description of the characteristics of all kinds of universal valves and special valves
i, ball valve,
ball valve, a valve with opening and closing parts (ball) driven by the stem and rotating around the axis of the ball valve.
features:
1, wear resistance: because the hard seal ball valve spool is alloy steel spray welding, sealing ring is alloy steel surfacing welding, so the hard seal ball valve in the switch will not produce too much wear.(its hardness coefficient is 65-70) :
2, good sealing performance: because the hard seal ball valve seal is artificial grinding, until the valve core and seal ring completely consistent can be used.so his seal performance is reliable.
3, light switch: because the bottom of the seal ring of the hard seal ball valve uses a spring to make the seal ring and the valve core tightly held together, so when the external force exceeds the spring's pre-tightening force, the switch is very light.
4, long service life: has been widely used in petroleum, chemical, power generation, papermaking, atomic energy, aviation, rocket and other departments, as well as people's daily life.
advantages:
1. the fluid resistance is small, and its resistance coefficient is equal to the pipe segment of the same length.
2. simple structure, small volume and light weight.
3. it is compact and reliable, and the sealing surface material of the ball valve is widely used in plastic, good sealing performance, and has been widely used in vacuum system.
4. easy to operate and quick to open and close. it only needs to rotate 90° from full open to full close to facilitate remote control.
5, convenient maintenance, simple structure of the ball valve, sealing ring is generally mobile, disassembly and replacement are more convenient.
6, a wide range of application, the size from a few millimeters, to a few meters, high vacuum or high pressure can be applied.
ii, the gate valve
(1) open stem gate valve: rotate the hand wheel, and lift or drop the valve plate connected with the stem through the advance and regress of the hand wheel and the stem thread, to achieve the function of opening and closing.
open stem gate valve has the following advantages:
1, fluid resistance is small, sealing surface by medium erosion and erosion.
2. opening and closing are less effort.
3, the flow of the medium is not restricted, no turbulence, no pressure reduction.
4, simple shape, short structural length, good manufacturing technology, wide range of application.
the disadvantages of open stem gate valve are as follows:
1, between the sealing surface easy to cause erosion and abrasion, maintenance is more difficult.
2. the external dimension is large, so it needs a certain space to open and close for a long time.
3. complex structure.
(2) blind bar gate valve: also known as rotary bar gate valve (also known as blind bar wedge gate valve).the stem nut is located on the gate, the hand wheel turns the stem and the gate is lifted, usually with a trapezoidal thread at the bottom of the stem, which changes the rotation motion into linear motion through the thread at the bottom of the valve and the guide groove on the disc, that is, the operating torque into operating thrust.
iii.butterfly valve: butterfly valve is also known as the flip valve, is a simple structure of the control valve, can be used for the low pressure pipeline medium switch control butterfly valve is to close the piece (disc or disc) for the disk, around the valve shaft rotation to open and close a valve.
iv, globe valve: check valve refers to the flow of the media itself and automatic open, closed disc, used to prevent media backflow of the valve, also known as reverse valve, one-way valve, reverse flow valve, and back pressure valve.check valve is an automatic valve, its main role is to prevent medium backflow, prevent pump and drive motor reversal, and the discharge of vessel medium.
v. safety valve: safety valve is a special valve in which the opening and closing parts are in a state of constant closure under the action of external force, and when the pressure of medium in the equipment or pipeline rises beyond the specified value, it can prevent the pressure of medium in the pipeline or equipment from exceeding the specified value by discharging medium outside the system.safety valve belongs to automatic valve, mainly used in boilers, pressure vessels and pipelines, control pressure does not exceed the specified value, personal safety and equipment operation plays an important role in protection.
vi. low drain and high seal valve: the role of low drain and high seal valve is to prevent the system from misoperation caused by accumulation of driving gas leakage in the pipeline.it is installed on the system startup pipeline and is in the open state under normal circumstances. it is closed only when the inlet pressure reaches the set pressure. its main function is to eliminate the leakage due to air source
vi, pressure reducing valve
(a) proportional pressure reducing valve: the opening of the guide valve is to use the top of the adjustment bolt clockwise twist, make the spring shrink produced elastic, make the guide valve diaphragm sag downward, action on the guide valve connecting rod force, make the downward displacement of the open valve.when the pilot valve is opened, the steam from the upstream steam inlet section a goes through the alpha channel (steam supply regulating channel), through the pilot valve into the guide valve ring steam chamber, and from the beta channel directly to the upper chamber of the piston cylinder below.under the continuous supply of steam in chamber a, the pressure continues to rise, pushing the piston downward to open the main valve, at which time the steam flows continuously from chamber a to chamber b.when the load of b chamber in the downstream outlet section is satisfied, the pressure in b chamber is constantly increased due to the excess steam.the rising pressure is fed back to the lower chamber of the guide valve diaphragm through the gamma channel (pressure induction channel), making the guide valve diaphragm protruding upward, overcoming the pressure of the upper regulating spring, and the guide valve is turned down or closed.thus, turn down or close the steam source from the alpha channel upstream.when the pressure in the upper chamber of the piston cylinder drops, the main valve is turned down or closed under the action of the lower reset spring. at this time, the pressure in the b chamber starts to drop, so as to achieve the purpose of pressure regulation again and again.
vii.direct pressure reducing valve: direct action spring film type pressure reducing valve direct action spring film type pressure reducing valve is mainly composed of adjusting spring, diaphragm, piston, seat, disc and other parts.the diaphragm is used to directly sensing the downstream pressure to drive the disc and control the disc opening to complete the function of reducing pressure and stabilizing pressure.
pilot operated regulator, pressure reducing valve (3) : pilot operated pressure reducing valve is a control valve open-close part of the opening in the body to adjust the flow of the medium, the medium pressure is reduced, at the same time with the aid of the role of the valve after pressure adjust the opening of open-close part, keep the valve after pressure within a certain range, under the condition of the inlet pressure changing, keep the outlet pressure within the scope of the set, protection appliances for production from then on.
viii, ball float valve: float always float in the water, when the water rises, float also follow the rise.floating up will drive the link up.the connecting rod is connected to a valve at the other end, and when it is raised to a certain position, the connecting rod supports a rubber piston pad to seal the water source.when the water level drops, the float also drops, and the connecting rod drives the piston pad to open.