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Edwina Dorsey Valves April 14th, 2019 - 12:32:43
The original principle of the operation of a valve was ingeniously basic. Operators were able to process the sometimes corrosive and abrasive water, generally caused by flooding, but the use of a "pinching" action that pressed down on a component now known as an elastomer sleeve, restricted the flow of water. This innovation was the foundation for the sophisticated Air operated Pinch Valves of today.
The second type is a product with override control to stop flow regardless of flow direction or pressure. It can not only close in response to backflow or insufficient forward pressure, but also can be deliberately shut by an external mechanism, thereby preventing any flow regardless of forward pressure.
Swagelok produces a variety of Check Valves to meet every need. All Check Valves are factory tested for crack and reseal performance with a liquid leak detector. Check Valves with fixed cracking pressures are cycled six times prior to testing. Every valve is tested to ensure it seals within 5 s at the appropriate reseal pressure. Check Valves with adjustable cracking pressures are tested at two pressure points. Every Valve is tested at a low-pressure setting and at a high-pressure setting, and all must seal within 5 s at the appropriate reseal pressure.
The third one is similar to ball check valves, but the plug that seals the valve is shaped like a cone. It also can be called a lift check valve in which the disc, sometimes called a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. The cone is held on a bar, allowing it to lift out of the way when the water is flowing and drop back into place when the water is off. If water backflows through the pipe, it pushes up against the cone, creating a seal that keeps it from going any further.
The sometimes highly specialized working environments in which manual operated sleeve valves must perform can include differing temperatures ranging from -60°F to 300°F. The sleeves themselves can be manufactured from natural rubber or a compounded elastomer, which provide specific operational capabilities. Control sleeve valves are recognized for their excellent abrasion resistance and ability to process animal and vegetable fats.
Added advantages of manual pinch valves include their ability to effectively control the flow of corrosives and abrasives. In addition, there is the lack of contact between any metal part of the valve and the transported material which is a major asset in circumstances where the purity of a product is a high priority. The versatility of the valve is displayed in its ability to handle waste-water, slurries, pulp, powder and pellets, as well as applications in medical and pharmaceutical processes.