Valve Disc and Gaskets are sometimes changed/substituted for better performance with a given fluid. The change is represented by the insertion of a letter representing the substituted Disc/Gasket material (see examples below).
|Seal Material||Temperature Range||Application Seal Recommendations|
|Buna-N||-40°F to +250°F||Water, Air, Brine, Gas, Oil, Solvent|
|PTFE||-500°F to +500°F||Liquid Oxygen, Cryogenics|
|Viton®||-20°F to +400°F||Diesel Fuel & Gasoline
Gaseous Oxygen applications Viton provides tighter seating
Valve Type Disc / Gasket Changes:
V ----- Viton® Disc (i.e. Type 18A44 with Viton® Seals becomes 18AV44)
T ----- PTFE Disc (i.e. Type 18A44 with PTFE Seals becomes 18AT44)
B ----- Buna-N Disc (i.e. Type 16L44 with Buna-N Seals becomes 16LB44)
Viton® is a registered trademark of DuPont Performance Elastomers.