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Teledyne API Model 201A NH
3
Analyzer Instruction Manual, 04689, Rev. B1
3.3 AutoZero Flow Check
Since the M201A is an ammonia analyzer, the flow through the AutoZero orifice is
especially important. Check the AutoZero flow as follows:
1. This procedure should be performed with the sample pump running.
2. Fold down the rear panel on the M201A chassis. Locate the vacuum manifold at the
center rear of the chassis. Locate the 1/8” tube fitting 2
nd
from the left. It will have a
label of “0.010”, indicating the flow orifice installed.
3. Remove the fitting and attach a calibrated flowmeter capable of measuring in the
range of 500 cc/min. The flowmeter should indicate a flow of 500 cc/min ±10%.
4. If the flow is outside this range (most likely lower, due to plugging):
1. Turn off the sample pump and instrument.
2. Remove the 1/8” pipe-to-tube fitting and remove the ¼” sintered filter (p/n
FL0001). This filter is meant to protect the orifice, it will usually become plugged and
need replacement rather than the orifice. Replace the filter, then re-assemble the
manifold. Re-start the sample pump and re-check the flow.
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