How to choose the correct use of diaphragm valve

Which type of valve does the diaphragm valve belong to? How to choose correctly?
The diaphragm valve is a clamping type valve, which is mainly used for opening and closing on the pipeline.
Diaphragm valves have two main advantages: one is that the valve does not require a separate stem packing seal structure, the diaphragm acts as a valve stem seal while cutting the medium, and the second is that the flexible membrane is closed reliably. Even good cuts can be made to the dirty liquid. Therefore, the operating mechanism and the media passage are completely separated, so that the diaphragm valve can be applied not only to the food industry and the medical and health industry, but also to some difficult to transport media and dangerous media.
Diaphragm valves are generally recommended for use or when required to have tight sealing properties, mud media, wear, lightweight construction, low pressure cutoff (small differential pressure), and a small amount of leaking, abrasive media to the atmosphere. Diaphragm valves are available for two-position adjustment, throttling, channel sag, low noise, cavitation and vaporization, and low steering torque. In the case of high temperature medium, high pressure medium, high pressure cutoff (large differential pressure), fast opening and closing action, and short structural length, diaphragm valves are not selected, except for metal diaphragm valves.
The structural feature of the metal diaphragm valve is to clamp a thin set of semi-spherical metal film into the valve body as a barrier between the valve stem and the fluid. The valve closing is achieved by pressing the valve disc against the valve seat through the stem head and the metal foil. The valve is opened by an internal spring that rises when the stem is raised and out of contact with the membrane. Since the stroke of the valve is equal to the stroke of the membrane, the characteristic lift of this valve is much smaller than that of a conventional valve. In order to overcome the resistance loss caused by the low lift, the valve seat and the flow area are larger than the general valve, in order to obtain a larger flow rate. Since the valve seat of this valve is large, its force is much larger than that of the conventional valve, so that sufficient sealing force is obtained on the valve disc because there is no direct contact between the valve stem and the valve disc. The valve disc does not pass the valve stem away from the valve seat, so the valve is suitable for use in a one-way flow with differential pressure, and typically the media is from under the valve seat. However, a large amount of backflow should be avoided during use to avoid affecting the closing of the valve. In general, it is economical and effective to use a metal diaphragm valve at high temperature and high pressure. The valve can also be used in low temperature and low pressure applications where synthetic rubber diaphragm valves are not desired.