Bürkert hydroformed diaphragm valve bodies benefit hygienic applications
Bürkert Fluid Control Systems has launched the latest incarnation of its diaphragm valve body that has been manufactured using hydroforming technology to deliver a number of benefits.
Designed for use in hygienic process applications, the new tube valve body meets the latest standards for pharmaceutical, cosmetic, as well as food and beverage industries.
Fluid control systems within hygienic applications demand high standards in terms of cleanability, which can be affected by a number of design characteristics.
The base material is normally 316L stainless steel, which requires an excellent surface finish in order to maximise the efficiency of the clean-in-place (CIP) process that is used to sterilise the process pipework.
Coupled with their required thermal properties, the design of process valves has become a complex process.
Bürkert has patented a new procedure to create process valves using hydroforming technology, which has reduced the amount of materials used, as well as allowing uniform laser welds that do not add further material to the component.
The process starts with the flange, which is laser-cut and milled, and the tube, both of which are manufactured from 316L stainless steel.
The tube is placed in a mould, filled with a water-oil emulsion, and subjected to around 3,000 bars of pressure to produce the required flow path to and from the weir.
The flange and tube are then laser-welded together before the new component is annealed in order to relieve residual stress within the material.
This heat treatment process also increases the durability of the material by improving the corrosion resistance, which is enhanced by precision machining of the surfaces of the flange before the final polishing stages are completed.
Bürkert has automated the polishing process and uses an abrasive paste that is repeatedly pumped through the valve body in order to achieve a surface finish of less than 0.4µm.
The process produces a uniform surface, which is then electro-polished to give a near mirror finish for all areas that come into contact with the process media.
“This new manufacturing process allows us to manufacture variants that are as much as 75% lighter than forged housings. The reduced volume of material means that the energy requirement for both heating and cooling during cleaning processes is also greatly reduced,” said Ian Webster, hygienic processing segment manager at Bürkert UK.
“The hygienic design and cleanability of the new valve body has been shown to be comparable with that of stainless process pipework and has been certified under EHEDG Type EL, Class I,” he said.
The manufacturing technique employed by Bürkert also has a reduced carbon footprint, making it more environmentally friendly.
An independent study showed that when manufacturing a DN25 cast valve body, almost 7,000g of CO2 were produced, compared to the hydro-formed valve body which only generates 2,000g.
The new tube valve body can be used with EPDM or PTFE diaphragms, both of which have high hygiene and chemical resistance qualities, and coupled with Type 2031 CLASSIC pneumatic actuator or a Type 3233 manual actuator to deliver process control solutions for any number of hygienic applications.
Initially, the valve tube bodies will be available in ½”, ¾”, 1”, 1½”, and 2” variants, suitable for welded connections.