ABB EasyLine Series Instructions For Installation Start-Up And Operation page 28

28 EasyLine EL3000 Series Commissioning Instructions
Gas Sampling
The nominal diameter of the line from the sampling point to the first
switch-over valve should be 4 mm.
A bypass can be positioned upstream of the first switch-over valve, in
order to obtain a faster analysis. With a nominal diameter of 4 mm, the
bypass should be longer than 3 m, in order to prevent back diffusion from
the ambient air.
The sample gas pressure must be reduced at the sampling point. An
evaporating pressure regulator must be provided for sampling from liquid
gas lines.
Sample Gas Supply Line
The sample gas supply line must consist of stainless steel tubing, be as
short as possible and have as few transitions as possible.
The diameter of tube from the beginning of the first switch-over valve
should be 3 mm on the outside and 2 mm on the inside. The sample gas
connection to the gas analyzer is specified for a tube with an outside
diameter of 3 mm. The connections should be executed as Swagelok
fittings.
The ZO23 oxygen trace analyzer module may not be connected in series
with other ZO23 analyzer modules or other gas analyzers.
Gas Outlet Line
The gas outlet line can be executed as a flexible tube. With a nominal
diameter of 4 mm, its length should be more than 3 m, in order to prevent
back diffusion from the ambient air.
Bypass
The gas analyzer is connected to a gas flow in the bypass at a constant
flow rate (approx. 30 l/h). The needle valve is installed upstream of the
branch to the gas analyzer and the bypass flowmeter downstream of the
branch to the gas analyzer.
The gas analyzer takes 8 l/h from the gas flow. A surplus of approx. 20
l/h remains. If several ZO23 analyzer modules are supplied with gas in
parallel (redundant measurement), the flow rate must be set, so that the
bypass has a surplus of 20 l/h.
With a nominal diameter of 4 mm, the bypass from the outlet of the gas
analyzer should be longer than 3 m, in order to prevent back diffusion
from the ambient air.
On account of possible leaks, the flowmeters are always placed in the
bypass feed path downstream of the branch to the gas analyzer,
respectively, downstream of the gas analyzer; they may on no account be
installed in the sample gas supply line upstream of the sample cell.
Waste gas
The sample gas and the bypass must be conducted into the atmosphere
or into an unpressurized waste gas collecting system at an adequate
distance from the gas analyzer. Long line runs and pressure variations
must be avoided. For metrological and technical safety reasons, sample
gas and bypass may not be discharged into the atmosphere in the vicinity
of the gas analyzer, since the ambient air serves as reference air and
also to exclude suffocation through a lack of oxygen. It must be ensured
that the waste gas only reaches respiratory air when adequately diluted.