Soft seat design: Provides repeatable bubble-tight performance before and after each relief cycle. Metal-to-metal seat design: Provides pilot valve performance in high temperature service. Bubble-tight seats near set pressure: Allows higher system operating pressure and, therefore, maximum process output; not as sensitive to vibrational and pulsating service; reduces product loss. Pop action available: No main valve throttling, which helps prevent freeze-ups in cryogenic or refrigerant type services. Modulating action available: Significantly cut product loss per relief situation; reduce environmental pollution; avoid oversizing consequences; not as sensitive to inlet pressure losses as pop action. Field test connection: Quick, simple verification of set pressure while valve remains in service. Balanced design: Lift unaffected by back pressure; no expensive and fragile bellows required to balance against high back pressure. Full lift at set pressure: No overpressure required for full lift; allows D.O.T. installation to be set higher than Maximum Allowable Operating Pressure (MAOP) when pop action is used. Replaceable soft seats and seals: All seats and seals are renewable easily and quickly; no expensive, time-consuming seat lapping required. High Gain Modulating Action available on 400 Series pilots providing full main valve lift by 5% overpressure while significantly cutting product loss during relief events. API 526 direct spring center-to-face dimensions available for Series 200, 400, 500 and 800 pilots eliminating the need for piping modifications during upgrades.