Questions about pneumatic valves?

1. If the handwheel can’t be opened, then what’s the use of a handwheel? 2. That cap is an exhaust vent.

The handwheel can be used to open it; that hole is an exhaust port, and there’s a small opening on the side of the plug at the top – that’s where heat dissipation and exhaust occur

That is an exhaust vent, also known as a breathing hole. It must not be blocked under any circumstances. The handwheel has automatic and manual mode switch buttons; it is currently in manual mode. When the white lever below the handwheel is rotated to the automatic position, turning the handwheel no longer works.

The handwheel is used to manually control the valve in emergency situations； The white one is the rain cover for the exhaust vent.

Thank you! Don’t understand the connection between the handwheel and the spring? This valve doesn’t have an automatic/manual switch; perhaps once that rod is locked, it can no longer be operated manually! It was manually activated a little, and after pressure built up in the subsequent pipelines, once the air system was repaired and a driving air source was available, it was activated via remote microcomputer control.

1. The air-actuated control valve moves in the direction of increasing its opening degree as the air pressure on the diaphragm increases; when the input air pressure reaches its maximum value, the valve is in its fully open state. Conversely, as the air pressure decreases, the valve moves in the direction of closure; when no air is supplied, the valve is fully closed. Therefore, valves of the air-open type are sometimes also referred to as fail-closed types; the handwheel is used in case something goes wrong. 2. The white component is a rain cover for the exhaust port, designed to prevent rain or liquids from entering the cylinder. In chemical plants, gases are often corrosive, and when they come into contact with water they can corrode the springs and diaphragms, thereby reducing the valve’s lifespan. 3. This type of solenoid valve uses the energization and de-energization of the coil to drive the valve stem and change the direction of the air flow.

The handwheel is used to manually control the valve opening; it is employed for control when there are issues with the air supply or electrical circuit, or when manual operation is required. The white one is the rain cover for the exhaust vent, which prevents rainwater from entering the membrane head (in winter in the north, water accumulation inside the membrane head can lead to freezing and valve failures). Additionally, when the membrane leaks, air will leak out through this exhaust vent, making it easier for maintenance personnel to detect and repair the issue

The handwheel is used to open the valve on-site in case of an automatic failure; it overcomes the spring force to open the valve, similar to how a gas source works. Once automatic control is restored, the handwheel needs to be turned to the closed position of the valve, with the nut locking it in place. The white cap serves as an opening for the gas on the spring side to escape freely; if the valve is blocked, it cannot be opened or closed. Once removed, water will enter when it rains, accelerating the aging of the spring and diaphragm. Additionally, insects such as wasps can get in before winter arrives.

The handwheel functions like an automatic/manual combined transmission; it’s simply a way to switch from automatic mode to manual mode when the automatic function isn’t working properly. There should also be a switching device, and the ones above are exhaust vents

The solenoid valve shown in the diagram is of the two-position five-way type with a pilot system. Generally, solenoid valves are not classified as single-acting or double-acting; they are categorized as single-electrode or dual-electrode control based on the number of solenoid coils used. The function of a solenoid valve is to switch pathways, not to maintain a position.