Nitrile (NBR) dominates basic Downhole Seal Stacks for its oil resistance and cost-effectiveness in temps up to 120°C and 5,000 PSI. With 90 Shore A hardness, it suits low-sour service in shallow wells. However, aromatic exposure causes swelling, limiting to brines and CO2. Blends with carbon black enhance tear strength for chevron rings. API 6A Class 2 certification validates its use... https://globalsealstech.com/media/