The O-Ring Seals (or O Rings) are toroidal cross-section sealing elements, essential for preventing the leakage of fluids or gases. Their operation is based on the elastic deformation of the material, which creates a hermetic seal when the ring is compressed between two surfaces.
They are incredibly versatile and used in a wide range of industrial, hydraulic and pneumatic applications. For your specific needs, Larosi offers a complete selection of seals in different compounds and sizes, guaranteeing the perfect solution for every application.
Catalog
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Consultation
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Larosi offers O Rings in different materials
1. NBR (Nitrile Rubber)
It is the standard material, the most widely used worldwide for seals.
- What it is: A copolymer of butadiene and acrylonitrile.
- Pros: Excellent resistance to mineral oils, greases, fuels and hydraulic fluids. Good mechanical strength.
- Cons: Poor resistance to ozone, weathering (UV) and high temperatures.
- Temperature: from -30°C to +100°C (with peaks up to +120°C).
- Applications: Automotive, general hydraulic and pneumatic systems.
2. VMQ (Silicone)
Ideal for extreme temperatures, but not for mechanical stress.
- What it is: Silicone rubber.
- Pros: Wide thermal range and excellent flexibility at low temperatures. It is physiologically inert (safe for food and medical use).
- Cons: Very fragile mechanically (cuts easily) and poor abrasion resistance.
- Temperature: from -60°C to +200°C.
- Applications: Food, medical, coffee machines and aerospace sectors.
3. FPM / FKM (Fluoroelastomer or Viton)
The “premium” material for severe chemical conditions.
- What it is: Fluorinated elastomer (FPM is the ISO designation, FKM the ASTM; often known by the trade name Viton).
- Pros: Extremely high resistance to aggressive chemicals, acids and hydrocarbons. It is non-flammable and resists aging well.
- Cons: High cost. Not suitable for acetone or glycol-based brake fluids.
- Temperature: from -20°C to +200°C.
- Applications: Chemical, petrochemical and high-performance engine industries.
4. EPDM (Ethylene-Propylene Rubber)
The best choice for water and atmospheric agents.
- What it is: Copolymer of ethylene and propylene.
- Pros: Exceptional resistance to ozone, UV rays and aging. Excellent with hot water and steam.
- Cons: Absolutely incompatible with mineral oils and greases (swells and degrades rapidly).
- Temperature: from -50°C to +150°C.
- Applications: Heating systems, braking systems (DOT fluid), window frames.
5. PTFE (Teflon)
It is not a rubber, but a rigid plastic material.
- What it is: Polytetrafluoroethylene.
- Pros: Almost total chemical inertness (resists almost everything). It has the lowest coefficient of friction among solids.
- Cons: Not elastic; once deformed it does not return to its original shape (“cold flow”). Difficult to install in closed housings.
- Temperature: from -200°C to +260°C.
- Applications: Chemical laboratories, industrial valves and ultra-low friction applications.
Special Types of O Ring Seals
Our product range is selected to guarantee maximum reliability and resistance in every industrial application. We offer a wide choice of technical components ready in stock, including:
- O-rings: versatile seals available in different compounds and standard or special sizes.
- Food-grade silicone O-rings: certified for use in the food & beverage sectors, guaranteeing safety and compliance with current regulations.
Applications and Functions of O-Ring Seals
Our seals are essential components for the correct operation of machinery and systems. Thanks to the high quality of the materials, our products perform critical functions such as:
- Hermetic sealing: prevention of fluid (liquid or gas) leaks in static and dynamic systems.
- Protection from contamination: effective barrier against the ingress of dust, dirt and external agents.
- Thermal and chemical resistance: operational stability even in the presence of extreme temperatures or aggressive substances.
- Wear reduction: protection of rotating shafts and mechanical seats to extend the service life of machinery.
Standard basic O-Ring compounds – Chemical resistance
Legend:
- A = excellent chemical resistance, slight swelling
- B = good chemical resistance, significant swelling
- C = poor chemical resistance, excessive swelling
- NR = not recommended
- — = data not available
| Substance | Recommended Polymer | NBR | EPDM | HNBR | MVQ | FKM |
| Acetaldehyde | EPDM, MVQ | NR | A | — | AB | NR |
| Acetamide | NBR, EPDM | A | A | A | BC | AB |
| Aluminum acetate | EPDM, FKM | B | A | — | NR | A |
| Butyl acetate | EPDM | NR | BC | — | NR | NR |
| Ethyl acetate | EPDM | NR | A | NR | B | NR |
| Methyl acetate | EPDM | NR | AB | NR | NR | NR |
| Isopropyl acetate | EPDM | NR | AB | NR | NR | NR |
| Acetylene | EPDM, NBR | A | A | — | BC | A |
| Vinegar | NBR, FKM, EPDM | B | A | — | A | A |
| Acetophenone | EPDM | NR | A | — | NR | C |
| Acetone | EPDM | NR | A | NR | BC | NR |
| Fatty acids | FKM, NBR | A | NR | B | C | A |
| Acetic acid | EPDM | C/NR | A | — | B | NR |
| Hydrocyanic acid | EPDM, FKM | B | A | B | AC | A |
| Hydrochloric acid | FKM, HNBR | NR | BC | BC | B | AB |
| Chromic acid | EPDM, FKM | NR | B | NR | B | A |
| Hydrofluoric acid | EPDM | NR | B | — | NR | NR |
| Formic acid | EPDM | NR | A | — | C | BC |
| Phosphoric acid | EPDM, FKM | C | A | — | NR | C |
| Nitric acid | FKM | NR | C | NR | B | C |
| Sulfuric acid | FKM, EPDM | NR | B | — | NR | C |
| Tannic acid | NBR, EPDM, FKM | A | A | A | B | A |
| Sea water | NBR, EPDM | A | A | A | AB | A |
| Hydrogen peroxide | FKM, MVQ | BC | BC | B | A | A |
| Drinking water | NBR, EPDM | A | A | A | B | A |
| Saturated steam | EPDM | NR | A | — | NR | B |
| Steam 100°C | EPDM | NR | A | — | NR | NR |
| Turpentine | NBR, FKM, HNBR | AB | NR | A | NR | A |
| Sewage | EPDM, NBR | A | A | A | AB | A |
| Butyl alcohol | NBR, FKM, EPDM | AB | AB | A | B | A |
| Ethyl alcohol | EPDM, NBR, FKM | AB | A | A | B | A |
| Methyl alcohol | NBR, EPDM | A | A | A | A | A |
| Amine | EPDM | C/NR | AB | — | BC | NR |
| Ammonia gas | NBR, EPDM | A | A | A | B | NR |
| Ammonia solution | EPDM, NBR | A | A | A | AB | AB |
| Aniline | EPDM, MVQ | NR | AB | — | A | C |
| Benzene | FKM | NR | NR | NR | NR | C |
| Butadiene | FKM | NR | NR | C | NR | AB |
| Creosote | NBR, FKM | AB | NR | — | NR | A |
| Sulfur hexafluoride SF6 | EPDM | B | A | B | AB | NR |
Food-grade O-Rings for the Food Industry
Discover our Food Grade Silicone Rings, perfect for the food industry!
Larosi invites you to visit the dedicated page, where you will find safe and certified solutions for your needs. We offer O-Rings compliant with FDA, EC 1935/2004 and NSF regulations, with the possibility of customization in sizes and compounds.
Our materials specifically designed for food contact allow the production of “food-grade” O-Ring seals that resist extreme temperatures and aggressive detergents, guaranteeing hygiene and durability. Discover also the innovative metal-detectable seals and the technical support of our experts.
Visit the Food Grade O Rings page now for more details!
Our range includes over 10,000 references of industrial spare parts, selected to precisely meet any technical and application need.
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