Teledyne API Model 200AH NOX Analyzer Instruction Manual, 06492, Rev. G2
6-5
6.4. Isolated 4-20 mA Current Loop Option The M200AH comes equipped with 4-20mA current loop. The electrical ground of this output is
part of the instrument ground. In certain applications the instrument ground must be isolated
from the external ground. For applications requiring electrical isolation, we offer optional
isolated current loop outputs. With the exception of electrical isolation, the setup and usage is
identical to the standard equipment current loop output. The calibration procedure is located in
the Troubleshooting Section 9.
6.5. Molybdenum Converter Option The Molybdenum Converter is used in applications where the NO2 concentration will not be
expected to exceed 5 ppm. In these applications it exhibits very high conversion efficiencies,
thus enabling the accurate measurement of low concentrations of NO2. Operating the Converter
where the concentrations exceed 5 ppm will cause lower efficiencies and will shorten the life of
the converter.
6.6. External Desiccant Canister Option This Option is located between the PermaPure Dryer and the ozone flowmeter. See Figure 2-2
for location and Figure 8-5 for pneumatic schematic. It is mounted external to the analyzer. It
should be used at extremely humid sites, or where the -70°C dewpoint air produced helps in
reducing reaction cell contamination and window clouding.
6.7. Alternate Bypass Flow Orifice Option The standard bypass flow is 250 cc/min. For those applications requiring a higher
sample flow, this option provides a 500 cc/min bypass flow. The overall sample flow is
550 cc/min with this option installed. The orifice is located in the vacuum manifold at
the rear of the instrument see
Figure 2-6.
6.8. M501 External Converter Option The M200AH can be ordered with a Model 501 Thermal Converter. Its conversion performance
is very similar to the Mini HiCon. The advantage of this converter is that it is less prone to
plugging because it is constructed of larger diameter tubing, also the conversion efficiency is
very high because the thermal converter is followed by a molybdenum converter. Since the
converter is external to the M200AH the response of the instrument is considerably slower if
operated in the NO/NOX switching mode. This is due to the larger internal volume that must be
purged during the NO/NOX measurement cycle. This effect is less noticeable if the M200AH is
being operated in the NOX only mode.