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You need to match this curve with datasheet specification to make sure the pump passed the performance test.Let's start with head-capacity curve, we draw a verticle line at 238.5 (in the horizontal axis), and it will cross head-capacity curve, then we draw a horizontal line from the cross point, and it crosses the vertical axis at 2640. What is the test result ( the head almost is 50.28 meters less than required value)? The API 610 at table 18 says the head can be /- 3% of the rated value.
The centrifugal pump performance test is conducted by pump manufacturer after completion of the assembly to prove the pump has the required specification as indicated in the pump datasheet and other purchase documents.
The performance test is conducted after completion of casing inspection, casing hydrostatic test, impeller, and rotor dynamic balancing.
So the measured head at the 238.5 m³/h is 2640 meter. The 3 % of the rated value (2690.28 x 3%) would be 80.7 which is greater than 50.28, the pump underperforming but the test result is acceptable.
Let's assess the power consumption; we repeat the same process but this time with the power curve.
This is expressed in meter or feet and represents the usable mechanical work transmitted to the fluid by the pump. The test is carried out at a nominally constant shaft speed, and the head (H) decreases as flowrate (q) increases, giving a negative slope to the curve.
(See above H-Q curve) Look at the following sketch; this illustrates a simple H-Q curve loop.So the result of the centrifugal pump performance test for the differential head, power consumption, and efficiency is satisfactory.The head value also shall be checked in shut off point but since this pump is high energy pump, the centrifugal pump performance test at the shut-off point (no flow at discharge valve) is not a requirement based on API 610. The pump manufacturers usually provide a tabulated format to make it easy for review.That is why they are using head instead of pressure.The following formula converts pressure to the head; H(meter) = 10.2 P/SG or H(feet)= 2.3P/SG Once the rated flowrate has been determined, the designer subsequently specifies the total head (H) needed at this flowrate.The valve is opened to give a flowrate greater than the duty flow (normally 120 or 130 percent q), and further readings are taken.The valve is then closed in a series of steps, progressively decreasing the flow (note that we are moving from right to left on the Q-H curve).It defines the rate at which a pump can push fluid through the system.Flowrate is the first parameter specified by the process designer, who determines the pump requirement on the flowrate that the process needs to function.The curve indicates the consumed power at 238.5 m³/h is 2600KW (power consumption was provided at the left side of the vertical axis).Compare 2600 KW with datasheet value which is 2985 KW.