Recirculating sample Point
Recirculating sample Point
(OP)
I have to design a sample point to be located on a diesel rundown header. My client is requesting that this be a recirculating sample connection. Normally this would be easy to do around a control valve or some other source of pressure drop. However, this is on rundown piping where there isn't pressure drop source. For this reason I have been considering installing a restriction orifice and sampling around that. However, my rundown rates vary from about 450 GPM to 1780 GPM. I was going to size the RO for 1780 GPM with a dp of 10 psi. At my min flowrate then the dp would only be 0.5 psi. Is this enough pressure drop for recirculation?
Any comments or other suggestions would be greatly appreciated.
Any comments or other suggestions would be greatly appreciated.





RE: Recirculating sample Point
As a side note: Sampling around a control valve as specified by many designers is not generally desirable in my field experience. This is because you must have a product flow to get a sample (i.e. to see if you are on spec), and when wish to stop all forward flow you must also remember to block in the field sample bypass.
just a thought, sshep
RE: Recirculating sample Point
Amother option I was considering was installing a small pump. Each time a sample was taken the operator would turn on this pump, flushing the line, and then take his sample.
RE: Recirculating sample Point
RE: Recirculating sample Point
roker
RE: Recirculating sample Point
You can also use zero dead leg valves(a three way type valve) which allow circulation and sampling as well. There will be total recirculation when the outlet port is closed.
Regards,
RE: Recirculating sample Point
m777182