re: How to determine the Pump reverse flow
re: How to determine the Pump reverse flow
(OP)
Hi,
I have a standby horizontal split case double volute pump in my system. When maintenance is perform in the sytem, there will be some reverse flow. Right now, some design modification is needed in the system which may result in an increase of the reverse flow. I am not too sure if this is a problem as the reverse flow must be sufficient large overcome the static friction and the produce inertia force to turn the pump. How can I estimate the value reverse flow rate limit to prevent the pump from rotate in the reverse direction?
Thanks
I have a standby horizontal split case double volute pump in my system. When maintenance is perform in the sytem, there will be some reverse flow. Right now, some design modification is needed in the system which may result in an increase of the reverse flow. I am not too sure if this is a problem as the reverse flow must be sufficient large overcome the static friction and the produce inertia force to turn the pump. How can I estimate the value reverse flow rate limit to prevent the pump from rotate in the reverse direction?
Thanks





RE: re: How to determine the Pump reverse flow
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: re: How to determine the Pump reverse flow
saludos.
a.
RE: re: How to determine the Pump reverse flow
- if fitted with mech. seals - these also need to be checked out.
Naresuan University
Phitsanulok
Thailand
RE: re: How to determine the Pump reverse flow
regards
RE: re: How to determine the Pump reverse flow
Suppliers appear to have the reverse characteristics curves to predict the torque as a percentage of rated values for a given flow, but indicated this may not be helpful.
The flow necessary to just start it rotating depends on the combined static friction within the pump and driver. It is an inertial characteristic which affects acceleration or spin down times, but not how much torque is required to start motion.
RE: re: How to determine the Pump reverse flow
How much and what is the nature of the reversed flow? Is it more than some minor leakage through a check valve? Are you trying to recover energy from this flow?
If you are just concerned about avoiding reversed rotation of the pump and motor due to a small flow, you may want to consider installing a backstop on the pump or motor shaft.
RE: re: How to determine the Pump reverse flow
ccfowler has mentioned "check valve".
Is there a check valve or a manual stop valve (usually a gate valve) in the pump discharge piping?
RE: re: How to determine the Pump reverse flow
There are a check valve and a motorized valve at a 6" pump discharge line. However, the concern is that there is also a 1" line with an orifice connected upstream of the check valve and motorized valve at one end and downstream of these valve at the other end. The reverse flow is from this 1" line.
RE: re: How to determine the Pump reverse flow
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com