How do you test NPSHr of a pump?
How do you test NPSHr of a pump?
During an NPSHr test, the pump is run at a constant flow and speed with the suction head reduced gradually to the point where cavitation and head loss are observed. Figure 2 below, from Hydraulic Institute’s Centrifugal Pump Test Standards, shows sample NPSHr test curve results for different flow rates.
What does NPSHr stand for?
Net Positive Suction Head Required
NPSHR – Stands for Net Positive Suction Head Required. • Cavitation occurs when the Available Suction Head is less than. Required for a specific pump. When Suction Pressure is too. low, fluid vaporizes.
How is NPSH test done?
For each step, the pump outlet valve is adjusted to keep the flowrate (q) at a constant value. The final reading is taken at the point where the pump head has decreased by at least 3 percent. This shows that a detrimental level of cavitation is occurring and defines the attained NPSHR value.
What is NPSHr vs NPSHa?
NPSHa (available) is a property of the system and is calculated by the system designer giving a value of the pressure on the suction side of the pump. NPSHr (required) is a property of the pump. This is calculated by the manufacturer as the point where cavitation occurs.
What is strip test of pump?
Strip inspection of pumps on completion of running tests, where specified in data sheet. Wearing surfaces to be checked and recorded. All materials to be checked against test certificates or Vendor`s bill of materials.
What is borehole pumping test?
A borehole pump test is a controlled experiment in which a borehole is pumped at a controlled rate and water-level response (draw-down) is measured. A yield test on a spring can vary from a basic bucket test to more prolonged monitoring.
How can NPSHr be reduced?
The NPSHr can be reduced through the following methods:
- Throttle the pump discharge using a throttling valve or a restriction orifice. This will increase the pump head by reducing the flow rate and operate the pump in a lower NPSHr region.
- Use an oversized pump.
- Use an impeller with a larger diameter eye.
Is NPSHr absolute or gauge?
absolute
The term is absolute by the very words that compose the acronym NPSH; Reason No. 2: NPSHr is understood to be absolute because of the nature and purpose of the NPSHr test.
Why is NPSH important?
NPSH or Net Positive Suction Head is a very important part of a pumping system. The systems NPSHA must be higher than the pump’s NPSHR in order for proper pump performance and to eliminate the risk of cavitation, which can damage a pump in short order and shut down operations that depend on that pump.
What is an API 610 pump?
API 610 is the API standard relating specifically to centrifugal pumps and centrifugal pumping systems. It provides design criteria for the design of the actual centrifugal pump, as well as how the centrifugal pump is to be tested, and what type of base it is to be mounted on.
How do you inspect a pump?
The third party inspector checks the following items in the centrifugal pump casing inspection process:
- Visual inspection for damage.
- Dimensional check to drawing requirements.
- Witness or review hydrostatic test.
- Witness or review NDE examination.
- Application of test marks.
- Visual examination of welded on connections.
What is the purpose of a pumping test?
The goal of a pumping test, as in any aquifer test, is to estimate hydraulic properties of an aquifer system. For the pumped aquifer, one seeks to determine transmissivity, hydraulic conductivity (horizontal and vertical) and storativity (storage coefficient).