Is it cavitating?
A fictional story, but it could be real. It’s about a noise pump and all the work that came with it.
We needed to get a pump for a new part of the process. A large day storage tank with a volume of 200 m3, 4 meters high. The piping was all done in 3D drawing, which made it easy for us to do the friction loss and static head calculation. We calculated the friction losses on the discharge side – with the result of 14m. We submitted our request to the supplier.
We requested a pump for 25 m3/hr and 1,4 Bar head pressure – what did we get?
Really great – we are happy! Let’s buy this one today, it has a delivery time of 4 months.
We finalized the construction and installed the pump. With the startup, the pump was making lots of noise. We measured the pressure and it was just over 1 Bar. Then we measured the flow and it was around 35 m3/hr.
So simple solution: start, closing the discharge valve till the noise is gone and we have a pressure of 1.4 Bar.
Now we started to go into full production. The feed tank was swinging up and down from nearly empty to 4 meters of level. And no surprise, the pump started making noise again with a full tank. What could be wrong? So we went through the same procedure. Closing the discharge valve more! And yes, great good flow, and no cavitation.
Now, what happens if the level in the feed tank is dropping to 1 meter? A lot of noise, and only 50% of the flow.
So, sending the operator out in the field and letting him open the discharge valve till the pressure drops back to 1.4 Bar. Alright, that works, but it is really not the right solution. We need a better solution.
What would you suggest to change in this case:
- Buy a different pump
- Install a frequency inverter
- Install a backpressure valve
- Install a flow meter
- Install an orifice
Let’s have the discussion here