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Model 400A
Air
SAMPLE HANDLING
2-4
NOTE
Always make sure the sample flow is present when using the 100% hydrogen
fuel option. Absence of sample flow can result in burning of detector tip when
using 100% hydrogen.
Burner air should be relatively free of hydrocarbons in order to ensure a low
background signal. Several grades of air are supplied by gas vendors for this
use. A maximum total hydrocarbon content of less than 1 ppm is required.
(Less than 1 ppm is the THC zero standard).
An alternate source of pure air for burner and zero gas can be provided by a
diaphragm pump and heated palladium catalyst which effectively removes
moderate amounts of both hydrocarbons and carbon monoxide from ambient
air on a continuous basis.
When applying sample pressures greater than 5 psig insure that the bypass regulator is fully
open to protect the bypass gauge.
Operating range for the internal sample pressure regulator is 4 to 5 psig (28 to
34 kpa) for an analyzer using 100% hydrogen fuel, and 1.5 to 5 psig (10 to 34
kPa) for an analyzer using mixed fuel. With either fuel, sample and calibration
gas(es) must be supplied to the sample inlet at a pressure slightly, but not
excessively higher than the desired setting on the internal sample pressure
regulator. The criterion for correct supply pressure is that the gas flow
discharged from the bypass outlet must be between 0.5 and 3.0 liters/minute
to operate within the control range of the sample pressure regulator. The flow
should be between 2 and 3 liters/minute to minimize system response time.
Using excess bypass flow will cause the sample pressure regulator to operate
outside its control range and rapid use of the sample and standard gases.
If the analyzer is equipped with the accessory 400A sample pump (P/N
621062) the acceptable pressure range at the pump inlet is approximately
-1 to +2.5 psig (-7 to 17 kPa). When used, the sample pump automatically
provides a sample bypass flow within the correct range. If the sample pump is
not used, the bypass flow adjustment is made by a flow controller or a throttle
valve in the customer's sample line, upstream to the sample inlet. Flow may
be measured by connecting a flowmeter to the bypass outlet.
In the event that flammable sample is to be introduced into the analyzer it must be equipped
with accessory kit P/N 624080, which restricts sample flow and provides automatic sample
shutoff in the event of burner flameout. DO NOT OPERATE WITHOUT SAMPLE FLOW
RESTRICTOR IN PLACE. The sample containment system should also be thoroughly leak
checked. This kit is designed considering application on hydrogen sample (LEL=4% v/v).
The instrument must not be used on a sample having a LEL less than 4% in air.
Instruction Manual
IM-103-400A, Rev. 1.0
December 2008
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