DK-LOK® V64 Series, PED Certified Relief Valves. Wide Media Applications: Air, Gases, CNG, and Liquid relief applications. High Performance Soft Seat: provides repetitive & reliable bubble-tight seal. Orifice: 0.404 in. (10.26 mm). Working Pressure: 6,000 psi (413 bar). Cracking Pressure Range: 15 to 5,500 psig (1.03 to 379 bar). Pre-Set to desired crack pressure settings.