ENVOY - DESIGN FOUNDRY: Research

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Lighting documentary

I watched an interesting documentary BBC Design rules: Light. It talked about the importance of light in a room. How surface materials texture and colour interact and how that effects the room and peoples reaction to that room. It also shows how lighting needs to be specific ie something that works in the defuse light of London won't work in the harsh light of Brisbane. I can see that these will play an important part in the surface finish of my design

Inside a smoke alarm

Ionization on the left Photoelectric on the right.

"An ionization smoke detector uses a radioisotope such as americium-241 to produce ionization in air; a difference due to smoke is detected and an alarm is generated. Ionization detectors are more sensitive to the flaming stage of fires than optical detectors, while optical detectors are more sensitive to fires in the early smouldering stage."^[4]^source

"An optical detector is a light sensor. When used as a smoke detector, it includes a light source (incandescent bulb or infrared LED-Light-Emitting Diode), a lens to collimate the light into a beam, and a photodiode or other photoelectric sensor at an angle to the beam as a light detector. In the absence of smoke, the light passes in front of the detector in a straight line. When smoke enters the optical chamber across the path of the light beam, some light is scattered by the smoke particles, directing it at the sensor and thus triggering the alarm." source

What happens in a fire

Studies on human behavior in reaction to fires have lead to the creation of the following equation

Image source

Detection time - Starts with fire initiation. Covers the time it takes for smoke to reach an alarm or to bee seen by a human

Alarm time - The alarm is triggered or someone raises the alarm

Recognition Time - The threat is received and understood

Response Time - The decision on how to act is made

Movement time - The time it takes to evade the threat

If the RSET is greater than the ASET then there is going to be a serious problem.

The quicker the RSET can be achieved the more favorable the outcome. Some things that can be implemented are more smoke alarms dispersed throughout the house. This will help during the early stages of detection and alarm time. The quicker the device can catch a threat the quicker it can then communicate that threat. If there can also be an improvement with how that information is communicated then that will shorten the alarm time and recognition time. Having an escape plan and drills will help with recognition response and movement times.

Technical information on alarms

The Australian Standard covering smoke alarms is AS3786-1993. This comprehensive document covers

SECTION 1 - SCOPE AND GENERAL
  1.1  SCOPE
  1.2  APPLICATION
  1.3  'Not applicable'
  1.4  INTERPRETATIONS
  1.5  REFERENCED DOCUMENTS
  1.6  CLASSIFICATION
  1.7  DEFINITIONS
  1.8  INTERPRETATION OF SPECIFIED LIMITING VALUES
SECTION 2 - GENERAL REQUIREMENTS
  2.1  GENERAL
  2.2  POWER SUPPLY
  2.3  BATTERIES AND BATTERY CONNECTIONS
  2.4  MATERIALS AND COMPONENTS
  2.5  DESIGN AND CONSTRUCTION
  2.6  MOUNTING FACILITIES
  2.7  SENSITIVITY ADJUSTMENTS
  2.8  CONNECTING FACILITIES
  2.9  ELECTRICAL SAFETY
  2.10 SELF TEST FACILITY
  2.11 RADIOACTIVE MATERIALS
  2.12 LIGHT EMITTING DIODE (LED) SOURCE LAMPS
  2.13 'Not applicable'
  2.14 ALARM SILENCING MEANS
  2.15 ALARM SIGNAL
SECTION 3 - PERFORMANCE REQUIREMENTS
  3.1  GENERAL
  3.2  SENSITIVITY
  3.3  ELECTRICAL REQUIREMENTS
  3.4  ENVIRONMENTAL REQUIREMENTS
  3.5  SOUND PRESSURE LEVEL
  3.6  STRENGTH OF SCREW THREAD AND FIXINGS
SECTION 4 - PRODUCT INFORMATION AND MARKING
  4.1  GENERAL
  4.2  INSTRUCTIONS
  4.3  PACKAGING
SECTION 5 - ASSESSMENT OF COMPLIANCE
  5.1  GENERAL
  5.2  DOCUMENTATION
  5.3  CRITERIA OF ACCEPTANCE AND TEST SCHEDULE

Abstract
Specifies the requirements for the design and performance of electrically operated smoke alarms containing detection and alarm facilities. It also allows, but does not require, for the inclusion within the smoke alarm facilities for inter-connection with other units or accessories. Where such facilities are included, the Standard specifies requirements for the connection interface. It is not intended that this interface be used for connection to remote monitoring stations. The Standard applies to smoke alarms for installation within residential accommodation where connection to remote monitoring is not required.

Scope
This Standard specifies requirements for the design and performance of electrically operated smoke alarms containing both detection and alarm facilities.
This Standard allows, although it does not require, the inclusion within the smoke alarm of facilities for interconnection with other similar units, or accessories. Where such facilities are included, this Standard specifies requirements for the connection interface. However, such an interface is not intended for connection to fire control stations.
This Standard applies to smoke alarms intended for installation within residential accommodation where connection to fire control stations is not required.

Application
A network of interconnected smoke alarms shall not be substituted for installations which require compliance with AS 1670.
The test methods included in this Standard are intended to assess the suitability of smoke alarms solely for residential applications.

History
First published as AS 3786-1990.
Second edition 1993.

SAI GLOBAL AS 3786-1993 Smoke alarms

Most smoke alarms in Australia have an output of 3000Hz at 84dB. Which you can sample for yourself hear here. (Please make sure you have your volume a low as it can be irritating) http://onlinetonegenerator.com/.

To give you an idea of the volume you can see where 84dB falls on this chart

Image source

NSW Fire and Rescue

I met with Andrew the Station Officer at Hamlyn Terrace Fire Station. He and his crew were more then happy to talk about there experiences with smoke alarms and the job.
I also got to have a little play with the TIC (Thermal Imaging Camera) one of the more important pieces of kit they have. Used for locating occupants and fires. It can even pick up the heat from footprints left behind (though only for a short period)