Common Problems

Double gate gate valve and single gate gate valve in the sealing performance of the difference?

Double gate gate valve and single gate gate valve in the sealing performance there are some differences, specific as follows:

I. Sealing principle

Single gate valve: mainly rely on the metal sealing surface between the gate and the valve seat to achieve sealing. In the closing, the gate in the stem driven vertical drop, and the valve seat to form a sealing vice, through the gate on the seat of the extrusion, to prevent the medium through. The sealing effect mainly depends on the processing accuracy of the gate and seat, surface flatness and the performance of the sealing material and other factors.

Double gate valve: usually double gate structure, the two gates through the top wedge or spring and other devices connected to each other and form a seal. In the closing process, the two gates in the valve stem push to the valve seat at the same time, relying on the mutual compression between the gate and the gate and the valve seat to achieve sealing. The sealing principle of double gate valve is relatively complex, in addition to the fit of the gate and seat, the fit between the gate also has an important impact on the sealing performance.

Second, sealing reliability

Single gate gate valve: sealing performance is relatively unstable, especially at high temperatures, high pressures or medium pressure fluctuations, the gate is prone to deformation due to thermal expansion and contraction or pressure changes, resulting in the sealing surface does not fit tightly, resulting in leakage. In addition, once the sealing surface of the single gate valve is worn or damaged, it is easy to cause the failure of the entire sealing vice, and it is necessary to replace the gate or valve seat in time.

Double gate gate valve: Due to the double gate structure, the two gates can compensate and adjust each other, and to a certain extent can adapt to the deformation and wear of the gate, so the sealing reliability is relatively high. Even if one of the

Even if one of the gates is slightly worn or deformed, the other gate can still maintain a good seal with the valve seat, thus reducing the possibility of leakage.

Third, the sealing range

Single gate gate valve: for general low pressure, room temperature conditions under the sealing requirements, in some of the sealing performance requirements are not particularly high occasions more widely used. For some small calibre single gate gate valve, under normal working conditions can also meet the requirements of good sealing, but with the increase in calibre, its sealing performance may be affected.

Double gate gate valve: in high pressure, high temperature and high requirements for sealing performance of the working conditions have obvious advantages, can maintain good sealing performance in a wide range of pressure and temperature. Double gate gate valve sealing range is wider, can be applied to some harsh working environment, such as petroleum, chemical, electric power and other industries of high temperature and high pressure pipeline system.

Fourth, the sealing material impact

Single gate gate valve: sealing materials are usually metal or a combination of metal and non-metal, such as stainless steel, copper alloy and other metal materials, as well as rubber, PTFE and other non-metallic materials. Different sealing materials have a direct impact on the sealing performance of the single gate gate valve, for example, rubber sealing materials have better elasticity and adaptability, but easy to age and deformation at high temperatures; metal sealing materials have high strength and wear resistance, but the sealing surface of the higher processing accuracy requirements.

Double gate gate valve: the same need to choose the right sealing material, due to its special double gate structure, the compatibility of sealing materials and synergistic performance requirements are higher. Generally speaking, the sealing material of double gate gate valve needs to have good abrasion resistance, corrosion resistance and elasticity, in order to ensure the sealing effect between the two gates as well as between the gate and the valve seat.

Fifth, the impact of maintenance on sealing performance

Single gate gate valve: maintenance is relatively simple, mainly to regularly check the sealing surface wear of the gate and seat, and timely replacement of damaged parts. However, once the sealing surface problems, may require the overall replacement of the gate or seat, maintenance costs are relatively high, and the replacement process may affect the normal use of the valve time.

Double gate gate valve: Maintenance needs to pay attention to check whether the connecting device between the two gates is normal, as well as the sealing of the gate and the valve seat. Due to the relatively complex structure of the double gate, maintenance is slightly more difficult, but under normal maintenance, its sealing performance can be a good guarantee, and in the event of wear and tear of some parts, can be adjusted or replaced by individual parts to restore sealing performance, maintenance costs are relatively low.