Type of Smoke Detectors on the market

Photoelectric Detectors

In one type of photoelectric device, smoke can block a light beam. In this case, the reduction in light reaching a photocell sets off the alarm.

In the most common type of photoelectric unit, however, light is scattered by smoke particles onto a photocell, initiating an alarm. In this type of detector there is a T-shaped chamber with a light-emitting diode (LED) that shoots a beam of light across the horizontal bar of the T. A photocell, positioned at the bottom of the vertical base of the T, generates a current when it is exposed to light.

Under smoke-free conditions, the light beam crosses the top of the T in an uninterrupted straight line, not striking the photocell positioned at a right angle below the beam.

When smoke is present, the light is scattered by smoke particles, and some of the light is directed down the vertical part of the T to strike the photocell. When sufficient light hits the cell, the current triggers the alarm.

 

Please note Ionisation alarms have received bad press recently due to their poor performance. PSL Fire & Safety don't offer for sale or advise the purchase of this type of alarm read more here: https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12052330



PSL News

FEATURED POSTS

How to measure for a proper coupling fit

How to measure for a proper coupling fit

by Lee Gilson on August 25, 2020

There are 2 ways of measuring for a proper...

Photoelectric vs. Ionisation Smoke Alarms

Photoelectric vs. Ionisation Smoke Alarms

by Lee Gilson on August 13, 2020

Smoke alarms use either photoelectric or ionisation sensors to detect smoke. You’ll find...

The evolution of PPE for the worlds female Fire Fighters

The evolution of PPE for the worlds female Fire Fighters

by Lee Gilson on August 07, 2020

Roger Startin, Joint Managing Director of Bristol Uniforms, looks...

Bristol Uniforms tackles PPE contamination head on

Bristol Uniforms tackles PPE contamination head on

by Lee Gilson on February 24, 2020

PPE contamination was at the top of the agenda...

Back to top
PSL Reviews

Let customers speak for us

267 reviews
90%
(239)
7%
(20)
1%
(2)
0%
(1)
2%
(5)
ResQm8 Rescue Knife
Essential Car Tool
Um4 four bay USB battery charger
Excellent