🔍 Key Concepts
• Gauge manifold flow paths between ports H, J, K, and the center passage E
• How needle/plug valves isolate either the external service port, the gauge, or the common manifold
• The difference between closing a valve (seating it) and back‑seating it fully open on some refrigeration/gauge valves
💭 Think About
• Trace, with your finger, the piping from port H up to gauge A and across to port J. Ask yourself: when the valve stem G moves to the right (closed), which of those paths does it block?
• Now imagine valve G screwed all the way out (back‑seated, fully open). In that position, which passages are in direct communication with each other: H, A, and/or J?
• Look carefully at whether the right‑hand valve C has any physical connection to the left gauge and valve; does reading gauge A actually depend on valve C at all?
✅ Before You Answer
• Verify which passages are shaded/arrowed together on the illustration when valve G is in the open position.
• Confirm whether closing G places a solid barrier between H and A, or between H and J, by following the drawn valve plug.
• Make sure you understand that back‑seating fully open on G is a different condition than simply “cracked open,” and consider what that means for the connection between gauge A and port H.