Is it VFD the best solution to control pump?
Case: I have a multistage centrifugal pump and used to change the volume by a variable frequency drive (VFD), but it cause lots of problems to the SCADA system. So I look for an alternative ways to do this job.
You shouldn't control the flow with a valve as this affects the hydraulic balance of the pump and leads to premature bearing and seal failure. You could trim the impeller or run a belt drive to vary the speed if you don't want to fit a VFD which is the best solution. Actually the best solution is to buy a properly sized pump in the first place!
Don't fit an orifice plate either for the same reason. Ball valves and butterfly valves are a bad idea too as a control valve. Globe valves are far more adjustable and that's why people have recommended them. Buy a pump the correct size!
Pulley also is not a good option to achieve variable flow. With pulley you can get fix flow or you need to carry set of pulleys as per flow (w.r.t. speed) requirements & changing of those is also time taking. Variable frequency drive is quite good as it will give variable speed & corresponding flow. But it is expensive too. Best option is to use globe valve in discharge line to control the flow.
Considering the VFD, it can be mounted on top of the motor or there are also models that can be mounted separate to the motor, the variable frequency drive can be setup so that the pump can deliver constant flow or pressure. It would be a simple solution to vary the flow and keep you energy usage under control.
Sounds like a VFD still be the best option. It's important to choose the brand/series that best fits your application and environment and avoid adding the hidden problems.
You shouldn't control the flow with a valve as this affects the hydraulic balance of the pump and leads to premature bearing and seal failure. You could trim the impeller or run a belt drive to vary the speed if you don't want to fit a VFD which is the best solution. Actually the best solution is to buy a properly sized pump in the first place!
Don't fit an orifice plate either for the same reason. Ball valves and butterfly valves are a bad idea too as a control valve. Globe valves are far more adjustable and that's why people have recommended them. Buy a pump the correct size!
Pulley also is not a good option to achieve variable flow. With pulley you can get fix flow or you need to carry set of pulleys as per flow (w.r.t. speed) requirements & changing of those is also time taking. Variable frequency drive is quite good as it will give variable speed & corresponding flow. But it is expensive too. Best option is to use globe valve in discharge line to control the flow.
Considering the VFD, it can be mounted on top of the motor or there are also models that can be mounted separate to the motor, the variable frequency drive can be setup so that the pump can deliver constant flow or pressure. It would be a simple solution to vary the flow and keep you energy usage under control.
Sounds like a VFD still be the best option. It's important to choose the brand/series that best fits your application and environment and avoid adding the hidden problems.
