Design and mode of operation of the direct shut-off valve

Direct-acting shut-off valves are used for controlled control of liquids in chemical processing plants. In everyday life, such devices are used to control the flow of water in household flow-type water heaters, as well as in fire extinguishing devices.


The direct shut-off valve consists of the following parts:

  1. Welded bellows, which is made of stainless steel (sometimes red brass) and is intended for hermetically sealing the surface of the product from the effects of external contaminants present in the working environment. The safety of any process depends precisely on the quality of the valve seat seal.
  2. Enclosures that can have multiple inputs (usually up to four). By

By default, the valves are manufactured with standard butt-welded joints designed for connecting pipelines of various nominal diameters.

  1. The internal assembly of the valve, which has several connection options – threaded or with a press fit. Materials designed for operation at certain temperatures are used for sealing.
  2. The drive, which is used as pneumatic units. They provide forced closure of the pipeline with a spring, and opening with compressed air, or from a separate seat displacement drive. For pipelines of small diameter and with small specific costs, direct shut-off valves with manual drive are used.
  3. Fasteners. It should differ in rigidity and strength, including high-temperature.

The designs of the devices in question are compact and suitable for installation in conditions of limited space.

Control over the operation

All modern versions of direct shut-off valves are distinguished by the presence of a feedback unit. They can be built-in, with consistent control characteristics, or with adapters designed for use in similar operating conditions.

Electromagnetic feedback units are installed in valves designed to supply fuel, gas and oil, which best meet the needs of the control system. The tracking units operate in two-way normally closed and normally open positions, with manual reset and three-way switching.

Most standard sizes of direct shut-off valves are designed for maintenance up to external temperatures not lower than - 50C. They are mounted in any position. The technical characteristics of these devices are regulated by the standards of GOST 9697-87.