8
3.2. Determining installation site
•
The installation site should be easy accessible and free of vibrations and shocks
•
Observe at least 120 mm (5 inch) clearance above the housing with the signal conditioning, in
order to be able to remove the sensing probe if necessary.
•
The ambient temperature should not exceed the value as stated in the specifications (see page 20)
– consider heating by radiation.
•
Air purity on the installation site according to ISO 8573-1:2010: at least class 3.4.4
•
The fluid should not condense at the installation site. Condensation on the tip of the sensing probe
must be avoided.
•
In compressed air systems, the installation must be downstream of the dryer. If there is no dryer, at
least steam trap and suitable filter must be present.
•
Observe the direction of the flow by the installation (see page 11).
•
Observe the recommended straight pipe lengths up and downstream, in order to warrant the speci-
fied measurement accuracy.
•
The flow meter should be installed as far as possible from any flow disturbance. Valves or check-
valves should be installed in a respective distance from the flow meter.
3.2.1. Process pressure
Because of the measuring principle the thermal mass flow meter EE771 is largely independent of the process
pressure and is factory calibrated at a pressure of 7 bar (100 psi).
In order to achieve the highest measurement accuracy, the slight dependence on process pressure can be
compensated for in two ways:
•
if the process pressure is stable, by programming the pressure value in the configuration software
(see page 30).
•
in case of strong fluctuations of the process pressure (e.g. 3 to 10 bar (40 to 150 psi)) an external
pressure transmitter can be installed and connected to the pressure-compensation input
(see page 31).
In order to install or remove the measurement section the pipeline system should
be depressurized.
