The design of knife gate valves of PA 510 series
Description of basic structural elements
|Soft seat||Seat – metal-on-metal|
PA 510 series knife gate valves are full-opening, that ensures a high working medium flow rate at low pressure drops. The internal body structure does not allow accumulation of solid deposits.
The knife gate valve body is made by casting, it consists of two halves bolted together. It can be made of the following materials:
– ductile cast iron GGG40
– carbon steel WCB
– corrosion-resistant steel CF8
– Corrosion-resistant steel with molybdenum CF8M
- special steels and alloys (upon the order)
Standard valves have an epoxy corrosion-resistant coating 250 microns thick.
Application of another protective coating is available.
By default, the knife material is stainless steel. The knife is polished on both sides, its design eliminates depositing on the knife surface and the seat. Upon the customer’s order, the knife can be made of various grades of stainless steel and special alloys.
PA 510 series knife gate valves can be manufactured with the following types of seats:
- Metal/metal for high-temperature, viscous, granular media (leakage on water up to 1.5% of the flow is allowed)
- Elastic seat made of materials such as EPDM, NBR, Viton, PTFE, natural rubber, ensuring a hermetic sealing of the working medium flow.
EPDM. It has high mechanical properties, to be used mainly for water and aqueous solutions. It is designed for operating temperature up to 90 °С in the constant mode, and not higher than 125 °С in the short-term mode. It can also be used for abrasive products.
NBR. Has a high hardness and relatively high abrasion resistance, to be used for liquids containing fats and oils. It is designed for operating temperature not exceeding 80 °С.
VITON. It has high resistance to temperatures and chemicals, to be used for corrosive liquids. It is designed for operating temperature up to 180 °C in the constant mode and up to 200 °C in the short-term mode.
Gland follower packing
Multilayer packing made of high-quality synthetic fiber with PTFE ensures tightness of the seat between the body and the gate, preventing any leakage to the environment. Gland followers are located in an easily accessible point and allow tightening, as well as packing replacement without removing the gate from the pipeline.
The knife gate valve stem is made of stainless steel. This ensures its high strength and excellent corrosion resistance. The knife gate valve design provides for both a rising and non-rising stem.