MKS P9B, Instruction Manual, Page: 87 / 112

General Information Chapter Seven: Maintenance
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Chapter Seven: Maintenance
General Information
In general, no maintenance is required other than proper installation and operation. Periodically check for
wear on the cables and inspect the enclosure for visible signs of damage. If a mass flow device fails to operate
properly on receipt, check for shipping damage, and check the device’s cable for proper power supply. Any
damage should be reported to the freight carrier and MKS Instruments immediately. If there is no obvious
damage, and the unit fails to operate properly, obtain an RMA Number (Return Materials Authorization
Number) before returning the unit to MKS Instruments for service to expedite handling and ensure proper
servicing of your instrument.
Recalibration
It is recommended that the instrument be recalibrated annually (once per year) if no other time interval has
been specifically established. Refer to the inside of the back cover of this instruction manual for a complete
list of MKS Calibration and Service Centers.
Flow Zero Adjustment
Recommended Interval
For the best accuracy and repeatability performance of the MFC, the zero flow output of the device should be
periodically checked and reset, if necessary. All MFCs should be zeroed under actual installation conditions
prior to use. Very slight offsets in the zero condition can contribute to flow measurement inaccuracy. This
may be especially noticeable at the lower end of the device range. At minimum, it is recommended that the
MFC be checked and zeroed, if necessary:

At the time of initial installation (or reinstallation).

Any time the ambient temperature at the MFC changes more than 10 degrees Centigrade.

Monthly, as part of a normal preventative maintenance procedure.
Methods to Adjust the MFC Flow Zero
There are multiple methods to adjust the Flow Zero of the P9B MFC. The methods available depend on the
I/O type, either analog or digital.
Analog I/O Devices

Manually - Depress and hold the zero (“Select”) button on the top of the device enclosure for three (3)
seconds.

Via the Ethernet UI – Connect to the device using the Ethernet UI and enter the Setup Mode. Go to the
Configure Tab and zero using the “Zero Flow” button on the screen. See Figure 26.

Electronically (15 Pin D analog only) – Pull Pin 9 to ground.
Digital I/O Devices

Manually - Depress and hold the zero (“Select”) button on the top of the device enclosure for three (3)
seconds.

Via the Ethernet UI – Connect to the device using the Ethernet UI and enter the Setup Mode. Go to the
Configure Tab and zero using the “Zero Flow” button on the screen. See Figure 26.