I design water meter transformation, 50WPD table, the original table before the installation of 50 anti-theft valve, table after the installation of 50 of the globe valve; master let me put anti-theft valve into anti-theft gate valve. Switch the stop valve to the gate valve. I'd like to ask what kind of valve is appropriate Why? And I checked from the Internet that the ball valve is generally used for small aperture, this aperture range is how much? Why?No copy paste, thank you......
First, the advantages and disadvantages of the ball valve1, advantages:Minimum flow resistance (actual 0);Because it is not stuck at work (without lubricant), it can be reliably applied to corrosive media and low boiling liquid;Complete sealing can be achieved in larger pressure and temperature range;It can realize quick opening and closing, and the opening and closing time of some structures is only 0.05~0.1s, so that it can be used in the automation system of the test stand. Quick opening and closing valve, operation without shock;The spherical closure can be automatically positioned at the boundary position;The working medium in the two-sided reliable seal;In the fully open and fully closed, the ball and seat sealing surface and the dielectric isolation, the high-speed media through the valve sealing surface will not cause erosion;It has the advantages of compact structure, light weight, it could be considered for most reasonable structure of the valve system of medium low temperature;To body symmetry, especially the welded body structure, can well withstand the stress from the pipe;The closure of parts can withstand the pressure differential.11;They all welded ball valve can be buried underground, so that the valve parts from erosion, the maximum life of up to 30 years, is the most ideal oil and natural gas pipeline valve.
Ball valve through the circular channel and smooth, compact ball valve, so the fluid through its resistance is very small (strong circulation). Quick and quick opening and closing, easy installation and more connection. Wide range of use. Its shortcomings, high cost.
Ball valve and valve are generally used for fluid switching and flow, usually can not be used for flow regulation, and in addition to the valve can be used for fluid switching and cut-off, can also be used for flow regulation. If you need to adjust the flow rate, it is better to use the medium valve. The valve operation is very convenient, rapid and labor-saving, generally as long as the valve handle can turn 90 degrees, and the ball can be used not too pure (solid particles) fluid because of its spherical valve core of the fluid in the opening and closing of the shear movement. The gate seal between easy to cause erosion and abrasions, maintenance more difficult, larger size, open need a certain space, opening and closing time is long, complex structure.As you say, the ball valve is generally used for small caliber, because small caliber production is simple, relatively inexpensive, caliber increased production accuracy requirements, production costs increased, so the price will be high. Generally small diameter threaded connections, from the G1/4~G2 have.
2, shortcomings:Because the main valve seat seal material is PTFE, it has almost all the chemical substances are inert, and the friction coefficient is small, stable performance, easy to aging, temperature range and excellent sealing characteristics of a comprehensive. But the physical properties of PTFE include high expansion coefficient, sensitivity to cold flow, and poor thermal conductivity. The design of seat seals must be carried out around these characteristics. Therefore, when the seal material hardens, the reliability of the seal will be damaged. What's more, polytetrafluoroethylene has a lower temperature range and can only be used at less than 180 degrees centigrade. Over this temperature, the sealing material will age. Consider long-term use, usually only at 120 degrees does not use.Its regulating performance is worse than the cut-off valve, especially pneumatic valve (or electric valve).Two, scope of application:Ball valves are used in petroleum refining, long distance pipeline, chemical, paper making, pharmaceutical, water conservancy, electric power, municipal, steel and other industries.
