Analyzer Overview
Manual CWD 2005
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Manual CWD2005.doc
3.2.
Gas connections
Gyrolok
¼” tube (6 mm) gas connections are located on the left hand side of the unit.
The process and calibration gases should be connected separately. If a very short
response time is required, a tube with a smaller diameter 1/8” (4 mm) can also be
used, depending on sample gas but check that the pressure drop is not too large.
The input pressure to the instrument must be between 20 and 40 mbar (12” H
2
O).
Lower calorific gases (1000 kcal) require a pre-
pressure of 40 to 60 mbar (24” H
2
O).
If the input pressure is too low, the pressure should be boosted with a sample gas
pump. A pump is available as an optional extra, and can be mounted on a panel with
the necessary pressure gauges and pre-pressure regulator.
The process gas tubing will need a sample gas filter and this can be ordered as an
option from the factory or supplied by the customer
A small filter will be sufficient when Natural gas is used because this gas is normally
clean. Larger filters are necessary for dirty gases such as Blast Furnace gas and
Coke Oven gas. The volume of the filter will effect the response time and the filter
element should have a large active face retention area and a small dead volume.
If the process gas is at a much higher temperature than ambient and the humidity of
the process gas is high, water can condense in the lower temperature sample tubing
runs and this must be avoided. The gas has to be dried or a water separator with a
drip leg installed at the lowest point of the process gas line. The gas rapidly warms
up above ambient inside the instrument so there is no danger of condensation.
3.3.
Gas consumption
Gas consumption will depend on the range orifice (Wobbe jet) in the instrument, and
the Specific Gravity of the process gas. Natural gases require 15-20 liters of gas per
hour. Blast furnace gases with low calorific values require up to 200 liters per hour.
Use the following formula to calculate the gas consumption based on Specific Gravity
and range orifice (Wobbe jet) diameter. Quantities expressed in scf/h or l/h.
hour
Litre
/
Gravity
Specific
d²
*
48
n
consumptio
Gas
Dimension:
Wobbe jet diameter in mm
Specific Gravity:
Process gas/calibration gas
hour
scf
/
Gravity
Specific
d²
*
1,695
n
consumptio
Gas
Dimension:
Wobbe jet diameter in mm
Specific Gravity:
Process gas/calibration gas