CR O-rings: Chloroprene Rubber Explained
Chloroprene rubber (CR), known as neoprene or Baypren, is an economical synthetic rubber with very good resistance to weathering, ozone, and cold. Here you can find out what CR O-rings are suitable for and where their limits lie.
- CR (chloroprene rubber) is also known as neoprene or Baypren and is a particularly economical sealing material.
- Temperature range from −40 °C to +100 °C, with special compounds up to 120 °C. This figure applies to the medium air.
- Very good resistance to ozone, weathering, and ageing, plus resistance to many refrigerants such as Freon and ammonia.
- Main applications: refrigeration and air conditioning technology, shipping, and outdoor applications.
- Weaknesses with acids, alkalis, fuels, and polar solvents. Other materials are better suited for these media.
What Are CR O-rings?
Chloroprene rubber (CR) is a widely used synthetic rubber with a long history of industrial use. Hoses, conveyor belts, and window profiles are just a few examples of CR-based products.
This already points to an important advantage of CR for sealing technology: O-rings made from this material are particularly attractive in terms of cost. When CR O-rings are used in line with their suitability profile, they are an extremely economical alternative for seals of all kinds in industrial applications.
One key application area is refrigeration technology. Since CR is resistant to chemicals such as ammonia and many coolants, the material is ideally suited for durable seals in process refrigeration systems or air conditioning systems. The high cold flexibility of CR ensures permanently tight connections between system components. Overall, the media resistance of CR is comparable to that of NBR.
In direct comparison, CR O-rings have only slight weaknesses in the area of acids and alkalis. Application experts also know CR O-rings under the common trade names Neoprene or Baypren.
The 5 Key Advantages
The key advantages of CR O-rings relate primarily to their very good usability in refrigeration and air conditioning systems. The thermally insulating effect of the material ensures low energy losses at the connection points between system parts. This property also ensures that the desired temperature gradient is maintained at seals between technical systems and the environment.
Together with its near-universal resistance to many refrigerants, this makes CR O-rings ideally suited for use in numerous technical devices.
The long-term durability of seals also plays a major role in industrial production plants or consumer products. Premature leaks can ultimately lead to costly machine downtime or extensive warranty claims. CR O-rings, however, are particularly unproblematic in this respect.
With good abrasion resistance and insensitivity to ageing mechanisms from contact with the environment, this sealing material enables very reliable seals. Unlike some alternative O-ring materials, this also applies to use in dynamic seals.
The 3 Most Common Application Areas
Shipping
Shipping represents a particularly important application. Thanks to their insensitivity to seawater, CR O-rings can be used without difficulty in this environment. Good mechanical properties and resistance to numerous chemicals open up many application possibilities for CR O-rings in watercraft for maritime shipping.
Outdoor Applications
Despite their focus on air conditioning and refrigeration technology, CR O-rings are not limited to this application. Within the limits of media resistance and temperature suitability, the material can also be used for many other seals. The applicability of sealing elements made from CR benefits above all from the attractive price level and their suitability for outdoor use.
Air Conditioning and Refrigeration Technology
CR O-rings are used in large quantities in air conditioning and refrigeration technology. CR is suitable for contact with common coolants such as Freon and ammonia. In addition, sealing elements made from CR also exhibit good resistance to ageing, ozone, and many other chemicals.
Even when CR O-rings come into contact with other media during use, they can still permanently and reliably seal coolant-carrying systems. This applies not only to stationary equipment used in industry or private households. With their insensitivity to weathering, CR O-rings are also perfectly suited for automotive air conditioning systems.
Media Resistance of CR O-rings
| Resistant to | Not resistant to |
|---|---|
| Paraffinic mineral oils with low EVI | Low-molecular-weight aliphatic hydrocarbons such as propane and petrol |
| Silicone oils and greases | Naphthenic mineral oils for lubrication |
| Water and aqueous solutions (within temperature limits) | Glycol-based brake fluids |
| Refrigerants | Polar solvents (ketones, esters, ethers, acetone) |
| Ozone, weathering, and ageing |
With an otherwise comparable resistance profile, CR O-rings have an advantage over their NBR counterparts: CR retains its material properties significantly longer under the influence of ozone and weathering.
In addition to many standard grades, CR O-rings are also available in special versions. Users with particular requirements can, for example, obtain CR O-rings in grades with increased fungal resistance. These prevent the material from being attacked by microorganisms when in contact with water.
You can find a detailed overview in our list of media resistances.
Temperature Resistance of CR O-rings
The temperature range of CR extends from −40 °C to +100 °C. This general figure applies to the use of standard grades and excludes contact with aggressive media.
In specific applications, CR O-rings can therefore have significantly different upper and lower continuous temperature limits. For example, the O-rings should not be used in contact with air above 90 °C. If the system to be sealed carries water at a temperature above 80 °C, an alternative sealing material should be used.
For special application areas, it is also possible to use special CR compounds. For example, maximum continuous temperatures of up to 120 °C can also be covered with CR O-rings.
In the low-temperature range, the cold resistance of CR is comparable to the materials EPDM and NBR. HNBR and FKM achieve similarly good cold properties in special grades. For very low temperature ranges, however, the silicone materials VMQ and FVMQ are significantly better suited.
CR is often compared to NBR in terms of its properties, but has better suitability for low-temperature applications.
Mechanical Properties
Thanks to their good abrasion resistance, CR O-rings are suitable not only for static seals such as pipe connections or inspection openings. Moving components can also be permanently sealed against each other or against the environment with these O-rings. In both cases, the good abrasion resistance has a positive effect.
Friction occurs when changing pressure conditions cause the O-ring to move within the groove, or when machine parts move. Both cause hardly any material loss with CR O-rings. Particles released from the surface would, on the one hand, impair the sealing effect and, on the other hand, could contaminate system components. CR O-rings achieve abrasion resistance values similar to HNBR, NBR, EPDM, or FKM.
CR also has antistatic properties that are necessary for some applications. For example, in medical technology there is a requirement that seals must not become electrostatically charged.
Groove Design and Installation
Groove Design for CR O-rings
- Compression in the groove should be around 20 % for static applications.
- Choose lower compression for dynamic seals.
- 20 % of the groove should still be free after compression.
- Always design grooves according to standard market tables.
- Permanent elongation after installation should be below 6 %.
- Permanent compression after installation should be below 6 %.
Installation of CR O-rings
- Thoroughly clean the groove space before installation.
- Do not stretch elastic O-rings by more than 50 % during installation.
- Provide lead-in chamfers between 15 and 20 degrees.
- Deburr bores, even if they are only passed over during installation.
- Round off sharp edges with a minimum radius of 0.1 to 0.3 mm.
- Use silicone grease to ease installation.
- Avoid twisting the O-ring.
Frequently Asked Questions
What is CR material made of?
What else are CR O-rings known as?
What is the resistance of CR like?
What is the difference between CR and NBR?
Is there a data sheet for CR O-rings?
