Black double diaphragm pump with green O-rings and flanged connections on a white background

Black industrial double diaphragm pump with flanged connections on a white background

3D render of a stainless steel double diaphragm pump.

Specialty Pumps

Heavy Duty Flap Valve Diaphragm Pump

The DP37 is a heavy duty flap valve pump designed for fluids containing solids up to 2 inches (50 mm) in diameter. It handles abrasive, chunky or fibrous materials that would block or damage standard ball check pumps. The horizontal flow path reduces fluid resistance, prevents accumulation, and allows easier maintenance. It delivers up to 171 GPM (647 LPM) at 120 psi (8.3 bar), with a dry suction lift of 8.3 m. The bolted construction and modular design make it easy to service in the field. The patented stall-free, lube-free air valve ensures reliable operation under load.

Maximum flow rate	171GPM(647LPM)
Maximum operating pressure	120psi(8.3bar)
Suspended solids max diameter	2 inches (50mm) in diameter
Fluid inlet	Flange: 2" ANSI Class 150 /DN50 PN10
Fluid outlet	Flange: 2" ANSI Class 150 /DN50 PN10

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Mining And Coal Handling Water And Wastewater Treatment

Key Benefits

What The Heavy Duty Flap Valve Build Buys You

The flap valve design and horizontal flow path are not just different - they solve specific problems that ball check pumps cannot.

Passes 50 Mm Solids Without Blockage

The swing flap valves open wide and allow solids up to 2 inches in diameter to pass through. This is not possible with ball check pumps, which are limited to 6.4 mm in the DP3X range. The horizontal flow path reduces resistance and prevents material from lodging in the fluid chamber.

No Fluid Accumulation In The Pump Body

The horizontal flow path means fluid moves through the pump in a straight line, not vertically. This prevents pooling, which can lead to contamination, corrosion or clogging in vertical flow designs.

Faster Trip-Over And Less Pulsation

The patented stall-free air valve shifts quickly and positively, reducing the time the pump spends at mid-stroke. This results in smoother flow and higher effective output compared to pumps with slower shift mechanisms.

Built For Field Service And Repair

The bolted construction and modular design allow the fluid end to be disassembled without removing the pump from the skid. The flap valves, seals and diaphragms are accessible from the top, reducing downtime during maintenance.

Ceramic Seals In Both Air Valves

Dual ceramic dynamic seals on the major and pilot air valves resist wear from dirty or low-pressure air supplies. They maintain tight sealing over long periods, even in harsh environments.

Anti-Icing By Design

The built-in vacuum chamber reduces discharge air pressure, which lowers the temperature drop that causes icing and reduces exhaust noise. The sound level is 80.5 dB(A) at 70 psi and 60 cycles per minute.

Who It Is For

Who Buys This Pump

This pump is for plants that move thick, chunky, or abrasive fluids where standard ball check pumps fail. It is not for clean liquids or high-pressure spraying.

Waste water and sludge treatment plants moving grit-laden slurry, grease, and fibrous debris
Metalworking shops pumping coolant with swarf, chips, and metal fragments
Mining and quarry operations transferring slurry with coarse particles
Food and beverage plants handling pulp, mash, or chunky condiments with fibrous material
Chemical plants transferring viscous or abrasive slurries that clog ball check pumps
Maintenance teams clearing blocked pipes or sumps with large solids

Problems It Solves

Problems This Pump Is Bought To Fix

Every order for this pump starts with a failure in one of these five areas.

A ball check pump clogs on solids larger than 6.4 mm, while this pump passes 50 mm solids without jamming
A vertical flow pump accumulates fluid in the chamber, leading to contamination or freezing, while the horizontal path prevents pooling
A pump with a slow air valve stalls at mid-stroke, while this one trips over cleanly and runs continuously
A pump with a welded body cannot be repaired in the field, while this one uses bolted construction for fast on-site service
A pump with a single wide opening flap valve is not supported by the data sheet; this pump uses dual flap valves with a proven design

Application Scenarios

Where It Ends Up In A Plant

01

Sludge And Wastewater Transfer

The pump handles thick sludge with grit and fibrous material, moving it from tanks to dewatering systems without clogging.

02

Coolant And Swarf Removal

It transfers coolant laden with metal chips from machine shop sumps to filtration systems, surviving abrasive wear and high solids content.

03

Pulp And Fibrous Material Handling

Used in food processing to move fruit pulp, mash, or vegetable chunks without blockage or damage to the pump.

04

Industrial Sump And Pit Emptying

One person can carry the pump to a pit, drop in the hose, and run it dry without damage, even with large solids present.

Technical Features

How The Air End Is Built

The air end is where Nuodean's patented design delivers reliability and long life.

Patented Stall-Free, Lube-Free Air Valve
The pilot air valve shifts the major valve mechanically and pneumatically, ensuring a fast, positive changeover. No lubricator is required, and the system remains clean and maintenance-free.
Dual Ceramic Dynamic Seals
Both the major and pilot air valves use ceramic dynamic seals. These resist wear from dust, moisture, and low air pressure, extending service life.
Anti-Icing Vacuum Chamber
The built-in vacuum chamber reduces discharge air pressure, which lowers the cooling effect and prevents ice formation in cold environments.
Horizontal Fluid Path With Swing Flap Valves
The fluid flows horizontally through the pump. Swing flap valves open fully to pass large solids and close tightly to prevent backflow. This design reduces resistance and prevents fluid accumulation.
Bolted, Modular Construction
The fluid end is bolted together, allowing disassembly without removing the pump from the skid. The diaphragms, valves, and seals are accessible from the top for fast repair.
Selectable Wetted Materials
Center body, fluid caps, manifold, seat, flap valve, diaphragm, and hardware are selected in the model code. Choose materials to match your fluid and service conditions.

Specifications

Published Performance

Transcribed from the Nuodean data sheet published for this pump.

Maximum flow rate	171GPM(647LPM)
Maximum operating pressure	120psi(8.3bar)
Suspended solids max diameter	2 inches (50mm) in diameter
Fluid inlet	Flange: 2" ANSI Class 150 /DN50 PN10
Fluid outlet	Flange: 2" ANSI Class 150 /DN50 PN10
Air inlet	3/4" BSPT(3/4" NPT Available On Request)
Maximum dry suction lift	27.2feet(8.3m)
Weight	130kgs
Pump Size	50-2"
Model series code	DP37-XXXXXXX, DP3X Series (DP37 model shown), DP37

Materials

Material Options

Set in the model code. Ask us if you need a combination the code allows but the sheet does not show.

Diaphragm options	2-Nitrile, 4-PTFE/Santoprene, 9-Hytrel, B-Santoprene
Ball check options	2-Nitrile, C-Hytrel, 4-PTFE, E-Santoprene
Seat options	1-Aluminum, 2-316 StainlessSteel, 4-PVDF(Kynar), 5-CarbonSteel, E-Santoprene, 8-Hard StainlessSteel, 9-Hytrel, G-Nitrile
Housing options	stainless steel (available material option), A-Aluminum, C-CastIron, S-StainlessSteel

Performance figures are transcribed from the Nuodean data sheet for this pump. Flow is measured at the pump discharge with water at ambient temperature; your duty point depends on air supply pressure, suction conditions, fluid viscosity and discharge head. Ask our engineers to confirm the duty point before you order.

Quality Control

Before It Is Crated

Every pump is run on air before shipment to verify shift behavior and air valve performance
Sound level is published at 70 psi and 60 cycles per minute, so you can verify it on site
All wetted materials are checked against the model code at assembly
The pump ships with the data sheet, the fluid section part list, and the air section part list

Customization

What You Can Change

Center body in aluminum or cast iron
Fluid caps and manifold in aluminum, 316 stainless steel or cast iron
Seat in aluminum, 316 stainless steel, PVDF, carbon steel, hard stainless steel, Santoprene, Hytrel or nitrile
Flap valve in nitrile, Hytrel, PTFE, or Santoprene
Diaphragm in nitrile, PTFE with Santoprene backing, Hytrel, or Santoprene
3/4 inch BSPT air inlet, with 3/4 inch NPT available on request
Flange connections: 2 inch ANSI Class 150 / DN50 PN10

Comparison

Against The Alternatives

Where this pump wins and where you should be buying something else.

Versus the 2 inch ball check pump (DP31-50)	The DP31-50 passes 6.4 mm solids and weighs 29.6 kg. The DP37 passes 50 mm solids and weighs 130 kg. Choose the ball check pump for clean fluids and portability. Choose the flap valve pump for solids.
Versus the 2 inch triple diaphragm pump (2-triple-diaphragm-pump-high-pressure)	The triple pump delivers 651 LPM at 6.9 bar and is designed for high-pressure spraying. The DP37 delivers 647 LPM at 8.3 bar but is built for solids, not pressure. Choose the triple pump for long lines and high pressure. Choose the DP37 for chunky fluids.
Versus the 1 inch ZG Series pump	The ZG Series reaches 378 LPM at 1.5 inch. The DP37 is 647 LPM at 2 inch. The ZG is for lower flow, lower pressure, and smaller solids. The DP37 is for higher flow and larger solids. Choose the ZG for compact duty. Choose the DP37 for heavy solids.
Versus the 1 inch triple diaphragm pump	The 1 inch triple pump delivers 133 LPM at 7 bar. The DP37 delivers 647 LPM at 8.3 bar. The triple pump is for high pressure and low flow. The DP37 is for high flow and large solids. Choose the triple pump for spraying. Choose the DP37 for bulk transfer.
Versus the 2 inch non-metallic pump	The polypropylene pump handles acids and alkalis that attack aluminum. The DP37 is for solids. Choose the non-metallic pump for aggressive chemicals. Choose the DP37 for solids and high flow.

Use Guide

Getting The Best Out Of It

Five things that decide whether this pump does 647 LPM or less.

Use Full Air Supply
Flow depends on air. Use a 3/4 inch inlet, keep the hose short, and ensure the compressor can maintain pressure at the required flow.
Do Not Throttle The Suction
Throttling the suction causes cavitation and reduces flow. Always keep the suction line clear and unobstructed.
Match The Elastomer To The Fluid
Diaphragm and flap valve material must be chosen based on fluid chemistry and temperature. Wrong material leads to rapid wear and failure.
Keep Suction Lift Within Limits
The published 8.3 m is dry lift. If the fluid is not flooded, the pump may not prime. Position the pump below the source when possible.
Stock The Repair Kits
Order the air section kit, DP37-Air50, and the fluid section kit, DP37-Flu50, coded for your diaphragm and flap valve material. These cover the most common wear parts.

Documents

Documents For This Pump

Straight from Nuodean's own literature: product data sheets, series catalogues.

PDF Heavy duty flap valve pump data sheet Product Data Sheets PDF 2.0 MB Download PDF DP11 Series Diaphragm Pump Catalogue Series Catalogues PDF 9.2 MB Download

Need a 2D or 3D CAD model of this pump? CAD on request via WhatsApp.

Answers

Heavy Duty Flap Valve Diaphragm Pump FAQ

What is the largest solid it will pass?

2 inches (50 mm) in diameter, as stated in the data sheet. This is due to the swing flap valves and horizontal flow path. No ball check pump in the range can pass this size.

Can it run dry?

Yes. The pump can be run dry without damage. It is designed to handle dry operation and dead heading against a closed valve, which is common in slurry and sump duty.

How is it different from a ball check pump?

The ball check pump uses vertical flow and small openings. The flap valve pump uses horizontal flow and wide openings. The flap valve design allows larger solids to pass and prevents fluid from pooling in the body.

Will it replace a competitor's heavy duty pump?

Yes, if the competitor's pump has a similar 2 inch flange connection and horizontal flow path. Send a photo of the nameplate and the flange layout and we will confirm compatibility.

Which diaphragm should I order?

Santoprene for general duty and long flex life, PTFE with Santoprene backing for aggressive chemicals, Hytrel for high temperature and abrasion. Tell us the fluid and temperature and we will recommend the right code.

How loud is it?

80.5 dB(A) at 70 psi and 60 cycles per minute, as printed on the data sheet. Slower cycling or a piped exhaust reduces noise further.

What connections does it have?

Fluid inlet and outlet are 2 inch ANSI Class 150 / DN50 PN10 flanges. The air inlet is 3/4 inch BSPT female, with 3/4 inch NPT available on request.