| Class | Material | Service | Working pressure | Working temperature |
| 12 | Vx1 | Highly corrosive fluids, strong (acid e.g. sulphuric acid, nitric acid 67%). | = 20 bar. | 180° C |
| 12 | PTFE metal renforced | Highly corrosive fluids, strong acid (e.g. sulphuric acid, nitric acid 67%). Good resistance. | = 20 bar. | 180° C |