Pump Performance Testing Procedures

Philippine Agricultural Engineering Standard PAES 115: 2000

• This standard was initiated by the Agricultural Machinery Testing and Evaluation Center (AMTEC).
• The project aimed to enhance the implementation of AFMA through improved agricultural engineering standards.
• Funding was provided by the Bureau of Agricultural Research (BAR) of the Department of Agriculture (DA).
• A technical committee reviewed the standard and sought feedback from various agencies.
• The Philippine Society of Agricultural Engineers (PSAE) were presented the standard.
• A public hearing was organized by the National Agriculture and Fisheries Council (NAFC).
• Comments from the presentation and hearing were considered in the finalization of the standard.
• It has been technically revised to align with PNS 01: Part 4:1998.
• The standard specifies test methods for centrifugal, mixed flow, and axial flow water pumps.
• The test includes performance, cavitation, and priming tests (for self-priming pumps).
• PAES 103:2000 (Agricultural Machinery – Method of Sampling) and PAES 114:2000 (Agricultural Machinery – Centrifugal Pump – Specifications) are referenced.

Definitions

• Axial Flow Pump: A pump that develops suction and discharge head by propelling or lifting action of the impeller vanes on the water.
• Base Plane: Datum elevation:
  • For horizontal shaft pumps, it is the distance from the water source to the pump shaft centerline.
  • For vertical single suction pumps, it is the distance from the entrance eye to the first stage impeller.
  • For vertical double suction pumps, it is the distance from the water source to the impeller discharge horizontal centerline.
• Cavitation: Formation of cavities filled with water vapor due to local pressure drop, collapsing when vapor bubbles reach high-pressure regions.
• Centrifugal Pump: A pump with vanes or impellers rotating inside a housing that draws water in through a central inlet and forces it out through a discharge outlet using centrifugal force.
• Discharge: Volume of water pumped per unit of time.
• Friction Head (hf): Equivalent head needed to overcome friction caused by flow through pipes and fittings, defined by the equation hf = k (lQ²)/(C²D²).
  • l is the pipe length in meters.
  • Q is the discharge in m³/s.
  • C is the friction coefficient (1.0 for steel, 1.5 for concrete, 0.8 for plastics).
  • D is the internal pipe diameter in meters.
  • k is equal to 10.
• Head: Quantity expressing energy content of liquid per unit weight relative to an arbitrary datum.
• Mixed Flow Pump: A pump that combines features of centrifugal and axial flow pumps, developing head partly by centrifugal force and partly by the lift of vanes on the water.
• Net Positive Suction Head (NPSH, hsv): Total suction head at the suction nozzle (corrected to pump centerline) minus the vapor pressure of water at the pumping temperature.
• Net Positive Suction Head Available (NPSHA): NPSH determined from actual suction piping conditions, using the formula NPSHA = (Pa/γ) - (Pvp/γ) - Hs
  • Pa is the atmospheric pressure in kg/m².
  • Pvp is the vapor pressure in kg/m².
  • γ is the specific weight of water in kg/m³.
  • Hs is the total suction lift/head in meters.
• Net Positive Suction Head Required (NPSHR): The performance characteristic of the pump and is the NPSH at the pump inlet, representing the minimum suction conditions to prevent cavitation.
• Performance Curve: Illustrates the relationship between capacity, head, power, NPSH, and efficiency of the pump.
• Pump: A device used to lift or transfer water from one source to another.
• Priming: Filling the pump with water to displace air and create a liquid seal inside the casing.
• Pump Efficiency (np): The ratio of power output to the power input of the pump.
• Shaft Power: Power required at the pump shaft, which is the input power to the pump.
• Static Discharge Head (hd): Vertical distance from the pump centerline to the discharge water level.
• Static Suction Head (hs): Vertical distance from the free suction water level to the pump centerline, present when the water source is above the pump centerline.
• Static Suction Lift (hs): Vertical distance from the free suction water level to the pump centerline, present when the water source is below the pump centerline.
• Total Discharge Head (Hd): Sum of static discharge head, friction, exit losses in discharge piping, plus velocity and pressure head at the point of discharge.
• Total Head (TH): Measure of energy increase imparted to the water by the pump determined by the algebraic difference between total discharge head and total suction head. Where suction lift exists total head is the sum of the total discharge head and total suction lift but where positive suction head exists, the total head is the total discharge head minus the total suction head
• Total Suction Head (Hs): Vertical distance from the pump centerline to the water level, minus friction losses in suction pipe and fittings, plus the pressure head on the suction supply.
• Total Suction Lift (Hv): Sum of static suction lift, friction, and entrance losses in the suction piping.
• Velocity Head (hv): Pressure in meters needed to create flow velocity, defined by hv= v²/2g.
  • v is the velocity in the pipe in m/s.
  • g is the acceleration due to gravity in m/s².
• Water Power: Theoretical power required for pumping, expressed as the head and capacity of the pump in kilowatt.

General Conditions for Test and Inspection

• Testing requires a commercially produced or prototype pump, with commercially manufactured pumps sampled per PAES 103.
• The manufacturer/dealer must provide the pump, specifications, and relevant information to an authorized agency.
• A manufacturer/dealer representative is appointed to handle the testing, and the manufacturer must abide by the testing agency conditions.
• Testing occurs in a laboratory or at the installation site.
• Water used should be clean and between 10–40°C.
• Head measurements use water columns or manometers, with mercury manometers, Bourdon gauges, electrical pressure transducers, or dead weight gauge testers for high pressure.
• Discharge is measured using a weighing tank for small flow rates, or a weir, venturi, nozzle, orifice plate, or Pitot tube for larger flow rates.
• Pump input power is measured with a dynamometer or calibrated primemover.
• All instruments used must be calibrated.
• Testing occurs at the smallest attainable suction head/lift for the basic performance curve.
• Ambient conditions, including atmospheric pressure, temperatures (dry bulb and wet bulb), and relative humidity are recorded at equal intervals.
• The test engineer may suspend the testing if the performance is impacted by a breakdown or malfunction during the test run.

Tests and Inspection

• Inspections verify the pump's mechanism, dimensions, materials, and accessories against the manufacturer's specifications, and a level surface is used for verification.
• A performance test determines pump performance characteristics: conducted at the manufacturer's recommended speed, and discharge and total head are varied by regulating the valve on the discharge side.
• In cases where tests must take place in situ, the static suction lift, static discharge head, size and length of pipes and number of bends of piping are recorded.
• Data measurements are taken at a minimum of ten different discharge values, from no-discharge to maximum flow rate (at least one measured at a head lower than the specified head, in the case of centrifugal pumps).
• During the test the Vacuum gauge on the suction side and the pressure gauge on the discharge side must are read and discharge and input power to pump are measured.
• The magnitude of vibrations and presence of extra-ordinary noises is determined during operations. Results should be presented in tabular and graphical forms for the following curves:
  • Total head vs. Discharge
  • Pump input power vs. Discharge
  • Efficiency vs. Discharge
  • Pump Speed vs. Discharge
  • NPSH vs. Discharge
• A cavitation test determines the suction conditions of the pumps using the same setup as performance testing using water between 10 - 40°C.
• Testing is conducted at the manufacturer's recommended speed, operating the pump at constant discharge and varying suction pressure.
• Measurements are recorded on discharge, suction, discharge pressure, and power at every suction pressure setting.
• Magnitude of vibrations and presence of extraordinary noises is determined.
• A priming test determines the priming time of a self-priming pump, mounted on a test setup with a static lift of at least 3 meters and without check or foot valves in the suction piping.
• Before operation priming chamber is filled with water at 10-40 °C, then operated to record time elapsed between starting and obtaining steady discharge gauge or full flow.

Test Report Format

The test report should include:

• Name of Testing Agency
• Test Report Number
• Title
• Summary
• Purpose and Scope of Test
• Methods of Test
• Description of the Pump
• Table 1 - Centrifugal Pump Specifications
• Table 2 - Results of Performance Test
• Table 3 - Results of Cavitation Test
• Results of Priming Test
• Observations
• Name and Signature of Test Engineers

Explore the procedures for pump performance testing, covering suspension criteria, preliminary inspections, and site-specific measurements. Learn about discharge value measurements for centrifugal, mixed flow, and axial flow pumps, and the importance of recording inspection details.