1, gate valve
Also known as gate valve or gate, gate valve gate movement direction perpendicular to the direction of the fluid, the gate valve can only be used for full open and full, can not be used for regulation and throttling. According to the sealing surface configuration can be divided into wedge gate gate valve and parallel gate gate valve, wedge gate gate valve can be divided into: single gate pole type, double gate type and resilient gate type; parallel gate gate valve can be divided into single gate type and double gate type.
Divided by the threaded position of the valve stem, it can be divided into two kinds of open stem gate valve and dark stem gate valve. Gate valve drive mode classification: manual gate valve, pneumatic gate valve, electric gate valve.
2, ball valves
Ball valves, standard GB/T21465-2008 "Valve Terminology" is defined as: the opening and closing parts (ball) driven by the valve stem, and around the axis of the valve stem for rotary motion of the valve.
Mainly used to cut off or connect the medium in the pipeline, can also be used for fluid regulation and control, which hard seal V-ball valve V-ball core and surfacing hard alloy metal seat has a strong shear force, especially suitable for containing fibers, tiny solid particles and other media.
And multi-way ball valves in the pipeline not only can flexibly control the media merge, shunt, and flow direction switching, but also can close any channel and make the other two channels connected. This type of valve in the pipeline should generally be installed horizontally. Ball valve classification: pneumatic ball valves, electric ball valves, manual ball valves.
3, butterfly valve
Butterfly valve, also known as the disc valve, the opening and closing parts for the disk plate and can rotate around the valve body axis of a valve. Mainly by the valve body, valve stem, disc plate and seal ring. The valve body is cylindrical, short axial length, built-in disk. The disc plate is driven by the valve stem, if it is turned through 90 °, it will be able to complete an opening and closing. Changing the deflection angle of the disk plate can control the flow of the medium.
The main sealing member is the sealing ring, its material according to the use and medium commonly used butterfly valve and flanged butterfly valve two. Clamped butterfly valve is a double-headed bolt will be connected to the valve between the two pipeline flange, flange butterfly valve is a valve with a flange, with a bolt will be connected to the valve on both ends of the flange on the pipeline flange.
4, globe valve
Globe valve belongs to the mandatory sealing valve, so when the valve is closed, the valve must be applied to the valve flap pressure to force the sealing surface does not leak. When the medium from below the valve flap into the valve, the operating force needs to overcome the resistance, is the stem and packing friction and the pressure generated by the medium of the thrust, the force to close the valve is greater than the force to open the valve, so the diameter of the valve stem should be large, otherwise it will occur the stem top bending of the fault.
In recent years, from the emergence of self-sealing valves, globe valves, the flow of media from the valve flap above into the valve cavity, then in the medium under pressure, off the valve force is small, and open the valve force is large, the diameter of the valve stem can be reduced accordingly. At the same time, under the action of the medium, this form of valve is also more tight. China's valve "three to" has stipulated that the flow direction of globe valves, always use the top down.
Expanded
Operating valves, a variety of valve parts should be complete, intact. The bolts on the flange and bracket are indispensable, and the threads should be intact and not allowed to be loose. Handwheel on the fastening nut, if found loose should be tightened in time, so as not to wear out the connection or lose the handwheel and nameplate. If the handwheel is lost, it is not allowed to replace it with a live wrench, and it should be matched in time. Packing gland is not allowed to be skewed or no preload clearance.
For valves that are susceptible to rain, snow, dust, wind, sand and other dirt stained environment, the stem should be installed with a protective cover. The scale on the valve should be kept intact, accurate and clear. Valve seals, caps, pneumatic accessories, etc. should be complete and intact. The insulating jacket shall be free of dents and cracks. It is not allowed to knock, stand people or support heavy objects on the running valve; especially non-metallic valves and cast iron valves are prohibited.
Baidu Encyclopedia - Valve