🔍 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.