How to according to the working condition and process operation comprehensively determine the structure of the pneumatic valve type

according to the working condition and process operation, integrated structure
of pneumatic valve. Technological requirements
ammonia corrosion of copper, cannot choose copper mass production of pneumatic valve. In the medium containing ammonia process, as the structure of the pneumatic valve and pneumatic valves, the sealing surface is made of babbitt.
with the pipe flow double should choose omnidirectional pneumatic valves. Stop running, in the refinery heavy oil pipeline, to reverse purging steam pipeline, in case of heavy oil block pipeline solidification, and therefore should not be adopt by the pneumatic valve. Because the reverse flow into the medium, easy to erosion by the pneumatic valve sealing surface, should choose brake pneumatic valve is preferred.
with some crystallization or contain sediment medium, unfavorable choose by the pneumatic valve and gate valve, because they are easy to crystallization and sediment wearing. Therefore, choose the pneumatic valve pneumatic valve or ball cock is relatively appropriate; Also optional pneumatic valve, flat gate tube but best used of pneumatic valve.
in the brake on pneumatic valve selection, rising stem single ram than non-rising stem double ram to adapt to the corrosive medium; Single ram is suitable for the viscosity of medium; Wedge double ram adaptability to high temperature and deformation of the sealing surface is better than wedge type single ram, there will be no card phenomenon due to temperature changes, especially the single ram is superior than without elasticity.
need accurate regulation of small flow rate, should not need by the pneumatic valve, needle type pneumatic valve or throttling valve should be adopted. The need to keep the pneumatic valve after pressure stability, reduced pressure pneumatic valve should be adopted.
to high pressure and ultrahigh pressure medium, often used by the pneumatic valve, right Angle type because right Angle by the pneumatic valve is usually made of forged steel, forged steel compression capacity is relatively better than cast steel.
。 Economic rationality
the corrosive medium, if the temperature and pressure is not high, should try to use non-metallic pneumatic valves; If the temperature and pressure is higher, lining pneumatic valves are available, and to save precious metals. When choosing a non-metallic pneumatic valves, still should consider economic rationality. For example, in can be used under the condition of polyvinyl chloride (PVC), need not teflon, because ptfe is higher than the price of PVC.
on the occasion of high temperature and pressure, the pressure gauge should be based on temperature, if the ordinary carbon steel pneumatic valve can satisfy the use requirement, unfavorable use steel alloy pneumatic valves, pneumatic valves for alloy steel price is much higher.
for larger viscosity medium, requires a small flow resistance, Y type once-through should be adopted by the pneumatic pneumatic valve, ball valve, gate valve, plug pneumatic valve and flow resistance small pneumatic valves. Pneumatic valve flow resistance is small, less energy consumption.
for low pressure and large flow of water, air and other media, the use of large diameter brake pneumatic valve and butterfly valve is quite reasonable. Butterfly pneumatic valve to make a truncation, and can make a throttle.
。 Safety and reliability
+ spheroidal graphite cast iron can be used on steam pipelines pneumatic valves and cast steel valves. But if in the steam pipe outside, stop gas supply, water freezes easily and make the pneumatic valve is broken, especially in northern China. Therefore, appropriate USES pneumatic valve steel casting or forging steel, also want to do a good job of freeze protection pneumatic valves.
acetylene class, flammable and explosive medium to high sealing requirements. In the pressure. MPa, should use pneumatic diaphragm valve, but should not be used on the pipeline vacuum equipment. Very dangerous radioactive medium and highly toxic medium, should adopt the structure of the corrugated pipe pneumatic valve, in case of medium leakage from the stuffing box.
for a drive, Electric, hydraulic, pneumatic) Pneumatic valves, in addition to the requirements drive safe and reliable, but also according to different working condition, the corresponding driving devices. For example, in need of fire conditions, should choose hydraulic pneumatic valves, pneumatic devices. To must choose the pneumatic valve with electric actuator, electric actuator should be explosion proof type, to avoid the arc cause fire.
。 Pneumatic valve operation and convenient maintenance
for large pneumatic valves and at high altitude, high temperature and high pressure, dangerous, long-distance pneumatic valve, should choose gear transmission, chain transmission, or with an electric device, pneumatic device, hydraulic pneumatic valves.
in the operating space is limited, should not be in a rising stem gate pneumatic valve, pneumatic valve to choose non-rising stem gate as well. It is best to use pneumatic valve adjustment.
to be quick, quick opening of pneumatic valve, pneumatic valve is unfavorable in general gate, globe pneumatic valve, should be based on other requirements, need pneumatic ball valve, cock pneumatic valve, pneumatic valve, quick release pneumatic butterfly valve, etc.
brake pneumatic valve and globe valve is one of the largest two types of pneumatic valves use the pneumatic valve. When choose, should be considered. Brake pneumatic valve flow resistance is small, medium of less energy consumption, but the maintenance is difficult; By the pneumatic valve and simple, easy maintenance, but large flow resistance. From the perspective of the maintenance by the pneumatic valve repair than brake pneumatic valve is convenient; Water and steam in the pneumatic valve, the pressure drop is not big, so stop pneumatic valve in the water, such as steam medium widely used in the pipeline. But in the petroleum products high viscosity medium, such as pneumatic valve repair is difficult, although the gate is still a large number of adoption. In pipeline welding connection, should choose as far as possible welding connection by the pneumatic valve, unfavorable choose the pneumatic brake valve welding connection. Because of pneumatic valve sealing surface on the pipeline repair gate is much more difficult than repair by the pneumatic valve sealing surface, and brake the pneumatic valve under the condition of the temperature change is big gate easily jammed with the pneumatic valve seat.