FIRE DETECTION and ALARM
SYSTEMS
What are the 4 stages of a fire in order? –
answ✔✔1) incipient stage
2) smoke stage
3) flame stage
4) high heat stage
What is the incipient stage? –
answ✔✔- stage 1
- no obvious signs of fire
- invisible tiny combustion particles, visible to detector but not human
eye
-smoke heat and flame may or may not be present at this stage.
* detection can still be made, should be made at this point to save lives
and property
what is the smoke stage? - answ✔✔-stage 2
- visible smoke can be seen
- combustion particles get bigger and theres more of them
- still no appreciable heat rise
,* causes most deaths at this stage
what is the flame stage? - answ✔✔-stage 3
- visible flame as gases and particles ignite
- outburst of flame produces heat
- great quantities of combustible gases are generated
what is the high heat stage? - answ✔✔-stage 4
- flames at their peak
- dense smoke present
- oxygen being rapidly consumed
- superheated gases are generated
Which of the 4 stages is the most deadly and why? - answ✔✔stage 2 is
most deadly, the smoke stage. smoke contains toxic and deadly gases
such as:
- carbon monoxide
- nitrogen oxides
- sulphur dioxide
- ammonia
What is the normal oxygen level of air? - answ✔✔- Usually air contains
21%
, - when is gets below 17% level, thinking and coordination become
difficult.
- when it gets below the 16% level, thinking may become irrational
- when it gets below 6%, breathing becomes impossible.
why is the smoke stage so dangerous? - answ✔✔Because a
smouldering fire may go undetected for hours and will continue to
develop and consume the oxygen and replace with toxic gases.
A basic fire alarm system shall contain at least the following 3 things? -
answ✔✔- control unit, to provide the logic processing system
- manual pull station (initiating device)
- audible signal appliance to alert the occupants to evacuate.
What are the 4 conditions of a fire alarm system to be considered? -
answ✔✔Fire alarm can be in:
1. normal condition
2. trouble condition
3. alarm condition
4. supervisory condition
What is normal condition? - answ✔✔- system is powered
- ready to receive input signals from detection devices
SYSTEMS
What are the 4 stages of a fire in order? –
answ✔✔1) incipient stage
2) smoke stage
3) flame stage
4) high heat stage
What is the incipient stage? –
answ✔✔- stage 1
- no obvious signs of fire
- invisible tiny combustion particles, visible to detector but not human
eye
-smoke heat and flame may or may not be present at this stage.
* detection can still be made, should be made at this point to save lives
and property
what is the smoke stage? - answ✔✔-stage 2
- visible smoke can be seen
- combustion particles get bigger and theres more of them
- still no appreciable heat rise
,* causes most deaths at this stage
what is the flame stage? - answ✔✔-stage 3
- visible flame as gases and particles ignite
- outburst of flame produces heat
- great quantities of combustible gases are generated
what is the high heat stage? - answ✔✔-stage 4
- flames at their peak
- dense smoke present
- oxygen being rapidly consumed
- superheated gases are generated
Which of the 4 stages is the most deadly and why? - answ✔✔stage 2 is
most deadly, the smoke stage. smoke contains toxic and deadly gases
such as:
- carbon monoxide
- nitrogen oxides
- sulphur dioxide
- ammonia
What is the normal oxygen level of air? - answ✔✔- Usually air contains
21%
, - when is gets below 17% level, thinking and coordination become
difficult.
- when it gets below the 16% level, thinking may become irrational
- when it gets below 6%, breathing becomes impossible.
why is the smoke stage so dangerous? - answ✔✔Because a
smouldering fire may go undetected for hours and will continue to
develop and consume the oxygen and replace with toxic gases.
A basic fire alarm system shall contain at least the following 3 things? -
answ✔✔- control unit, to provide the logic processing system
- manual pull station (initiating device)
- audible signal appliance to alert the occupants to evacuate.
What are the 4 conditions of a fire alarm system to be considered? -
answ✔✔Fire alarm can be in:
1. normal condition
2. trouble condition
3. alarm condition
4. supervisory condition
What is normal condition? - answ✔✔- system is powered
- ready to receive input signals from detection devices
