recirculation valve
recirculation valve
(OP)
This is kind of a general question but based on a real situation. In a fuel loadout pumping system, the loading centrifugal pumps have a backpressure valve to control the pressure in the system, and at the same time, assure a minimum flow in the pumps.
A second set of centrifugal pumps (smaller), inject other fuel to the same system. For this second set of pumps, it has been specified relief valves in the recirculation line. there is a flow control valve downstream the second set of pumps to assure the injection is done in the correct proportion. The relief valve would be there only to satisfy the minimum flow.
I wonder if backpressure valves would be a better choice for the second set of pmps for the following reasons:
- Recirculation control would be more gradual. Relief valve now tend to pop open as safety valves do, posibly affecting the control of the right proportion. Blow down can also affect the system.
- A backpressure valve would be easier to regulate in the field.
Might be that the relief valve is cheaper, but it doesn't look like the right choice. What do you think?
A second set of centrifugal pumps (smaller), inject other fuel to the same system. For this second set of pumps, it has been specified relief valves in the recirculation line. there is a flow control valve downstream the second set of pumps to assure the injection is done in the correct proportion. The relief valve would be there only to satisfy the minimum flow.
I wonder if backpressure valves would be a better choice for the second set of pmps for the following reasons:
- Recirculation control would be more gradual. Relief valve now tend to pop open as safety valves do, posibly affecting the control of the right proportion. Blow down can also affect the system.
- A backpressure valve would be easier to regulate in the field.
Might be that the relief valve is cheaper, but it doesn't look like the right choice. What do you think?





RE: recirculation valve
If the scope of what you want to accomplish is to ensure that the minimum flow allowable is at least maintained in a centrifugal pump that is susceptible to dead-heading or drastic flow reductions, than you should be applying something like Yarway’s automatic recirculation control (ARC) valve.
So-called “relief” valves (much as are used in positive-displacement gear pumps) are meant for safety purposes, never for process control. To rely on this kind of relief device to control flow is to misapply it and never really accomplish what the scope is intended to do. The Yarway valve comes as close to protecting a dynamic machine such as a centrifugal pump as there is available in a simple, unitized device. Go to Tyco’s website and download the literature pertaining to the model that applies to your application:
http://ww
RE: recirculation valve
That again will, at a given process, mean that you have to check all variabels and possible points to influence or regulate the process, not limiting yourself to the pipeline and valves.
In addition to valves (types, placement, CV, sequence)this could begeneral for the process you describe: pumps (types, capacity, soft start or stepless regulating), consumption and requirements for flow regulation, allowable pressure and mixture, viscosity, temperature, pipeline size and layout,pressure peaks ('waterhammer'), startup and closedown time restrictions, measure instrumentation and measurement requirements (if any), safety rules and restrictions ..etc, etc....
RE: recirculation valve
But just because these pumps are running in parallel with other, larger centrifugal pumps, do not assume that they are also centrifugal.
Johnny Pellin
RE: recirculation valve
RE: recirculation valve
I can tell for sure that the pumps in the second set are also centrifugals. Also, the main group of pumps even at shutoff, won't be raising the pressure above the design pressure of the system.
As an additional data (I just didn't want to complicate the case), there is a third set of pumps (this time positive displacement for sure) injecting additives to the system. This set do have relief valves. What I don't like from these pumps is that they also have a flow control valve downstream for the same reason (correct proportioning of the additive). That looks to me as a very poor design, because again, the relief valve will be opening each time the control valve closes to adjust the flow rate. Been small pumps, I think that a better designed system would have the controller acting directly over the driver of the pumps (controlling speed), and leaving the relief valve to do just what it is design to do, protect from overpressure.
RE: recirculation valve
Regarding that third set of pumps, back pressure control doesn't do a thing in terms of varying the flow out of a positive displacement pump (I'm assuming that's how someone's tried setting yours up, if the PSV lifts as the valve throttles). The only two ways you can control those is by recirculation or, as you suggest, by speed control (sometimes stroke adjustment is an option on certain reciprocating designs).