There is no such thing as a DUMB question. However there are DUMB ways to ask questions. This is just another example.
"What is the guide line for the centre line radius of a bend in a pump suction line?"
We see lots of these. It would so be much better if the person posting the question would set the stage and give the situational conditions about the problem.
On this post we do not know:
- The line size?
- The type of pump?
- The commodity?
- The pressure?
- The temperature?
- The source?
- The line class/flange rating?
- Why is this question being asked?
We don't know everything and we might not be able to help you, but please, give us a chance.
In general you want as little pressure drop in the suction line as possible. But this is not a universal "law". Basically you want to make sure that your available NPSH is greater than the pump's required NPSH. If you are pumping cold water out of a tall tank then it probably doesn't matter what fittings you use. If you are pumping boiling liquid out of the bottom of a vacuum column it could be critical.
The pressure drop is roughly inversely proportional to the 5th power of the pipe diameter. So a short radius bend of one size larger than a given long radius bend will probably have a lower pressure drop than the smaller diameter long radius bend.
So in summary - it depends on the circumstances and you cannot make a hard and fast rule.
checking back over the past few months, it would appear that - mechanicaldup - is the master of one-liners, or just maybe has a lot of spare time on his / her hands.
