Hotel Service Unit 15 Fire Q3 – Answer

  1. (a) Define EACH of the following:
    (i) Flash Point;
    (ii) Ignition Point
    (iii) Auto Ignition Temperature.
    (2)
    (2)
    (2)
    (b) Explain the requirements for the discharge of CO₂ of a machinery space fixed firefighting installation with regard to volume and time.
    (4)

(a) Definitions (6 marks total)

(i) Flash Point (2 marks)

  • The lowest temperature at which a liquid gives off enough vapour to form an ignitable mixture with air, which will ignite if an external flame or spark is applied.

(ii) Ignition Point (2 marks)

  • The lowest temperature at which the vapour–air mixture of a substance will continue to burn once ignited, even after the ignition source is removed.

(iii) Auto-Ignition Temperature (2 marks)

  • The lowest temperature at which a substance will ignite spontaneously in air without any external flame or spark.

(b) CO₂ Discharge Requirements (4 marks)

For a machinery space fixed CO₂ firefighting system, SOLAS requires:

  1. The system must be capable of discharging not less than 85% of the required quantity of CO₂ gas within 2 minutes into the protected space.
  2. The total CO₂ quantity must be sufficient to give a minimum concentration of 35% by volume of the gross volume of the space.
  3. Discharge must be rapid and uniform, ensuring oxygen concentration is reduced quickly enough to extinguish the fire.
  4. The arrangement must be such that CO₂ reaches all parts of the protected machinery space effectively.