REFRIGERATION SYSTEM SERVICE VALVES – PROCESS VALVE
Used solely to provide access to the closed refrigerant system. It is not installed in the normal path of refrigerant flow through the system. The valve positions used in this description are defined as follows:
Front-Seated — Valve stem turned all the way in (fully clockwise).
Back-Seated – Valve stem turned all the way out (fully counterclockwise).
Cracked — Valve stem turned about one turn counterclockwise from the front-seated position.
• In this position, the service port is isolated from the system. This position is used for normal (non-service) operation.
• This position is used when attaching the gauge manifold set or other service equipment to the valve.
• Used when evacuating, recovering refrigerant, or charging the system. This position presents the least resistance to refrigerant flow.
• When cracked, the service port is opened to the system. This position is used only if a pressure reading is required. One counterclockwise turn is enough to crack the valve for this purpose.
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