Chapter G - Explain Atmospheric Burners Flashcards
Why are most residential and commercial gas fired equipment equipped with atmospheric burners?
Low cost.
What is Bernoullies Theorem?
When velocity increases, pressure decreases. When velocity decreases, pressure increases. When pressure decreases, the velocity increases. When pressure increases, velocity decreases.
What are other terms for flame speed?
Rate of flame propagation, ignition velocity, and burning velocity.
What is the flame speed of natural gas?
25 inches per second.
What is the flame speed of propane?
32 inches per second.
What is the flame speed of butane?
33 inches per second.
What is port loading? What’s the formula for port loading?
Port loading is the amount of gas-air mixture passing through a port. Port loading = Input Rate (BTU/h) / Port Area (inches squared)
What are two common results of unstable flames?
Flashback and flame liftoff.
Under what conditions may flashback occur?
Reduced flow velocity, faster burning gases, underfired burner, leaking burner, during ignition, extinction pop, and overheated burner.
When does flashback occur?
When flame speed increases over flow velocity and there is a combustible mixture in the burner head.
When does flame liftoff occur?
When the flow velocities of the gas-air mixture is greater than the burning speed.
Under what conditions may flame liftoff occur?
Lower burning speed, increased flow velocity, shallow ports, overfired burner, excessive gas pressure, and cold burner.
What causes yellow tips?
A problem with the primary air intake.
What causes waving flame?
When the flame is pushed off the burner by excessive air movement due to drafts or cracked heat exchangers.
What does floating flame indicate?
Incomplete combustion.
