Metering Devices: TEV Bulb Locations

 Valve Identification:

• Types of Connections:
  • Flare Connection: External equalized valve; the external equalizer port is visible.
  • Sweat/Braze-On Connection: Internal equalized valve; requires heat sinking to protect the valve during brazing.
  • Flange Connection: Larger valves; includes external equalizing port with flange plates and gaskets.

TXV Bulb Placement:

• General Recommendations:

  • For suction lines 7/8 inch and larger: Place the bulb at the 4 o'clock or 8 o'clock position on the horizontal section line.
  • For suction lines below 7/8 inch: Bulb can be placed anywhere between 4 o'clock and 8 o'clock positions.
  • Avoid placing the bulb at the bottom of the horizontal suction line (6 o'clock position) to prevent inaccurate temperature readings due to the presence of oil.

• Best Practices for Bulb Placement:

  • Ensure the bulb is on a smooth pipe surface.
  • Use stainless steel hose clamps (worm gear clamps) to secure the bulb for better thermal contact.
  • Avoid crushing the bulb when tightening clamps, as this can lead to loss of charge and the need for valve replacement.
  • Horizontal suction lines are ideal for bulb placement; if vertical placement is necessary, ensure the tube on the bulb comes off the top to maintain proper contact.

Examples of Bulb Placement:

• Good Placement:
  • Horizontal suction lines with proper thermal contact and worm gear clamps.
• Poor Placement:
  • Bulbs placed over pipe joints or on the bottom of horizontal suction lines, leading to gaps and poor thermal contact.