Vent Valve; Primary/Secondary Relief Valve - CAIRE COMPANION 1000 Technical Manual

2.1.5
2.1.6
2-4 Theory of Operation

Vent Valve

The vent valve (Figure 2-6) is a lever-actuated, spring-loaded poppet valve that vents the
inner container to atmosphere. Venting of the inner container is required to fill the
Companion 1000/T Portable with liquid oxygen. To open the vent valve, position the
valve lever parallel to the portable side cover, moving the spring-loaded poppet off its
seat and allowing flow through the valve. To close the valve, return the lever to its
original position, flush with the side of the unit, allowing the spring force to seat the
poppet and shut off flow.

Primary/Secondary Relief Valve

The primary and secondary relief valves are identical in design and function, differing
only by their nominal setpoint (Figure 2-7). The primary relief valve sets the operating
pressure at 22 psig (152 kPa). The secondary relief valve is a safety backup in the event
that 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 is
normally closed by the force of the spring. When system pressure acting on one side of
the poppet overcomes the spring force and atmospheric pressure acting on the opposite
side, the poppet lifts off its seat and vents gas to atmosphere. The venting gas lowers the
system pressure until equilibrium is established between the opening and closing forces
on the poppet. If system pressure increases rapidly, the relief valve poppet opens a
greater amount and vents additional gas to maintain the force equilibrium on the
poppet.
Figure 2-7: Primary/Secondary Relief Valves
Companion 1000/T Liquid Oxygen System Technical Manual
LOSED
Figure 2-6: Vent Valve
PEN CL SED
OPEN
B-701964-00 Rev. C