Applications and Notes of Knife Gate Valves in the Factory
Abstract: This article briefly describes the structural characteristics of PZ73 knife gate valves, their application in practice, notes and common abrasion. It puts forward the direction that users want to improve.
After heavy medium transformation in a washing plant in 1998, the coal washing process mainly consists of jigging rough separation, the heavy medium cyclone selection and slime flotation. The heavy medium process pipeline mainly consists of heavy medium suspension mixed with solid liquid in two phases, which caused serious wear to the pipeline and equipment. The gate valve used in the pipeline was mainly knife gate valves.
The knife gate valve used in the washing plant is divided into manual type, electric type and electro-hydraulic type. The models are mainly the PZ73 manual knife-type gate valve, PZ973 electric knife-type gate valve and PZ273 electric hydraulic knife-type gate valve. . The knife gate valve is composed of the valve body, valve plate, valve stem, hand wheel (driving device) and seals. The gate plate, valve stem and cover are made of stainless steel with good wear resistance. The valve body is carbon steel. Seals are divided into rubber, fluorine plastic and alloy steel seals. The opening and closing part of knife gate valves is the gate plate. The movement direction of the gate plate is perpendicular to the direction of the fluid. It relies on the handle or elector-hydraulic device. The gate plate can be driven to realize the opening and closing of the gate valve through the valve stem.
1. Characteristics of the knife gate valve
1) The knife gate valve adopts the clip-on structure in small volume and light weight. It is easy to install. The opening and closing of the gate valve can save labor. It reduces the labor intensity of maintenance workers.
2) The bottom end of the knife gate valve is in the shape of a knife blade, which has the function of cutting off materials, fibers and sundries. It is not easy to block the gate. It has good opening and closing functions.
3) It has a reasonable sealing surface and packing seal design. It makes the valve seal reliable.
4) The ram has multiple support points so that the ram has a good self-alignment.
5) A hard polytetrafluoron mud scraper is installed at the top of the knife plate, which can prevent dust, gravel and other abrading substances from entering the packing box and improve the life of the gate plate.
2. Applications and notes of the knife gate valve
1) PZ73 type clipped knife gate valve is mainly used in heavy medium and slime water pipelines in our factory. It is mainly used as a cutoff in the pipeline and can not be used as a flow adjustment. The gate should be fully opened or fully closed to avoid sealing or gate erosion, accelerate wear and greatly reduce the service life.
2) Pay attention to the installation direction of valves during installation. The chamfered side of the gate is the pressure side after the valve is closed, and the arrow direction of the valve body is the flow direction of the medium after the valve is opened.
3) The valve should be regularly used for the moving parts of the oil.
4) After long-term use of the valve, it should be replaced in time if the packing is worn. Packing gland bolts should be tightened evenly. It should not be pressed into a skewed state, so as to avoid damage to hinder the movement of the valve stem or cause leakage.
The knife gate valve has been used in the processing pipeline of the washing plant. The use effect is very good. It is convenient for the workers to install and maintain. The maintenance labor intensity is low. During use, the gate valve leakage is mainly caused by the serious wear of the gate body. The whole set of gate valves needs to be replaced after five or six months. It is the hope of the users to improve the material of the valve body or the structure of the internal flow parts of the gate body to improve the service life of the gate valve in the worn medium pipeline.
