ISO 2858:1975

Overview

ISO 2858:1975 defines the designation, nominal duty point and principal dimensions for end-suction centrifugal pumps with a maximum operating rating of 16 bar. The standard standardizes how pumps are identified and sized to support interchangeability, correct pump selection and flange compatibility for branch sizes from 50 mm to 200 mm. A representative figure (side and front views) and a tabulated list of nominal duty points and dimensions accompany the standard.

Key Topics

• Designation format: The pump designation comprises three numbers - inlet diameter, outlet diameter and nominal impeller diameter. Example: 80-50-250 (inlet 80 mm, outlet 50 mm, impeller 250 mm).
• Nominal duty point and dimensions: Tabulated nominal duty points and dimensional data are provided for specified branch sizes; unspecified forms and dimensions are left to the manufacturer's discretion.
• Flange and connection guidance: Flange sizes covered in the standard range from 50 mm up to and including 200 mm. All threaded connections are to comply with ISO/R 228.
• Static test pressure: The standard specifies static test pressure at 1.5 times the maximum discharge pressure but not exceeding 24 bar; relations between cold test and hot operating pressures must be agreed between manufacturer and user.
• Tapping points and rotation: Typical tapping points include a 3/8 in. connection for cooling/heating and stuffing-box tapping up to 1/2 in. Rotation is clockwise when viewed from the driven end.
• Referenced ISO documents: ISO/R 228, ISO 496 (shaft heights), ISO/R 775 (shaft ends), ISO 3069 (seal cavities) and ISO 2084 (flange dimensions) are cited for related dimensional and connection requirements.

Applications

ISO 2858:1975 is intended for manufacturers, specifiers and end users involved in:

• Pump selection and procurement where standardized designation and interchangeability reduce engineering effort.
• Mechanical and piping design, ensuring flange compatibility and consistent connection sizes across suppliers.
• Quality assurance and testing, using the prescribed static test pressure rules.
• Technical communication between OEMs, contractors and plant operators when defining nominal duty points and dimensional requirements.

By following ISO 2858:1975, organizations can streamline spare-part matching, simplify maintenance logistics and reduce mis-specification risk.

Related Standards

• ISO/R 228 - Pipe threads where pressure-tight joints are not made on the threads.
• ISO 496 - Driving and driven machines - Shaft heights (referenced for shaft geometry).
• ISO/R 775 - Cylindrical and conical shaft ends.
• ISO 3069 - Seal and packing cavity dimensions for end-suction pumps.
• ISO 2084 - Flange dimensions (noted as a useful reference for flange details).

For practical implementation, consult the full ISO 2858:1975 document together with the referenced ISO standards and the pump manufacturer to confirm temperature limits, alternative dimension options and any branch-size exceptions.