The choice of ice storage system valve Do you know what valve sealing materials? What are the characteristics of the sealing material?
Valve selection should pay attention to the problem:
(1) electric control valve, switch valve sealing performance should be strict with the process of freeze and melt, ethylene glycol side in a certain stage will run at 2.19 ¡ÃƒÂ¦ / 5.56 ¡æ temperature range, on the other side of the plate in the chilled water in 12 ¡æ, 7 ¡æ / usually run, if the board in ethylene glycol side closed lax for leaks, will cause the plate in the frozen water freezes on one side, Freeze-cracking equipment.
(2) Inspection valve and bypass valve should be set on both sides of the electric valve; For system maintenance, and manual operation.
The electric valve must have convenient manual adjustment device.
Do you know what valve sealing materials? What are the characteristics of the sealing material?
Principle of valve sealing
Sealing is to prevent leakage, so the principle of valve sealing is also from preventing leakage research. There are two main factors causing the leakage. One is the main factor affecting the sealing performance, that is, there is a gap between the sealing pair, and the other is there is a pressure difference between the two sides of the sealing pair. The principle of valve sealing is also from the liquid sealing, gas sealing, leakage channel sealing principle and valve sealing pair and other four aspects to analyze.
01 Tightness of liquid
The tightness of a liquid is determined by its viscosity and surface tension. When the valve’s leaking capillary is filled with gas, surface tension may repel or draw liquid into the capillary. And that forms the tangent Angle. When the tangent Angle is less than 90, the liquid is injected into the capillary tube and leakage occurs. The cause of leakage lies in the different properties of the medium. Experiment with different media, under the same condition, will get different results. You can use water, air, kerosene, etc. When the tangent Angle is greater than 90, leakage will also occur. Because of the relationship with the oil or wax film on the metal surface. Once these surface films are dissolved, the characteristics of the metal surface change, and the liquid, which was previously repelled, will wet the surface and leak. In view of the above situation, according to Poisson’s formula, the purpose of preventing leakage or reducing leakage can be realized under the condition of reducing capillary diameter and medium viscosity.
2 Gas tightness
According to Poisson’s formula, gas tightness is related to gas molecules and gas viscosity. Leakage is inversely proportional to the length of the capillary and the viscosity of the gas, and proportional to the diameter of the capillary and the driving force. When the diameter of the capillary and the average degrees of freedom of the gas molecules are the same, the gas molecules will flow into the capillary with free thermal motion. Therefore, when we do the valve sealing test, the medium must be water to play the role of sealing, with air or gas can not play the role of sealing. Even if we reduce the capillary diameter below the gas molecule by plastic deformation, the flow of the gas still cannot be stopped. The reason is that gas can still diffuse through metal walls. So when we do the gas test, we have to be more rigorous than the liquid test.
3 Sealing principle of leakage channel
The valve seal is composed of two parts, roughness, which is composed of the roughness of the unevenness spread on the waveform surface and the waviness of the distance between the peaks. Under the condition that the elastic force of most metal materials is low in our country, we need to raise higher requirements for the compression force of metal materials, that is, the compression force of material should exceed its elasticity, if we want to achieve the sealing state. Therefore, in the design of the valve, the sealing pair combined with a certain hardness difference to match, under the action of pressure, it will produce a certain degree of plastic deformation sealing effect. If the sealing surface is metal material, then the surface of the uneven convex point will appear early, at the beginning only with a small load can make these uneven convex point plastic deformation. When the contact surface increases, the surface unevenness will become plastic – elastic deformation. Then the roughness of the two surfaces in the concave place will exist. These remaining paths can be made to fit when a load that causes severe plastic deformation of the underlying material is applied and the two surfaces are in close contact, along the continuous line and in the ring direction.
4. Valve sealing pair
The valve seal pair is the part of the valve seat and shutoff that closes when they are in contact with each other. The metal sealing surface is prone to damage from clamping media, media corrosion, wear particles, cavitation and erosion during use. Such as wear particles. If the wear particles are smaller than the surface roughness, the surface accuracy will be improved when the sealing surface is run in, and will not deteriorate. On the contrary, it will make the surface accuracy worse. Therefore, in the selection of wear particles, the material, working condition, lubricity and corrosion of the sealing surface should be considered comprehensively. As wear particles, when we choose seals, we should comprehensively consider various factors that affect their performance in order to play the function of leakage prevention. Therefore, materials that resist corrosion, abrasion and erosion must be selected. Otherwise, the lack of any one of the requirements will make its sealing performance ** reduced.
2. Main factors affecting valve seal
There are many factors affecting the valve seal, mainly the following:
Post time: Aug-06-2022
