How to choose a suitable needle valve

A needle valve is a valve that can be precisely adjusted for a wider range of uses than other valves. For example, the cutting torch for flame cutting, the knob for adjusting the flame temperature is a needle type valve, which is an important part of the instrumentation measuring pipe system, mainly includes a stop valve and a ball valve. Its function is to open or cut the pipe passage . The role of any valve is to cut off the fluid. According to the different spool, can be divided into globe valve, gate valve, plug valve, ball valve, butterfly valve, needle valve and so on. Needle valve spool is a very sharp cone, like a needle inserted into the seat, that is, as the name implies named needle valve. Needle valve valve valve than other types of valves to withstand greater pressure, good sealing performance, it is generally used for smaller flow, high pressure gas or liquid medium seal. Needle valve The main parameters Nominal pressure: PN2.5 PN4 PN6.4 PN16 PN32Mpa Nominal diameter: DN5 ~ DN25 Applicable medium: oil, water and gas and other non-corrosive or corrosive media Suitable temperature: -20 ℃ ~ 440 ℃ -70 ℃ ~ -240 ℃ ≤540 ℃ ≤570 ℃, etc. Manufacturing materials: 20 #? 1Cr18Ni9Ti? 304? 316? 316L? 12Cr1Mov Under normal circumstances, the needle valve material should be based on the performance of its parameters and materials according to this Standard selection, and should be consistent with the provisions of the relevant product standards. Can also use the performance of not less than the provisions of this standard or other materials agreed upon by both parties to the contract. Special requirements needle valve technical requirements are as follows: 1, gray cast iron needle valve for nominal pressure pN≤1.0MPa, the temperature of 10 ~ 200 ℃ water, steam, air, gas and oil and other media of gray iron System valve. 2, malleable iron needle valve for nominal pressure pN≤2.5MPa, temperature -30 ~ 300 ℃ water, steam, air and oil and other media malleable iron valve. 3, ductile iron needle valve for nominal pressure pN≤4.0MPa, the temperature of -30 ~ 350 ℃ water, steam, air and oil and other media ductile iron valve. 4, copper alloy needle valve for nominal pressure pN≤2.5MPa of water, seawater, oxygen, air, oil and other media, and the temperature is 40 ~ 250 ℃ vapor medium copper alloy valve. 5, carbon steel needle valve for nominal pressure pN ≤ 32.0MPa, temperature -30 ~ 450 ℃ water, steam, air, hydrogen, ammonia, nitrogen and petroleum products and other media of carbon steel valves. Valve inlet pump 6, high temperature steel needle valve for the nominal pressure pN ≤ 16.0MPa, the temperature is less than or equal to 550 ℃ steam and petroleum products and other media high temperature steel valve. 7, low temperature steel needle valve for nominal pressure pN≤6.4MPa, temperature higher than or equal to -196 ℃ of ethylene, propylene, liquid natural gas and liquid nitrogen and other medium-temperature low-temperature steel valves. 8, acid-resistant stainless steel needle valve for nominal pressure pN ≤ 6.4MPa, temperature less than or equal to 200 ℃ nitric acid, acetic acid and other media stainless steel acid-resistant steel valve. First of all, the body of the anti-corrosion, mainly the correct choice of materials. Although the anti-corrosion information is very rich, but it is not easy to choose the right thing, because the problem of corrosion is very complicated. The difficulty of choosing the valve body material lies in that it can not only consider the corrosion problem, but also must consider the ability of pressure and temperature resistance, economically reasonable and easy to purchase and other factors. Followed by the lining measures, such as lead-lined, lined with aluminum, lining engineering plastics, lined with natural rubber and various synthetic rubber. This is a saving method if the media conditions permit. Third, in the pressure, the temperature is not high, the valve body with non-metallic materials, often very effective control of corrosion. In addition, the outer surface of the needle valve body is also subject to atmospheric corrosion, the general steel materials are to paint to protect. This article Keywords: valve