Water Mist Fire Suppression Systems for Building and Industrial Applications: Issues and Challenges

Round 1

Reviewer 1 Report

Please see attached file for detailed comments.

Comments for author File: Comments.pdf

Author Response

The authors are grateful to the editor and anonymous reviewers for the valid, insightful, and constructive comments. All the review comments have been adequately addressed and incorporated into the revised manuscript. The comments of the reviewers are in black text, while our answers are in red font. The authors also attached a newly revised version of our manuscript, in which we marked up with “ red colour for changes” and aligned it with the response letter. The incorporation of the review comments has significantly improved the quality of the manuscript. Below are the details of the discussions and modifications made to the revised manuscript.

Reviewer 1: Comments and Suggestions for Authors

 In the current paper, the authors reviewed previous research and industry data regarding the suppression mechanisms, applications, products, design standards, test protocol and limitations of water mist fire suppression systems. The current review is informative, with a wide range of information from both academia and industry available. However, too wide of a topic range has been considered in the current manuscript, and the depth of some selective contents was lacking. The current manuscript can be improved mainly by a careful revision by reducing some redundant results while discussing more quantitative data and findings of each case/study reviewed. It is believed that this article falls within the readership of the journal “Fire”, and it is recommended to be reconsidered following major revision. Please see some of my detailed comments below:

The authors are very much grateful to the reviewer for the valid and constructive comments. The authors try to address all the comments with the following response:

Comment (1). It would be very beneficial if the authors could develop a collection of nomenclatures and abbreviations, as many terminologies and symbols are used.

Response:

A table containing nomenclature and abbreviations has been added between the abstract and introduction. (see page 2)

Comment (2). It would be beneficial if the cases reviewed by the authors could be categorized by experiments and/or simulations.

Response:

The summary of the reviewed literature in Table 2 has been updated with an additional column to indicate which findings are from experimental “E” or numerical “N” research. (see page 14)

Comment (3). Authors used K-Factor as a parameter to characterize mist nozzles; however, this particular parameter is more often used to describe sprinklers. Water mist systems are more often characterized by their operating pressure and droplet size. I’d suggest not to confuse readers with these parameters.

Response:

The authors understand why this maybe create confusion with sprinklers as k-factor is commonly used in describing sprinkler nozzles. Though in fire protection, k-factor is also used to calculate discharge rates from all types of nozzles including spray nozzles, hose reel nozzles, water monitors, deluge systems and water mist nozzles and not just restricted to sprinklers. The literature reviewed as part of this manuscript use K-factor when discussing nozzle relationship between flow rates and operating pressure as this relationship prove to be important to system performance.

To make clear, this has been updated in the revised manuscript (see page 20).

Comment (4). Is there a reference for Equation 3? These kinds of equations are not common sense for wider readerships, and as a review paper, this should be referred to properly.

Response: The below reference is added in the revised manuscript. Please see page 8.

[24]     Hurley MJ, Gottuk DT, Hall Jr JR, Harada K, Kuligowski ED, Puchovsky M, Watts Jr JM, Wieczorek CJ, SFPE handbook of fire protection engineering, Springer, 2015.

Comment (5). For section 3, please give some quantitative figures on other researchers’ findings, such as % improvement and suppression time etc., instead of generic descriptions of who did what. What’s their studies’ significance, and what particular finding do they have for the cases studied?

Response:

Section 3 has been edited to include discussion in each sub-section about what the research means and why it is important. Section 4 includes quantitative results from the research reviewed. No experiment from separate research is similar enough to compare together. Authors didn’t include any figures for quantitative analysis for each application for limiting the lengthy paper size.

Comment (6). Table 2, suppression additives, how do the last four points relate to additives?

Response:Table 2 has been updated and removed irrelevant points. Please check page 14.

Comment (7). Same table, operating pressure, many of the findings are case-dependent. Is it appropriate to put them as generic conclusions/findings? For example, the second, fifth etc. How does the eighth even relate to operating pressure? The last few points from this section seem repetitive.

Response: Table 2 has been updated to remove case-dependent findings and reduce repetitive findings listed. Please check page 14.

Comment (8). Same table, the corresponding relationship between the conclusions and references are not clear. Please revise your format.

Response:

Table 2 has been updated to a new format that specifies the references for each finding and includes a description of the type of research in the 3^rd column. Please check page 14.

Comment (9). Same table, some of the conclusions from the table are too generic, and some of them are too case-dependent. These two extremes are not very useful for readers to develop a good understanding of the points discussed. Please carefully revise the conclusions you summarize in the table.

Response:

Table 2 has been updated to remove case-dependent findings and reduce repetitive findings listed. Please check page 14.

Comment (10).  Section 4.1.1, how do additives affect spray dynamics? The relationship is unclear and does not fit in the scope of section 4.1.

Response:

Heading 4.1 has been changed from “Spray Dynamics” to “Spray Characteristics” to categorise the section to include any characteristic or feature of the system that will affect the systems output from the nozzle. Additives are seen to alter the viscosity of the suppression agent and ultimately the spray pattern and suppression performance. Please check page 14.

Comment (11). Figure 12 is obviously not from ref [44]. Please carefully check if there are any other mis-referenced figures.

Response: The below reference is added.

[28]     Liu H, Wang C, Cordeiro IMDC, Yuen ACY, Chen Q, Chan QN, Kook S, Yeoh GH, Critical assessment on operating water droplet sizes for fire sprinkler and water mist systems, Journal of Building Engineering, 2020;28: 100999.

Comment (12). Line 508-515,the dependent relationship between K-Factor and spray momentum is wrong. K-Factor is a way to characterize nozzles. It is not K-Factor affecting spray momentum, but spray momentum gives a K-Factor for any given nozzle.

Response:

This has been revised. Please check section 4.1.5.

Comment (13). Figure 17, this figure does not seem complete.

Response:

This has been revised. Please check Fig. 17.

Comment (14). Line 536-537, I don’t see this very significantly from Figure 19.

Response: To make clear this, the authors revised the statements. Please check section 4.1.6.

Comment (15). Line 593-594, why is the main mechanism changed here? Previously it was identified as oxygen displacement. What’s the difference？

Response:

The main suppression mechanisms of water mist discussed in the introduction and throughout are heat extraction, oxygen displacement, and radiation attenuation. Flame penetration relates to the water mists ability to cool the flame (heat extraction). It is seen how this is confusing and a better explanation has been added to make this relationship clear.  Please check revised manuscript, section 4.2.4.

Comment (16). Line 608, This is contradictory with the statement at line 578, where a statement of “There is minimal literature available 578 on the effects of different nozzle heights on a water mist system” was made.

Response:

The statement “There is minimal literature available on the effects of different nozzle heights on a water mist system “  has been removed to avoid the confusion of the reader.

Comment (17). Section 4.3, I don’t quite see how this section contributes to the academic community.

Response:

The authors intention for this review is to identify the issues and challenges related to water mist fire suppression technology. This section aims to highlight the limitations of existing water mist systems available on the market and links to the next section of how these systems are tested and approved for use.

Comment (18). Fig 26, again, this figure seems not complete.

Response:

Figure formatting has been corrected and legend has been updated to include item 11. Discharge isolation valve. Please check the revised Fig. 26.

Comment (19). Section 6, it is better to give some direct evidence, such as research papers or numbers from papers to support the challenges raised by the authors. For example, for operation and maintenance, what specific challenge is met during operation? What specific requirement is needed? Are there any recommendations that the authors or previous studies can make for this challenge?

Response:

This has been revised and added two research papers to support the challenges discussed in this manuscript. Please check section 6.

Reviewer 2 Report

This review paper introduces the fundamentals of water mist fire suppression systems such as suppression mechanisms, applications, products and design standards.

I think this research is able to support the industry demand that will use water mist systems to protect various fire risks such as commercial buildings, electrical equipment and even nuclear power plants.

Consequently this comprehensive review seems to be very useful to identify the issues and challenges related to the technology.

Author Response

The authors are thankful to the reviewer for the insightful feedback. The authors also agree with the reviewer that this research is able to support the industry demand

Reviewer 3 Report

This paper gives a comprehensive review on water mist fire suppression systems, previous studies on the fire control and suppression mechanisms, applications of water mist systems, design codes for water mist systems, and current products for water mist systems are described and summarized. This paper is well organized and my comments are as follows:

1.       Line 147-149, Please check this sentence.

2.       Fig. 10, Please check the title of vertical coordinate.

3.       Fig. 13, it is better to use a dotted line for the data of 100μm to give a clear presentation, especially in black and white version.  

4.       Line 543, “shown in in Fig. 20 and is important…”, the word “in” is repeated.

5.       Please check the references carefully. The formats of some authors' names in some references are wrong, for examples, reference 20 and reference 34.

6.       In some sections, for example sections 3 and 4, the authors just stated the results of previous studies. It is better to give some discussions or summaries.

Author Response

The authors are grateful to the editor and anonymous reviewers for the valid, insightful, and constructive comments. All the review comments have been adequately addressed and incorporated into the revised manuscript. The comments of the reviewers are in black text, while our answers are in red font. The authors also attached a newly revised version of our manuscript, in which we marked up with “red colour for changes” and aligned it with the response letter. The incorporation of the review comments has significantly improved the quality of the manuscript. Below are the details of the discussions and modifications made to the revised manuscript.

Reviewer 3: Comments and Suggestions for Authors

This paper gives a comprehensive review on water mist fire suppression systems, previous studies on the fire control and suppression mechanisms, applications of water mist systems, design codes for water mist systems, and current products for water mist systems are described and summarized. This paper is well organized, and my comments are as follows:

The authors are thankful to the reviewer for the insightful feedback. The authors try to address all the comments adequately with the below response:

Comment (1).       Line 147-149, Please check this sentence.

Response:

This sentence has been re-written as follows: “A flame will be extinguished if it’s temperature is reduced below its critical temperature.”   Please check the revised manuscript, page 6 lines 155-156.

Comment (2).       Fig. 10, Please check the title of vertical coordinate.

Response:

This has been revised. Fig. 10 (a) has been updated with the correct spelling of “Extinguishing”

Comment (3).       Fig. 13, it is better to use a dotted line for the data of 100μm to give a clear presentation, especially in black and white version. 

Response:

Figures 13(a-c) has been updated to show dotted lines to clearly shown the difference in data, even if printed in black and white. Please check the revised manuscript, page 18.

Fig 13. Effect of various water mist droplet sizes [19]

Comment (4).       Line 543, “shown in in Fig. 20 and is important…”, the word “in” is repeated.

Response:

Repeated word has been removed.

Comment (5).       Please check the references carefully. The formats of some authors' names in some references are wrong, for examples, reference 20 and reference 34.

Response:

References has been rechecked and updated. Please check the revised manuscript.

Comment (6).       In some sections, for example sections 3 and 4, the authors just stated the results of previous studies. It is better to give some discussions or summaries.

Response:

For Section 3 Application of Water Mist Systems, a discussion has been made for each sub-section about the research that has been presented to explain its importance.

For Section 4 Research and Development on Water Mist Systems, discussion and explanation has been added where research has been state with no explanation of its importance.

The below discussions have been added in the revised manuscript.

“……According to the study, using water mist to protect machinery spaces from fire is a better option. The quantity of water mist test protocols that are written specifically for machine space protection is in support of this. The industrial environment is constantly changing as a result of new technology, so it is crucial that fire protection techniques like water mist adapt as well to account for the new risks….  ” (line 267-271,page 10)

“……Cycling discharge research for turbines should be tested for other applications and fire risk to determine if the benefits can be applied to other fire risks. Because power generation is an expensive process with numerous potential safety hazards, fire protection methods are critical to turbine operators and insurers. Water mist has proven to be an effective method of fire suppression, but it will require ongoing research and development as new methods of power generation and storage are established. Water mist must be suitable for electrical equipment in order to be used in the power generation industry….  ” (line 290-297, page 10)

“…These findings show that that water mist can be used safely in various applications including control rooms for vital machinery or data storage facilities. The water mist suppression can do this as a more environmentally safer alternative to previously used gases that contribute to ozone depletion. Many industrial facilities place a high priority on the protection of this equipment to ensure fire safety with their normal operations…”(line 310-315, page 10)

“….. This research has significance because every type of transportation vehicle requires low profile fire protection equipment. The equipment cannot significantly reduce the amount of space that can be used for cargo or passengers and must be installed within aircraft, sea vessels, and road vehicles without adding extra weight that reduces travel distances and increases fuel consumption. Comparing water mist to other fire suppression techniques like sprinklers, it can be said that water mist belongs to the category of low-profile equipment. The world is moving towards more freight due to import trade and online shopping. which requires support from the fire protection sector in the form of ongoing research and development. In big cities with a growing population and commuter problems, transportation safety is a crucial issue. Road tunnels are a common solution for this which presents another fire risk that can be addressed using water mist.……” (lines 356-365, page 11)

“……The research is in furtherance of using water mist in road tunnels. As tunnel construction varies, it is crucial that it be used in each individual case. To prove its effectiveness in conjunction with other protection systems like extraction exhaust fans or fire detection techniques, research and testing would need to be conducted. Current research on fire protection in tunnels is intense, and more study on the use of water mist should be done. Nuclear power generation is another sector that has invested significantly in water mist research.…” (lines 384-389, page 12)

“…Nuclear power is always brought up when discussing alternative energy generation methods. It is critical that it is done safely if it is to be used globally. Water mist fire protection should be investigated if it can improve nuclear power plant safety. It may be useful for other aspects of nuclear power safety. Studies have shown, for example, that it can be used as an explosion hazard mitigation system as well as a fire suppression system.…….” (lines 399-403, page 12)

“……During this literature review, there was little research found on this topic. It appears to be an intriguing application that should be further developed. The majority of the research found is on fire suppression of industrial equipment, including commercial and industrial cooking oil fat fryers.……..” (lines 415-416, page 12)

“……According to the literature review, water-mist for oil fat fryers appears to have a significant advantage over alternative methods. It is clearly a strong option because there are minimal methods for suppression that are acceptable for food processing. More food processing facilities are being built in metropolitan areas to allow for quick delivery to consumers, as the popularity of mass production of "ready to eat meals" has grown in recent years. Large fryer converters require fire protection in these facilities. Water mist should be researched further to see if it can be used on these conveyor type fryers to protect the equipment and the people working around them. The primary motivation for fire protection is to protect people, so it's crucial to investigate the use of water mist in commercial structures as well.…..” (lines 428-437, page 13)

“………Sprinklers have been proven to be a reliable fire protection strategy in commercial structures. Before the industry switches from using standard sprinklers, the advantages of water mist over sprinklers would need to be further proven. Although more testing needs to be done, water mist suppression has potential as an alternative. The use within commercial buildings links to the application of water mist within residential buildings. ……….” (lines 451-455, page 13).

Reviewer 4 Report

General comments

1. I would question to what extent much of the content of the paper has already been covered elsewhere. For example in the 5^th edition SFPE Handbook chapter:

·         J. Mawhinney and G. Back, ‘Water mist fire suppression systems’, in SFPE Handbook of Fire Protection Engineering, 5th Edition., Springer, 2016, pp. 1587–1645.

I think it would be useful for the authors to highlight in detail in the introduction what it is about this review which is novel when compared to what is already available in existing literature.

2. A lot have advances have been made in recent years on the activation methods used for water mist systems. It would be useful to discuss the common activation methods of water mist nozzles (heat responsive elements) and any advancing technologies, and the implication this might have on system performance. For example, reference to more responsive electronically controlled or operated nozzles has recently been integrated into NFPA 750. See the following research work on this topic:

·         Hopkin, M. Spearpoint, Y. Muhammad, and W. Makant, ‘Estimating the suppression performance of an electronically controlled water mist system from BS 8458:2015 fire test data’, Fire, vol. 5, no. 5, 2022, doi: 10.3390/fire5050144.

·         M. Spearpoint, C. Hopkin, Y. Muhammad, and W. Makant, ‘Replicating the activation time of electronically controlled watermist system nozzles in B-RISK’, Fire Safety Journal, 2022.

3. A common criticism levied against water mist systems is a lack of reliability data, particularly for novel applications. An advantage that sprinklers have in comparison is their longstanding use in buildings and hence the collation of large quantities of historical fire incident data on their reliability. For example, see:

·         W. Koffel, ‘Reliability of Automatic Sprinkler Systems’, Alliance for Fire and Smoke Containment and Control, Sep. 2005.

·         New Zealand Fire Service Commission, ‘Effectiveness of fire safety systems for use in quantitative risk assessments’, Marsh, Wellington, New Zealand, Research Report 89, 2008.

·         K. Frank, N. Gravestock, M. Spearpoint, and C. Fleischmann, ‘A review of sprinkler system effectiveness studies’, Fire Science Reviews, vol. 2, no. 1, p. 6, Oct. 2013, doi: 10.1186/2193-0414-2-6.

This limitation is briefly touched upon in Section 3.4.8, but I think it would be beneficial to discuss this relative lack of data for water mist somewhere as a current challenge / issue.

4. In reviewing the references, it appears in many instances that outdated versions of standards are being referenced. For example NFPA 750 2010, which has since been revised three times (2015, 2019, 2023). Similarly, older DD versions of British Standards are referenced rather than the more recent BS 8458 and BS 8489-1. I would therefore question whether much of the content of Section 5 on design codes is out of date and no longer applicable in the context of the most recent industry standards.

5. With respect to water mist in residential applications (e.g., Section 3.4.8), there is work around this area which would be beneficial to discuss. See:

·         Arvidson, M. An Evaluation of Residential Sprinklers and Water Mist Nozzles in a Residential Area Fire Scenario; Research Institutions of Sweden, Borås, Sweden, 2017; RISE Report 2017:04.

·         Arvidson, M.; Larsson, I. Residential Sprinkler and High-Pressure Water Mist Systems; SP Swedish National Testing and Research Institute: Borås, Sweden, 2001; SP Report 2001:16.

·         Chow, W.K. Heat release rate of an open kitchen fire of small residential units in tall buildings. In Proceedings of the 3^rd International Performance Buildings Conference, Purdue, IN, USA, 14–17 July 2014.

Specific comments

6. page 1. Line 14, change ‘cooking area’ to ‘cooking areas’

7. Page 1. Line 35, change ‘maybe’ to ‘may be’.

8. Page 1. Line 38. This line could be interpreted as indicating water damage is only a concern in timber structures and libraries, but it is a concern for many building situations and not exclusive to the two mentioned here.

9. Page 2 Line 76, change ‘nozzel’ to ‘nozzle’.

10. Page 4 Line 144. Reference could also be made to the fact that water’s relative abundance and easy accessibility is another contributing factor for why it is used as a common suppressing agent.

11. Equations 1 through 3. When discussing these equations and introducing the nomenclature, it would be beneficial to specify units in each case.

12. Page 7 Fig. 6. Change ‘temperrature’ to ‘temperature’.

13. Page 10, line 307. First mention of ‘Ro-ro’, so this should be expanded.

14. Page 11, lines 359 and 360. It is stated that smaller droplet sizes than 1 μm are not achievable by existing products. Can a reference be included for this statement?

15. Page 11, Section 3.4.8, studies elsewhere have indicated that the impact of water mist on cooking oil fires can produce an initial but rapid increase in the heat release rate, owing to water droplets colliding with the fuel surface and increasing the surface area. See:

·       Qin, J.; Yao, B.; Chow, W.K. Experimental study of suppressing cooking oil fire with water mist using a cone calorimeter. Int. J. Hosp. Manag. 2004, 23, 545–556.

16. Page 12, Section 4. Reference is made to small scale tests or much larger-scale experiments inside aircraft hangers and warehouses. There also enclosure fire tests which are commonly required in test standards – these are broadly representative of room dimensions which might be observed in residential or commercial buildings. For example, see the enclosure fire tests described in BS 8458 or BS 8489-7. This is worth mentioning.

17. Page 12 Table 2. First mention of the initialism ‘MC’, so this should be expanded / explained.

18. Page 12 Table 2. Change ‘HHR’ to ‘HRR’. This is the first mention of the HRR initialism as well, so it should be expanded.

19. Page 12 Table 2, Operating pressure, ninth bullet, change ‘comparted’ to ‘compared’.

20. Page 18, line 523, change ‘spay’ to ‘spray’. This error is made in multiple places, so check throughout.

21. Paged 18, Equation 4. As per previous comment, it would be beneficial to specify the units for each item.

22. See the Plumis Automist system described in the references of comment 2 previously, which may be worth mention given its novel activation mechanisms and its positioning relative to the floor level. Its design operation and maintenance (DIOM) manual can be found here: https://plumis.co.uk/sites/plumis-co-uk/files/2019-07/Smartscan%20Hydra%20Handbook%20v1.7.1.pdf

23. Page 27, lines 713 and 714. It is indicates here that NFPA 750 does not make reference to residential applications. However, Section 10 of NFPA 750 in fact makes reference to occupancy protection systems for residential applications.

24. Page 28, lines 729 and 730. The line suggests that BS 8458 was released in 2010, but it was DD 8458-1:2010 that was published on this date. BS 8458 was published in 2015. This section also makes reference to DD 8489-1 for industrial and commercial buildings, but this was superseded by BS 8489-1 in 2016.

25. Page 28, line 734, change ‘budlings’ to ‘buildings’.

26. Page 30, line 789. Here it stated that water mist is unable to be used in commercial or residential buildings. However, previously it is shown that there are a number of standards and test procedures available internationally for their use in these building types. I would agree that further research is needed but their application is becoming more commonplace in these building types.

Author Response

Reviewer 4: Comments and Suggestions for Authors

General comments

1. I would question to what extent much of the content of the paper has already been covered elsewhere. For example in the 5^th edition SFPE Handbook chapter:

• J. Mawhinney and G. Back, ‘Water mist fire suppression systems’, in SFPE Handbook of Fire Protection Engineering, 5th Edition., Springer, 2016, pp. 1587–1645.

I think it would be useful for the authors to highlight in detail in the introduction what it is about this review which is novel when compared to what is already available in existing literature.

Response:

Additional research was done after 2016, but no thorough review paper on water mist was realised after that year. In order to provide the community involved in fire safety with the most recent information on water mist, the current paper has been written. Additional explanation is provided in the introduction section.

Please check the revised manuscript, pages 3-4.

“…….. By looking at the existing literature on water mist systems, this review discusses how this knowledge can potentially be used in new and emerging industries and protect people and property from their associated fire risks. The study also extended to existing design codes of water mist systems for different countries and highlight how legislation and system approvals may be restricting the potential applications for this firefighting method……..”

2. A lot have advances have been made in recent years on the activation methods used for water mist systems. It would be useful to discuss the common activation methods of water mist nozzles (heat responsive elements) and any advancing technologies, and the implication this might have on system performance. For example, reference to more responsive electronically controlled or operated nozzles has recently been integrated into NFPA 750. See the following research work on this topic:

• Hopkin, M. Spearpoint, Y. Muhammad, and W. Makant, ‘Estimating the suppression performance of an electronically controlled water mist system from BS 8458:2015 fire test data’, Fire, vol. 5, no. 5, 2022, doi: 10.3390/fire5050144.
• M. Spearpoint, C. Hopkin, Y. Muhammad, and W. Makant, ‘Replicating the activation time of electronically controlled watermist system nozzles in B-RISK’, Fire Safety Journal, 2022.

Response: Discussion has been included with updated references:

     “ It has been established that the physical phenomenon of fire suppression by water mist is complex. Extensive research has shown that there is a lot of factors contributing to the suppression of the fire including water droplet size [9, 19, 28, 52, 57, 59-61], spray momentum [70], nozzle angle [5, 24, 91], nozzle height [5, 9, 64], compartment size [6, 9], ventilation [6, 9], burning fuel load [18, 82, 92] and the spray nozzle activation method [93,94]. The varying effects of these parameters makes it difficult to design a water mist suppression system by applying first principles.” (lines 895-901, pages 31-32)

References:

[93] Hopkin C, Spearpoint M, Muhammad Y, Makant W. Estimating the suppression performance of an electronically controlled residential water mist system from BS 8458: 2015 fire test data. Fire, 2022; 5: pp. 144.

[94] Spearpoint M, Hopkin C, Muhammad Y, Makant W. Replicating the activation time of electronically controlled water mist system nozzles in B-RISK. Fire Safety Journal,2022; 130: pp. 103592.

3. A common criticism levied against water mist systems is a lack of reliability data, particularly for novel applications. An advantage that sprinklers have in comparison is their longstanding use in buildings and hence the collation of large quantities of historical fire incident data on their reliability. For example, see:

• W. Koffel, ‘Reliability of Automatic Sprinkler Systems’, Alliance for Fire and Smoke Containment and Control, Sep. 2005.
• New Zealand Fire Service Commission, ‘Effectiveness of fire safety systems for use in quantitative risk assessments’, Marsh, Wellington, New Zealand, Research Report 89, 2008.
• K. Frank, N. Gravestock, M. Spearpoint, and C. Fleischmann, ‘A review of sprinkler system effectiveness studies’, Fire Science Reviews, vol. 2, no. 1, p. 6, Oct. 2013, doi: 10.1186/2193-0414-2-6.

This limitation is briefly touched upon in Section 3.4.8, but I think it would be beneficial to discuss this relative lack of data for water mist somewhere as a current challenge / issue.

Response: The below mentioned changes has been addressed in the revised manuscript.

………..It is shown that water mist is becoming more common place for residential use in areas that follow the NFPA and British Standards. Before it is accepted in Australia and other parts of the world,  an increase in performance data and historical evidence of its ability to control fires needs to be established [95,96]….(lines 918-921, page 32)

……When considering the approval of water mist system for a life safety residential or commercial application, the information available is limited [95, 96]. (lines 923-925, page 32)

References:

[95] Frank K, Gravestock N, Spearpoint M, Fleischmann C. A review of sprinkler system effectiveness studies. Fire science reviews,2013; 2(1), 1-19.

[96] Gravestock N. Effectiveness of fire safety systems for use in quantitative risk assessments. New Zealand Fire Service Commission, Wellington, NZ, 2008.

4. In reviewing the references, it appears in many instances that outdated versions of standards are being referenced. For example NFPA 750 2010, which has since been revised three times (2015, 2019, 2023). Similarly, older DD versions of British Standards are referenced rather than the more recent BS 8458 and BS 8489-1. I would therefore question whether much of the content of Section 5 on design codes is out of date and no longer applicable in the context of the most recent industry standards.

Response: The updated versions of standards are included in the revised manuscript and added below references. Please check the reference numbers [8] and [90] in the revised manuscript.

[8]  NFPA 750 (2023). Standard on water mist fire protection systems.

[90] British Standards. BS 8489-1 2016: Fixed fire protection systems. Industrial and commercial water mist systems – Code of practice for design and installation. 

5. With respect to water mist in residential applications (e.g., Section 3.4.8), there is work around this area which would be beneficial to discuss. See:

• Arvidson, M. An Evaluation of Residential Sprinklers and Water Mist Nozzles in a Residential Area Fire Scenario; Research Institutions of Sweden, Borås, Sweden, 2017; RISE Report 2017:04.
• Arvidson, M.; Larsson, I. Residential Sprinkler and High-Pressure Water Mist Systems; SP Swedish National Testing and Research Institute: Borås, Sweden, 2001; SP Report 2001:16.
• Chow, W.K. Heat release rate of an open kitchen fire of small residential units in tall buildings. In Proceedings of the 3^rd International Performance Buildings Conference, Purdue, IN, USA, 14–17 July 2014.

Response: The section “Residential Buildings” is updated based on below latest reference only and did not cite the references published in 2001 and 2014.  

[54]     Arvidson M. An evaluation of residential sprinklers and water mist nozzles in a residential area fire scenario, Research Institutions of Sweden; RISE Report 2017: 04.2017

Specific comments

6. page 1. Line 14, change ‘cooking area’ to ‘cooking areas’

Response:

‘cooking area’ has been replaced with ‘cooking areas’. Please check the revised manuscript, Page 1, line 14.

7. Page 1. Line 35, change ‘maybe’ to ‘may be’.

Response:

maybe’ has been replaced with ‘may be’. Please check the revised manuscript. Page 2, line 36.

8. Page 1. Line 38. This line could be interpreted as indicating water damage is only a concern in timber structures and libraries, but it is a concern for many building situations and not exclusive to the two mentioned here.

Response:

Specification has been removed to avoid this interpretation.

9. Page 2 Line 76, change ‘nozzel’ to ‘nozzle’.

Response:

‘nozzel’ has been replaced with ‘nozzle’. Please check the revised manuscript. Page 3, line 78.

10. Page 4 Line 144. Reference could also be made to the fact that water’s relative abundance and easy accessibility is another contributing factor for why it is used as a common suppressing agent.

Response:

This has been added to this section. Please check the revised manuscript. Page 6, line 154.

11. Equations 1 through 3. When discussing these equations and introducing the nomenclature, it would be beneficial to specify units in each case.

Response:

This has been updated. Please check the revised manuscript, equations 1-3.

12. Page 7 Fig. 6. Change ‘temperrature’ to ‘temperature’.

Response:

‘temperrature’ has been replaced with ‘temperature’. Please check the revised manuscript. Page 8, Fig. 6.

13. Page 10, line 307. First mention of ‘Ro-ro’, so this should be expanded.

Response:

Added introduction of Ro-ro. Please check the revised manuscript. Page 11, line 337.

14. Page 11, lines 359 and 360. It is stated that smaller droplet sizes than 1 μm are not achievable by existing products. Can a reference be included for this statement?

Response:

Comment based on what has been found across all of the literature. This has been reworded to make this clear. Please check the revised manuscript. Page 12, lines 414-416.

15. Page 11, Section 3.4.8, studies elsewhere have indicated that the impact of water mist on cooking oil fires can produce an initial but rapid increase in the heat release rate, owing to water droplets colliding with the fuel surface and increasing the surface area. See:

•       Qin, J.; Yao, B.; Chow, W.K. Experimental study of suppressing cooking oil fire with water mist using a cone calorimeter. Int. J. Hosp. Manag. 2004, 23, 545–556.

Response:

The suggested reference is included in the revised manuscript. Please check below reference:

[47]     Qin J, Yao B, Chow WK. Experimental study of suppressing cooking oil fire with water mist using a cone calorimeter. International Journal of Hospitality Management, 2004; 23 (5 SPEC.ISS.), pp. 545-556. 

16. Page 12, Section 4. Reference is made to small scale tests or much larger-scale experiments inside aircraft hangers and warehouses. There also enclosure fire tests which are commonly required in test standards – these are broadly representative of room dimensions which might be observed in residential or commercial buildings. For example, see the enclosure fire tests described in BS 8458 or BS 8489-7. This is worth mentioning.

Response:

The authors would like to thank to the reviewer for this valuable comments.  This has been added in the revised manuscript. Please check section 4. Please check the revised manuscript. Page 14, lines 487-489.

17. Page 12 Table 2. First mention of the initialism ‘MC’, so this should be expanded / explained.

Response:

Multi-component (MC) introduced and included in abbreviation table at the start of article. Please check the revised manuscript. Page 2.

18. Page 12 Table 2. Change ‘HHR’ to ‘HRR’. This is the first mention of the HRR initialism as well, so it should be expanded.

Response:

‘HHR’ has been replaced with ‘HRR’. Please check the revised manuscript. Page 14, Table 2.

19. Page 12 Table 2, Operating pressure, ninth bullet, change ‘comparted’ to ‘compared’.

Response:

‘comparted’ has been replaced with ‘compared’. Please check the revised manuscript. Page 14, Table 2.

20. Page 18, line 523, change ‘spay’ to ‘spray’. This error is made in multiple places, so check throughout.

Response:

‘spay’ has been replaced with ‘spray’. Please check the revised manuscript, Page 20, line 593.

21. Paged 18, Equation 4. As per previous comment, it would be beneficial to specify the units for each item.

Response:

This has been updated. Please check the revised manuscript. Page 20, line 588.

22. See the Plumis Automist system described in the references of comment 2 previously, which may be worth mention given its novel activation mechanisms and its positioning relative to the floor level. Its design operation and maintenance (DIOM) manual can be found here: https://plumis.co.uk/sites/plumis-co-uk/files/2019-07/Smartscan%20Hydra%20Handbook%20v1.7.1.pdf

Response:

The authors thank to the reviewer for this suggestion.

23. Page 27, lines 713 and 714. It is indicates here that NFPA 750 does not make reference to residential applications. However, Section 10 of NFPA 750 in fact makes reference to occupancy protection systems for residential applications.

Response:

This has been updated. Please check the revised manuscript. Page 28, lines 723-824.

24. Page 28, lines 729 and 730. The line suggests that BS 8458 was released in 2010, but it was DD 8458-1:2010 that was published on this date. BS 8458 was published in 2015. This section also makes reference to DD 8489-1 for industrial and commercial buildings, but this was superseded by BS 8489-1 in 2016.

Response:

This has been updated. Please check the revised manuscript. Page 30, line 852.

25. Page 28, line 734, change ‘budlings’ to ‘buildings’.

Response:

‘budlings’ has been replaced with ‘buildings’. Please check the revised manuscript. Page 29, line 824.

26. Page 30, line 789. Here it stated that water mist is unable to be used in commercial or residential buildings. However, previously it is shown that there are a number of standards and test procedures available internationally for their use in these building types. I would agree that further research is needed but their application is becoming more commonplace in these building types.

Response:

Great point. This has been revised. Please check the revised manuscript. Page 31, lines 884-893.

Round 2

Reviewer 1 Report

The authors have adequately addressed all my comments.

Reviewer 4 Report

The authors have made an effort to address my comments. I have no further comments and advise to accept in the present form.