Cut-off Valve
1. Feed machinery equipment accessories globe valve product introduction
In the feed production process, the globe valve is an important fluid control accessories, widely used in the pipeline of liquid raw materials (such as additive solution, grease, etc.) and the pipeline system of steam, compressed air and other media.
2. Structure composition
Valve body
The valve body is the main part of the globe valve, usually made of casting or forging process. Its shape is generally cylindrical, with an internal seat and fluid passage. The material of the valve body depends on the application scenario and the characteristics of the medium, the common materials are cast iron, carbon steel, stainless steel and so on. The cast iron valve body has low cost and is suitable for some ordinary medium pipelines with low corrosion resistance requirements; Carbon steel valve body has higher strength and better economy, and is widely used in general industrial fluid control. The stainless steel body has excellent corrosion resistance and is often used to transport corrosive liquids or in food grade and feed grade production environments with high hygiene requirements. The two ends of the valve body are usually designed with connection flanges or threaded interfaces to connect with the piping system, and the choice of connection mode depends on the material of the pipe, pressure grade and installation requirements.
Valve clack
The valve flap is a key part of the globe valve to control the flow of fluid, generally in the shape of a disc, and it achieves the sealing function with the seat. The material of the disc is usually matched with the valve body or more wear-resistant and corrosion-resistant materials are selected according to the specific sealing requirements. For example, when transporting liquids containing particulate impurities, the disc may be veneered with cemented carbide or ceramic materials to improve its wear and erosion resistance. The valve flap is connected with the external driving device (such as hand wheel, electric actuator, etc.) through the valve stem. Under the action of the driving device, the valve flap can move up and down along the axis of the seat, so as to realize the opening and closing of the valve and the flow regulation operation. The sealing surface of the disc is usually carefully machined to ensure a good seal between it and the seat to prevent media leakage.
Valve stem
The valve stem is a transmission component connecting the valve disc and the drive device, and its material requirements have high strength and good corrosion resistance, generally made of stainless steel or alloy steel. The upper end of the stem is connected with the drive device, and the lower end is fixed with the valve disc. During the operation of the valve, the stem converts the rotating motion or linear motion of the drive device into the up and down movement of the valve disc. In order to prevent media leakage along the valve stem, a sealing device such as a stuffing box is usually arranged between the valve stem and the valve body. The packing box is filled with sealing filler, such as graphite filler, polytetrafluoroethylene filler, etc. By tightening the packing gland, the filler can be tightly wrapped around the valve stem to form a reliable seal, while not producing too much resistance to the movement of the valve stem.
Sealing element
The sealing performance of the globe valve mainly depends on the seal between the disc and the seat and the seal between the stem and the valve body. The seal between the disc and the seat is usually made of metal seal or soft seal material. Metal seals are generally used in high temperature, high pressure or the sealing performance requirements of the occasion, the sealing surface using carbide or metal-to-metal coordination, through precision machining and grinding, to ensure the flatness and finish of the sealing surface, to achieve reliable sealing. Soft sealing materials are commonly used rubber or polytetrafluoroethylene, etc. These materials have good elasticity and sealing properties, suitable for general pressure and temperature media, can effectively prevent leakage, and have a certain buffer protection effect on the seat and valve disc when the valve is closed. In addition to the packing seal mentioned above, the seal between the stem and the valve body may also use auxiliary sealing methods such as O-ring to further improve the reliability of the seal.
Driving device
The driving device of the globe valve is used to operate the motion of the valve disc, and the common driving methods are manual, electric and pneumatic. The manual drive device is usually composed of a handwheel, valve stem nut, etc., and the operator drives the valve stem nut to rotate by rotating the handwheel, so that the valve stem moves up and down to realize the valve switching operation. The manual globe valve has simple structure and low cost, and is suitable for occasions where frequent operation is not required or the degree of automation is not high. The electric drive device is composed of a motor, a reducer, a coupling, a valve stem nut, etc., which controls the up and down movement of the valve stem through the positive and reverse of the motor to achieve remote control and automatic operation of the valve. Electric globe valves are suitable for large feed production equipment or piping systems requiring centralized control, which can improve production efficiency and ease of operation. The pneumatic driving device uses compressed air as the power source, and realizes the valve switching action through the cylinder, piston, valve stem and other components. Pneumatic globe valves have the characteristics of rapid action and fast response, and are often used in occasions where the valve switching speed has high requirements, such as emergency cut-off valves or valves that need to respond quickly to process changes on automated production lines.
3. Material characteristics
Valve body material
Cast iron: such as gray cast iron (HT200, HT250, etc.), with good casting performance and processing performance, low cost. Its compressive strength can meet the requirements of low-pressure pipeline systems in general feed production, but its corrosion resistance is relatively poor, and it is not suitable for transporting corrosive media or for use in humid, acid-alkali environments. In the ordinary water and air piping system of some small feed processing plants, the globe valve with gray cast iron body can play its economic and practical advantages.
Carbon steel: commonly used carbon steel materials are Q235, 20# steel and so on. Carbon steel valve body has high strength and toughness, can withstand high pressure and temperature, suitable for medium and low pressure, normal temperature or medium temperature fluid transmission pipeline. Compared with cast iron, the corrosion resistance of carbon steel has been improved, but in the environment with corrosive media, anti-corrosion treatment is still needed, such as galvanizing, painting and so on. In feed production, for some non-corrosive liquid raw materials (such as some additive solutions) or steam, compressed air and other media of the pipeline, carbon steel body of the globe valve is widely used.
Stainless steel: such as 304 stainless steel and 316 stainless steel. 304 stainless steel has good corrosion resistance, oxidation resistance and health properties, can resist the common water, acid and alkali components and microbial erosion in the feed production environment, suitable for food grade, feed grade liquid raw material transportation pipeline, such as pet feed production additive solution transportation. 316 stainless steel is more excellent in corrosion resistance, containing molybdenum element so that it can work stably in the environment containing chloride ions and other highly corrosive media, often used in some special feed production process or in the seaside and other harsh environment of the feed mill corrosive media pipeline system.
Disc material
Stainless steel: Stainless steel valve disc and stainless steel body used together to ensure the overall corrosion resistance and stability of the valve. For some less corrosive media, 304 stainless steel valve disc can meet the requirements; For highly corrosive media, it is necessary to use 316 stainless steel valve disc or use special surface treatment, such as hard chrome plating, spraying ceramic, etc., to improve the wear resistance and corrosion resistance of the valve disc.
Tungsten carbide: such as tungsten cobalt carbide, tungsten titanium cobalt carbide and so on. Carbide disc has extremely high hardness and wear resistance, suitable for conveying media containing particle impurities, high flow rate or heavy wear on the disc. In feed production, when conveying some liquids containing solid additives that are not completely dissolved or under high pressure differences, the cemented carbide valve disc can effectively resist erosion and wear, extending the service life of the valve.
Ceramic: Ceramic disc has excellent corrosion resistance, wear resistance and high temperature resistance, and its hardness is second only to diamond. Ceramic valves are often used to transport highly corrosive, high temperature or high purity media, in some high-end feed production processes, such as the production process of biopharmaceutical additives and feed mixing, the purity of the medium is very high, the ceramic valve valve can ensure that the medium is not contaminated, while ensuring the long-term stable operation of the valve.
Seal material
Rubber: Rubber seals commonly used nitrile rubber, fluorine rubber and so on. Nitrile rubber has good oil resistance, wear resistance and sealing properties, and is suitable for conveying liquid media containing grease additives, but corrosion resistance is relatively weak. Fluororubber has excellent corrosion resistance, high temperature resistance and oil resistance, and can work in more harsh environments, such as in high temperature, strong acid and alkali feed additive solution pipeline, fluororubber seals can effectively prevent leakage.
Polytetrafluoroethylene (PTFE) seals have a very low coefficient of friction, excellent corrosion resistance and good self-lubrication, and are able to maintain stable performance over a wide temperature range. It is almost free from any chemical corrosion, suitable for a variety of corrosive media and high purity media of the globe valve seal. In food-grade and feed-grade liquid transmission pipelines, PTFE seals are ideal to ensure the purity of the medium and the reliability of the valve seal.
4. Performance characteristics
Good sealing performance
Through the precise fit between the disc and the seat and the action of the seal, the globe valve can achieve a good sealing effect. Whether it is in the closed state of the valve to cut off the fluid, or in the low flow regulation, it can effectively prevent media leakage. In feed production, for some expensive additive solutions or environmentally polluting media, good sealing performance can avoid waste and environmental pollution to ensure the safety and economy of the production process. For example, in the production of pet feed, some vitamins, minerals and other additives in the pipeline with a stop valve, its reliable sealing performance can ensure the accurate measurement and delivery of additives, to prevent product quality problems caused by leakage.
Precise flow regulation
The globe valve can precisely regulate the flow of fluid by controlling the opening height of the disc. Its flow characteristics are generally linear or equal percentage characteristics, and the operator can accurately adjust the opening of the valve according to the requirements of the production process, so that the fluid flow is stable within the required range. In the feed mixing process, it is necessary to accurately control the flow of various liquid raw materials, and the stop valve can meet this requirement to ensure that different raw materials are accurately mixed in accordance with the formula ratio, and produce feed products with balanced nutrition and stable quality. For example, in the production of aquatic feed, the flow control accuracy of additive solutions such as fats and amino acids is required to be higher, and the globe valve can be fine-tuned by hand wheel or electric actuator to ensure the accurate addition of additives.
Wide range of application
The globe valve can be applied to a variety of media, including liquid, gas, steam, etc. Different materials of the globe valve can adapt to different media characteristics and working environment, such as stainless steel globe valve can be used for corrosive liquids and food grade, feed grade media transportation; Cast iron and carbon steel globe valves can be used for general industrial fluid control. At the same time, the pressure range of the globe valve is also wide, from low pressure to high pressure there are corresponding products to choose from, to meet the needs of different pressure pipeline systems in feed production. The globe valve can be seen in the steam supply system, compressed air pipeline and various liquid raw material conveying pipeline in the feed mill.
Simple structure and high reliability
The structure of the globe valve is relatively simple, mainly composed of the valve body, valve disc, valve stem, seal and drive device and other components, without complex internal structure and wearing parts. This simple structure makes the stop valve have high reliability and stability, and can run stably for a long time under normal use and maintenance conditions. In feed production equipment, the globe valve is a commonly used fluid control component, and its reliability is crucial to ensure the continuity of the entire production process. For example, on the steam pipe of the feed pelletizer, the stop valve needs to be opened and closed frequently to control the flow and pressure of the steam, and its stable performance ensures the smooth progress of the pelleting process, reducing equipment failures and downtime.
5. FAQ
Q: What is the main material of the globe valve?
A: Stop valves are usually made of stainless steel, carbon steel or cast iron to ensure adequate strength and corrosion resistance. These materials can withstand high loads and long periods of use.
Q: What are the surface treatment processes of the globe valve?
A: Common surface treatment processes for globe valves include electroplating, spraying and heat treatment. These processes can improve the hardness and wear resistance of the surface and extend the service life.
Q: How long is the replacement cycle of the globe valve?
A: The replacement cycle of the globe valve depends on the frequency of use, the working environment and the operating condition of the equipment. In general, when it is found that significant wear, leakage or cannot be effectively controlled, a new stop valve should be considered.
Q: What are the special requirements of the globe valve in different application scenarios?
Answer: In different application scenarios, the globe valve may have different special requirements. For example, a globe valve used in a high temperature environment needs to have high temperature resistance; For use in corrosive environments, corrosion-resistant materials are required.
