A pumping station equipped with Swedish-made eccentric screw pumps model AHLEX 752BA is installed in the basement.
According to the flow meter, the pumps were delivering too low flows.
A reference measurement in which we clocked the lowering of the pumping pump also gave a signal that the pumps were emptying too slowly.
Two independent measurements showing the same thing are usually enough to look for causes on the pumps themselves.
We still chose to measure the flow with an external, surface-mounted flow meter provided by Gustav Fagerberg.
We closed the main line out of the pumping station and circulated the flow inside the station, while creating different back pressures by throttling a valve and monitoring the back pressure.
A series of measurements were taken at different back pressures and flows and the bee now got the correct flows according to spec.
Now everything pointed to the flow meter not working as intended. An overhaul was carried out and the flowmeter was fixed.
The fact that the pump indicated a slow emptying was due to the fact that the inflow was not switched off.
It happened to give the same false indication as the flowmeter.
All's well that ends well!
Experience in service and systematic troubleshooting pays off.
- Well done Mr Carlsson!
