Measurement Units; Elimination Of Temperature Effects - Michell Instruments Promet EExd User Manual

Promet EExd User's Manual
1.6

Measurement Units

The Promet EExd offers complete flexibility for the user to select their preference of
hygrometric units. Integral pressure measurement enables unit conversions from dew
point to moisture content, or dew point to dew point for different pressure conditions.
The available units of dew point/moisture content are as follows:
Dew-Point Temperature
• °C or °F dew point
• °C or °F dew point calculated for a set pressure level input by
the user, for either ideal or natural gas
Moisture Content (parts per million)
• ppm for ideal gas (
V
• ppm for natural gas (
V
Moisture Content (pounds per million standard cubic feet)
• lb/MMscf for natural gas (
Milligrams per normal cubic meter
• mg/m
3
The firmware of the Promet EExd incorporates conversion data for ideal gases and
natural gas. For natural gas the conversions are performed based on the long established
IGT Research Bulletin No. 8 or the recently published ISO 18453, to customer order
preference.
1.7

Elimination of Temperature Effects

To ensure continuous optimum analysis conditions the Promet EExd Main Unit is
temperature controlled (internally) at a stable level. The control temperature level is
selected to suit the climate at the point of installation, being set to the normal maximum
temperature. Such steady state control within the analyzer greatly reduces the effects
of diurnal (day-night) swings in temperature. These temperature changes could induce
transitional adsorption and desorption effects of the flowing sample, resulting in
erroneous measurements.
In addition, the Promet EExd utilizes an advanced temperature compensation algorithm
that automatically maintains best possible measurement accuracy in the event of heater
failure or if the prevailing climate exceeds the set temperature level.
Michell Instruments
Ppm(v) IG
Ppm(v) NG
LBMMSCF
natural gas ( mgm-3 )
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INTRODUCTION
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