OFV are angle-way pressure regulating valves, which have adjustable opening pressure and cover the deferential pressure range (ΔP): 2 - 8 bar (29 ‑ 116 psi). The valve can be closed manually, e.g. during plant service and have backseating, enabling the spindle seal to be replaced with the valve still under pressure. The valves are especially designed to prevent fluttering due to low velocity and/or low density. In consequence it is possible to apply the valves with wide fluctuations in capacity demands, i.e. from maximum performance to part load. A flexible O-ring provides perfect sealing over the seat.