Michell Instruments QMA401, User Manual

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QMA401 User’s Manual
30 97450 Issue 2, March 2018
OPERATION
NB. If User1, 2 or 3 is selected as the carrier gas then a new parameter box
will appear underneath the carrier gas toggle box called ‘User Gas Entry’. This
can be seen below.
Figure 26 Measurement Screen
When the User Gas option is selected from the carrier gas list, the user can enter the
user gas settings, using the User Gas Setup page which is opened. See Appendix B for
further information on calculating User Flow Correction Factors.
3.7.1.2 DP Calculation Method
Selects the calculation method used for dew point and lbs/MMscf. Options are:
• IGT - as per IGT Bulletin #8
• ISO - as per ISO18453
• Ideal Gas
3.7.1.3 Purge
The purge feature will allow the user to purge the sensor crystals with high flow dry gas
quickly – this is a flush through/cleaning process for the internal gas path if switching
gas or wishing to disconnect any service items to ensure they are clean. This is done
by energising the reference solenoid and de-energising both the calibration and sample
solenoids. The flow control through the MFC is also increased up to 400ml/min from
100ml/min. These two actions allow the dry gas to flow through the sensor block. During
this time the heating control in the oven may be compromised due to the increased
power consumption of the solenoid. If this happens it can take roughly 20 minutes to
cool down to its set point of within 60°C ±0.05°C for a period of at least 15 minutes.