0. Buna-N is a common trade name for nitrile rubber, while Viton is a trade name for Fluorocarbon rubber. Viton has better chemical and temperature resistance than Buna, but Buna is usually less expensive. The exception is applications involving ammonia gas, where Buna has superior resistance to attack.Our advice is to choose the Viton for most applications.iton has better chemical and temperature resistance than Buna, but Buna is usually less expensive. The exception is applications involving ammonia gas, where Buna has superior resistance to attack.