After you have determined the o-ring size, navigate to Section 6 of this Seal Design Guide to evaluate and select the appropriate o-ring material.
Section 6 contains the Material Selection Guide for a full list of elastomers with their descriptions, key uses, temperature ranges, features and limitations and the Chemical Compatibility Table highlights the performance of specific o-ring materials when exposed to the degrading effects of a number of chemical agents.
Prior to seal purchase, make sure to take into account all the factors discussed in Section 6. In addition, you may want to consider availability and cost. If so, refer to the "economy" column in the General Properties of O-ring Elastomers Chart.
If a material is not shown, contact Apple Rubber for availability.