Option 3: Fire stopping and penetration seals, cavity barriers, ductwork and dampers and the building envelope Flashcards
Describe, with the use of an example, the situations where the following fire stopping products
and services would be used:
a) penetration seals
(2 marks)
b) small cavity barriers
(2 marks)
c) open state cavity barriers
(2 marks)
Penetration seals are used to firestop a service that penetrates a compartment wall or floor. An example is a pressure exerting graphite sealant used to firestop a CPVC sprinkler pipe
Small cavity barriers
Used to firestop at imperfections of fit between a wall and roof for example. A typical product used may be an elastomeric linear joint seal that would allow for deflection/movement.
Open state cavity barriers
Between elements of a building, for example rain screen cladding, where the cavity barrier is
open in the cold state to allow for the free movement of air for ventilation. In a fire situation,
the cavity barrier closes preventing the spread of fire.
a) Stone wool mineral products are supplied in a number of forms when used as fire stopping.
State the forms that such products take and state the factors to take into account when
installing these products.
(3 marks)
b) State three examples of places where stone wool products may be used to provide fire
stopping.
(3 marks)
Mineral wool forms are
Batts that can be cut and shaped as required. Edges and screws need to be protected as stated by manufacturer. May require additional support. example of use is in a lined multi service letterbox
Pre shaped - pre shaped for use with profile decks for example. Area of use is in small cavity barrier where compartment wall meets the underside of profile deck - may require additional coating as stated by manufacturer.
Large cavity/fire barrier
Flexible with a face of steel wire mesh. Used to continue a compartment wall in roofs or ceiling/floor voids. Require fixing and joining to substrate as per manufacturers instruction. e.g. fixed with angle which is screwed at defined distances. Joined as instructed
a) Explain the purpose of pipe closures.
(2 marks)
b) Describe how pipe closure systems work and give two examples of such systems.
(6 marks)
Pipe closures are designed to preserve the integrity of a fire resistant compartment where various
plastic pipes, plastic trunking, steel pipes with insulation or plastic pipes with insulation pass through
floors or walls.
Unlike metal or cable service penetrations, these service penetrations soften and collapse under
heating, therefore some means of preventing the passage of fire is required. This is achieved by
compressing the cross-section of the softened pipe or trunking. High pressure exerting graphite is used, this expands when exposed to the heat of a fire.
Examples are pipe collars, pipe wraps, intumescent insulated pipe sleeves and HPE sealants
Describe the purpose of ventilation duct systems and explain why it is important that fire
precautions should be implemented in ventilation ductwork.
(4 marks)
The purpose of ventilation ductwork systems is to replace stale air with fresh or conditioned air.
It is important that ductwork has firestopping implemented to prevent smoke and combustion gasses from penetrating compartment lines. Plastic ducting is generally very thin walled and will very quickly collapse in fire conditions. Fire precautions are required to maintain integrity of the large voids that can be left.
a) Explain the purpose of a fire damper.
(2 marks)
b) Describe the operation of an intumescent fire damper.
(4 marks)
Fire dampers are used to prevent fire and smoke spreading from one compartment to another through
the ductwork that penetrates walls and floors. Normally, the fire damper is open, but in a fire, it closes.
Intumescent fire dampers incorporate components, which expand by intumescent activity under the
action of heat, to close the airway to prevent the passage of fire. The intumescent materials form the
main component for fire integrity. In some instances, this may be supported with a mechanical device
to prevent cold smoke leakage.
Activation temperatures will be influenced by the type of intumescent material selected and these
temperatures typically range typically from 120°C to 270°C.
