Flame Rectification Flashcards
What was the major weakness of early, AC conductivity flame detection systems?
Carbon deposits created by flame impingement could create a “bridge” between the electrodes that had a similar resistance/conductivity as the flame. Thus creating an unsafe situation.
What is the minimum and preferred ratios of ground electrode to flame electrode?
- Minimum 4:1
- Preferred 10:1
Where is the ground electrode usually located?
In the burner head
What is rectification?
The conversion of an alternating current to a direct current
How does a diode work?
It operates like a check valve. It has low resistance in one direction and high resistance in the other
What is identified by the flame safeguard to prove that a flame is present?
The imbalance of current flow. In this way the flame safeguard can distinguish between a short to ground and a flame
What are the three characteristics of a premix pilot?
- Strong
- Stable
- Higher flame propagation
(A raw gas pilot is the opposite of these)
How quickly can a flame rod amplifier detect the loss of flame?
Within microseconds
What must be done when setting a pilot burner/flame rod system?
A pilot turndown test must be performed
On an in-shot burner the flame rod should be position above the burner.
TRUE / FALSE
False
What are the two main advantages of flame rod systems?
- Quick response to flame failure
- Flame rods cannot be bypassed or defeated
Flame rods can be used with fuel oil systems.
TRUE / FALSE
False
Flame rods can be used to supervise pilot only, main flame only or pilot and main flame.
TRUE / FALSE
True
What do you use to clean a flame rod?
A Scotch Brite pad
