Elster Instromet RABO, Instruction Manual

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Elster-Instromet
13
73021678d © Elster GmbH • All rights reserved • Subject to technical modification
English
9. Commissioning
11. Function Check by Means of Pressure Loss Measurement
In order not to damage the meter,
- slowly fill the system until operating pressure is reached.
- The pressure rise may not exceed 350 mbar/s. You should use a bypass line
for filling (recommendation: 12 mm pipe diameter).
- Do no exceed the measuring range even briefly!
- Conduct a tightness test!
Important! Dirt particles, such as welding beads, swarf and other foreign bodies, may
be contained in the gas for a short while after installation.
For this reason, always fit a coarse filter (e.g. cone strainer) in order to avoid
damage to the piston. Do not forget to remove the coarse filter after approx. 4 – 6
weeks since, should it become saturated, this would produce an obstacle to flow.
The correct function of the rotary gas meter can be inferred by measuring the pressure
loss. If the pressure loss has increased by more than 50% compared to the value at
the initial start-up, then there may be dirt, for example, in the measuring chamber that
can lead to an incorrect result being obtained. In comparing the pressure loss, the load
and the operating pressure must be considered.
We recommend recording the pressure loss at several points in the flow when
commissioning and logging these with the current operating pressure. If the current
flow rate and operating pressure in later checks deviate from the original values, then
the nominal pressure loss can be calculated from the original values. The pressure
loss is proportional to the absolute pressure (p
abs
) and the square of the flow rate (Q).
∆p ~ p
abs
.Q
2
10. Decommissioning
- Slowly decrease the pressure (350 mbar/s).
- Open the couplings when the operating pressure is zero.
- Only remove the meter when the pipe has been depressurized.