Solid-Body Design for Strength and Smooth Operation

An important construction element in Almatec? air-operated double-diaphragm (AODD) pumps is the solid-body design. Only a solid-plastic body can support the necessary weight for an oscillating pump. The individual components can be designed so that the required wall thicknesses is arranged where they are needed. The mechanical machining of a solid-plastic block is economical thanks to modern CNC technology, enabling tight tolerances to be achieved. The high-static mass leads to smooth operation and eliminates the need for unnecessary external metal parts that would otherwise be used for reinforcement. All Almatec pumps use only virgin PE and PTFE produced in Germany.

Polyethylene (PE)

As an air-operated diaphragm pump housing, polyethylene (PE) is very tough, exceptionally resistant to wear, has low water absorption capacity and displays good general resistance to chemicals. Only strong oxidants such as nitric acid, oleum and halogens can damage PE.

PE competes with polypropylene (PP), which is frequently used in the manufacture of pumps. Thermally and chemically speaking, there are virtually no differences between the two materials. However, the similarity ends where the mechanical properties are concerned. Trials based on the sand-slurry method have shown that the abrasion resistance of the PE (material sample on top) is seven times higher than that of PP (middle) and even 1.6 times higher than that of steel (bottom). It is also more wear-resistant than, for example, cast iron or aluminum.

This high resistance to abrasion plays a vital role in many applications (e.g. slurry delivery in the wafer manufacturing in the photovoltaic industry, pickling baths in the electroplating industry, printing inks, lime slurry for wet desulfurization, ceramic mass and glazes in the ceramic industry). For explosion-proof areas (ATEX conformity) and for flammable liquids, PE conductive housing material is available.

Almatec pumps with PE housing: E-Series, C-Series, FUTUR Series, AHD/AHS Series, CXM Series

Polytetrafluorethylen (PTFE)

Also used for our AODD pump housings is PTFE, which has a smooth surface, very low friction coefficient, is physiologically safe, can be used over a wide range of temperatures and displays virtually universal resistance to chemicals. However, pure PTFE has very little resistance to abrasion and tends to cold flow. For explosion-proof areas (ATEX conformity) and for flammable liquids, PTFE conductive as housing material is available.

Almatec pumps with PTFE housing: E-Series, C-Series, FUTUR Series

Stainless Steel

Stainless steel 1.4408/SS316 (G-X 6 CrNiMo 18 10) is a cast steel that is resistant to corrosion and acids, and is frequently used for fittings and pump casings because of its good general chemical stability. In a precision lost-wax casting operation, stainless steel is used for wetted housing parts. The lost-wax process is a complex casting process yielding a smooth and dense surface with increased resistance to corrosion.

Another stainless steel pump housing material is 1.4435/SS316L (Basel Standard II, ferrite content < 1%). It has a surface roughness of ≤ 0.4 μm. 1.4404/SS316L will be used for the wetted housing material of MM and FUTUR S Series pumps.

Almatec pumps with 1.4408 housing: CHEMICOR Series
Almatec pumps with 1.4435 housing: BIOCOR Series
Almatec pumps with 1.4404 housing: MM Series, FUTUR S Series