Teledyne 4020 – Hydrocarbon analyzer (special version for automatic background gas switching) - Manual (Page 45)

Total Hydrocarbon Analyzer Installation
Teledyne Analytical Instruments 27
3.3.5.1 S AMPLE G AS
An oil-free, metallic diaphragm regulator must be installed as close
to the sample point as possible. Use new tubing in the installation. The
output pressure of the regulator should be 30 psig, whenever possible, to
match the settings of other regulators on the support gas tanks; sample
inlet pressure must exceed the operating sample pressure by at least 10
psig and provide at least 1 SCFH bypass flow. In any case, the zero and
span gas regulators should be set to match the sample pressure
regulator—as the back-pressure regulator within the analyzer ultimately
determines the sample flow to the detection cell. Refer to Chapter 4:
Sampling.
3.3.5.2 E FFLUENT
All the gases introduced into the detection cell vent from one fitting
at the rear of the analyzer. TAI recommends that the cell be permitted to
vent directly to the atmosphere wherever possible.
If a vent line is required, the installation must include a drop-out pot
to collect the water that is formed by the burning of the hydrogen fuel.
The vent line must be constructed so that water and dirt cannot collect in
it.
3.3.5.3 S AMPLE B YPASS V ENT
The sample bypassed by the back-pressure regulation system vents
from a separate port at the rear of the analyzer. If a vent line is required,
it must be installed so that water and dirt cannot accumulate in it.
3.3.5.4 F UEL AND A IR C ONNECTIONS
The fuel used to provide combustion should be a gas mixture
comprised of 40% H
2
and 60% N
2
. The fuel is mixed with air to provide
a combustion source for the analyzer. Connect the fuel and air sources to
the instrument according to the gas connection diagram included at the
back of this manual.
Note: For applications where the sample gas is hydrogen, the
sample gas doubles as the fuel for combustion and is
diluted with nitrogen. Connect a nitrogen source (40 psig)
to the fuel inlet port. See Figure 3-1.