Steamfitter/Pipefitter exam: Steam traps

Key points

• Traps remove condensate and air while holding back steam.
• Mechanical traps (float, inverted bucket) work on density.
• Thermostatic traps work on temperature.
• Thermodynamic (disc) traps work on velocity and pressure.
• A trap failed open wastes steam. Failed closed backs up condensate and causes water hammer.

Study tip

Match each trap to its operating principle and you will handle most of these questions.

Try these

1. An inverted bucket trap is a:

   1. Thermostatic
   2. Mechanical
   3. Thermodynamic
   4. Manual
   Show answer

   B. Mechanical It works on density.

2. A trap that has failed closed causes:

   1. Lost steam
   2. Condensate backup
   3. Lower pressure
   4. Dry steam
   Show answer

   B. Condensate backup Condensate cannot leave.

3. Disc traps operate on:

   1. Density
   2. Temperature
   3. Velocity and pressure
   4. Weight
   Show answer

   C. Velocity and pressure Thermodynamic principle.

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