Manual diaphragm valve is a special form of shut-off valve, with the core component being the diaphragm. It mainly consists of valve body, diaphragm, valve cover, valve stem, and handwheel.

When manually rotating the handwheel, the diaphragm moves up and down inside the valve body through the transmission effect of the valve stem. When in the closed state, the diaphragm tightly adheres to the sealing surface of the valve body, separating the medium from other parts of the valve and blocking the flow of the medium. When it is necessary to open the valve, continue to rotate the handwheel, and the valve stem drives the diaphragm to move upward, forming a certain gap between the diaphragm and the valve body. The medium can then flow through this gap.

The diaphragm isolates the medium from the metal parts of the valve, which can prevent corrosion of the medium on the metal parts and also prevent contamination of the medium by the metal parts. It is especially suitable for corrosive media or situations with high hygiene requirements. Moreover, by changing the shape and position of the diaphragm, the flow rate and velocity of the medium can be effectively controlled, achieving good regulation of the fluid.

Measurement steps for manual diaphragm valve:

1. Appearance inspection:

-Check the overall appearance, including the valve body, handwheel, connecting parts, etc., to ensure that there are no obvious signs of damage, deformation, corrosion, or leakage.

-Check whether the diaphragm is damaged, aged, cracked, etc. If any problems are found, replace the diaphragm in a timely manner.

2. Sealing test:

-Closed state test: Install on the test pipeline, close the valve, apply the specified pressure from the inlet end (usually according to the nominal pressure of the valve), maintain for a certain period of time (such as 5 minutes), and observe whether there is leakage at the outlet end. If there is no leakage, it indicates good sealing performance in the closed state.

-Open state test: Open the valve and apply pressure from the inlet end to check the sealing between the valve and the pipeline connection, as well as between the diaphragm and the valve body, to ensure that there is no leakage even when the valve is fully open.

3. Operation function testing:

-Manually operate the handwheel, feel the flexibility and resistance of the operation, check whether the valve opens and closes smoothly, and whether there is any jamming phenomenon.

-Check whether the opening and closing positions of the valve are accurate by marking the corresponding opening positions and observing whether the actual opening degree matches the markings.

4. Traffic characteristic testing:

-Under certain pressure differential conditions, gradually change the opening of the valve, record the flow values at different openings, and draw the flow characteristic curve of the valve to evaluate whether its regulating performance meets the requirements.