A gate valve is a valve that uses a gate and a seat to control opening and closing. Gate valve mainly has a valve body, valve seat, gate, valve stem, valve cover, stuffing box, packing gland, valve stem nut, hand wheel, and other components. Depending on the change in the relative position between the gate and the valve seat, the channel size can be changed and the channel can be cut off. In order to make the gate valve close tightly, the mating surface of the gate plate and the valve seat are ground.
Types of gate valves:
According to the different structural shapes of the gate valve, the gate valve can be divided into two categories: wedge type and parallel type.
The gate of a wedge-type gate valve is wedge-shaped, the sealing surface and the center line of the channel into an inclined angle, using the role of the wedge between the gate and the valve seat to achieve sealing (closed).
The sealing surface of the parallel gate valve is parallel to each other and perpendicular to the center line of the channel, divided into two types with and without the propping mechanism. When the gate is lowered, the wedge block of the two parallel gates will be propped up on the seat by the inclined surface to cut off the flow channel, and when the gate is opened, the wedge block will be detached from the mating surface of the gate, and the gate will be raised to a certain height, and the wedge block will be held up by the tab on the gate. The double gate without a propping mechanism, when the gate slides into the valve seat along the two parallel seat surfaces, the fluid pressure will press the gate on the valve body at the outlet side of the valve to seal the fluid.
1. Flat plate gate valve
The use of flat plate gate valve occasions:
(1) Oil and natural gas transmission pipelines, and flat plate gate valves with pilot holes also facilitate the cleaning of the pipeline.
(2) pipeline and storage equipment for oil products.
(3) Oil and natural gas extraction port device.
(4)Pipelines with suspended particle media.
(5) City gas transmission pipelines.
(6)Water supply project.
Flat gate valve selection principles:
(1) oil, natural gas transmission pipeline, choose a single gate or double gate plate gate valve. If you need to clean the pipeline, use a single gate with a guide hole of the bright rod flat gate valve.
(2) oil pipeline and storage equipment, the choice of single or double gate plate gate valve without a pilot hole.
(3) oil, natural gas mining mouth device, choose the dark rod floating seat with a single or double gate plate gate valve with guide hole.
(4) with suspended particles media pipeline, the choice of knife-shaped flat gate valve.
(5) city gas transmission pipeline, choose a single or double gate soft seal open rod flat gate valve.
(6) water supply project, choose a single or double gate without a guide hole bright rod gate valve.
2. wedge gate valve
Wedge gate valve occasions:
Of various types of valves, the gate valve is the most widely used one, it is generally only applicable to fully open or fully closed, and can not be used for regulation and throttling.
A wedge gate valve is generally used in the valve size is not strictly required, and the use of harsh conditions of the site. Such as high-temperature and high-pressure working medium, requiring the closing member to ensure long-term sealing, etc.
Usually, the use of conditions that require reliable sealing performance, high pressure, high-pressure shut-off (large differential pressure), low-pressure shut-off (small differential pressure), low noise, cavitation and vaporization phenomenon, high-temperature media, low temperature (deep cold), the recommended use of wedge gate valve. Such as the power industry, petroleum refining, petrochemical, marine oil, urban construction in the water supply project and sewage treatment project, chemical industry, and other fields of application.
Selection principles:
(1) the requirements of the valve fluid characteristics. Small flow resistance, strong flow capacity, good flow characteristics, sealing requirements of the strict working conditions selected gate valve.
(2) high temperature, high-pressure media.
(3) low temperature (deep cold) media. Such as liquid ammonia, liquid hydrogen, liquid oxygen, and other media.
(4) low-pressure large diameter. Such as water works, and sewage treatment works.
(5) installation location: when the installation height is restricted by the choice of dark stem wedge gate valve; when the height is not restricted by the choice of open stem wedge gate valve.
(6) can only be fully open or fully closed, and can not be used to regulate and throttle the occasion, to choose the wedge gate valve.
TAG: gate valve, selection principles, use occasion, wesdom, wesdom valve
