Steiner Pumps – Aluminium Diaphragm Pump (MK Aluminium)
The MK series aluminium diaphragm pump is a pneumatic double-diaphragm pump with a wetted housing made of aluminium alloy. It operates on compressed air, requires no power supply, is self-priming and can run dry. The aluminium version is available in five sizes: MK 15/20, 25, 40, 50 and 80. General information on the series and model coding can be found on the page Steiner Pumps.
Where is an aluminium diaphragm pump used?
Aluminium is chosen for environments where resistance to concentrated acids is not required, but mechanical casing strength and moderate weight are.
Typical applications: oils and greases, solvents, petroleum products, paints, varnishes and coatings, adhesives, sealants and high-viscosity adhesive materials, construction mastics, mine and process water, slurries with solid inclusions, process and contaminated liquids in shipbuilding, wastewater, sludges and sediments.
The aluminium housing is almost twice as light as the cast-iron one of the same frame size: an aluminium MK 80 weighs 50 kg, while the cast-iron version weighs 125 kg. For mobile applications and frequent relocation, this is a decisive factor.
For pumping flammable liquids, a conductive design (code C in the article number) and explosion-proof equipment are used; the specific marking is confirmed upon ordering.
Five standard sizes: technical specifications
| Parameter | MK 15/20 | MK 25 | MK 40 | Mk 50 | MK 80 |
|---|---|---|---|---|---|
| Suction / discharge nozzles | 1/2″, 3/4″ | 1″ | 1 1/2″ | 2″ | 3″ |
| Maximum flow rate | 57 litres per minute (3.42 m³/h) | 157 litres per minute (9.42 m³ per hour) | 358 litres per minute (21.5 m³ per hour) | 587 l/min (35.2 m³/h) | 1,060 l/min (63.6 m³/h) |
| Maximum head | 84 m | 84 m | 84 m | 84 m | 84 m |
| Maximum inlet air pressure | 8.4 bar | 8.4 bar | 8.4 bar | 8.4 bar | 8.4 bar |
| Compressed air inlet | 3/8″ | 1/2″ | 1/2″ | 1/2″ | 3/4″ |
| Self-priming head, dry | 4 m | 4 m | 5 m | 5 m | 5 m |
| Self-priming height, primed | 7.6 m | 8 m | 8 m | 8 m | 8 m |
| Maximum particle size | 2.5 mm | 4 mm | 5 mm | 6 mm | 9.4 mm |
| Mass | 4.5 kg | 11 kg | 20 kg | 27 kg | 50 kg |
Delivery head and air pressure are different quantities. 8.4 bar refers to the air at the pump inlet; 84 m is the height to which the pump delivers liquid. All ratings are based on water tests at 20 °C.
Compressed air consumption and supply regulation
Flow rate and pressure are regulated by a single parameter: the inlet air pressure. A separate frequency converter, bypass or control valve on the line is not required for this.
Air consumption increases with the feed rate. Approximate values from the operating characteristics:
| Size | Air consumption within the operating range |
|---|---|
| MK 15/20 | 0.056–0.56 m³/min (1.97–19.78 scfm) |
| MK 25 | 0.28–1.12 m³/min (10–40 scfm) |
| MK 40 | 0.56–2.24 m³/min (20–80 scfm) |
| Mk 50 | 0.7–2.8 m³/min (25–100 scfm) |
| MK 80 | 1.4–9.8 m³/min |
These figures are needed at the design stage: the compressor and pneumatic line are selected for the upper end of the range, otherwise the pump will not reach its rated delivery.
Materials of diaphragms, balls and valve seats
The body is made of aluminium, but the contact elements are selected separately depending on the environment.
Membrane. Santoprene, Hytrel, PTFE (Teflon), Viton (FKM), EPDM, Buna-N. Temperature limits: Viton −40…+121 °C, PTFE +4.4…+104 °C, Santoprene −40…+82 °C, Hytrel −29…+82 °C, EPDM −12…+82 °C, Buna-N −12…+82 °C.
Valve ball. For MK 15/20 — PTFE, stainless steel, Santoprene. For MK 25 and larger — Santoprene, Hytrel, PTFE, Viton, stainless steel, ceramic.
Valve seat. For MK 15/20 — SS304, SS316. For MK 25 and larger — Santoprene, Hytrel, PTFE, Viton, stainless steel.
Central unit. For MK 15/20 — polypropylene. For MK 25 and larger — polypropylene, aluminium or stainless steel.
For petroleum products and fuels, the basic membrane choice is Buna-N or Viton. For solvents, PTFE or Viton. For abrasive slurries, Santoprene or Hytrel, with a ceramic or stainless steel ball.
Mounting dimensions and connections
Threaded connections, BSP or NPT. Support foot with holes for anchor fastening.
| Size | Dimensions (W × H) | Fasteners | Hole pitch |
|---|---|---|---|
| MK 15/20 | 235 × 302.6 mm | — | — |
| MK 25 | 293 × 367 mm | M10 × 4 | 227 × 126 mm |
| MK 40 | 370 × 487 mm | M12 × 4 | 285.5 × 150 mm |
| Mk 50 | 428 × 588 mm | M12 × 4 | 329 × 150 mm |
| MK 80 | 558 × 838 mm | M16 × 4 | 368 × 258 mm |
The pump is installed without a foundation and without alignment: the support foot is placed on the frame or on the floor, and the pipelines are connected with a thread. Operation in a submerged position and mobile application are also permitted.
When should you choose an aluminium diaphragm pump and when another body material?
Aluminium — oils, solvents, petroleum products, paints, adhesives, general industrial applications. Lower weight compared to cast iron and stainless steel.
Cast iron — the same environments, but where maximum mechanical strength and abrasion resistance are required, and mass is not critical.
Stainless steel SS304 / SS316 / SS316L — food, pharmaceutical and cosmetics production, sanitation, hygiene requirements.
Polypropylene, PVDF, POM — concentrated acids, alkalis and organic solvents, where metal is unsuitable. PVDF withstands up to 107 °C, PP and POM up to 65.5 °C.
Find out more: MK Plastic, MK Stainless steel, MK Plastic electric.
Frequently asked questions about the aluminium diaphragm pump
What is the maximum capacity?
1060 l/min (63.6 m³/h) — MK 80 with 3-inch connections.
What is the smallest aluminium pump in the series?
MK 15/20 with 1/2″ and 3/4″ connections, maximum flow rate 57 l/min. In the smallest model size of the series, MK 06/10, there is no aluminium version — only PP, PVDF and POM.
Is 8.4 bar the discharge pressure?
No. This is the maximum inlet compressed air pressure for the pump. The delivery height is up to 84 m.
What is the maximum size of solid particles that can pass through?
From 2.5 mm (MK 15/20) to 9.4 mm (MK 80).
Is a high-capacity compressor needed?
Air consumption depends on the model size and operating mode: from 0.056 m³/min for the MK 15/20 at a low delivery rate up to 9.8 m³/min for the MK 80 at maximum. The compressor is selected for the upper point of the operating range.
Does the pump withstand dry running?
Right. The design has no dynamic seals, so running dry does not damage the pump.
Is it permitted to work with solvents and flammable liquids?
The pump does not require a power supply, which is a basic prerequisite. For such environments, a conductive design (code C) is used and a PTFE or Viton diaphragm is selected; the explosion protection marking is confirmed upon ordering.
Is aluminium suitable for food?
Stainless steel construction is provided for food, pharmaceutical and cosmetic production facilities. Aluminium is intended for general industrial and chemical applications.
How do you regulate the supply?
By changing the inlet compressed air pressure.
What is needed for the selection?
Medium and its concentration, viscosity, density, temperature, size of solid inclusions, required flow rate, delivery head and pipeline length, available pressure and flow rate of compressed air, explosion protection requirements.
