Stop valves and control valves from Schubert & Salzer are regarded as standard equipment in the chemical industry. The medium-sized company has now introduced a range of hygienic right-angled control and pinch valves to the market for pharmaceutical applications. cpp spoke to Dr. Rainer Lange, Managing Partner, and to the head of sales, Manfred Wörz.
Schubert & Salzer Control Systems develops and manufactures stop valves and control valves in various configurations. The range extends from angled seat valves and pinch valves right through to sliding gate valves. “It is the sliding gate valves”, according to Dr. Lange, “that have helped us to come of age. We regard them as our speciality, having proved their worth in a wide range of applications by solving complex control challenges. The closure element of these valves consists of two slotted disks that slide against each other. Since they do not move against the flow, but instead at right angles to it, small actuation forces only are needed to operate them.” Actuators, positioners and position controllers as well as other accessory equipment complete the product range of this Ingolstadt company.
The valves, made from a variety of different materials, are used to control energy carriers, process and auxiliary media. The main customers for the industrial valves are manufacturers of plants and machinery for the process industry, such as for the production of steel and plastics, textile processing and for the chemical industry. In the pharmaceutical and food industries, valves have been restricted mostly to areas where hygiene was not critical and there was no contact with the product.
The Ingolstadt company has been able to use a widespread sales network to sell its products. The medium-sized company maintains sales subsidiaries in the USA, France and Great Britain. Alongside these, contractual partners of many years’ standing sell its products in over 40 countries. Referring to this, Wörz explained that they were looking for sales in the Eastern European and particularly the Asian markets with increasing interest: “For more than a year, we have been receiving more and more inquiries from Far Eastern countries. This applies particularly to our sliding gate valves, but also for the remainder of our products. The cause of this welcome development is the growing involvement of German plant and machinery manufacturers in the Asiatic economic region.”
Hygienic valve ranges
“The new items in our product range”, added Dr. Lange, “are valves for hygienic and aseptic applications in the food, drinks and pharmaceutical sectors. This involves the hygienic 6020 right-angled control valve, the aseptic 6021 right-angled control valve, the 7073 pinch control valve and the 7077 endless sleeve control valve. All hygienic valves can be combined with the available actuators. The same applies to our pneumatic, electro-pneumatic and digital positioners. And now we are offering a special version for the food and pharmaceutical industries.” Coupled with the desire to open up new markets, compatibility with existing system components was a deciding factor for venturing into hygienic process engineering. The right-angled control valves in the 6020 and 6021 ranges are designed for CIP/SIP with nominal diameters from DN 15 to DN 40. They are designed for a temperature range up to 140 °C and 135 °C respectively, and a nominal pressure of PN 16. Both valves have an integrated positioner made in stainless steel and can be fitted with an end-of-travel switch if required. The self-evacuating valves, with no dead spaces, are used to control gases, vapours and liquid media. All parts coming into contact with product are made in stainless steel and can be produced with surface smoothness finishes typical for hygienic applications. The sealing materials used comply with FDA requirements.
“The spindle seal in the hygienic 6020 valve”, explained Dr. Lange, “uses a scraping action. This type of seal does not, however, completely remove the risk of product entrainment. This is where the aseptic 6021 right-angled seat valve comes into its own. The spindle seal is achieved by using a rolling membrane made from EPDM or silicone. Product entrainment is eliminated and provides for a long stroke up to 16 mm, guaranteeing a high degree of control.”
Cracking eliminated
A critical factor in this type of diaphragm seal that has to resist large mechanical stresses is the clamping points. The Schubert & Salzer Control Systems’ development engineers came up with a clever solution to this problem: the diaphragm is clamped with a vulcanised ring. Furthermore, the geometric shape of the rolling diaphragm prevents tensile stresses on the clamping point. “We have carried out comprehensive tests on the aseptic valves with rolling diaphragms”, explained Wörz. “And the results were undisputable. After a million complete strokes under load, we were unable to detect any cracks or similar signs of wear in the diaphragms.”
Both right-angled control valve ranges meet the 3-A Sanitary standard. Moreover, the aseptic 6021 valve has an EHEDG certificate. The hygiene and aseptic angled seat valves are connected into the pipeline with welded connections complying with DIN and ISO. Other connection methods, such as using clamps, are available on request. The valve bodies are manufactured from the solid. Either 1.4404 stainless steel (6020 range) or 1.4435 stainless steel (6021 range) is used.
The sleeve does the job
Pinch valves have always formed part of the product range of Schubert & Salzer Control Systems. The decision to offer these valves now in a version specifically designed for the food and pharmaceutical industries is based on two factors, according to Dr. Lange. On the one hand, hose lines are ideally suited for hygienic applications since they have no dead spaces. The other reason is that some cus-tomers have already used Schubert & Salzer’s conventional sleeve valves for hygienic control of liquid media. A shaped sleeve made from EPDM, NBR or Viton lies at the heart of the 7073 pinch valve. It is clamped into the valve body and is squeezed by a pressure plunger. “Due to the mechanical properties of the sleeve”, explained Dr. Lange, “these valves that are significantly less expensive to buy than other types of valve are only suitable for coarse metering.” The 7073 pinch valves are available in nominal diameters from DN 15 to DN 50. They are connected into the process line using DIN and ISO welded couplings or with special threaded couplings (BSP, NPT). Working pressures and temperatures depend on the sleeve material used.
The 7077 endless sleeve valve corresponds to the 7073 valve range in construction and working principle. The shut-off device is an endless sleeve already provided by the user, and is placed in the valve body. The valves are designed for sleeve diameters of DN 6 to DN 15. Adjustable limiting elements prevent overstressing of the sleeve in the closed position. Schubert & Salzer Control Systems offer their 7077 endless sleeve valves in a fully stainless steel version. Furthermore, both pinch valve ranges are available as control valves incorporating positioners. (le)
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