Specifications

S
TARTUP AND
O
PERATION
748410-A
August 1999
24
Chemiluminescense Detector Analyzer Module
Rosemount Analytical NGA 2000
3
F
IGURE
3-8. C
ONVERSION
E
FFICIENCY AS A
F
UNCTION OF
C
ONVERTER
T
EMPERATURE
3.7.4 R
EPLACEMENT OF
C
ONVERTER
If the subnormal conversion efficiency is real, and not due to measurement error introduced
by the test setup, the converter must be replaced. See Section 4.
The usual cause of converter failure is destruction of a large part of the catalytic material by
excessive heat. This is due either to an excessively high temperature setpoint or failure of
the converter temperature control circuitry.
3.7.5 C
APILLARIES
Replacement vent and pump capillaries should be installed finger-tight. Use of a wrench can
constrict capillaries, thus changing flow rate. Sample capillary is metal; use a wrench for
tightening.
3.7.6 TEA S
CRUBBER
The presence of NO
2
in the NO cylinders can cause inaccurate converter efficiency values.
The TEA Scrubber accessory (P/N NL635741) can be used to remove residual NO
2
from
the NO cylinders. Use of this accessory allows an NO
2
-free NO calibration gas.
Final 2 degree
higher
adjustment
Final 1 degree lower
adjustment
About
97%
Converter Temperature
Converter
Efficiency