Introduction to Rubber O-Rings

Rubber O-rings are elastic sealing rings with a circular cross-section, made from various rubber materials. They achieve sealing through elastic deformation and are one of the most commonly used sealing elements in mechanical equipment.

 

Core Characteristics

Characteristic	Description	Advantages
Simple Structure	Monolithic circular cross-section structure	Simple manufacturing, low cost
Reliable Sealing	Self-tightening seal under medium pressure	Zero leakage in static sealing
Easy Installation	Small size, light weight, simple installation	Easy maintenance and replacement
Wide Applicability	Multiple rubber materials available	Adapts to different working conditions
Low Friction Resistance	Low motion friction resistance	Suitable for dynamic sealing applications

 Common Materials

Material Type	Characteristics	Temperature Range (°C)	Main Applications
Nitrile Rubber (NBR)	Good oil resistance, excellent overall performance	-30~100	Hydraulic oil, lubricating oil seals
Fluoroelastomer (FKM)	High temperature and chemical resistance	-20~200	High temperature, chemical media seals
Silicone Rubber (VMQ)	High and low temperature resistance, good elasticity	-60~200	Food and medical equipment seals
EPDM Rubber (EPDM)	Good weather and ozone resistance	-40~120	Hot water, steam seals
Neoprene (CR)	Relatively good weather and ozone resistance	-30~100	Outdoor equipment seals

Performance Parameters

Performance Indicator	NBR	FKM	EPDM	Test Standard
Hardness (Shore A)	50~90	60~90	50~90	ASTM D2240
Tensile Strength (MPa)	10~25	10~20	10~15	ASTM D412
Elongation (%)	100~600	100~300	100~500	ASTM D412
Compression Set (%)	15~30	10~25	15~30	ASTM D395

 Selection Guide

1. Working Condition Analysis:

   · Medium type and concentration

   · Operating temperature and pressure

   · Motion type and speed

2. Material Selection:

   · Consider chemical compatibility

   · Determine temperature range

   · Evaluate cost factors

3. Size Determination:

   · Select according to standard sizes

   · Consider installation space

   · Confirm compression ratio

 

Installation Requirements

1. Pre-Installation Inspection:

   · Confirm O-ring specifications

   · Check surface quality

   · Clean sealing surfaces

2. Installation Precautions:

   · Use dedicated tools

   · Avoid twisting during installation

   · Ensure no sharp edges or burrs

3. Lubrication Requirements:

   · Apply proper lubrication during installation

   · Choose compatible lubricants

   · Avoid using incompatible greases

 

 Application Fields

1. Hydraulics and Pneumatics: Hydraulic cylinders, pneumatic cylinders, valves

2. Automotive Industry: Engines, transmissions, braking systems

3. Home Appliances: Washing machines, refrigerators, air conditioners

4. Medical Devices: Syringes, infusion equipment

5. Food Machinery: Food processing equipment

 

Common Failure Modes

1. Installation Damage: Scratches, cuts

2. Compression Set: Elasticity failure

3. Chemical Corrosion: Swelling, aging

4. Extrusion Damage: Excessive pressure

5. Thermal Aging: Cracking, hardening

 

Maintenance

1. Regular Inspection:

   · Check sealing performance

   · Observe aging condition

   · Replace failed seals promptly

2. Storage Requirements:

   · Store away from light

   · Keep away from heat sources

   · Prevent deformation under pressure

3. Service Life:

   · Note effective service period

   · Regular replacement

   · Maintain replacement records

 

Rubber O-rings, as simple and effective sealing elements, can meet most sealing requirements through proper material selection, correct installation, and regular maintenance. Their economy and reliability make them indispensable basic sealing components in mechanical equipment.