EMS 5002 Operator's Manual page 22

Maintenance
Oil/Water Separator with Can Cooler Ice Bath
· Diesel Testing when Urea is used to reduce NOX (SCR) : The EMS analyzer
is fully capable of diesel testing. Your HC reading will only be accurate for Hex-
ane gas, so a Smoke/Opacity meter would be required to check PM. All other
gases will be accurate including NOX. For diesel systems using the SCR system
that sprays UREA in the exhaust to eliminate NOX, this chemical reaction pro-
duces Ammonia. The presence of ammonia in vehicle exhaust presents some
problems for gas analyzers and sampling systems. Ammonium salts readily
precipitate in the exhaust sample stream, which can contaminate FID and
optical gas bench components. To protect the AMBII bench, a special version of
the inline filter element, EMS-5093-CS, has been developed that will absorb the
ammonia before entering the analyzers. This would need to be added in the
field, or ordered as an extra accessory for any new units.
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