How to Read ANSI Pump Size Codes

What Each Part of a Size Code Means

The first two numbers are the nozzle sizes and the number after the dash is the nominal impeller diameter, all in inches. Which nozzle comes first depends on the pattern; some codes add a group prefix or a suffix.

B73.1 groups sizes under dimension designations from AA to A120 (see ANSI/ASME B73.1 explained); the pump type is covered in what is an ANSI pump.

Why the Same Size Is Written 2x3-13 and 3x2-13

Manufacturers order the nozzles differently: the Goulds 3196 pattern writes discharge first; the Durco Mark 3 pattern writes suction first, often with the group in front; YSM’s D Mark III always writes the group (2K3x2-13).

How to Convert a Goulds 3196 Pattern Code to a Durco Mark 3 Pattern Code

Reverse the two nozzle numbers and keep the impeller number (Goulds-pattern 2x3-13 becomes Durco-pattern 3x2-13), then confirm the B73.1 designation in the table below.

1. Establish which pattern the code came from.
2. Reverse the nozzle numbers; suffixes do not always carry across (Goulds-pattern 1x2-10 corresponds to Durco-pattern 2x1-10A).
3. Look up the designation and confirm it against the nameplate and the installed pump drawing; for Durco-pattern 3x2-13 the corresponding D Mark III code is 2K3x2-13.

ANSI Pump Sizes by B73.1 Designation (Conversion Table)

Match a Goulds 3196 pattern size to a Durco Mark 3 pattern size by B73.1 designation: A30 is Goulds-pattern 2x3-13, Durco-pattern 3x2-13 and D Mark III 2K3x2-13. The same designation means the same B73.1 installation envelope for that designation; it does not mean the same impeller, curve or parts.

Low-flow sizes have no designation in the ASME B73.1M-1991 dimension table or in YSM’s tables; their installation dimensions come from the certified drawing.

Installation dimensions are on the G196 vs Goulds 3196 and D Mark III vs Durco Mark 3 pages and in technical downloads; casing and impeller references by size are on the Goulds 3196 pattern and Durco Mark 3 pattern pump parts pages. The certified drawing governs.

Open dataset. The size designations, frame and group families and item numbers for YSM’s G196 and D Mark III series are also published as an open dataset (CC BY 4.0, version 1.0.0) on Zenodo: doi.org/10.5281/zenodo.22920668, with mirrors on Hugging Face and GitHub.

When a Reversed Code Is Not the Same Designation

A suffix, a larger nominal impeller or a size missing from one table can change or hide the designation, so always finish on the designation.

• A suffix changes it. 3x4-10 and 4x3-10 are A70 (D 8.25 in, X 11 in); 3x4-10H and 4x3-10H are A40 (D 10 in, X 12.5 in).
• Sources disagree. Goulds-pattern 1.5x3-8 is AB (D 5.25 in, X 6.5 in); 3x1.5-8 has no designation in YSM’s D Mark III table (D 7 in, X 7.5 in). Goulds-pattern 2x3-6 is AC; 3x2-6 is A10 in YSM’s D Mark III table, and references give different dimensions for it. For both, the certified drawing governs.
• The impeller number differs. From A90 to A120 most Goulds-pattern and Durco-pattern strings differ in the impeller number (13 or 15 in vs 14 or 16 in): A90 is Goulds-pattern 6x8-13 but Durco-pattern 8x6-14A.

The Group Prefix: 1K, 2K, 3K

The prefix is the power-end group in the Durco Mark 3 pattern naming, which the D Mark III also uses: 1K is Group 1, 2K Group 2, 3K Group 3. It fixes the power end and, in YSM’s tables, the CP dimension; D, X and the other mounting dimensions follow the B73.1 designation, which the prefix alone does not identify (Group 2 spans eight designations).

Goulds-pattern frames are not written in the code; see the ANSI pump power frame cross-reference.

Suffix Letters (A, H, HH, G, N) and the LF Tag

Suffix letters mark variants of a size. YSM’s Durco Mark 3 pattern parts page describes A, H and HH as alternative hydraulics of a size (H and HH high-head); for Goulds-pattern G, H and N the meaning is OEM-specific and is confirmed from the OEM literature or the nameplate. In the tables above:

• A appears only on Durco-pattern strings (2x1-10A, 3x2-10A, 6x4-13A); G and N only on Goulds-pattern strings (3x4-8G, 4x6-10G, 8x10-15G; 6x8-15N); HH only on Durco-pattern 4x3-13HH, which is A40 like 4x3-13.
• H can change the designation (3x4-10H is A40, not A70) or leave it unchanged (6x4-10H stays A80, 10x8-16H stays A120).
• LF marks the dedicated low-flow hydraulic. The G196 Low Flow places it after the impeller number (1x2-10LF); the D Mark III Low Flow places it before the dash (2K2x1LF-10).

Nameplate size strings can carry other letters or a value after a slash; send the string exactly as written.

What a Size Code Does Not Tell You

A size code gives the nozzle sizes and the nominal impeller diameter only. It does not give the flange rating (Class 150 or 300), facing or nozzle orientation, auxiliary connections, baseplate type, the MTX or LTX frame, the trimmed impeller diameter, materials or the performance curve; for what to send, see the pump nameplate and drawing guide and information needed before replacing an ANSI process pump. Nor does it size a new pump: selection against a duty point is covered in the ANSI pump selection guide.