How to firestop single, multiple and mixed-service penetrations
The number and type of services passing through a single opening directly determine which firestop solutions can be used. Installers often apply a firestop product tested for one service to openings with multiple services. However, every service within the opening must be included in the tested firestop configuration. However, this is often not the case, as the tested firestop application must include the complete service configuration.
For example, let’s take a simple scenario where a combustible pipe and some cables go through the same opening. Many installers believe that using an approved fire collar around a pipe together with any approved sealant around the cables is sufficient. However, this is not always the case, and it will depend on:
- Whether the firestop products belong to the same manufacturer
- And whether that manufacturer has actually tested this scenario.
Types of penetrations
Before taking a deeper look into this, it is important to understand the testing procedures for different types of penetration seals and make a clear distinction in the terminology, as stated in BS EN 1366-3:2021 (Fire resistance tests for service penetrations). The British Standard gives the following definitions:
Single Service Penetration Seal – A penetration seal intended for penetrations with only one service passing through.
Multiple Service Penetration Seal – A penetration seal intended for penetrations where more than one service of the same type (e.g. cables) or pipe material group passes through.
Mixed Penetration Seal – A penetration seal intended for penetrations where more than one type of service (e.g. cables and pipes or pipes of different pipe material groups) pass through.
Now let’s look at an example of each of the above so we can make this more easily understood.
Single service penetration seals
An example of a single service penetration would be a single combustible PE pipe Ø75mm going through a flexible wall. In Walraven’s case, to fire seal this pipe penetration, we could recommend our Walraven Pacifyre® MKII fire sleeve. By reviewing the ETA documentation for this product (ETA-20/0732), an extract of which is shown here, you can verify that the product is approved for this application and achieves a fire resistance classification of EI 120 minutes.
Multiple service penetration seals
A multiple service penetration is one that has several identical pipes that need to be fire-stopped. So, using the same example as above. This could be a single opening with three combustible PE pipes, all Ø75mm, going through a flexible wall.
In Walraven’s case, to fire-seal this multiple service penetration. We could again recommend our Walraven Pacifyre® MKII fire sleeve. To evidence the suitability of this, we can again look at the ETA. The following extract from the ETA shows you that the fire resistance in this scenario will again be EI120. (It’s worth noting that in this specific example, the fire resistance is the same as for a single pipe, but this may not always be the case for other pipe types and scenarios).
For multiple service configurations, the ETA goes one step further by explaining the exact service arrangements for which this product has been tested, as shown here.
We can see that the Walraven Pacifyre® MKII fire sleeve can be used when identical pipes are installed in a cluster, vertical row and horizontal row with minimum distances between them.
Mixed penetration seals
As mentioned before, this is the scenario where several different services or pipe materials pass through the same opening. Naturally, this is the most challenging scenario with regard to fire stopping and careful planning. Design and installation are required.
Here is an example. This photo shows a mixture of pipes (made of different materials and different sizes), cables and cable trays going through the same opening in a concrete wall.
In this case, it is not sufficient to install individual firestop products that have been approved for use on each individual type of service. For this scenario, the firestop manufacturer needs to provide a tested detail or an ETA for the whole system required for sealing the opening.
This would usually comprise the fire batt (closing the entire opening) along with all the individual firestop components required for each penetrating service, such as fire collars, sealants, wraps, etc. All individual components must have been tested for use together in one single opening like this. Only if they have been tested together like this can they be approved for use in a mixed-service opening.
In this example, the ‘system’ approval provides a specific fire resistance. Usually dictated by the critical service approach (e.g., the system’s overall rating will match the rating of the weakest element that would fail first in a fire test).
In summary
The examples above show that mixed penetrations are by far the biggest challenge in fire stopping. Firestop solutions can only be used if they have been tested and approved for the same combination of services as a whole. Not if they have only been tested for each individual service element on their own.
So when designing the installation of M&E services, it is useful to take a moment and think. Can this installation of pipes and cables actually be fire-stopped? And is there enough test evidence for it? If in doubt, you can always reach out to manufacturers or industry experts directly to ask for further advice.
