1.    Gasket Material
       Some families of cylinders are available with gaskets made of different materials.

1.1.    Polyurethane: The best in terms of long-life, resistance to wear and reduced friction.

1.1.1.    Chemically Compatible With:
?    Pure aliphatic hydrocarbons (butane, propane, gasoline).
?    Mineral oil and grease (some additives can chemically attack the material)
?    Silicone oil and grease.
?    Water up to + 50°C
?    Resistance to ozone and ageing

1.1.2.    Not Compatible With:
?    Any Impurities (moisture, alcohol, acid or alkaline compounds) can chemically attack polyurethane.
?    Ketones, esters, ethers
?    Alcohols. glycols
?    Hot water, steam, alkali, amines, acids.
?    Good elasticity down to -35°C (for low temperature PU version only).

1.2.    NBR
These gaskets have a shorter life than polyurethane gaskets. However, they are recommended for use in environments causing the formation of water condensate, such as tropical climates, where polyurethane gaskets may tend to deteriorate quickly due to hydrolysis.
1.2.1.    Chemically Compatible With:
?    Methane, butane, propane, oily acids
?    Aliphatic hydrocarbons
?    Lubrication oils.
?    Gasoline.
1.2.2.    Not Compatible With:
?    Ozone and exposure to sunlight.
?    Good elasticity down to -35°C (for low temperature NBR verisol only).

1.3.    Viton
Can withstand temperatures as high as 150°C. This makes them ideal for use on rodless cylinders, high speed applications, involving high temperatures at the sliding lips.
1.3.1.    Chemically Compatible With
?    Mineral oil and grease, slight swelling with oil grade ASTM no. 1 and 3.
?    Silicon oil and grease
?    Animal and vegetable oil and fat
?    Aliphatic hydrocarbons (gasoline, butane, propane, natural gas)
?    Aromatic hydrocarbons (benzol, toluene)
?    Chlorinated hydrocarbons (tetrachloroethylene)
?    Fuels
?    Ozone, atmospheric agents, ageing Not compatible with:
?    Polar solvents (acetone, methylethylchetone, diethyl ether, dioxane)
?    Glytol-based brake fluids
?    Ammonia gas, amines, alkali
?    Superheated water vapour .
?    Low molecular organic acids (formic and acetic acid)

1.3.2.    Not Compatible With:

2.    Principle of Pneumatics
2.1.    Pressure

The ratio between a force and the surface on which it acts.