Materials
How to choose a rubber compound: NBR, EPDM, silicone, neoprene or FKM
Start from what the part touches, the temperature it works at and how it moves. A practical way to pick between the common rubber compounds before you ask for a quote.
Most rubber parts fail for one of three reasons: the compound swells or hardens in the fluid it touches, it is worked outside its temperature range, or it cannot take the movement. Choosing the compound is mostly a matter of answering those three questions in order.
1. What does the part touch?
This is the question that rules compounds out fastest.
- Mineral oil, diesel, grease: nitrile (NBR) is the usual choice. EPDM and natural rubber swell in oil and should be avoided.
- Water, steam, outdoor weather: EPDM resists water, sunlight and ozone, which is why it is common in cooling towers and outdoor seals. It is not for oil.
- Oil and weather together: neoprene (CR) is a reasonable middle ground for outdoor parts with some oil contact.
- Hot oil, fuel or many chemicals: FKM (fluoroelastomer) takes higher temperatures and a wider range of chemicals, at a higher cost.
- Aggressive chemicals at high heat: perfluoroelastomer (FFKM) is the specialist option for critical duty.
If you are not sure what the fluid is, the name of the machine and where the part sits is often enough for us to work it out.
2. How hot and how cold does it get?
Typical continuous working ranges for standard grades. These are general figures from published elastomer references, not the rating of a particular Mangal compound:
| Compound | Typical range | Common uses |
|---|---|---|
| Natural rubber (NR) | −50 to +80 °C | Pads, bushes, rollers, mountings |
| Nitrile (NBR) | −30 to +100 °C | Oil seals, O-rings, pump parts |
| EPDM | −40 to +130 °C | Water, steam and outdoor gaskets |
| Neoprene (CR) | −35 to +100 °C | Outdoor gaskets, boots, bellows |
| Silicone (VMQ) | −55 to +200 °C | LED and lighting gaskets, static seals |
| FKM | −20 to +200 °C | Hot oil and fuel seals |
Short peaks can go beyond these figures and special grades extend them, while fluids, pressure and movement can narrow them. The compound for your part, and its working range, is confirmed with the quotation.
3. Does it move?
A static gasket and a moving seal ask different things of the rubber.
- Static seals and gaskets need the right hardness so the joint closes without the rubber squeezing out.
- Moving parts such as diaphragms, bellows and wiper seals need flex and tear strength. Silicone handles heat well but tears more easily, so it is a weaker choice for parts that rub or flex hard.
- Wear parts such as wheels and rollers often use polyurethane or a hard natural rubber for abrasion resistance.
What to send us
You do not need to name a compound to get a quote. Send the drawing or the old part, what it touches, the temperature, and whether it moves. If your drawing already specifies a compound or hardness, we follow it.
See the full compound comparison, or send your part details.
