Thin-film control valve
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How are diaphragm control valves with air opening and those with air closing functions compared? In what applications are they used respectively? ^Z|l%
Air-operated diaphragm control valve: When no pressure signal is applied, the valve closes completely； When a pressure signal is present, the valve begins to open, and the greater the input signal, the more the valve opens. Pneumatically actuated diaphragm control valve: when no pressure signal is applied, the valve is fully open; whereas when a pressure signal is present, the valve starts to close ； The larger the input signal, the smaller the valve opening ； When the input signal reaches its maximum value, the valve closes completely. The principle for selecting a valve is to determine the state in which it should be under emergency conditions. If the least harm occurs when the valve is open, a air-locked type should be chosen; if the least harm occurs when the valve is closed, an air-open type should be selected.
Same as upstairs~~~~~~~~~~~~
Mainly, in cases where there is a gas cut-off at the site and the valve needs to be open, it is a normally open type. If the valve is required to be closed, then it is a normally closed type.