Shaft seals are an important part of stainless steel tanks. The shaft seal is a dynamic seal, and its function is to keep the equipment in a stable positive pressure or vacuum state, and prevent the material from being stirred and the infiltration of impurities, so it is not the type of rotary shaft seal that can be used for stirring equipment. In mixing equipment, commonly used shaft seals include liquid seals, packing seals and mechanical seals.
Liquid seal
When the working pressure in the mixing equipment is normal pressure, and the function of the shaft seal is only to prevent dust and impurities from entering the equipment, or to prevent the working medium from contacting the environmental medium around the mixing equipment, a liquid seal can be selected. The structure of the liquid seal is simple, and there are no parts that cause friction in direct contact with the drive shaft. However, in order to meet the design requirements for the clearance between the cylindrical shell or the stationary element and the rotating element, the processing and installation requirements of the sealing parts are relatively high.
At the same time, due to the influence of structural characteristics, the use range of liquid seals is narrow. Generally, it is suitable for occasions where the working medium is non-flammable, explosive or mildly hazardous, the working pressure in the equipment is equal to atmospheric pressure, and the temperature range is 20-80 degree .
In addition, the liquid working medium cannot fill the equipment; and the sealing liquid should use the working medium in the equipment as much as possible, or a neutral liquid that does not have physical and chemical interactions with the working medium, and at the same time seldom volatilizes and does not pollute the atmosphere.
packing seal
It is a kind of shaft sealing structure adopted earlier in stainless steel storage tanks, which has the advantages of simple structure, low manufacturing requirements and convenient maintenance. However, its packing is easy to wear and has poor sealing performance. Generally, it is only suitable for normal pressure or low pressure, low speed, non-corrosive and weakly corrosive media, and allows regular maintenance of stainless steel storage tanks.
Machinery Seal
The mechanical seal is a device that changes the sealing surface of the rotating shaft from the axial direction to the radial direction. The mechanical seal has low leakage rate, good sealing performance, low power consumption, long service time, and does not require frequent maintenance. Sealing requirements for abrasive media and media containing solid particles.
