This preview shows page 1. Sign up to view the full content.
Unformatted text preview: ow silica gel turns lo a shade of green. Intensity of green color depends on CO - contraction. SMOKE DETECTORS: These are classified by method of detection. LIGHT REFRACTION TYPE/PHOTO ELECTRIC SMOKE DETECTOR It consists of photoelectric cell a beacon lamp and a light trap all mounted in lay brinth. Air samples are drawn into detector unit. An accumulation of 10% or more causes photo electric cell to conduct current. The detector supplies signal to the smoke detector amplifier which in turns activates a warning bell and light. During test 28V DC test relay energized. Voltage is applied to indication, comes on if beacon and test lamp photo electric cell smoke detector circuit are operable connected in series. Ionization type: In uses a small amount of radioactive material to ionize of oxygen and nitrogen molecules in the air sample drawn in to detector cell. These ions allow small current to flow through detector cct. If smoke is present in air small particles of smoke attach themselves to the oxygen and nitrogen gas reducing electr...
View Full Document
This note was uploaded on 03/09/2011 for the course AIRCRAFT 2008.09.00 taught by Professor Dr.alan during the One '11 term at TAFE NSW - Sydney Institute.
- One '11