An O-ring is a closed circle usually made of flexible rubber (elastomer). The dimensions are defined by the inside diameter d1 and the cross section d2. 2-1-2 SEALING EFFECT The O-ring is usually housed in a rectangular groove. The DIN standard distinguishes two types of sealing systems, either static or dynamic. Elastomers are incompressible and react under pressure as the fluids that transmit the forces subjected to pressure from all sides. The circular cross section of the O-ring is deformed between the two surfaces (see Figure 1). In an installation space without pressure, the required clamping force Po to obtain a sealing, is created by the resistance to deformation of the rubber. The pressure Ps caused by the fluid to be sealed, increases the deformation of the cross section of the seal ring and thus the pressure required for sealing (see Figure 2). 2-1-3 AVANTAGES The simplicity of the geometry of the O-ring is the dominant feature of this sealing element. With a suitable choice of the quality of the elastomer and a precise definition of the cross section according to the size of the groove, the O-ring is an efficient, cost- effective and simple sealing system.

˾ 2-2 DESIGN AND DETAILED INSTRUCTION 2-2-1 DESIGN INFORMATION The installation spaces are calculated according to the criteria of the standard DIN 3771/5. The inside diameter of the O-ring may, during the installation, be extended by 6% while the cross section can be compressed by 3 %. In any given application it is always prudent to adopt the largest possible O-ring cross section in relation to the inside diameter d1 when selecting the cross section d2. It is particularly advisable to select the next larger cross section in connection with unfavorable tolerance conditions, in order to achieve...

2-2-4 SELECTING O-RING CROSS SECTION THICKNESS In the DIN 3771/5 standard, each O-ring inside diameter is assigned to a corresponding string section. This assignment should also be observed for the O-rings non-normalized because the degree of compression depends essentially on the tolerances of the cross section thickness and the groove. Assignments of the inner diameter d1 to the cross section thickness d2 Cross section thickness ISO 3601 Piston rods All dimensions in mm - ST : Static sealing - HY : Hydraulic - PM : Pneumatic 2-2-5 INSTALLATION SPACES Radial, internal seal Radial, external seal...

2-2-6 COMPRESSION FORCES OF O-RINGS ACCORDING TO DIN 3771/5 External seal, static External seal, Hydraulic Internal seal, Hydraulic External seal, Pneumatic Internal seal, static Internal seal, Pneumatic

2-2-7 INSTALLATION DIMENSIONS AND TOLERANCES Installation dimensions in accordance with DIN 3771/5 for elastomers with a hardness of 70 IRHD.

All dimensions in mm - ST : Static, axial sealing - DH : Static and dynamic hydraulic sealing - DP : Dynamic pneumatic sealing

2-2-8 TOLERANCES FOR O-RINGS IN ACCORDANCE WITH ISO 3601 - DIN 3773 dl

2-2-10 INSTALLATION RECOMMENDATIONS Before starting installation, check the following points : - Bores must be deburred and edges rounded. - Machining residues, and other foreign particules must be removed. - The sharp edges, slots and threads must be covered. - The media compatibility should be ensured with the elastomer material. Following points should be considered during the installation : - The O-ring must not be overstretched. Short term expansion up to 50% of the O-ring inside diameter is allowed for assembly. For hardnesses over 80 SH, higher strength elastomers (ex FKM) or special mixtures,...

2-2-12 SPECIAL SURFACE TREATMENT O-rings may be subjected to a special surface treatment, for example, to prevent them from sticking together, to reduce the coefficient of friction or to simplify the installation. Following benefits may be accrued depending on the coating method used : - Amplification of the dynamic properties - Assembly simplification - O-Ring refining 2-2-13 MOULDED WELDED O-RINGS In contrast to the O-ring, which is made through vulcanization from form tools as a complete ring, the welded moulded O-ring is cut to length from a moulded cord. The joint is cut obliquely or straight...

2-3-2 O-RING DIMENSIONS FOR STRAIGHT THREAD TUBE FITTINGS IN ACCORDANCE WITH AS568A

2-3-3 O-RING DIMENSIONS FOR METRIC THREAD IN ACCORDANCE WITH ISO 6149

2-3-4 O-RING DIMENSIONS IN ACCORDANCE WITH SMS1586

2-3-5 O-RING DIMENSIONS IN ACCORDANCE WITH ISO3601/NFT 47-501 dl

2-3-6 O-RING DIMENSIONS IN ACCORDANCE WITH JIS B2401 REF

2-3-8 METRIC O-RING DIMENSIONS

O-Ring Standard Size (Metric) dl

O-Ring Standard Size (Metric) dl

O-Ring Standard Size (Metric) dl

O-Ring Standard Size (Metric) dl

O-Ring Standard Size (Metric) dl

O-Ring Standard Size (Metric) dl

O-Ring Standard Size (Metric) dl

O-Ring Standard Size (Metric) dl

O-Ring Standard Size (Metric) dl These tables are not exhaustive and serve only as an indication. Our 700 formulas and our tool park enable us to offer more than 17,000 dimensions. We are at your disposal ; do not hesitate to contact us with your most demanding specifications. ^42)