Water Mist System Design and Review – IWMA’s Matrix
An Instrument to Assist Fire Engineers in Selecting the Suitable Systems and The Authority Having Jurisdiction in Reviewing Them for Approval
Preface
The water mist technology can now be considered a mature fire suppression technology as it has entered the third decade of installation both in marine and in land-based applications. Initiated more than 30 years ago – when Halon was banned and had to be replaced on board ships – the technology grew rapidly capturing almost 100% of the marine fire protection market protecting all the hazards from the machinery spaces to the accommodation as well as public spaces on board passenger ships.
By the end of the millennium many applications to land based occupancies were developed, based on several fire test protocols that were published by international organizations including Factory Mutual Approvals, UL, VdS, LPCB and others. Nevertheless, in the land-based market the technology has not yet achieved the diffusion that it could. One of the various reasons is the difficulties that fire engineers, designing and/or reviewing water mist system for acceptance, find in the process of selecting the system appropriate for each application and in verifying the adequacy of the design parameters that have been used per each system.
To support the fire engineers in this, the International Water Mist Association (IWMA) has developed a descriptive document: The Matrix! A working tool which is updated semi-annually and is available on the IWMA webpage.
Documents available from the IWMA website
The first document, referred to as “The IFAB Project” (also available from the association website) is a complete list of all the fire test protocols available on the market at the date of its publication with the description of the occupancies to which they apply and the indication of the organizations that developed and published them. As such, the IFAB Project already represents a valuable instrument for fire engineers dealing with water mist systems. However, it is a publication requiring a significant knowledge of the water mist technology to be used in practice.
Consequently, an IWMA task group developed The Matrix which is a chart for the fire engineers with a structure closer to the design and review activity a fire engineer usually undertakes. The fact that it is updated regularly makes it a “state of the art document” which is key designing and installing an advanced technology fire suppression system.
The Matrix is published both for marine- and land-based applications. As the table is substantial it is best to go to the IWMA webpage to look at it in full to appreciate what it actually contains.
The Matrix – An Interpretation
The first column is easy to understand. It refers to the business segment of the case under consideration, divided into residential, commercial and industrial. There is nothing further to add.
For the fire engineer the second column is the most important one. It is the part of The Matrix which is dedicated to the applications and at the same time the key point for the correct interpretation of The Matrix. It is important to understand that the selection of the application that most accurately represents the fire hazard related to the “formal” applications for which a test protocol exists, requires a considerable judgment from the fire engineer. In fact, it should be considered that to put the actual application in direct relationship with one of the test protocols shown in the list of The Matrix provides the information to proceed with the design of the system. It also implies that the captioned application can be protected with a water mist system.
In other words, the meaning of the “application column” of The Matrix is the key to the feasibility of a specific fire suppression system for a given application.
Of course, the real world is not so simple, because the applications listed in the “application column” of The Matrix are not easily related to the actual application under consideration, Paragraph 4.1.3.2 of the EN 14972-1 states: “Test protocols: one of the greatest challenges to engineering of water mist fire suppression systems lies in determining whether the conditions of a particular and recognized test protocol are representative of the actual conditions in a given application based on an understanding of the dynamics of the interaction of water mist with fire.”
Some applications can be regarded as clear and straightforward. A “car garage / parking garage” for example can easily be identified as a space where automobiles are parked. Or “industrial oil cookers” are easily identified as gadgets where food is deep fried. But there are other applications where a classification is more difficult. For example “residential occupancies” or “data halls”. In these cases additional information is needed to relate the applications listed in The Matrix to the real world. We will come to this later.
The third column of The Matrix is the part that includes the test protocols. And the third and fourth fully identify the test protocol(s) existing for a given application. It has taken the IWMA task group some time to gather all the information and their aim is to make sure that this list remains the most updated list of water mist fire test protocols available worldwide.
As mentioned, there are many applications for which more than one protocol is available. How to select the protocol that best fits the actual application under consideration is again a matter related to the correlation between the formal test protocol defined in the test protocol document listed in the third and fourth columns and the actual application under consideration. And again, it is the main responsibility of the fire engineer in charge of the design or the review of the system to ascertain it.
The last column identifies the type approval that can be obtained by “positively passing” each test protocol mentioned in the previous columns. This is also a very important column to be considered because it distinguishes the test protocols in those that lead to a formal approval ( the organization granting the type approval is listed in column 5) from those protocols that do not lead to a formal approval but are simply offered to the market as reference protocols to be used by the authorities having jurisdictions, the laboratories (like the Baltic Fire Laboratory in Poland and the Danish Fire Laboratory in Denmark), the verification agencies, the manufacturers etc.
For those that are not familiar with the type approval process, the explanation could be that the fire test protocols are the procedures issued by the organizations involved in the water mist fire suppression technology to run each of the mentioned test. They list the materials to be used, the procedure to run the tests and the pass-fail criteria to determine the outcome of the tests. The delivery of the laboratory that performs the test is a fire test report describing all the steps followed to carry out the test and the results obtained. In some cases, also the interpretation of the results is left to somebody else who will use the test report for the design and installation of a water mist system.
There are not many organizations issuing fire test protocols for water mist applications. They can be divided into two groups: the approval bodies and the standardization bodies.
Approval bodies for water mist applications include FM Approvals1, UL2 and VdS3. The standardization bodies include the CEN4 committee on water mist system and the BS5. As it is possible to see in The Matrix table, the approval bodies always grant a type-approval for the system passing the test protocol for the specific application. The standardization bodies normally do not, except for the residential applications tested according to BS standard 8458 that are approved by LPCB6.
The approval issued by an approval body is a useful information document also for the above-mentioned matter concerning the correlation between the test protocol and the actual application under consideration. The approval body will certainly define in detail the applications that can be effectively protected by the approved systems. An example is chapter 1.2 of the FM standard 55607 where all the 16 applications for which FM Approvals have issued a test protocol are described in detail with all the applicable limitations and/or extensions.
The same does not apply to the test protocols issued by the standardization bodies that also include a paragraph per each protocol describing the scenarios to which the protocol can be applied, but this information is “embedded” in the test protocol text and is not easily available to the fire engineer.
The above is a complete description of The Matrix content. There is a considerable effort behind the table summarizing all the results, because all the information included in the table is carefully verified and checked by the IWMA task group that includes some of the most relevant professionals dealing with the water mist technology in the world.
Now follow some comments and actions to take into consideration to make it more useful to the fire engineer.
Comments
As mentioned in the text, the correlation between the fire test protocol and the actual application under consideration is not easy for a fire engineer. It straightforward, when talking about test protocols issued by approval bodies (that are liable for what they indicate and that shall give all the information necessary for the correct use of the protocols). It is less straightforward for the standardization body protocols.
The second and most important comment is related to the real availability of the system on the market. With The Matrix it is only possible to say that, for a given application, one or more test protocols exist and whether they lead to a type approval or not but no information is given about the availability of one or more manufacturers that can provide a water mist system designed and installed in accordance to the test protocol under consideration. This second issue has been discussed many times among the association members, but the commercial implications that are related to the mentioning of one or more manufacturers would lead to problems that are outside of the scope of the association. The identification of the manufacturer(s) holding an approval or having carried out a fire test according to one of the test procedures issued by the standardization bodies remains a responsibility of the fire engineer in charge for the design of the system.
Future Steps
The maintenance of The Matrix is of utmost importance for the tool itself as well as for the association. The aim is to provide a concrete help for fire engineers involved in the design, installation or verification of a water mist system in land-based applications.
The addition of a column to the current ones with a detailed description of the application to which the protocol is applicable, or the implementation of a “second page” in the summary with each line of the protocols completed with the description of the applicable scenarios given in the protocol itself could be of help in finding correct protocol to use for a given application.
When it comes to the availability of water mist systems on the market: this cannot be included in The Matrix. But there are other sources of information. Considering the fact that the number of organizations issuing protocols is minimal makes it is easy to check with each one of them which manufacturers have been tested per each protocol. To help fire engineers with their search, a list of the approval guides giving details of the approved manufacturers can be found in the bibliography.
More difficult will be to find the manufacturers that have systems successfully tested according to the fire test protocols issued by one of the standardization bodies because in these cases, there is no specific entity that lists the performed tests and the unique source of information will be the manufacturers themselves that should be consulted to provide the information and possibly the test report. This is essential to document that their systems have successfully passed the necessary fire test protocols because, as stated in the last sentence of the introduction to EN 14972-1: “Water mist is a specific application solution which needs to be proven for each individual application and/or occupancy.”
Written by Luciano Nigro, Jensen Hughes Italy – Member of the Board of IWMA – luciano.nigro@jensenhughes.com
Main feature image copyright of the Baltic Fire Laboratory
Bibliography
- General Bibliography:
SFPE Handbook of Fire Protection Engineering – Chapter 46 – Water Mist Fire Suppression Systems.
- Specific Bibliography:
- FM Approvals – https://www.approvalguide.com/search?searchParams=groupid=ODU=
- UL – https://www.ul.com/services/water-mist-system-equipment-component-testing
- VdS.- https://vds.de/en/certification/companies-and-specialist-professionals/fire-protection/installer-company-for-fire-extinguishing-systems
- CEN – CEN/TC191/WG10 – Water Mist Fire Fighting Systems – EN 14972 series
- BS – https://www.bsigroup.com/en-GB/search-results/?q=Water%20Mist%20Systems&Page=1&tab=Standards
- LPCB – https://www.redbooklive.com/pdfdocs/redbook-vol1part3.pdf?rn=47100
- FM Class Number 5560 – Examination Standard for Water Mist Systems – January 2021 edition
