Diaphragm valves definition and principles
Diaphragm valve is a special form of cutting off valve, whose hoist part is diagram made of a piece of soft materials, it will separate the body inner cavity and bonnet inner cavity. Diaphragm valves in fact nothing more than "clamp" valve, a flexible and interference diaphragm can be connected to the compressed fittings by using bolt, compressed fittings are operated by the stem and move up and down, when the compressed fitting raises, diaphragm will hold up, which leads to access, when the compressed fitting falls, diaphragm will press on body weir (in case that is the weir-type valve) or press at the bottom of the outline (in case that is the straight-through), diaphragm valve is suitable for the switch and throllte uses.
BS Diaphragm valve working temperature is also limited by the diaphragm and the body lining material, its operating temperature range is about -50 ~ 175 degrees. Diaphragm valves structure is simple, only composed by the body, diaphragm and bonnet assemblies three main components. The valve is easy for quick demolition and repair and replacement of membranes can be at the scene and within a short time. Control mechanism and separated media access make diaphragm valves not only applies to the food and medical health industrial production, but also applies to a number of difficult and dangerous transmission medium. More is applied to kinds of synthetic rubber and engineering plastics, and a wider selection of body lining material, making diaphragm valves used widely in the various fields of modern industry.
The structural design reason of GB rubber-lined, fluorine-lined diaphragm valve is special suitable for ultra-pure media or serious pollution, a very viscous liquid, gas, corrosive or inert medium. When combined with the control equipment, the GB rubber-lined, fluorine-lined diaphragm valve can replace other traditional control systems, especially those applied to the inert solid and easy-contaminated media. Products are mainly used in bio-pharmaceuticals, food industries; and power, chemical, electroplating, and other industries of industrial water treatment, also used in the production of semiconductor wafers, diaphragm valves are especially suitable for transporting corrosive, viscous fluid, such as mud, food, medicines, woven-dimensional bonding liquid and so on, because of the diaphragm valve operating mechanism is not exposed to the delivery of fluid in the pipelines, therefore with non-polluting and does not require packing, valve stem packing part is also not likely to leak.
BS rubber-lined, fluorine-lined diaphragm valve principle is the body's anti-regulation, when the entrance pressure increases, auto-reducing diameter, to reduce the flow rate changes, and vice versa. If the reverse, this regulating system is not working. And the disc that acting as a regulator also is directional. The reversed pressure even can reduce the closed flow. Since the installation of diaphragm valves is in order to make better heating, so it does not exist anti-loading problem. If it is anti-loaded, that is human error, of course, would be corrected. Working principle is through changing the valve core and seat gap (ie, opening degree), to change the flow resistance of fluid flowing through the valve, to achieve the purpose of regulating flow. Diaphragm valve is equivalent to a partial resistance that is a changeable throttle components, to the incompressible fluid, can be calculated by the flow equation.
Kv is straight-flow rubber-lined diaphragm valve coefficient. It is defined as: When the straight-flow rubber-lined diaphragm valve front and latter pressure differential is 1bar (about 1kgf/cm2), the flow value that flows through diaphragm valves (m3 / h). when straight-flow rubber-lined diaphragm valve is fully open, the valve flow coefficient is equivalent to normal valve flow capacity. If the balance valve opening remains unchanged, then the valve coefficient Kv unchanged, that is the valve coefficient Kv is determined by the opening degree. Through the measurement to obtain different opening degrees valve coefficient, diaphragm valves can be adjusted as a quantitative flow throttling element.
When debugging diaphragm in the pipe network, using hose to connect the small presure mearsurement valve of the diaphragm valve used to debug and special intelligent instrument, meter will show that the value of fluid flows through the valve (and pressure drop value), through talking to the meter man-machine, after input the flow value required by diaphragm valve to instrument, instrument through calculating, analysis to get the valve opening degree value when the pipe system achieves the waterpower balance. Diaphragm Valves belong to regulating valve, the working principle of internal thread diaphragm valves is through changing the valve core and valve seat gap, changing the flow resistance of fluid flow through the valve, to achieve the purpose of regulating flow. 1. Should not arbitrarily change in diaphragm valves opening degree pipe network system, after installation and having test conditions, using a dedicated intelligent instrument to debug and set for all the diaphragm valves and locking the valve opening degree, so that pipe network hydraulic conditions to achieve balance. During the pipeline system normal operation, you should not arbitrarily change the opening degree of diaphragm valves, in particular, should not change opening locking device. 2. Do not have to install globe valve, when in the maintenance of one circuit, they can close the loop on the diaphragm valve, diaphragm valve at this time to play the role of the globe flow valve, after its repair and then revert to the original locked position. Therefore, if installing the diaphragm valves, you do not have to install the globe valve. 3. System added (or Cancel) loop should be re-debug to the whole set at a pipe network system, an additional (or Cancel) loop, in addition should increase (or off) the corresponding diaphragm valves, in principle, all of the new diaphragm valves and original system curcuit should be re-commissioning (original curcuit formerly branch diaphragm valves do not have to re-adjustment). In the air-conditioning and heating system, the water balance of the water system, that waorkde as energy transmission and distribution is very important.
