CC and CL Chemical resistance Seal
CC and CL bearing seals – the problem – solvers
Perfect for use in sea water and other harsh environments!
The combination of bearing shaft seals featuring a PTFE sealing lip and a stainless steel (grade 316) housing make this sealing solution a good option for difficult and extreme conditions. Ideal for use underwater at sea, in dirty environments, for applications with corrosive chemicals or extreme temperatures. There are two types of PTFE seal available and one of them is maintenance-free for the lifetime of the bearing unit – so grease it and forget it!
PTFE does not age, it is UV resistant, flame retardant and not hygroscopic. The water absorption is less than 0.01%. PTFE does not melt and is therefore not suitable for injection moulding. Blow molding and vacuum forming are also not possible. In addition, PTFE from Polyfluor has the following properties:
- Dual or triple PTFE sealing lip
- Works under high pressure up to 40 bar
- Suitable for unhardened shafts as well
- The ideal choice for high speeds of up to 30 m/s
- For wide temperature range from -79°C up to 260°C
- Excellent chemical resistance
- Suitable for food and pharma applications (FDA-approved)
- Good dry running capability
- Wear-resistant and low friction
- FDA approved
- Greatest resistance to fatigue
- Flame resistant – UL94V0
- Antistick properties
- Low co-efficient of friction
- UV-resistant (does not age)
- Not hygroscopic (water absorption < 0,01%)
- Very good dielectric insulation properties
Two types of PTFE seals
These seals are useful for problematic applications such as where temperatures are extreme or chemical resistance is needed. Extreme Bearing supplies two standard types of PTFE lip seals.
CC flushes dirt away
The CC type is the version with two lips placed on the outside to keep the elements and unwanted contaminants out of the bearing housing. When the housing is filled up with grease, the lips will release the excess grease and discharge the contamination from the sealing surface.
CL is maintenance-free
Where as CL type cannot flush away the contamination from the sealing surface because this seal is equipped with an additional third lip intended to keep the grease inside. The nature of the PTFE material makes it possible for the other two sealing lips to work effectively without lubrication. This makes the CL seal unique for bearing assemblies because it does not need to be regreased and therefore is maintenance-free.
Limited seal lift prevents penetration of dirt
Normal stresses in the grease, due to the high shear rates in the shaft area or in the seal contact area, generate a contact force on the seal lip. This is in addition to the lift generated by elastohydrodynamic lubrication. Because of the overall design of the seal, this lift effect will be limited. Therefore the PTFE lips fit more tightly and with more tension around the shaft. This makes it more difficult for dirt to get under the lip and wear a groove into the shaft.
In grease-lubricated Extreme Bearings such as the CC seal, it is not only the small gap between the seal lip and the shaft that provides sealing against contaminants. The grease in between the sealing lips also provides a sealing action.
Examples of grease diagrams using CC and CL seals
If the contamination is only on one side of the bearing unit, a seal combination such as those shown in the diagrams can be chosen. By refilling the grease on this side, it will flow and be released from the bearing housing and the contamination along with the grease will flow away from the sealing lips.
Chemical resistance PTFE
PTFE is affected by some alkali metals (molten or in solution) and rare fluorinated compounds at high temperatures and/or pressures. Some organic and halogenated solvents are absorbed causing minor dimensional changes but these effects are physical and also reversible.
Note: The chemical resistance of each polymer is mainly determined by the chemical structure of the material and the strength of the weakest link in this specific structure.
R – Resistant
LR – Limited Resistance
NR – Not Recommended
ND – No Data
Actual properties may change due to processing method, compound type, extruded dimensions and other variables. It is the user’s responsibility to evaluate and fully test the suitability of the product for their specific application.
|Acetic acid (10%)||R||R||R|
|Acetic acid (glac./anh.)||R||R||R|
|Acetyl salicylic acid||R||R||R|
|Bromide (K) solution||R||R||R|
|Bromine liquid, tech.||R||R||R|
|Bromine water, saturated aqueous||R||R||R|
|Caustic soda & potash||R||R||R|
|Chlorates of Na, K, Ba||R||R||R|
|Chlorides of Na, K, Ba||R||R||R|
|Chromic acid (80%)||R||R||R|
|Copper salts (most)||R||R||R|
|Cresylic acids (50%)||R||R||R|
|Fatty acids (>C6)||R||R||R|
|Hydrobromic acid (50%)||R||R||R|
|Hydrochloric acid (10%)||R||R||R|
|Hydrochloric acid (conc.)||R||R||R|
|Hydrofluoric acid (40%)||R||R||R|
|Hydrofluoric acid (75%)||R||R||R|
|Hydrogen peroxide (30%)||R||R||R|
|Hydrogen peroxide (30 – 90%)||R||R||R|
|Hypochlorites (Na 12-14%)||R||R||R|
|Lactic acid (90%)||R||R||R|
|Manganate, potassium (K)||R||R||R|
|Nitrates of Na, K and NH3||R||R||R|
|Nitric acid (<25%)||R||R||R|
|Nitric acid (50%)||R||R||R|
|Nitric acid (90%)||R||R||R|
|Nitric acid (fuming)||R||R||R|
|Oils, lubricating + aromatic additives||R||R||R|
|Oils, vegetable and animal||R||R||R|
|Phosphoric acid (20%)||R||R||R|
|Phosphoric acid (50%)||R||R||R|
|Phosphoric acid (95%)||R||R||R|
|Sugar, syrups & jams||R||R||R|
|Sulphates (Na, K, Mg, Ca)||R||R||R|
|Sulphur dioxide, dry||R||R||R|
|Sulphur dioxide, wet||R||R||R|
|Sulphur dioxide (96%)||R||R||R|
|Sulphuric acid (<50%)||R||R||R|
|Sulphuric acid (70%)||R||R||R|
|Sulphuric acid (95%)||R||R||R|
|Sulphuric acid, fuming||R||R||R|
|Tannic acid (10%)||R||R||R|
|Wetting agents (<5%)||R||R||R|
Mounting CC and CL chemical resistant PTFE Seals
Tips for mounting CC and CL seals:
- PTFE shaft seals are press fitted into receiving hole.
We recommend the sealing rings are glued into the receiving hole. Use sealing compound (e.g. Loctite 601,641)
- Use conical fitting tool to protect sealing lip
- Before fitting, the seal lip must be inspected for contamination/damage
- The sealing lips must not be deformed
- These seals require expert installation
It is important when mounting a CC and CL seal that there is a tapered end on the shaft. The required dimensions are given here in mm.