Pumps & Systems, February 2013
The Hydraulic Institute’s new test standard, ANSI/HI 14.6 Rotodynamic Pumps for Hydraulic Performance Acceptance Tests, provides the pump community with a globally accepted standard for testing rotodynamic pumps of the centrifugal, mixed flow and axial types. It supersedes two test standards: ANSI/HI 1.6 Centrifugal Pump Tests and ANSI/HI 2.6 Vertical Pump Tests. The new standard features significant changes in test acceptance requirements and in educational content. It also includes “must-know” requirements for anyone involved with the hydrostatic or performance testing of pumps.
With ANSI/HI 14.6, two significant standards now have identical pump acceptance test criteria with worldwide acceptance. The other is ANSI/HI 11.6 Rotodynamic Submersible Pumps for Hydraulic Performance, Hydrostatic Pressure, Mechanical, and Electrical Acceptance Tests.
For more than a decade, the previous versions, ANSI/HI 1.6 and ANSI/HI 2.6, served as the standards that defined testing requirements for centrifugal pumps. ANSI/HI 14.6 has similar test methods and procedures but with noticeably different changes to test acceptance requirements and informational details. The updated standard is also formatted and organized in a way that provides quick and easy access to information regarding rotodynamic pumps; terms and definitions; multiple acceptance tests; various testing procedures; and an array of useful information regarding pump characteristics, performance and guidelines.
ANSI/HI 14.6 is meant to be used for acceptance testing at pump test facilities or laboratories only and cannot be used in its entirety for testing in the field. This standard applies to the pump (flange-to-flange relationship), without any fittings. However, additional information regarding pump testing with fittings and other equipment can be found in the standard’s appendices. If contractually agreed upon by the manufacturer/supplier and the purchaser, the pump may also be tested with a combination of fittings. The differences between the previous versions of the test standard and the new standard are significant enough to warrant the pump community’s attention.
These terms appear throughout the body of the standard as well as in the appendices:
- Normative: “What is written in the standard must be adhered to comply with the standard.”
(ANSI/HI 14.6, p. vii)
- Informative: “Written to inform and educate the user and do not require compliance.”
(ANSI/HI 14.6, p. vii)
- Guarantee point: “The specified and contractually agreed on rated point (duty point).”
(ANSI/HI 14.6, p. 10)
- NPSH3: “Unless otherwise specified, a 3 percent drop in head (the accepted industry practice) will be used to determine NPSHR and defined as NPSH3.” (ANSI/HI 14.6, p. 19)
These terms clarify to the pump community to which processes and procedures they must adhere and which may be recommended for further consideration. NPSH3 allows the pump community to know exactly what percentage of a drop in head is used to determine the NPSHR (required), removing ambiguity regarding that value. As a result, NPSH3 is used instead of NPSHR.
Throughout ANSI/HI 14.6, the pump community will find sections labeled “General” for pump acceptance tests, measurement uncertainty, test procedures and test arrangements, hydrostatic pressure testing, recommended tests, NPSH test requirements, measurement of pump power input, and special test methods.
These sections provide an introduction and background information in advance of the substance and specific procedures of the topics. This added feature helps the document flow from section to section and highlights the importance of the respective topics.
Acceptance Grades and Tolerances
Pump performance acceptance grades for flow, head, efficiency and power are used in ANSI/HI 14.6 when evaluating the acceptance of a pump for a guarantee point. Note that power or efficiency can be specified but not both. The previous versions used two grades of accuracy for pump acceptance criteria, while ANSI/HI 14.6 uses three. Table 22.214.171.124 is an addition to the new standard and is used to refer to acceptance grades and tolerance bands.
Six pump performance test acceptance grades are used: 1B, 1E, 1U, 2B, 2U and 3B. Grade 1 is the most stringent, and the “U” specifies having a unilateral tolerance band. The “B” specifies having a bilateral tolerance band. Acceptance grade 1E can be used when energy efficiency is of importance and is also bilateral.
Table 126.96.36.199. Pump test acceptance grades and corresponding tolerance band
The purchaser and manufacturer must agree on a specific grade to use and judge if a particular pump will meet a guarantee point. If no acceptance grade is specified, the standard reverts to the default test acceptance grade in Table 14.6.4.