Technical Specifications: As a 9904-series liquid fuel component, it operates with light distillate fuel (SG 0.82–0.85, viscosity 32–58 SSU), maximum fluid supply pressure 1200 psig (8274 kPa), proof test pressure 1800 psig (12411 kPa), minimum burst pressure 6000 psig (41370 kPa).

Functional Features: Provides fail-safe operation — upon loss of hydraulic trip pressure, a return spring forces the piston to the full bypass position. The valve performs controlled-rate opening and faster controlled-rate closing via an integrated orifice.

Materials & Construction: Internal metering cage and sliding metering piston are made from hardened stainless steel and electroless nickel-plated hardened materials respectively. Dual seal design with vent port prevents cross-contamination between fuel and hydraulic oil.

Working Principle: Fuel inlet feeds the center of a double-piston arrangement. The actuation/metering piston shuttles in the metering bushing. When the piston moves left, the valve opens to the turbine port; moving right closes it and sends fuel to the bypass port.

Installation: Uses 2-inch (50 mm) or 3-inch (75 mm) SAE flanges per SAE J518 Code 61. Piping must meet the 25 μm at Beta 200 fuel filtration standard.