The "Rainbow C" recognition system was devised by Elastotech in order to facilitate assembly operations when O-rings of similar dimensions but with different compounds or grades of hardness must be inserted in the same element. To avoid incorrect assembly, the seal rings can be supplied in different colours according to their compound or hardness. As well as this, the substitution of a damaged O-Ring can take place without the risk of error in the choice of the replacement piece.The colouring of the compound does not cause the modification of the physical-chemical characteristics in any event and is permanent. The "Rainbow C" system foresees the colouring of each compound in a predefined colour, but in the case of specific aesthetic and technical requirements by the Client, these colours can be modified accordingly. In table 8.4 we show the standard colours of the "Rainbow C" system.
Table 8.4
Base elastomer |
Denomination DIN/ISO |
Elastotech Compound |
Hardness (° shore) |
Standard Rainbow colour |
Nitrile butadiene |
NBR |
ME0072/YY |
From 50 to 80 |
White |
Ethylene-propylene diene |
EPDM |
ME0175/YY |
From 40 to 80 |
Lilac |
Fluorocarbon |
FPM |
ME0270/YY |
From 50 to 90 |
Military green |
Silicone |
MVQ |
ME0370/YY |
From 30 to 85 |
Bright red |
Liquid silicone (LSR) |
MVQ |
ME2020/YY |
From 10 to 80 |
Blue |
Hydrogenated nitrile |
HNBR |
ME0870/YY |
From 60 to 90 |
Yellow |