . . . . . . . . . . . . . a way of incorporating error checking into a RS232 data transmis- sion (on a character by character basis) to check if the data has been received correctly

pounds of water per

million standard cubic feet . (LBS H2O/mmscf) the mass of water vapor present in unit volume of moist air at standard temperature and pressure.

a measurement unit for moisture, typically used in the natural gas industry

ppm . . . . . . . . . . . . . . . . . . . . parts per million - usually based on volume measure, but must be stated whether it is by volume or by mass (weight)

ppmV . . . . . . . . . . . . . . . . . . parts per million based on volume measure, volume of water vapor per total volume of gas for an ideal gas.

pressure correction . . . . . . . . computation of dewpoint at a pressure different from the pressure at the sensor

PROM . . . . . . . . . . . . . . . . . . Programmable Read Only Memory - a device that can be pro- grammed so that data is permanently stored in it (typically used for computer programs)

RAM . . . . . . . . . . . . . . . . . . . Random Access Memory - a device that holds data as long as it has power applied to it (the data can be changed with out limit)

regenerative dryer purge . . . . small flow of dry air from drying column passing through regener- ating column and desorbing water from desiccant at low pressure

response time . . . . . . . . . . . . time it takes for a sensor to react to change in its environment