The use of O-ring

1. The use of O-rings at high pressure is due to the compressive stress of the material to play a sealing function. In addition, the pressure of the sealing fluid plays a safe sealing effect. Therefore, the limit of pressure should be considered in principle. The actual use of the O ring must generate the pressure of the sealing medium fluid to keep the O-ring from being squeezed in. Therefore, the actual pressure resistance of the O ring is determined by the relationship between the mechanical strength of the material (as a representative value: hardness) and the gap.

When the retaining ring is subjected to pressure from two directions, a retaining ring can be installed on both sides of the O-ring. When the retaining ring is subjected to pressure from one direction, a retaining ring can be installed on the opposite side of the pressure. The shape of the retaining ring has a ring type, an oblique cut There are two kinds of formulas. From the perspective of use effect, the circle-shaped effect is the best. From the point of view of installation convenience, it is convenient to be chamfered.

2. Use for different purposes Cylindrical static seal Even if the O-ring and groove size are used as standard, the inner diameter of the groove may sag due to the combination of different dimensions. Please install it so that the O-ring does not bite.

3. The plane static seal can be divided into two categories: the occasion (a) under internal pressure and the occasion (b) under external pressure. In the case of (a) for internal pressure, in principle, the O-ring outer diameter D is used. In the case of external pressure (b), in principle, the inner diameter of the O-ring is used. Since the collapse rate is usually not a problem during installation, it can be considered that the elongation of the bolt and the deformation of the flange surface after being subjected to pressure are better than the cylinder static The seal is bigger. In the case of (C), since it is not attached to the wall, it may wear or fall off due to pressure changes, so please do not use it. When the inner diameter is relatively large (above 150) and the cut diameter is small (below 3), the O-ring may fly out as shown in Figure-5, and the clamping and part of the O-ring may be trimmed. A coarser cut diameter can be used. Seals for vacuum flanges Compared with general hydraulic O-rings used in vacuum appliances, the following points should be paid attention to. For O-rings in vacuum equipment, since the sealing medium is gas, it is easier to leak from the gap between the contact surfaces than liquids. Therefore, pay attention to the surface roughness of the contact parts. In the case of using under internal pressure, the D size is relatively small (about 30 or less), and sometimes the installation is not suitable, the D size should preferably be slightly larger (about 0.2 ~ 0.3mm) for convenience. Pneumatic seals 1. When oil injection is used, one O-ring can be used for the piston seal, and two are recommended for life and sealing. It is recommended to use one O-ring and one dust-proof seal for the piston rod seal, and please apply lubricating oil between the O-ring and the dust-proof seal.

4. When using the oil-free method, two O-rings can be used for the piston seal, and grease is applied to the O-ring as a lubricant. Please refer to the oil filling method for the piston rod seal.

5. Precautions for design Clearance and squeezing gap The O-ring is squeezed by the groove part, which is determined by the pressure of the fluid, the gap and the hardness of the rubber (the value is obtained from the pressure when the cylinder is not expanded) , the diameter gap at high pressure can be designed about 75% of this value). Compression allowance From the perspective of sealing function, the minimum value of the compression allowance is about 8%, and the maximum value is about 30% or less of the rubber compression set. When using the O-ring, please refer to the groove size in the dimension table. surface roughness of the part