HI 40.6 – A Proven Standard for Uniform Pump Efficiency Tests

HI 40.6 Methods for Rotodynamic Pump Efficiency Testing, initially published in 2014 and most recently revised in 2021, establishes minimum testing protocols for uniform testing and determination of rotodynamic pump efficiency. From providing prescriptive test procedures to establishing suitable time periods for calibration of test instruments, HI 40.6 provides pump users, engineering consulting firms, pump manufacturers, pump distributors, and suppliers to the pump industry with a common understanding among all stakeholders of how to perform efficiency tests and how pump efficiency is determined. This was accomplished via the standards development consensus process utilized by the Hydraulic Institute to publish standards and guidelines for the pump industry.

A pump efficiency test consists of measurement of flow, head, and pump power input. Pump efficiency is a dependent variable that is calculated from these measured independent variables. Uncertainty must be considered, as is the case with all tests. The uncertainty of a measurement depends on the residual uncertainty of the measurement device and on the method of measurement used.

To determine the overall (wire-to-water) efficiency of a motor pump unit or a complete pump (i.e., bare pump, drive mechanical, driver and drive coupled together and treated as an integral unit), the driver or control power input and the pump power output are measured with the drive working under test conditions.

The ratio between pump power output and driver or control power input yields the overall efficiency. The driver or control power input is measured at the input terminals of the motor or control, if present on the pump under test. If the tested pump efficiency and the efficiency of all pump components are known, the product of the pump and all component efficiencies may be used to calculate overall efficiency.

It is important to note that the HI 40.6 standard is intended to be used for efficiency testing at pump test facilities or laboratories only. This is because industry experience has shown that it is very difficult to perform measurements accurate enough to meet the acceptable limits of measurement uncertainties when testing to this standard in the field. Therefore, field testing is not permitted as a method of efficiency testing.

The HI 40.6 test standard was developed out of a need to have an industry standard that can be incorporated by reference by the U.S. Department of Energy (DOE) in its efforts to develop energy conservation standards for pumps. This is a common practice by federal agencies, which are directed by the National Technology Transfer and Advancement Act to use technical industry standards that are developed by voluntary consensus standards bodies. This eliminates the cost to the government of developing its own standards and reduces the potential of conflicting with industry’s proven methods.

After the initial publication of the HI 40.6 test standard, the Hydraulic Institute (HI) subsequently launched the Pump Test Laboratory Approval Program (PTLAP) to position pump manufacturers to participate in the HI Energy Rating Program and provide support in complying with the testing requirements of the Energy Conservation Standard. Through the lab program, pump manufacturers’ test facilities and independent laboratories can have third-party verification that pump tests are being performed in accordance with the HI 40.6 test standard.

The scope of the HI 40.6 standard is limited to the pumps listed in 10 CFR 431.464. This was done intentionally since the standard was developed solely to support the regulation efforts. The scope of regulated products in this section are divided into three types of clean water pumps, (a) general pumps, (b) dedicated purpose pool pumps and (c) circulator pumps. As of March 24, 2023, DOE expanded the scope of general clean water pumps covered, within certain pump characteristics, as follows: 

• End suction close-coupled (ESCC);
• End suction frame mounted/own bearings (ESFM);
• In-line (IL);
• Radially split, multi-stage, vertical, in-line casing diffuser (RSV);
• Submersible turbine (ST) pumps;
• Radially-split, multi-stage, horizontal, end-suction diffuser casing (RSHES);
• Radially-split, multi-stage, horizontal, in-line diffuser casing (RSHIL);
• Small vertical in-line (SVIL); and
• Vertical Turbine (VT).

Note that despite the scope of the HI 40.6 being limited to the scope of the federal regulation, it can technically be used perform an efficiency test on any type of rotodynamic pump. This is because the testing requirements and procedures contained HI 40.6 reflect common industry methods derived from ANSI/HI 14.6 Rotodynamic Pumps for Hydraulic Performance Acceptance Tests. To develop HI 40.6 the grade 2 test requirements that pertain specifically to the determination of efficiency were extracted from ANSI/HI 14.6. However, the criteria for acceptance in ANSI/HI 14.6 was not incorporated into HI 40.6, which illustrates that HI 40.6 and ANSI/HI 14.6 serve different purposes. For acceptance criteria and grades, refer to ANSI/HI 14.6.

Industry standards to test the efficiency of pumps are not new and can be traced back in Hydraulic Institute Standards preceding 1950. Although HI 40.6 has been published for less than ten years, its requirements are based on over 70 years of industry experience, has been fine-tuned over the decades through the consensus process, and serves as a trusted standard for efficiency testing of rotodynamic pumps.

For more information about estimating and testing pump efficiency, refer to ANSI/HI 20.3 Rotodynamic Pumps Guideline for Efficiency Prediction and HI 40.6 Methods for Rotodynamic Pump Efficiency Testing. For frequently asked questions related to pump efficiency, refer the HI Pump FAQs on pumps.org.

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