Generally, gate valves are prone to leakage and rusting. Soft sealed gate valves overcome the shortcomings of general gate valves, such as poor sealing, elastic fatigue, and susceptibility to rust. Soft sealed gate valve is a new generation product of traditional gate valve, which uses an elastic material gate plate and utilizes the micro deformation compensation effect generated by the elastic material to achieve good sealing effect. Soft sealed gate valves have significant advantages such as lightweight opening and closing, reliable sealing, good elastic memory, and long service life. They can be widely used as regulating and shut-off devices in fluid pipelines such as tap water, sewage, construction, food, power, metallurgy, textile, energy systems, etc. Soft sealed gate valves not only have the advantages of elastic seat sealed gate valves, but also have a more intuitive valve opening and reliable opening and closing. Therefore, they are often used in fire and industrial systems and are generally installed at a higher height above the ground. When applied to fire protection systems, if the installation position of the gate valve is high above the ground, a rising stem gate valve is generally used, which can clearly indicate the valve opening. If the installation position is low, an attached opening indicator gate valve is needed.

Soft sealed gate valve stem sealing (using a 3-way O-ring structure, the third O-ring can reduce the pressure at the gland, and at the same time, it can replace the upper 2 sealing rings in the pipeline under medium pressure (changing the stem seal and packing under pressure is very dangerous, so this method is not recommended). Compared with using a stuffing box structure, the O-ring sealing structure can reduce the opening and closing torque of the valve. It is not recommended to use the stuffing box structure in the water supply industry, especially in buried soft seal gate valves, as the stuffing box structure requires external water seepage lubrication and the valve stem seal cannot use materials containing asbestos. The O-ring sealing structure requires higher machining accuracy and surface roughness accuracy for the valve stem than the packing structure, otherwise cutting of the O-ring may occur. The trapezoidal thread of the valve stem should be extruded, with a low friction coefficient on the surface. The requirements for rubber material, process, and performance are in accordance with standard specifications, otherwise rubber aging will affect valve life. It is recommended to use EPDM (ethylene propylene diene monomer) rubber. The valve stem limit is designed in a stepped manner, taking into account the convenience of assembling the third sealing ring, or it can be designed in a combination.