Share a bellows valve design knowledge you don't know!

Bellows are widely used in instruments and meters. Their main purpose is to be used as measuring elements of pressure measuring instruments to convert pressure into displacement or force. The bellows have thinner walls and higher sensitivity, with a measuring range of tens of Pa to tens of MPa. Its open end is fixed, the sealed end is in a free state, and an auxiliary spiral spring or reed is used to increase elasticity. When working, it stretches along the length of the tube under the action of internal pressure, causing the movable end to produce a displacement that is related to the pressure. The movable end drives the pointer to directly indicate the size of the pressure. Bellows are often combined with displacement sensors to form a pressure sensor with an output of electrical quantity, and are sometimes used as isolation elements. Since the extension of bellows requires a large volume change, its response speed is lower than that of Bourdon tubes. Bellows are suitable for measuring low pressure. Nowadays, people have higher and higher requirements for valve sealing, especially in nuclear devices or petrochemical industries. So what are the precautions in the design process?

1. The gap between the bellows and the valve stem is usually 1 to 2 mm.

2. Bellows cannot withstand torque. The design should ensure that bellows can only stretch and contract.

3. When metal bellows valves are in the open and closed state, the bellows are in the contraction and stretching state respectively.

4. Bellows should have the minimum laminate thickness required to withstand pressure, and require testing.

5. Pay attention to the compatibility of bellows materials. Practice has proved that inconel alloy is a better material for bellows to withstand high temperature and high pressure.

6. The welding quality of bellows should have technical appraisal and welding records.

7. The bellows valve used as throttling should consider the influence of flow rate on bellows.

8. Bellows have a certain rigidity, and the increase of operating torque caused by bellows stretching or contraction should be considered.

Using bellows instead of the stuffing box on ordinary valves or using it together with the stuffing box can make the valve stem leak-free to prevent the leakage of radioactive substances or precious substances, or maintain high vacuum. In addition, the application scope of bellows is constantly increasing, so it is necessary to design bellows valves to ensure that bellows are well used during the operation process.

Bellows gate valves are relatively widely used in the petrochemical industry, metallurgical industry, etc. A valve that can be relatively widely used in many fields must have its own advantages. So what are the advantages and characteristics of bellows gate valves?

Feature 1: Strong durability. During the research and development of bellows gate valves, attention is paid to optimizing material selection, so that bellows gate valves have strong durability and support long-term production of enterprises.

Feature 2: Good performance. Bellows gate valves have good high and low temperature resistance, so this type of gate valve can be used in areas with relatively large annual temperature differences; bellows gate valves have good corrosion resistance, and can be used in pollution control, because bellows gate valves have strong acid and alkali resistance, toxicity resistance and dirt resistance; bellows gate valves have strong working stability and can work for a long time, thereby supporting the sustainable production of enterprises. In addition, the bellows gate valve also has a high degree of precision, which can avoid leakage and escaping during the use of the gate valve. This helps to support the green development of enterprises.

Feature 3: Maintenance is relatively simple. As we all know, in order to ensure the good performance of the gate valve, it is necessary to perform regular maintenance and repair of the gate valve during use. If the gate valve structure is relatively complex, it will be very troublesome to maintain the gate valve. The structure of the bellows seal gate valve is relatively simple. Therefore, the enterprise can maintain it very conveniently, so as to ensure the stability of its work and extend its service life.