Compressed Air Diaphragm Pumps

Compressed-air diaphragm pumps operate purely pneumatically. They are self-priming, dry-run-proof, and require no electrical connection. Flow rates up to 1,040 l/min, pressures up to 8.6 bar.

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Products

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.

Highlights

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.
FDA- and Ex-certified
Hygiene Applications in the Food and Pharmaceutical Industries – RFM with FDA Certification, Explosion Protection in Both Series.
View compatible pumps

Applications

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

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.

In practice

Case studies

Safely Convey Viscous and Thixotropic Paints
Promoting Finger Paint: Safely Pumping Viscous, Thixotropic Paints with the FDM 25 Air-Operated Diaphragm Pump
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.
Pumping Sludge and Transporting Wastewater
In water and wastewater treatment, abrasive slurries, as well as wastewater and industrial water, must be pumped out.

All projects

Technology

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.

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)

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

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

Compare

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

Comparison of the Compressed Air Diaphragm Pumps versions
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

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.

Motors and accessories

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)