Hi folks,
Looking for some advice on the design of suction pipework which would be able to accommodate two different centrifugal pumps, but first let me describe our current setup.
We have a waste water pit approximately 4 meters deep where pH is adjusted by dosing either acid or caustic. We currently have a high spec end-suction centrifugal pump which circulates this water during neutralisation and discharges it back to the pit. When the pH is in the desired range, we switch to another valve on the discharge side which discharges the water off site. First picture attached shows our current setup.
Due to high cost of this pump and life span of a few years, we have acquired a cheaper self-priming centrifugal pump which we want to use in its place. However should the new pump fail, we would like to be able to switch back to the old one which will be kept as a spare. The only problem is the pumps have different suction and discharge diameters.
Current, non self-priming pump: Suction diameter 100mm, discharge 65mm
New, self-priming pump: Suction diameter 80mm, discharge 80mm
Our existing suction pipework is 150mm from the very bottom up to the pump suction, where it reduces down to 100mm. I have been told by the manufacturer of the new pump that you cannot go from a larger diameter down to 80mm on the suction side, it will have to be 80mm for the entire length. This rules out the possibility of keeping the current 150mm pipework.
So my thinking is to have flanged spool pieces on the suction and discharge for each pump to allow them to be swapped out if required. Please see second picture attached (discharge not shown).
Any input, thoughts or alternative ideas would be much appreciated.
Also with regards to the current inverted U-bend design, I’m led to believe this is to keep the pump primed if the vertical section was to drain? That line coming off at the top of the U-bend is blanked off and not sure what it was used for in the past, perhaps degassing any accumulation of air? I understand three 90 degree bends right before the suction isn’t ideal due to turbulence, but I’m reluctant to get rid of it if it’s serving a purpose.
Thanks
Attached Files
Edited by -G-, 29 June 2016 - 05:08 AM.