CAIRE COMPANION 1000 Technical Manual

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CAIRE COMPANION 1000 Technical Manual Manual pdf 32 page image

Companion 1000/T Liquid Oxygen System Technical Manual2-4 Theory of Operation B-701964-00 Rev. C2.1.5 Vent ValveThe vent valve (Figure 2-6) is a lever-actuated, spring-loaded poppet valve that vents theinner container to atmosphere. Venting of the inner container is required to fill theCompanion 1000/T Portable with liquid oxygen. To open the vent valve, position thevalve lever parallel to the portable side cover, moving the spring-loaded poppet off itsseat and allowing flow through the valve. To close the valve, return the lever to itsoriginal position, flush with the side of the unit, allowing the spring force to seat thepoppet and shut off flow.Figure 2-6: Vent Valve2.1.6 Primary/Secondary Relief ValveThe primary and secondary relief valves are identical in design and function, differingonly by their nominal setpoint (Figure 2-7). The primary relief valve sets the operatingpressure at 22 psig (152 kPa). The secondary relief valve is a safety backup in the eventthat the primary relief valve does not maintain system pressure in the acceptable range.The secondary relief valve is set to open at a pressure of 30 psig (207 kPa).The relief valve consists of a poppet with an elastomer seal and a spring. The poppet isnormally closed by the force of the spring. When system pressure acting on one side ofthe poppet overcomes the spring force and atmospheric pressure acting on the oppositeside, the poppet lifts off its seat and vents gas to atmosphere. The venting gas lowers thesystem pressure until equilibrium is established between the opening and closing forceson the poppet. If system pressure increases rapidly, the relief valve poppet opens agreater amount and vents additional gas to maintain the force equilibrium on thepoppet.Figure 2-7: Primary/Secondary Relief Valves