Basic knowledge of valves, common use of various valves.

The valve stem of the internal thread hidden rod gate valve rotates, and the gate valve with the transmission thread in the inner cavity of the valve body quickly opens and closes the gate valve quickly. The valve stem rotates and moves up and down. The diameter of the channel in the valve body of the contraction chamber gate valve is different. The gate valve with the diameter of the sealing surface of the valve seat smaller than the diameter of the flange joint can be divided into gate valves with diversion holes and gate valves without diversion holes. Flat gate valves with diversion holes can be pigged through the ball. Flat gate valves without diversion holes can only be used as opening and closing devices on pipelines. Automatic valve Automatic valve is a valve-driven valve, which acts on its own according to the capacity of the medium. The drive valve is a gate valve operated manually, electrically, hydraulically or pneumatically. The slide valve is driven by the valve stem. The invention relates to a valve parallel gate valve which moves up and down along the sealing surface of a valve seat. A gate valve with parallel sealing surfaces on both sides of a slide valve wedge-shaped gate valve has wedge-shaped sealing surfaces on both sides, and an outer screw rod which rises through the stem of a handwheel gate valve moves up and down. The center of rotation (i.e. the center of the valve shaft) of the butterfly valve butterfly plate of the gate valve with the transmission thread outside the body cavity rotates around the fixed shaft. The butterfly valve is located at the center line of the valve body and the rotation center of the butterfly plate of the single eccentric butterfly valve in the sealing section of the butterfly plate (that is, the center of the valve shaft). The double eccentric butterfly valve is located on the center line of the valve body, forming a size offset with the sealing surface of the butterfly plate, and the rotating center of the butterfly valve (that is, the center of the valve shaft) forms a size offset with the sealing section of the butterfly plate. And forms another dimension offset from the center line of the valve body. The rotation center of the butterfly plate of the triple eccentric butterfly valve (that is, the center of the valve shaft) forms a size offset with the sealing surface of the butterfly plate and another size offset with the center line of the valve body. The center line of the sealing surface of the valve body forms an angular deviation with the center line of the valve seat (that is, the center line of the valve seat), the rotary valve of the valve rotates relatively along the axis of the sealing curved surface of the valve seat, and the ball valve (ball) is opened and closed. Valve floating ball valve rotates ball valve around the axis perpendicular to the channel. Ball valve has no fixed shaft. Ball valve has fixed shaft. Ball valve has flexible ball valve. Ball valve has poor elasticity. Ball valve is equipped with ball valve plug valve. A valve with a plug opening and closing part (plug) rotating around its axis has no packing in the plug body of the plug valve. The sealing of the sealing surface between the plug and the plug body depends on tightening the nut under the plug. Plug ring and packing plug valve The seal between the plug and the plug body of self-sealing plug valve with packing seal mainly depends on the pressure of the medium itself. Plug valve oil seal plug valve lubrication plug valve plug valve with grease seal, disc valve with plug opening and closing part (cylindrical plug) rotating around its axis, valve stop valve with baffle valve opening and closing part (baffle) moving relatively on the sealing surface of valve seat but not passing through the sealing surface of valve seat, and stop valve opening and closing part (disc) driven by valve stem. The upper threaded stem of the valve moving up and down along the axis of the valve seat (sealing surface) The outer threaded stem of the stop valve shell has the same direction as the two channels of the stop valve medium in the stop valve shell. The inlet and outlet of angle stop valve medium with 180 angle stop valve are 90. Triangle globe valve has three channels. The DC globe valve has an angled stem and plunger globe valve. The nger type globe valve plunger globe valve is a variant of the conventional globe valve, and its disc and seat are designed according to the plunger principle. The disc is designed as a plunger and the valve seat is designed as a complete set of rings. Needle cut-off valve is sealed by the cooperation of plunger and valve ring. The size of the valve seat hole of needle globe valve is smaller than the nominal diameter. The throttle valve of the stop valve passes through the opening and closing piece (disc). Valve hook disc throttle valve is a groove disc throttle valve which adjusts the flow and pressure by changing the cross-sectional area of the channel, and is often used in cryogenic devices. Window disc throttle valve is suitable for throttle valve with larger nominal diameter. Plug-type throttle valve is suitable for small and medium diameter throttle valves.

The opening and closing parts (disc) of check valves and check valves rely on the force of the medium, that is, swing check valves can automatically prevent the medium from flowing backwards. Single disc swing check valves have only one disc swing check valve. Multi-disc swing check valves have more than two disc swing check valves. Valve lift check valve disc moves perpendicular to the axis of the valve seat hole. The check valve bottom valve is installed at the end of the suction pipe of the pump to ensure that the suction pipe is full of water. Spring lift check valve can not only reduce surge pressure, but also make the flow channel smooth. Compared with the lifting check valve with ordinary structure, the spring-loaded annular disc lifting check valve with small flow resistance has shorter disc stroke and the spring load makes it close quickly. Therefore, the multi-ring flow passage lifting check valve is more conducive to reducing surge pressure. This valve has the smallest disc stroke, so it closes faster. Butterfly swing check valve is similar to butterfly plate in shape. Check valve with disc rotating around fixed shaft (without rocker) Pipeline check valve Pipeline check valve is a check valve with disc sliding along the center line of valve body. This valve is small in size, light in weight and good in processing technology, but its flow resistance coefficient is slightly larger than that of swing check valve. Empty check valve No-load running check valve is a special check valve used at the outlet of boiler feed water pump. Slowly close the check valve to prevent the medium from flowing back and play the role of exhaust. A buffer device is arranged on the swing check valve or the lifting check valve to form a slow-closing check valve, which can effectively prevent the diaphragm check valve from being impacted by water. This valve is a check valve with a new structure, although its use is limited by temperature and pressure. But its water hammer protection pressure is much smaller than that of the traditional swing check valve. The conical diaphragm check valve is installed between two flanges of the pipeline. It closes very quickly. Annular braided diaphragm check valve adopts folded annular rubber diaphragm, which has extremely fast closing speed. But its application scope is usually a spherical check valve with limited pressure difference (△ P < 1 MPa) and temperature (T < 70). Under the action of medium, rubber balls (single ball and multiple balls) roll back and forth along the center line of the valve body in a short stroke to realize its opening and closing action. Safety valve is an automatic valve that does not rely on any external force. On the contrary, the rated amount of fluid is discharged by the force of the medium itself to prevent the pressure in the system from exceeding the predetermined safety value. When the pressure returns to normal, the valve is closed again to prevent the medium from flowing out.

Counterweight safety valve A check valve that uses a lever and a heavy hammer to balance the disc pressure. This structure can only be used for fixed equipment. The weight of its heavy hammer should generally not exceed 60kg. Spring safety valve is a kind of safety valve which uses the force of compression spring to balance the pressure of disc and seal it. The spring force of this safety valve should generally not exceed 20000N N. The pulse safety valve is designed with a main valve and an auxiliary valve. The pulse action of the auxiliary valve drives the main valve to act. This structure is usually used for small lift safety valves with large caliber, large displacement and high pressure systems. The opening height of the disc is 1/40~ 1/20 of the throat diameter of the valve seat. The opening height of the disc of the falling safety valve is equal to or greater than 1/ of the throat diameter of the valve seat. 4. When the tgpe safety valve with fully enclosed safety valve cover is opened for discharge, the medium will not leak to the outside, but will be completely discharged through the discharge pipe. This structure is suitable for the semi-closed safety valve with flammable, explosive and toxic media when the semi-closed bonnet safety valve is opened and discharged. Part of the medium is discharged through the discharge pipe, and the other part leaks from the joint between the valve cover and the valve stem. This structure is suitable for ordinary steam and exposed safety valves that have no pollution to the environment. When the medium is discharged, the medium is directly discharged from above the valve disc. This safety valve is suitable for occasions where there is no requirement for environmental pollution. The direct load safety valve directly uses mechanical load, such as weight, lever weight or spring, to overcome the force generated by the medium pressure under the disc. The safety valve with auxiliary device is assisted by power auxiliary device. It can be opened at a pressure lower than the normal opening pressure. Even if the auxiliary device fails, this valve should still meet the standard requirements. The safety valve with additional load always maintains an additional force to strengthen the seal until the pressure at its inlet reaches the opening pressure. The additional force (supplementary load) can be provided by an external energy source. When the safety valve reaches the opening pressure, it should be released reliably. Its size should be set so that the safety valve can still reach the rated displacement under the premise that the inlet pressure does not exceed the percentage of the opening pressure stipulated by the state without releasing additional force. Pilot safety valve is a safety valve driven or controlled by pilot valve. The pilot valve itself should be a direct load safety valve lever and a weight load safety valve that meet the standard requirements. Use lever to transfer force to disc. Bellows seal balance safety valve uses bellows to balance back pressure to keep opening pressure constant. Two spring safety valves are connected in parallel. The pressure reducing valve of the same imported safety valve group reduces the pressure of the medium through the throttling of the opening and closing parts, and makes the pressure behind the valve automatically meet the predetermined requirements by using the energy of the medium itself. The piston pressure reducing valve of the valve piston uses the piston as the sensitive element. Diaphragm pressure reducing valve which drives the disc to move adopts diaphragm as sensitive element. The air bag pressure reducing valve drives the disc to move, and the pressure of the valve is balanced by the pressure of the air bag after entering the valve. Spring diaphragm pressure relief valve is a bellows pressure relief valve, which uses spring and diaphragm as sensors to drive the disc to move up and down. The pressure reducing valve adopts bellows mechanism to drive the disc to move up and down. Lever reducing valve uses lever mechanism to drive disc to move up and down. Pressure reducing valve The outlet pressure of the fixed pressure reducing valve remains unchanged. Reducing valve proportional reducing valve proportional reducing pressure. The outlet pressure of the pressure reducing valve keeps a certain proportion with the inlet pressure or a certain reference pressure. The outlet pressure of the pressure reducing valve with fixed differential pressure keeps a certain differential pressure or a certain reference pressure with the inlet pressure. Straight moving type relief valves takes advantage of changes in export pressure. The pilot pressure reducing valve consists of a main valve and a pilot valve. The change of outlet pressure is amplified to control the action of the main valve. The main valve is located in the pilot pressure reducing valve. A valve controlled by a pilot valve that regulates and controls the circulating medium. In the pilot pressure reducing valve, the front acting pressure reducing valve has a front valve for controlling the main valve; Reverse-acting pressure reducing valve, the inlet medium acts on the disc in the same direction as the rising direction of the disc; Pressure reducing valve, the inlet medium acts on the disc in the direction opposite to the rising direction of the raft; Rotary Pump Caster Red Wine Unloading Relief Valve and imported medium act on the disc to approach or balance.

Trap for automatically discharging condensed water and preventing steam leakage Mechanical trap drives the opening and closing parts through the change of condensed water level, thus completing the action of blocking and draining steam. The floating ball steam trap uses hollow spheres to float in condensed water. Drive the trap of opening and closing parts. The free floating ball steam trap causes the opening and closing parts (free floating ball) to open and close due to the change of condensate level in the shell. The valve can discharge saturated water and can continuously discharge condensed water. The lever float trap causes the opening and closing action of the opening and closing part (lever float) due to the change of condensed water level in the shell. The lever mechanism of the valve has the characteristics of expansion buoyancy, so the free semi-floating ball trap can be used in the occasion of super-large displacement. The free semi-floating ball trap adopts a semi-spherical float (free semi-floating ball) that can move freely. Float itself has the function of valve flap, which is a structure that can open and close the valve port without hinge, lever and connecting rod mechanism. It is also the simplest steam trap with downward opening. The float of the inverted bucket trap opens downward, and the opening and closing action of the opening and closing parts is caused by the change of condensate level in the float. Most of these valves do not directly fix the disc to the float. Instead, a lever mechanism is used to expand buoyancy. Barrel-opening steam trap, also known as floating barrel steam trap, is a kind of steam trap with a floating barrel in condensate water to drive the opening and closing parts. Thermostatic trap drives the opening and closing parts through the change of condensate temperature. Bellows seal trap, a trap that can stop steam and drain water, is a low boiling point volatile liquid sealed in a snake-shaped container as a temperature sensing element. The disc is fixed on the bellows. With the change of temperature, the diaphragm trap, a trap with bellows that can be opened and closed, is of steam pressure type, and its opening and closing parts are driven by the imbalance between the pressure of condensed water in the deformable element and the steam pressure of volatile liquid. Bimetal element trap and bimetal trap will not cause gas blockage. A steam trap that drives the opening and closing parts to move. The valve will not be blocked. Thermal power trap is a kind of trap that drives the opening and closing parts by the change of condensate power characteristics to stop steam and drain water. Dise steam teap is a steam trap that uses the different thermal properties of steam and condensate, as well as the change of static pressure and dynamic pressure to make the valve plate move.

Pulse trap uses the secondary evaporation of steam in two-stage throttling to cause the pressure change of steam and condensate, while labyrinth or orifice trap makes the opening and closing parts move. This type of trap controls the discharge of condensed water through the orifice and changes the hot condensed water. The diaphragm valve to reduce steam outflow is driven by the valve stem and moves up and down along the axis of the valve stem. Valve Cut-off Diaphragm Valve Spherical Diaphragm Valve Body and Diaphragm Valve Cut-off Check Valve are similar in shape to the cut-off valve body. The cut-off check valve is a valve that can play two roles of cut-off and check-back. This valve is suitable for stop check valve throttle valve Serew-down stop check valve and throttle valve. It is a three-purpose valve that can stop, stop and throttle. The valve is widely used in stop check valves and safety valves, and is used in oil wells and water injection equipment. Check ball valve with three-way valve with safety function is a dual-purpose valve, which can be used as check valve and ball valve. Weir diaphragm valve is a kind of diaphragm valve with ridge structure and diaphragm forming sealing pair in the flow passage of valve body. Wedge diaphragm valve is a diaphragm valve with a disc similar to wedge gate valve. Multi-purpose valves have the original sources of various valves: www.famen0 1.com.