lift station engineering

[a1jkinder]

I have a lift station in service 3 yrs, it begins to read negative flow meter readings after a big rain. The vault with the mag meter was wet so i called my meter guy, waiting for him 3 days later. One pump sheared the shaft.between the time i called to have the pump pulled the other pump shaft sheared, rented aux pump in. i have asked hydromatic , the designers and the installers and we are all stumped..ok they are 40 hp pumps .a 1200ft. force main run and a 50ft. rise to a 100 ft drop and and gravity to the other end.there is a pressure relief valves 25 ft. from the lift station that works and one at the top of the rise and run that i cant find...the check valves have been shown to be working..thoughts would be appreciated. Thanks.

 

[SteveWag]

How are the motors started? VFD, solid state soft, red. voltage soft??

Steve

 

[bimr]

It appears that you have two problems. Water in the electronics of the meter. And storm debris in the wet well causing your pumos to break.

It is unlikely that the pump is running backward, especially with the check valves, and even if it is, running backwards would not cause the shaft to break.

 

[PersonalProfile]

Maybe (long shot) the pumps were running backwards (as indicated by the flow meter - crap in the NRV's) and a pump start was attempted - this has resulted in failures in other installations.

Regards,
Lyle