A compact rotary valve is often used in water supply, heating, ventilation and industrial facilities. It takes up little space and is easily automated, but it does not replace a gate valve in every system.<\/p>\n\n\n\n
A butterfly valve is a shut-off or shut-off-control pipeline valve. A round disk inside the housing rotates around an axis and blocks the passage. The name butterfly valve arose due to the similarity of the disk to the wings of a butterfly. Hence the names "butterfly valve" and "butterfly valve".<\/p>\n\n\n\n
The main purpose of the device is to cut off the flow of liquid or gas. Some models regulate the flow rate, but this must be specified by the manufacturer. Long-term operation with a nearly closed disc can cause noise, vibration, cavitation and wear of the seal. For throttling, the valve is selected according to the design characteristic, not just the diameter.<\/p>\n\n\n\n
The shaft connects the disc to the handle, gearbox or actuator. The drive rotates it, and the valve changes position: in the open state, the disc is located parallel to the flow, and in the closed state - across the pipe. The stroke is 90\u00b0, so the valve belongs to the quarter-turn type.<\/p>\n\n\n\n
During closing, the edge of the disc is pressed against the seat. In concentric models, the shaft axis passes through the center of the disc. In double and triple eccentric designs, the axes are offset, which reduces friction over a large part of the stroke. The tightness class and permissible flow direction are checked in the product data sheet.<\/p>\n\n\n\n
The housing holds the operating elements and connects to the pipeline. The disc interacts with the flow, the shaft or stem transmits torque from the actuator, the seat seals the passage, and the shaft seal prevents leakage to the outside.<\/p>\n\n\n\n
Common connection options: <\/p>\n\n\n\n
The most common body is made of cast iron with an anti-corrosion coating. In industry, carbon and stainless steel, special alloys or plastics are used. The disc can be cast iron with a polymer or nickel coating, stainless or bronze. Brass is more often found in small-diameter fittings and individual parts.<\/p>\n\n\n\n
The materials of the body, disc, shaft and seal must be compatible with the medium. Impurities, temperature, flow rate and abrasiveness are taken into account.<\/p>\n\n\n\n
The elastomeric seat seals the disc and can isolate the body from the operating environment. EPDM (ethylene propylene diene rubber) is often used for water and coolants, NBR (nitrile butadiene rubber) for certain lubricants and petroleum products. FKM (fluororubber) is chosen for increased chemical and temperature resistance. PTFE (polytetrafluoroethylene, or fluoroplastic) is compatible with many aggressive media, and a metal seat is used at high operating temperatures.<\/p>\n\n\n\n
The final choice is made according to the manufacturer's chemical resistance table: the behavior of the material depends on the composition of the medium, temperature, and pressure.<\/p>\n\n\n\n
A butterfly valve and a gate valve perform the same function - they block the flow in a pipeline, but they do it differently. In a butterfly valve, the disc rotates inside the passage, while in a wedge valve the gate moves perpendicular to the flow and, after opening, leaves the passage section. A gate valve is appropriate where maximum free passage is required, and a butterfly valve is appropriate where compactness, low weight and the possibility of automation are the priority.<\/p>\n\n\n\n