🔍 Key Concepts

• Thermostatic expansion valve (TXV) bulb purpose and how it senses suction line temperature • Importance of good metal-to-metal contact between the bulb and the suction line • How insulation and surface condition affect heat transfer between the bulb and the pipe

💭 Think About

• Which option would most improve direct heat transfer between the bulb and the suction line so the valve can respond accurately? • Do any of the choices introduce a layer or coating that would actually slow down heat transfer instead of helping it? • What must be done to the metal surfaces if you want the bulb to sense the true pipe temperature quickly and accurately?

✅ Before You Answer

• Identify which choices add a thermal barrier (something between the bulb and pipe) versus improving direct contact • Consider that the bulb should sense actual suction line temperature, not be insulated or shielded from it • Confirm that the surface condition of the bulb and pipe will allow tight, clean contact for best heat conduction