Alma Kelley Valves April 14th, 2019 - 12:17:08
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.
Valves are mechanical devices that obstruct pipes or passages of liquids and gases either wholly or partially to control the flow rate as required. In our lives we come across many valves daily, but might have never noticed them. The taps that we open and close to control the flow of water is a valve. The regulators that we use to control the flow of gas from our gas pipelines are also valves. There are gas control valves in our cookers too. These valves are not limited to man-made things, but are found naturally and that too in our bodies. Our heart has valves that help in regulating the flow of blood in our body.
If the sealability is not good or the strength is not intensive, the parts may be destroyed. Thus, it will result in the economic loss in different degree, such as transporting the poisonous, explosive or corrosive fluid. And even it will lead to the serious accident. In order to ensure the sealing and strength of the valve, the manufacture should not only obey the related standards to design and produce the product but also should properly select the material.
Ball - the heart of the valve. Leading manufacturers attach great importance to the quality of the surface of ball valves. Brass Balls are diamond grinding, they applied anticorrosion coating of nickel or chromium. As a result, the ball gets a perfect mirror surface. Symptom of products of low quality - a dim, muddy or rough surface of the ball.
Valve response time is another important factor for us to consider. For optimum control of many processes, it is important that the valve reach a specific position quickly. A quick response to small signal changes is one of the most important factors in providing optimum process control. Valve response time includes both the valve assembly dead time, which is a static time, and the dynamic time of the valve assembly. It is important to keep the dead time as small as possible. Dead band, whether it comes from friction in the valve body and actuator or from the positioner, can significantly affect the dead time of the valve assembly.
Needle Valves are designed in many different materials. The valve is generally metal - here stainless steel, or a steel alloy, brass, or bronze are most often used, The seat is usually made from an elastomeric material such as PVC, CPVC, PTFE or a suitable type of the wide range of plastics and thermoplastics on the market. Valves are available in different materials - here customer choice will be determine by the specific application the valve is to be used for, along with the conditions it will be subject to. You have to take into account whether the fluid is particularly high or low in temperature, likelihood of corrosion, and how much wear the valve will be subject to you. Swagelok will be able to consult with you, and advise you what type of valve is best for the application you require it for. Swagelok Tube Fittings are available in additional Valve Body Materials on request - these include carbon steel and 25Cr super duplex stainless steel.