There are many kinds of valves, such as ball valves, butterfly valves, gate valves, globe valves, check valves, etc. And also all kinds of material like WCB, A105, F304, F316, CF8, CF3, CF8M, CF3M, Inconel 6625, F11, F22, WC9, WC6, etc. And also all kinds of seat, like EPDM seat valves, PTFE seat valves, metal to metal seat valves, stainless steel+graphite laminated seat valves, etc.
So to choose the right valves includes the design of chemical craft, system, safety and environment, saving energy, pipelines and equipment set, and so on, and it must consider factors of the fluid characteristics, operating situation, external environment, economy and related regulations, specifications and standards, etc.
1. From the fluid performance, we shall consider the following matters: the chemical characteristics, molecular formula, impurities and content; the risk of the fluid (like the poison class, flammability and corrosion); the physical properties (like the density, viscosity and rheology); the chemical performance (like reactivity, the reaction heat effect and the reaction rate, polymerization, scaling, oxidation and PH value, etc.).
2. From the operation situation, except the normal operation of the design condition, we must consider the max value and min value under all kinds of condition(including the fail situation), operation modes of every kind of situations, and the max changing rate of operation.
3. From the flow situation, the inside valve flow is in turbulent area for normal operating valves. The high speed flow control valves, will have vibration or noisy (gas) after tortuous flow of high turbulence.
When choosing the valve type and size, we must pay attention to the follows. Safety relief valves, bidirectional blocking flowing, hurrying closing, or the closing of check valves when pump is in fail, all will lead to the pressure and flow speed varied, resulting water hammer phenomenon. (Gas) water phenomenon will cause noisy and vibration to make the valves injured. In order to avoid the water hammer, control equipment of on-off like handle, lever or gear box is needed, or anti-impact facilities (like slow-closing tank, gas/liquid separating tank) are necessarily set. At last, the bi-directional flow is very important to choose the right valves.
When the liquid comes across the valves, the out pressure will be lower than the liquid saturated vapor pressure so to produce flash steam and gas corrosion, which will not only reduce the valve flow and sealing performance, but also seriously damage the body, seat, trim and sealing structure, even leading the valve pressure bearing problem. So DBV valve group suggests to choose the right pressure, right material with heating treatment valves. You can ask us freely to choose the right valves for you too providing the conditions to us. Everything is our work next from the choosing of valves.