INTRODUCTION
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Manual EMC 500 · EN01 · 2008-02
1
Introduction
In addition to the
superior calorific value
, the EMC 500 / 500-L measuring device
continuously
determines the
inferior calorific value
,
Wobbe index
and
standard density
of fuel gases.
The Wobbe index is a measured quantity for monitoring and controlling the heat output of gas
burners and is defined as follows:
rd
H
W
air
,
n
n
rd
Where:
W
is the Wobbe index (W
i
, W
s
)
H
is the calorific value (H
i
, H
s
)
rd
is the relative density
n
is the standard density of the measuring gas
n,air
is the standard density of the air
The heat output of a gas burner can be maintained at a constant level if the gas supply is controlled
in such a way that the Wobbe index remains constant.
The inferior and superior calorific values and the standard density are thermic characteristics which
are used for monitoring the composition and energy content of fuel gases.
The EMC 500 measuring device is suitable for custody transfer flow measurements of the superior
calorific value, the standard density and the CO
2
content of natural gases and their mixtures.
The version EMC 500-L is also suitable for natural gases which have been conditioned with up to
20% of air. This version may be used for custody transfer flow measurements of the superior
calorific value and the CO
2
content. After a special test the standard density may be used for the
calculation of the compressibility.
In contrast to conventional methods, the EMC 500 / 500-L measuring device determines the
measured values without burning the measuring gas. Combustion-free measurement has significant
advantages, such as:
-
Low maintenance requirements
no cleaning of the burner
no maintenance of the air supply system
-
No air for combustion has to be supplied, and therefore, the ambient air has no effect on the
measured value.
-
No undesired heat is produced at the place of installation.
The EMC 500 / 500-L detects changes in measured values within a very short time. So also
automatic recalibration is terminated within a few minutes.
Moreover, the min./max. limits of the measured values and the temperature of the sensor are
monitored.
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