Michell Instruments MDM300 I.S, User Manual

Page: 52 / 72

MDM300 I.S. User’s Manual
44 97213 Issue 5, October 2017
CALIBRATION
6.2 Calibration Method
!
WARNING:
These procedures require the use of specialized test
equipment and calibration adjustments should only be carried
out by qualifi ed personnel. If not correctly carried out, the
instrument’s calibration can be lost.
The calibration procedure for the instrument is as follows:
1. Switch on the instrument. Wait for the initialization period to complete
and allow sufficient time for it to stabilize.
2. Ensure the instrument is set up with sample gas as
AIR
and operating pressure
as
ATMOS
.
3. Ensure that the temperature units are set up as
°C
and the primary display is
reading
Dew point
.
4. Ensure that all sample tubing and connectors are made from stainless steel and
are of suitable quality.
5. Connect the MDM300 I.S. to a dew-point generator and establish a gas flow
through the instrument.
6. Apply a dew point of -100°C and allow the instrument’s reading to stabilize for a
minimum of 96 hours (including dry down).
7. Record the applied
REF
dew point and the corresponding MDM300 I.S. display
reading.
8. Repeat steps 6 and 7 at all the required dew-point values over the operating
range of the instrument, as shown in Table 12, allowing the stabilization times
shown before recording consecutive readings.
A set of results similar to that shown below could be generated over the calibration range of
the instrument.
DP REF
°C
Stabilize
Time
(Hours)
MDM300 I.S.
Rdg °C
DP REF
°C
Stabilize
Time
(Hours)
MDM300 I.S.
Rdg °C
-100 96 -99.8 -30 1 -30.1
-80 12 -79.7 -20 1 -19.9
-70 8 -70 -10 1 -10
-60 4 -59.8 0 1 0.1
-50 2 -49.8 10 1 10
-40 1 -39.9 20 1 20
Table 12 Example Of Calibration Run Readings