Chapter 3: Installation
18
2. Install the flow controller in the gas stream such that the flow will be in the direction of the
arrow on the side of the controller.
Take into consideration the specified leak through the closed control valve in case of a
mass flow controller. The specified value refers to new and unused units, but may change
during operation by age, cycles, temperature and gas. To achieve best possible leak
tightness we strongly recommend the use of positive shut off valves.
The normal position is horizontal, the process interface connector pointing upwards or
vertical with flow direction either upwards or downwards.
It is possible to mount the units the way that the connector points downwards but control
performance and valve leak can be affected. This applies especially to units with higher
flow ranges. Therefore the ‘ceiling mount attitude’ should be avoided.
3. Allow adequate clearance for the tubing. Take into account when designing the plumbing
that a unit may be removed later, e.g. for service or maintenance.
To de-install units with metal ferrule compression fittings (for example Swagelok) the tubing
must be moved away some millimeters in axial direction whereas VCR fittings allow the
instrument to be removed sidewards also out from complexive and stiff plumbing systems.
4. Allow adequate clearance for the cable connector.
5. Position the unit to provide access to the zero button and rotary switches for address
setting. Make sure that the status LED is visible.
6. The device dissipates considerable power, related to it’s small volume. Make sure that the
maximum specified ambient temperature close to the device is not exceeded, by providing
adequate cooling. The main temperature is radiated on the both sides of the device.
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