Application Assessment of Electrical Cables during Smoldering and Flaming Combustion

Round 1

Reviewer 1 Report

This study compared the fire properties of several electrical cables during smoldering and flaming combustion including extinction modulus and smoke and CO concentrations, etc. The paper is more like an experimental report rather than a scientific article since the connection between the fire properties of each cable and their material composition, layer thickness, and flammability, etc. was not discussed/quantified in detail. This makes the paper too weak to contribute some useful knowledge for future research. The comments from the reviewer are as follows:

 1) Introduction: The Introduction is too wordy. It should concisely express the key knowledge gaps of the existing studies and the research objective of this work.

2) 2.1 Materials: Since tests were designed to compare the fire properties of cables listed in Table 1, it is necessary to define the specific material and thickness of each layer of the cables.

3) 2.2 Methods: There is no need to provide every detail of the components in the control and measurement system. Providing the key parameters of the key components for the test purposes are pretty enough.

4) Figure 1: A detailed cable arrangement and ignition methods should be zoomed in/replotted. Also, the relevant position of the cable tray and the detectors should be quantified and discussed.

5) Results and discussion: Obviously, the authors evaluated the fire properties of each cable through direct comparisons of their extinction modulus, smoke and CO concentrations, and then got the conclusions shown in the “Conclusions” section. Without discussing the relationship between fire properties of each cable with their material composition, layer thickness, flammability, etc., how could the conclusions drawn in this work be useful for other researchers?

6) Moderate editing is required to improve the language and to fix misnomers and typos.

Author Response

1 Thank you very much for your attention. The introduction has been rewritten, shortened to 1478. The information of the purpose of the research and the research gap has been added.
2 Thank you very much for your valuable comment. The data regarding cable thickness has been added to the table.
3. thank you very much for your attention. The unnecessary details of the components of the control and measurement system have been removed.
4 Thank you very much for your attention. The drawing has been corrected.
5. thank you very much for your attention. The conclusions of our research are mainly to help in the selection of appropriate fire detectors in relation to the cables used. As well as about the amount of toxic gases emitted by burning cables depending on the coatings from which they are made. The research is important due to the fact that human lives are at risk during the occurrence of a fire.

Reviewer 2 Report

The article focused on the effects of combustion and smoldering on the response time of fire smoke detectors, the concentrations of CO, SO2, NO2, NO, HCN, HCl, HBr, and HF gases produced in the process of cable combustion, and also the effects of cable type and combustion method on detector activation times. It contributes to cable fire prevention and escapes in confined spaces with extreme innovation and practicality. But there are still some deficiencies that need to be modified.

1. Article involves only the cable types and the different combustion modes, so whether the cable cross-section or other physical characteristics affect the combustion significantly.

2. Generally, the cable combustion in the building is accompanied by the disturbance of airflow, resulting in changes in the amount of oxygen. If this influence is ignored, whether the monitoring effect of the sensor is the same as in the article.

3. Figure 8 shows the monitoring results of a variety of toxic gases, but the gas release rate is not constantly related to the combustion progress, so how is ppm calculated in figure 8?

4. The detector is not only installed on the top floor, but also on the side wall. At this time, it is more appropriate to replace the height of the monitor with the distance.

5. In line 437, the second picture in Figure 6 lack of title.

To sum up, if the authors respond well to the above comments, it is suggested that the journal accept the article.

Author Response

1 Thank you for your attention. Cable cross-sectional area affects the current capacity and resistance of cables, as well as the amount of energy that can be conducted through the cable. The larger the cable cross-section, the higher the current capacity and lower the resistance, which can lead to higher thermal losses during power transmission. In the event of a fire, a larger cable cross-section can lead to more heat generation and more smoke. Insulation material, conductor type, sheath thickness and the presence of additional materials such as fillers or coatings can also affect cable combustion during a fire. More information has been added to Table 1 regarding cable diameters and number of conductors. 
2 Thank you for your attention. The reduced amount of oxygen in the air that results from cable combustion can affect the detector's response and delay fire detection. The smoke given off by burning cables may be less visible than the smoke given off by burning other materials, which may make it more difficult for smoke detectors to detect a fire. In our closed chamber prepared for the experiments, the natural conditions were fully reproduced, including the reduction of oxygen in the room. The response time of the detector will be the same as in the article depending on the cable material.
3.The ppm values were read using the ULTRAMAT 23 gas analyzer device.
4 Thank you for your suggestion. We fully agree with the reviewer's suggestion. In our research, the main idea is the distance of the detector from the cables where coating combustion can potentially occur. The shorter the distance, the faster the response of the detector. Therefore, in our research, we adopted a distance further away, that is, the ceiling distance. 
5 Thank you sincerely for your attention. The figure has been corrected.

Reviewer 3 Report

Dear authors, the article is relevant, interesting, well structured and presented. Some recommendations for its improvement.

1. Abstract. Supplement from the conclusion what exactly the results were obtained.

2. Introduction. The purpose is expressed vaguely. Objectives are not set. The provisions of the solved tasks should be displayed in the conclusion. Place emphasis on the scientific novelty of the goal. The review is large, but you need to highlight what new you are going to contribute to science with your research.

3. Materials and methods. Setting - standard? Where else has it been used? Has the same one been used in other studies? and what is the difference? 

4. Lines 210 - 213 are the objectives of the study.

Author Response

1 Thank you for your attention, the abstract has been corrected.
2 Thank you for your attention. The purpose of the article is presented, the scientific novelty that our research introduces is presented.
3. gas analyzer designed mainly for industrial applications. With a single analyzer it is possible to continuously measure the concentrations of one to three infrared active components (e.g.:CO, CO2, NO, SO2, CH4, freons) and in addition oxygen by electrochemical method.
4 Thank you. The objective has been moved to introduction.