Fire stopping are at times refer to as fire barrier system
The fundamental principle in compartmentation is that the floors and walls forming the compartment must be maintained. Buildings under construction tend to leave openings on walls and floors to allow mechanical pipes and electrical cables to pass through. Many of these openings are concealed or partly concealed by ceiling or riser ducts or in the remote part of the basement. Fire has been found to spread along cables up the floors or through the rooms causing fire incidents. Fire stopping all structural /compartment openings is vital to maintain the integrity of each fire zone. Various fire stopping system has been developed for that purpose.
All fire and smoke barriers should be of fire retardant materials or systems make up of non combustible building materials. It is therefore critical that the material used for sealing these openings in the event of fire has the capability to provide the fire resistance and maintain the required performance of the compartment. Services passing or penetrating a compartment are considered as elements that would compromise the fire performance of a compartment. For instance, fire could breach through combustible pipes and thus, providing a passage for fire to spread through protected floors and walls. Fire stopping these services is a must to control fire spread from one compartment to another. On top of that, fire stopping is also a great method to seal off any small gaps or imperfections that could exist in other type of fire rated construction.
All fire stopping shall be tested to the relevant codes and standards e.g.:-
BS 476: Part 20: 1987 – Fire tests on building materials and structures – Method for determination of the fire resistance of elements of construction (general principles)
BS EN 1366-3: 2009 –Fire resistance tests for service installation: Penetration seals
AS 1530.4: 2005 (Section 10) –Fire resistance test of elements of construction: Service penetrations and control joints
AS 4072.1: 2005: – Components for the protection of openings in fire-resistant separating elements: Service penetrations and control joints
ASTM E814- 13a –Standard Test Method for Fire Tests of Penetration Firestop Systems
Following are some of fire stopping materials or systems that are available on the market.
a. Fire rated bulkhead System – High density mineral fibre panel of density 170kg/m3 is coated with an intumescent fire retardant paint coating. They are cut to size to fit large floor or wall openings. The one side coated mineral mineral fiber panel will over both sides of the opening with an air gap in between forming a good insulation layer. all the joints including perimeters of the opening and areas surrounding pipes or cables, trunking, ladder will be seal with fire resistant putty. To finish off the fire stopping, both side of the Bulkhead surface will be coated with intumescent paint again including coating of all pipes, cables, trunking and ladders up to 1.00m away from the opening. The intumescent coating will prevent fire, smoke and toxic gases propagation through cables or trunking to the other side of the opening. For new addition of pipes, cables or trunking, the bulkhead is easily removed (at the portion affected) and restored without losing the fire integrity of the fire barrier system. To be effective, the mixture between intumescent paint and water shall follow in accordance with the ratio determine by the manufacture.
2. Fire-rated mortar – Fire rated mortar is a specially formulated light weight cement supplied as a pre-mixed cement like granule powder. O On-site mixing with specific portion of water to form a mortar like structure, and can be trowelled flat to seal openings required for passage of cables and metal pipes through walls and floors. Need form work support and needs to cure after drying up.
3. Fire-rated Collars – A ring structure to be fitted and clamped around PVC sewerage pipes on the ceiling and secured to the underside fo the floor slab to prevent vertical fire propagation. Layers of internally lined intumescent strips inside the collar expands rapidly when the pipes are burnt and close the opening occupied by the pipe permanently. The intumescent hardens after closing the pipe gap and stops fire and smoke propagation from floor below to floor above
4. Fire-rated Sealants – Typically acrylic or silicone based sealants. They are non-combustible and have excellent adhesive properties. These sealants are designed to prevent the spread of fire and smoke through joints and small gaps in fire rated walls, floors and around service penetrations. The sealants are also useful in securing any imperfections in a constructed system making it the most widely used fire stopping material. Bearing in mind that some sealants are not suitable to be exposed constantly to moisture and need to be cured properly to obtain its full performance.