pumps

All elevations (heights) are to be measured from the center of the pump impeller.

Here is a good, free reference book for all things pump related:

http://www.lightmypump.com/pump_book.htm

Actually, the height is measured from the level of the liquid being pumped. The (vertical) distance (in feet, meters, etc.) from there to the discharge point is the static head. The Total Dynamic Head (TDH) would be that vertical distance plus the friction losses in the total length of the system piping. That is the suction line as well as the discharge line. If the level of the water is above the beginning end of the suction line, the total pipe is to be considered since the flow still has to pass through the sumberged pipe. However, the static head would not extend to that submerged pipe end, only to the liquid level. Similarly, if the height of the pumped liquid is above the centerline of the pump, the elvation differnce is positive suction head, and the pump exerts no energy getting the liquid to that level since atmospheric pressure would do that.

In answer to the questioner's thread ( as accurately as I can with the way the question is asked)

"Does that mean it is calculated on the suction and discharge dia which is made by the manufacturer?"

the answer is "No. That means just what it says: The pump is delivering a certain GPM at a certain height." The way it is calculated is not indicated by that statement. The fact is that it is not calculated at all. It is measured. You can calculate with some amount of certainty what a pump is expected to deliver from available data such as the head as I have stated above, the pump curve and any restrictions. But to find what the pump is actulally delivering, it must be measured.

And, finally, as to the question about the diameters of the suction and discharge of the pump, these are not considered. The characteristic curve of the pump manufacturer details what the pump will deliver at its discharge flange, plus the attached discharge piping and suction piping. Good engineering practice dictates that the discharge piping should be of adequate size (diameter) that it does not exert a friction head that is overly demanding on the pump and driver, and it dictates that the suction piping should be of sufficient size such that it does not restrict the free flow of liquid into the pump. That normally requires a suction pipe no smaller than the pump suction. Sometimes this pipe is larger than the pump connection if the flow is rather great or the suction distance is rather extended. The same can be said for the discharge line. All the above assumes the pump is a centrifugal pump. With other types, all is changed.

The volume is determined by the size (diam and width) and the shape of the impeller and vanes, the shape of the volute, the speed the power available and the pressure the pump must work against.

The suction diameter usually matches the size of the impeller eye. If it is made smaller or bigger in may not work as efficient, The suction pipe is almost always bigger to reduce friction.

The delivery pipe is mostly smaller than the suction and is sufficient for handling the discharge volume for a short distance.

The delivery piping is also made bigger to reduce losses and improve the economics of the system. The costs is balanced between capital and running cost over the lifetime of the equipment.

The pump curve made by the manufacturer will provide you all data about your pump in different conditions.

The system will operate where the pump curve and the system curve intersect.

Yes, it's the stated flow at the stated total delivery head across the pump, measured in metre (or feet) fluid. Strictly speaking it's the static pressure rise across the pump plus discharge velocity head minus suction velocity head. If the pump connections are the same size the velocity heads cancel, but often the discharge dia is smaller than the suction.

Also if velocities are moderate velocity heads are quite small. But discharge velocity 10 m/s at end of curve is not unknown, and that gives velocity head ~ 5m. If so, the main delivery run needs to be bigger/lower velocity than pump discharge, and to recover the velocity head it's best to have a gentle taper between the two (or make sure you've allowed for the loss in calculating total head to specify to the pump supplier).

The suction and delivery pipes only come into it in working out the total head required.

Cheers....Codey

Usually rated pump capacity is done by manufacturer using water. You are converting this values to your handled liquid.