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Air-operated Diaphragm Pumps

Air-operated diaphragm pumps are used wherever fluids need to be pumped in a self-priming, dry-run-safe manner without an electrical connection.

FLUX compressed air diaphragm pumps are available in solid construction (RFM) and injection-molded versions (FDM) —with flow rates up to 1,040 l/min and pressures up to 8.6 bar, for virtually all media, from low-viscosity to highly viscous or abrasive.

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RFM Series

Solid-core construction

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FDM Series

Spray-Coated Version

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Accessories

Diaphragms, Pulsation Dampers, Replacement Parts

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Overview

FLUX compressed-air diaphragm pumps are oscillating positive-displacement pumps that operate purely pneumatically—no electrical connection required.

The RFM series, with its solid construction, delivers up to 375 l/min at up to 7 bar, while the FDM series, with its injection-molded design, delivers up to 1,040 l/min at up to 8.6 bar. Both series are self-priming, dry-run-proof, and available for use in hazardous areas.

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Self-priming & dry-run protected

No filling required; reliable conveyance even without a medium

Pneumatic Actuator

No power connection; continuously variable control via air flow. Cost-effective.

Wide range of applications

Up to 1,040 l/min, up to 8.6 bar, up to 15,000 mPas, solids up to 50 mm

Certifications

Explosion protection (ATEX), FDA (depending on the model)

Advantages

Self-priming and protected against dry running

No priming required—suction height up to 4.5 m when dry, up to 9.5 m when filled with fluid.

RFM Series

No power connection required

Purely pneumatic drive—suitable for use in hazardous areas; no electrical installation required.

FDM Series

Solids up to 50 mm

Even abrasive, viscous, and solids-laden media—gentle positive displacement pumping.

FDM Series

FDA- and Ex-certified

Hygiene Applications in the Food and Pharmaceutical Industries – RFM with FDA Certification, Explosion Protection in Both Series.

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Applications

Typical applications and areas of use for FLUX compressed air diaphragm pumps.

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Chemicals and Petrochemical industry

Corrosive acids, alkalis, and solvents—in durable plastic or metal containers.

Paints and Varnishes

Viscous paints, adhesives, and coatings—gentle positive displacement pumping without shear forces.

Food and Pharmaceuticals

FDA-certified materials – RFML version with a solid-state design for hygienically sensitive processes.

Wastewater and Environmental Technology

Wastewater, sludge, and media containing solids—self-priming, dry-run protected.

Areas Protected Against Explosions

Flammable media and solvents – ATEX-certified; no electrical connection required.

Surface Technology

Pickling baths, anodizing solutions, and electroplating solutions—high chemical resistance thanks to PTFE and PVDF.

Compressed-Air Diaphragm Pumps in Practical Use

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Safely Convey Viscous and Thixotropic Paints

Promoting Finger Paint: Safely Pumping Viscous, Thixotropic Paints with the FDM 25 Air-Operated Diaphragm Pump

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Pumping Lime Milk from IBCs with Minimal Wear

Safely and efficiently transfer lime milk from IBCs—using a compressed-air diaphragm pump designed for abrasive media.

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Pumping Sludge and Transporting Wastewater

In water and wastewater treatment, abrasive slurries, as well as wastewater and industrial water, must be pumped out.

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Media Examples

FLUX compressed-air diaphragm pumps handle aggressive, abrasive, viscous, and highly flammable fluids. The appropriate model depends on the fluid, solids content, temperature, viscosity, and any Ex or FDA requirements. Here are a few examples:

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FDM 12 – injection-molded version, plastic and metal versions
  • Alcohols in the Pharmaceutical Industry
  • Gasoline
  • Chlorine bleach
  • Cleaning agents
  • Pickling solutions
  • Wastewater
  • Abrasive media
  • Viscous media
FDM 25 – injection-molded version for higher flow rates
  • Alcohols in the Pharmaceutical Industry
  • Gasoline
  • Chlorine bleach
  • Cleaning agents
  • Pickling solutions
  • Wastewater
  • Highly flammable media
  • Substances containing solid particles up to 3.2 mm
FDM 80 – injection-molded version for high flow rates
  • Wastewater
  • Pickling
  • Cleaning agents
  • Gasoline
  • Chlorine bleach
  • Abrasive media
  • Viscous media
  • Media containing solid particles up to 9.5 mm
RFM 10 – Solid Construction, PP/PTFE
  • Highly Concentrated Sodium Hypochlorite
  • Chlorine-containing media
  • Wastewater from industrial hardening machines
  • Solvent mixtures
  • Pickling baths
  • Highly flammable media
  • Media containing solid particles
RFM 25 – Solid Construction, PP/PTFE
  • Highly Concentrated Sodium Hypochlorite
  • Chlorine-containing media
  • Wastewater from industrial hardening machines
  • Solvent mixtures
  • Pickling baths
  • Highly flammable media
  • Media containing solid particles
RFM 40 – Solid-construction design for chemically aggressive media
  • Highly Concentrated Sodium Hypochlorite
  • Chlorine-containing media
  • Wastewater from industrial hardening machines
  • Pickling baths
  • Abrasive media
  • Media containing solid particles up to 7.5 mm
  • Viscous media

Knowledge and Technology

Selecting the right compressed-air diaphragm pump depends on the medium, the required discharge pressure, and the material requirements. The following sections explain the operating principle, the differences between the series, and the available materials.

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Function and Design of the FLUX Compressed Air Diaphragm Pump

FLUX compressed air diaphragm pumps are oscillating positive displacement pumps consisting of two pump housings and a control housing. The pump housings contain vertically mounted diaphragms that are centrally connected to a shaft and move simultaneously relative to one another.

Via the compressed-air-regulated control unit, the shaft ensures that the inner diaphragm chambers are simultaneously filled and vented. When air is forced into one chamber, the diaphragm moves outward—the connecting shaft pulls the opposite diaphragm inward, creating a suction process. The direction then reverses, and the process repeats continuously.

  • Self-priming & dry-run-proof: No filling required; safe operation even without a fluid
  • Pneumatic drive: No power connection, infinitely variable control via air volume
  • Gentle pumping: Positive displacement principle—even for viscous, abrasive, and solids-laden media
  • Performance specifications: Up to 1,040 l/min, up to 8.6 bar, suction lift up to 9.5 m (when filled with product)

A Comparison of Compressed Air Diaphragm Pumps

An overview of the key specifications and features of the most popular compressed air diaphragm pumps.

Feature
RFM 10
RFM 25
RFM 40
FDM 12
FDM 25
FDM 80
Max. flow rate 30 l/min 110 l/min 375 l/min 55 l/min 178 l/min 1040 l/min
Max. discharge pressure 15 bar 15 bar 15 bar 7 bar 8 bar 8 bar
Max. viscosity 30,000 mPas 80,000 mPas 100,000 mPas 15,000 mPas 15,000 mPas 15,000 mPas
Dry suction head 3 m 3 m 4 m 7.6 m 6.0 m 4.2 m
Construction method Solid construction Solid construction Solid construction Sprayed Sprayed Sprayed
Materials PP, PTFE PP, PTFE PP, PTFE AL, PP, GG AL, PP, GG AL, PP, GG
Explosion protection
 ✓ ✓ ✓ ✓ ✓ ✓
FDA ✓ (RFML) ✓ (RFML) ✓ (RFML) – – –
Ideal for Small quantities, chemicals Medium quantities High pressure, industrial Versatile Medium volumes High-volume
  RFM 10 RFM 25 RFM 40 FDM 12 FDM 25 FDM 80

The maximum flow rate is a test bench value, measured with water at 20 °C at the pump’s discharge port, without any attachments (hose, dispensing nozzle, flow meter). The flow rate that can be achieved in practice is lower and depends on the specific application, the properties of the fluid, and the pump configuration. Specifications are for an axial rotor, unless otherwise noted.

Detailed Technical Specifications

Compressed-air diaphragm pumps in the FDM and RFM series cover a wide range of fluids. The appropriate model depends on the fluid, chemical resistance, solids content, viscosity, and operating environment.

FDM Pumps RFM Pumps
Pump Materials and Typical Applications
Material Available Series Typical Applications
Polypropylene FDM 07, FDM 12, FDM 25, RFM 10, RFM 25, RFM 40 Chemicals, cleaning agents, wastewater, viscous media
Conductive polypropylene RFM 10, RFM 25 Highly flammable media, hazardous areas, conductive plastic version
PVDF FDM 12, FDM 25 Corrosive media, chemically demanding applications
PTFE RFM 10, RFM 25, RFM 40 Highly aggressive media, etching baths, chlorine-containing media
Conductive PTFE RFM 10, RFM 25 Chemically aggressive and highly flammable media
Conductive acetal FDM 07, FDM 12 Highly flammable media, compact explosion-proof applications
Aluminum FDM 12, FDM 25, FDM 80 Industrial applications, fuels, abrasive and viscous media
Stainless steel FDM 12, FDM 25, FDM 80 Chemical, pharmaceutical, cosmetics, food-related applications
Gray cast iron FDM 80 High flow rates, heavy-duty industrial applications

 

Connectors / Adapters
Series Pressure Port Suction port
FDM 07 3/4 NPTF 1/4 NPTF, G 1/4
FDM 12 1/2" NPT 1/2" NPT
FDM 25 G 1 or 1" flange G 1 or 1" flange
FDM 80 G 3 G 3
RFM 10 G 3/8 G 3/8
RFM 25 G 1 G 1
RFM 40 G 1 1/2 G 1 1/2

 

Performance and Media Comparison
Series Max. discharge pressure Max. solid particle size Max. viscosity Special Feature
FDM 07 8.6 bar 1.6 mm 15,000 mPas Very compact, low air consumption
FDM 12 7 bar 2.4 mm 15,000 mPas Plastic and metal versions
FDM 25 8 bar 3.2 mm 15,000 mPas G-thread or flange connection
FDM 80 8 bar 9.5 mm 15,000 mPas For very high flow rates
RFM 10 7 bar 2 mm 15,000 mPas Solid construction, FDA version available
RFM 25 7 bar 3 mm 15,000 mPas For chemically aggressive media
RFM 40 7 bar 7.5 mm 15,000 mPas High solids tolerance in solid construction

 

Models and Certifications
Series Model Characteristics
FDM Injection-molded version Versatile standard series for industrial, chemical, wastewater, and Ex applications
RFM Solid construction Thick-walled construction for high chemical resistance and temperature resistance
FDM Ex Explosion-proof version available For highly flammable media and potentially explosive areas
RFM FDA FDA version available For applications with increased requirements for materials and media safety
RFM with flap valve Available as an option For media containing solids and heavy-duty conveying tasks

 

Solid construction or sprayed version?

The choice between RFM and FDM depends on the application:

The RFM series with a solid-body design is particularly suitable for high outlet pressures and applications requiring minimal diffusion. The thick-walled construction is virtually diffusion-tight and reduces passive corrosion. Composite diaphragms with an integrated metal core ensure durability even at high pressures.

The FDM series, featuring a molded design, offers a wider variety of materials—from plastic to metal—and higher flow rates of up to 1,040 l/min. An integrated silencer ensures quiet operation. When combined with FLUXTRONIC® and a stroke counter, the FDM is also suitable for metering processes.

About the RFM Series (Solid Construction) About the FDM Series (injection-molded version)

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