Features of soft-seal elastic seat gate valve and the difference from hard-seal gate valve

Soft-seal elastic seat gate valve is mainly used in water supply and drainage systems. Temperature ≤80℃, nominal pressure ≤PN25, diameter ≤800mm. The valve body material is cast iron or ductile iron, cast steel or stainless steel. Standards adopted: CJ/T216-2013 Soft-seal Gate Valve for Water Supply and Drainage, GB/T 24924-2010 Elastic Sealed Gate Valve for Water Supply System. AWWA C509:2001.

Main features:

The outer surface of the metal gate is molded by vulcanization or injection vulcanization, and the whole is covered with rubber EPDM or NBR. When closed, the rubber on the gate sealing surface is elastically deformed to complete the seal. It is corrosion-resistant, has good sealing performance, and can achieve zero leakage. The gate is wedge-shaped, which reduces the wear of the valve plate sealing surface.
There is no groove at the bottom of the valve body. The fine particles in the medium will pass through the valve body with the medium, and no impurities will accumulate. The inner diameter of the flow channel at the valve seat is equivalent to the pipe, which is consistent with the nominal size. There is almost no flow resistance.
Epoxy resin powder is used for electrostatic spraying. After the coating is cured, it does not dissolve in water and does not affect the water quality. Epoxy resin powder coating is a dry solid ultra-fine powder. During coating, an electrostatic spray gun is used to drive compressed air to adsorb the charged coating particles on the surface of the valve body. Then the valve body is sent to the furnace for baking. The temperature is 180°~200° to melt the coating and form a coating on the surface of the valve body.
Epoxy powder coating has the following advantages: low melt viscosity, so the coating film has good leveling properties, and the adhesion to the metal substrate is very good, so no primer is required. The paint film has high hardness, good scratch resistance and good mechanical properties such as impact resistance, and the paint film has good water resistance, acid resistance, alkali resistance and salt water resistance.
The gate valve stem position is sealed with three O-rings. Effectively prevent the valve stem from leaking out. At the same time, a dust ring is set at the top to prevent impurities and dust from entering. It can be replaced online under pressure.
The main replacement of the elastic soft seal gate valve is: GB/T12232-2005 general valve flange connection iron gate valve. Including nominal pressure PN1~25, nominal diameter DN50~2000 flange connection gray cast iron and ductile iron gate valves.

The main differences between the two:

1. The gate of the soft seal elastic seat seal gate valve is wrapped with rubber as a whole, forming a soft seal with the valve body sealing surface, with good sealing performance. When repairing, generally only a new gate plate needs to be replaced, which is convenient for maintenance.
The valve body and gate sealing surface of the hard seal gate valve are made of body material, copper alloy, and stainless steel. After wear, the valve body and gate need to be repaired at the same time, which is more complicated.
2. The valve body of the soft seal elastic seat seal gate valve adopts a groove-free design. It will not cause impurities to accumulate.
Due to the sealing surfaces on both sides of the valve body, the hard-sealed gate valve has grooves at the bottom of the valve body. Over time, some impurities will be deposited in the grooves. This will prevent the gate from descending and cause the seal to fail.
3. The valve body of the soft-sealed elastic seat-sealed gate valve is sprayed with epoxy resin paint. Epoxy resin paint is corrosion-resistant and pollution-free, and can be used in tap water pipes.
Most hard-sealed gate valves are sprayed with paint, which pollutes the water quality to a certain extent, but now hard-sealed gate valves in tap water pipelines are also sprayed with epoxy resin.
4. The standard for soft-sealed elastic seat-sealed gate valves stipulates that the valve stem shaft seal must have at least three O-ring seals, which can be replaced when the gate valve is fully opened under working pressure.
The hard-sealed gate valve standard GB/T12232-2005 stipulates that there must be no less than two sealing rings. Dustproof seals must also be set.
5. The upper valve cover of the soft-sealed elastic seat-sealed gate valve uses hexagon socket screws. After tightening, wax is filled on it to seal it. This prevents rust between the screws and the valve body threads. This facilitates screw disassembly and maintenance in the future.
The original hard-sealed gate valve usually uses hexagonal bolts. But some hard-sealed gate valves also use similar structures.
6. The applicable medium temperature is different. In the tap water pipeline, soft-sealed gate valves are increasingly used. Hard-sealed gate valves for some high-temperature medium pipelines are also the main products.