Estimating static head on existing system
Estimating static head on existing system
(OP)
Im investigating the feasibility of installing VSDs on a system and am aware that potential savings are impeded on a system with a relatively high static head.
My question is: How do I determine what proportion of total head on an existing system is static head and what proportion is friction head? There are no pipe isometric drawings/ P&IDs or system curves available for the system. Further more I can't "walk the line" and develop the system curve again from scratch as most of the pipe runs are inaccessible.
All suggestions most welcome.
My question is: How do I determine what proportion of total head on an existing system is static head and what proportion is friction head? There are no pipe isometric drawings/ P&IDs or system curves available for the system. Further more I can't "walk the line" and develop the system curve again from scratch as most of the pipe runs are inaccessible.
All suggestions most welcome.





RE: Estimating static head on existing system
RE: Estimating static head on existing system
Don't forget that it may not always be just simple static head that's a problem. Any relatively high head that must be maintained more or less at all flows, such as the pressure necessary to pump into a boiler, or downstream pipeline holding a nearly constant pressure, will result in the same poor performance when coupled with a vsd.
What would you be doing, if you knew that you could not fail?
RE: Estimating static head on existing system
You will also need to add to the static head any constant pressure from items such as pressure regulating valves, or any backpressure that you are pumping against.
RE: Estimating static head on existing system
rmw
RE: Estimating static head on existing system
When people install VSD, normally it is required by process such as to control the flowrate of the pump or control the level of the vessels.
VFD (variable frequency driver) is better than VSD (variable speed driver). Some people use them interchangeably.
RE: Estimating static head on existing system
Static head is the difference between the level of tank up stream and tank downstream. It is not the pump level. There are quite a few pumps many metres below the tank level and act as booster pumps between reservoirs.
"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.
http://waterhammer.hopout.com.au/
RE: Estimating static head on existing system
A variable-frequency drive (VFD) is a system for controlling the speed of a rotational or linear alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor. A variable frequency drive is a specific type of adjustable-speed drive. VFD's are also known as adjustable-frequency drives (AFD), variable-speed drives (VSD), AC drives, microdrives or inverter drives.
RE: Estimating static head on existing system
"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.
http://waterhammer.hopout.com.au/
RE: Estimating static head on existing system
What would you be doing, if you knew that you could not fail?
RE: Estimating static head on existing system
That's what I mean. You can easily find the static head for the pump from the suction tank level and discharge tank level or the discharge point.
RE: Estimating static head on existing system
Yes, the poster is interested in determining the static head. But it would be a mistake to tell him just that and neglect the other constant pressures in his piping system.
If your system consists of constant pressure losses, then the potential for energy savings with a VFD will not exist.
For example, if you have a system with zero static head, zero friction head and are pumping into a pressurized tank, there are no energy savings if you switch to a VFD control.
RE: Estimating static head on existing system
What would you be doing, if you knew that you could not fail?