Butterfly Valve Selection

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Butterfly Valve Selection

Post  landoo on Mon Aug 12, 2013 11:53 pm

Butterfly valve seat, stem and other materials used in a wide variety. Under normal circumstances, the choice is not specified if the butterfly valve body material, when required valve pressure 1.6MPa or less, the manufacturers have a gray cast iron butterfly valve for supply. When the desired pressure is greater than 1.6MPa valve, the manufacturers will be supply by carbon steel butterfly valves. Gray cast iron and carbon steel butterfly valves not be processed if the inner core is directly mounted on the domestic water system, use will produce yellow rust, which is not allowed, so the body material should be used in ductile iron.
In addition, the butterfly valve sealing material if it is rubber, nitrile rubber should be used. If vendors are other types of rubber, they should be required to provide environmental monitoring by qualified and meet the requirements of drinking water health report card.
When the valve flange connection on both sides, the valve body and the valve body and other similar material compared to its strength due to its structural reasons to be weak for some, but cast iron flanged butterfly valve body strength is relatively weaker Some. For outdoor pipe network, the impact of thermal expansion, there had been pulled valve cracking phenomenon. Because the proposed use of cast iron flanged butterfly valve is best not used for outdoor pipe network project, should be used if you want to use cast iron or cast iron butterfly valve connection, but large changes in temperature pipeline project should not be made of cast iron flange connection the butterfly valve.
You can use two-way butterfly valve, butterfly valve using only one-way, which is sure to pay attention during installation. Eccentric butterfly mark on the body in the direction indicated by the arrow is not the direction of medium flow inside the tubes, but said that when the eccentric butterfly valve is closed the pressure medium pipe direction. For example, from an air conditioning system for the return water pipe leads to a set of branch pipe, then the group manifold supply and return two eccentric butterfly valve must be installed in the same direction, namely shear head point towards the end of the manifold. From eccentric butterfly valve sealing structure is easy to see, in a pressurized, the pressure increases the force of butterfly plate tightly closed, before the disc is pressurized, hydraulic disc relationship weakened tightening force. Therefore, after the closure of the disc, the disc after bearing capacity is much greater than the pressure in front of the disc capacity. Practice has proved that the larger the disc, the disc before closing time on the difference between bearing capacity greater; Conversely, the smaller the disc, the disc when it is closed around the bearing capacity on the difference is smaller.
Butterfly valve can be installed at any angle of the pipe, but not flip, usually side vertical or horizontal installation, to prevent impurities in the pipe sealing surface retention.

landoo

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