Instruction manual

7 - 2
NGA 2000 MLT Hardware
MEASUREMENT/CALIBRATION//SWITCHING OFF
Emerson Process Management GmbH & Co. OHG
Instruction Manual
90002929
07/2005
CALIBRATION
7.2 Calibration
To insure correct measurement results, zeroing and spanning should be carried out once a week.
Other intervals are possible.
The zero-level must always first be set before any other calibrations are attempted.
For the calibration procedure the required test gases have to be fed to the analyzer through the
respective gas inlets (cf. section 5.3) with a no - back - pressure gas flow rate of about 1 l/min (the
same as with sample gas) !
❏ For correct adjustment and/or “system calibration” of the analyzer please look at MLT
software manual !
General notes!
Each measuring channel of MLT can be equipped with up to four various measurement ranges.
There is the possibility to adjust the sensitivity (span) of the measurement ranges together (standard) or
separately.
The zero-gas adjustment is carried out together for all measurement ranges of a measuring channel. Off-
set setting (value differing from zero i. e.) can be provided if a corresponding zero gas requires this (e.g.
substitute gas instead of zero gas with nitrogen).
The span adjustment can be carried out at common sizing of all measurement ranges in the largest
measurement range. Due to a common linearization (small measurement ranges represent merely a
range of the complete) for all measurement ranges as standard (divergent procedures look at order
confirmation) the specifications for the linearity deviation are valid for all measurement ranges, i. e. for the
smallest full-scale range. The calibration deviation to be expected depends on the quality of the test gas
and affects all measurement ranges in a similar manner.
Certain applications and legal handicaps can require adjustment of separate measurement ranges,
though!
An constant input pressure (± 70 hPa or ±1 psig) between 1,500 to 3,000 hPa
(20 to 43 psig) is necessary for sample gas as well as for zero gas and span gas
because of internal pressure regulator (different input pressures look at order
confirmation).
MLT 1 ULCO and MLT 3 for gas purity measurement have to be calibrated on a
daily basis! Other far longer intervals are application dependent (see TÜV
suitability test report with prolonged calibrating interval)!