York 022W10074-000 Three-Way Pressure Relief Valve

How the York 022W10074-000 Three-Way Relief Valve Works

First, a clarification: 022W10074-000 is technically a three-way shut-off valve, not the valve that actually pops open. The actual pressure relief is performed by two single relief valves​ (e.g. 022-10078-000, set at 235 psig). The York manual defines the assembly as follows: "Dual relief valve consists of one three-way shut-off valve and two single relief valves."

Construction​ - The valve body has three ports: one lower inlet connected directly to the vessel opening (evaporator, condenser or oil separator), and two upper outlets, each carrying one single relief valve. Inside is a rotating selector plug driven by the top handle or handwheel.

Operation

Normal position (mid-position)​ - The plug sits in the centre so the vessel is open to both relief valves at the same time, giving maximum relieving capacity. The chiller normally runs locked in this position.

When service is required​ - Turning the handle to one side closes the passage to valve A while valve B stays connected to the vessel. Valve A is now isolated and can be safely removed for testing or replacement, while the vessel never loses protection. Once the work is done, the handle is returned to the mid-position.

Mechanical interlock​ - The plug and its stop arrangement make it physically impossible to shut off both sides simultaneously, exactly as stated in the manual: "will not allow both valves to be shut off at the same time." Each single valve is also sized independently so that "each relief valve has sufficient discharge capacity when used alone" - meaning one valve alone already meets the vessel's relieving requirement. The chiller therefore does not have to be shut down or pumped down during servicing.

The actual relieving action​ - If vessel pressure rises to the set point because of fire, operator error or control failure (235 psig on YR units, 300 psig on YS/YT units), the spring-loaded relief valve still in circuit is forced open and refrigerant is vented outdoors through the relief piping; once pressure falls the valve re-seats itself. Should all electronic safeties fail and pressure keep climbing, the rupture disc set at 345 psig bursts as the final line of defence.

In short​ - the three-way valve selects the flow path, the relief valves do the relieving, and together they allow service without shutdown while keeping the vessel code-compliant.