ANSI/ASME B73.1 · Durco Mark 3 type · Non-OEM manufacturer
D Mark III Series — ANSI B73.1 Pumps Interchangeable with the Durco Mark 3 Type
The D Mark III series is YSM’s family of ANSI/ASME B73.1 chemical process pumps built to the Durco Mark 3 dimensional pattern with a reverse-vane impeller. Three pumps share the same Group 1 / 2 / 3 power ends and the same materials programme: the D Mark III General Purpose, the D Mark III Low Flow and the D Mark III Unitized Self-Priming. Each is dimensionally interchangeable with the corresponding Mark 3-type pump in the same size and group, and each is supplied as a non-OEM replacement pump or as replacement parts for an installed pump of that pattern.
Series-level published range of the general-purpose sizes; working pressure to 27 bar (400 psi). Individual size, impeller diameter, material and seal arrangement set the limits for a given pump.
YSM (Jinan Yingsiman Machinery Co., Ltd.) manufactures the D Mark III in China to its own drawings and patterns. This page is the entry point for the Flowserve / Durco-type range; the three product pages carry the size tables, dimensions, materials, parts lists and part-number cross-references.
The D Mark III family
| Pump | Duty | Sizes / groups | Interchangeable with |
|---|---|---|---|
| D Mark III General Purpose | Clean and lightly contaminated liquids, general chemical and utility transfer | 26 sizes, Groups 1 / 2 / 3 | Durco Mark 3 pattern (same size and group) |
| D Mark III Low Flow | Low flow at high head: injection, dosing, reflux | 4 sizes, Groups 1 / 2 | Durco Mark 3 LF pattern |
| D Mark III Unitized Self-Priming | Liquid source below the pump; lines that empty between starts | D Mark III power ends | Durco Mark 3 unitized self-priming pattern |
General purpose
D Mark III General Purpose
Clean and lightly contaminated liquids, general chemical and utility transfer. 26 sizes, Groups 1 / 2 / 3. Interchangeable with the Durco Mark 3 pattern (same size and group).
View productLow flow
D Mark III Low Flow
Low flow at high head: injection, dosing, reflux. 4 sizes, Groups 1 / 2. Interchangeable with the Durco Mark 3 LF pattern.
View productUnitized self-priming
D Mark III Unitized Self-Priming
Liquid source below the pump; lines that empty between starts. D Mark III power ends. Interchangeable with the Durco Mark 3 unitized self-priming pattern.
View productSeries performance envelope
The general-purpose sizes cover flows to 1,700 m³/h (7,500 US gpm), heads to 300 m (990 ft), working pressures to 27 bar (400 psi) and temperatures from −73 °C to 370 °C (−100 °F to 700 °F). Individual size, impeller diameter and material set the limits for a given pump; low-flow and self-priming selections are confirmed on the reviewed curve for the submitted duty point.
Power-end groups and parts commonality
Within a group the bearing housing, adapter, shaft, hook sleeve, bearing isolators and seal chamber hardware are common to the general-purpose, low-flow and self-priming pumps.
| Group | General-purpose sizes | Low-flow sizes | Bearing frame / housing (YSM ref.) | Shaft / sleeve (YSM ref.) |
|---|---|---|---|---|
| Group 1 (1K) | 1K1.5×1-6, 1K3x1.5-6, 1K3x2-6, 1K1.5×1-8, 1K3x1.5-8 | 1K1.5x1LF-4, 1K1.5x1LF-8 | D1119 / D1201 | D1105, D1105S / D1177 |
| Group 2 (2K) | 2K3x2-8, 2K4x3-8, 2K2x1-10A, 2K3x1.5-10A, 2K3x2-10A, 2K4x3-10, 2K4x3-10H, 2K6x4-10, 2K6x4-10H, 2K3x1.5-13, 2K3x2-13, 2K4x3-13, 2K4x3-13HH, 2K6x4-13A | 2K2x1LF-10, 2K3x1.5LF-13 | D2119 / D2201 | D2105, D2105S / D2177 |
| Group 3 (3K) | 3K8x6-14A, 3K10x8-14, 3K6x4-16, 3K8x6-16A, 3K10x8-16, 3K10x8-16H, 3K10x8-17 | — | D3119 / D3201 | D3105, D3105S / D3177 |
Full dimension tables (weight, X, O, D, E1, E2, CP, F, H, U, keyway, V, Y), the sectional parts list and the complete part-number cross-reference are on the D Mark III General Purpose page; low-flow sizes are on the D Mark III Low Flow page. Group 3 has no low-flow size in the current programme; a Group 3 low-flow duty is reviewed against the general-purpose sizes with the selection.
Materials of construction
Casing, impeller, rear cover, seal chamber and gland are cast in WCB carbon steel, CF8M (316 stainless steel), CF3M (316L stainless steel), CD4MCu duplex stainless steel, super duplex stainless steel, CN7M (Alloy 20), Monel, Nickel, Inconel, Hastelloy B and Hastelloy C, Titanium and Zirconium alloy. Higher alloys use the same patterns as the CF8M pump, so an exotic-alloy D Mark III keeps the same dimensions and the same interchangeability. Shafts are SAE 4140 or 316SS with hook sleeves in the wet-end alloy; bearing housings and adapters are ductile iron.
Seal chambers
CBS (cylindrical bore, standard), CBL (cylindrical bore, large), FMS and FML (flow-modifier) chambers and a packed stuffing box are available across the series; FMI-type chambers and jacketed rear covers are not offered. The chamber is selected with the seal type, solids content and cooling need; the recommendation is issued with each selection.
Replacement programme
The D Mark III is also supplied as a non-OEM replacement for, and is dimensionally interchangeable with, a Summit Clark 3 of the same size and group, which follows the Mark 3 pattern. The Summit Clark 3 replacement page carries the group cross-reference. The ANSI Replacement Pumps and Parts hub lists all replacement pages and the parts programme. Parts for the Mark 3 pattern by Group and size designation, with the OEM part numbers they correspond to, are listed on the Durco Mark 3 pattern parts page.
Non-OEM Mark 3-type pumps and parts manufactured in China
YSM is an independent manufacturer. Pumps and parts are produced to YSM’s own drawings and patterns, to the ANSI/ASME B73.1 dimensional standard, and are not supplied by or associated with the original equipment manufacturer. Every impeller is dynamically balanced, every casing is hydrostatically tested and every assembled pump can be performance-tested on request; material certificates, balance reports and test reports are issued with the order, and a dimensional inspection report can be issued with it. Factory witness testing and third-party inspection (SGS, BV, TÜV) are accepted.
Identify an installed pump before ordering
Send the model, size (for example 2K4x3-10), group (1, 2 or 3), serial number and, where available, the outline drawing and existing part numbers. Our nameplate and drawing identification guide explains where to find each item.
Where a part is obsolete or no drawing exists, it can be reverse engineered from the removed part or a sample.
Documentation
D Mark III performance coverage curves, sectional drawings with parts lists, installation dimensions and interchangeability tables (Rev. A, 2026-07) are available as PDFs on the Technical Downloads page.
D Mark III Series FAQ
What does 'Durco Mark 3 type' mean on this page?
It identifies the dimensional pattern the D Mark III series follows: the ANSI/ASME B73.1 envelope with the reverse-vane impeller and the Group 1 / 2 / 3 power-end structure used by the Durco Mark 3. A D Mark III of the same size and group fits where a Mark 3 was installed. Durco and Mark 3 are trademarks of their owner; YSM is an independent non-OEM manufacturer.
How is the reverse-vane design different from an open-impeller ANSI pump?
The impeller vanes face the rear cover, so the running clearance is set between impeller and cover and adjusted at the bearing housing. Removing the casing does not disturb the setting, which simplifies seal work and in-place maintenance; the G196 series uses the front-clearance open impeller of the 3196 pattern instead. On the D Mark III the reverse-vane impeller is standard, and open impellers are available for part of the size range, confirmed per size during review.
Which D Mark III pump should I start from?
General purpose for most chemical and utility duties; Low Flow when the duty sits far left of a standard pump’s best efficiency point; Unitized Self-Priming when the liquid source is below the pump. Send the duty point and liquid data and we route the enquiry.
Do the three pumps share parts?
Yes. All three are built on the D Mark III Group 1 / 2 / 3 power ends, so bearing housings, adapters, shafts, hook sleeves, bearing isolators and seal chamber hardware are common within a group. Casings, rear covers and impellers are specific to each pump type and size.
Can YSM replace a Summit Clark 3 with the D Mark III?
Yes. The Summit Clark 3 follows the Mark 3 pattern, so the D Mark III of the same size and group is supplied as a non-OEM replacement for, and is dimensionally interchangeable with, an installed Clark 3. The Summit Clark 3 replacement page carries the group cross-reference; the interchange is confirmed from the nameplate before order.
All manufacturer names, model numbers and trademarks are used for reference and compatibility identification only. YSM Pumps (Jinan Yingsiman Machinery Co., Ltd.) is not affiliated with, sponsored by, or endorsed by any of these manufacturers. All pumps and parts are non-OEM and manufactured by YSM.
Request a D Mark III series selection or interchange review
The form below carries the initial request. The selection review uses, where available:
- Duty point: rated flow and total head (state units), plus minimum and maximum flow if the pump will run across a range.
- Liquid: name or composition, concentration, temperature, specific gravity, viscosity, solids content and size, vapour pressure if volatile.
- Suction conditions: NPSH available, suction lift or flooded suction, tank or vessel layout.
- Installed pump data for replacements: nameplate model, size and frame or group, serial number, and a photo of the nameplate; the pump outline or foundation drawing if available.
- Materials, seal type, seal flush plan, motor supply (voltage, frequency, phase) and any documentation you require (material certificates, test reports, drawings).
We reply with a reviewed selection, the size and frame proposed, materials, seal arrangement and a quotation. Where the enquiry is a replacement for an installed pump, we confirm the dimensional interchange from your nameplate and drawing data before order. Drawings and nameplate photos can follow during review.
Pump RFQ
Replied by the technical team with the size-specific configuration and quotation scope.
D Mark III Selection Decision Guide
Selection boundaries save both sides a review cycle: the fastest quotation is the one that starts on the right page. The D Mark III is the family default for reverse-vane B73.1 duties; the lists below mark where a different starting point serves the duty better. Crossing a boundary is not a downgrade — an open-impeller family or a heavy-duty stock pump is simply a different answer to a different duty.
Start with D Mark III when
- An ANSI/ASME B73.1 reverse-vane process pump is the preferred starting point.
- The enquiry includes general chemical transfer, wet-end parts or an existing D Mark III-style reference.
- The required review involves Group 1, 2 or 3 power-end context.
Review another page when
- The duty point is specifically low-flow: compare the D Mark III Low Flow page.
- An open-impeller family is preferred: review the G196 Series.
- Heavy-duty paper-stock service is the main question: review the G 3175 / 3180 / 3185 Series.
D Mark III Application Guides
Use the chemical liquid transfer guide, low-flow application guide and ANSI process pump maintenance and replacement path to prepare a reviewed enquiry.
Wastewater and Material Review
Apply the wastewater chemical-transfer boundary and material input checklist before proposing a D Mark III configuration.