Development of a Programmable System Used for the Preparation of a Mixture of Flammable/Explosive Gases

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript describes a computerised bench for the preparation of flammable/toxic/explosive gas mixtures, which provides a material basis for achieving volumes of homogeneous gas mixtures used in scale physics experiments for controlled explosions in parallel hexagonal tubes at programmable, verifiable concentrations. However, the manuscript is not sufficiently well developed, and the specific changes are described below:

Comment 1:

The abstract section needs to summarize what is being researched in this paper, not all of it is the current state of research.

Comment 2:

In section 2.4, it is stated that the programmable mixer eliminates the disadvantages of the known methods, and its principles can be appropriately described.

Comment 3:

The title of chapter 3 does not correspond to the contents therein, and it is suggested that it be changed.

Comment 4:

Whether the pictures in chapter III could be properly labelled.

Comment 5:

The font size of the figures in figure 3 is suggested to be a bit larger for readers' convenience.

Comment 6:

In Chapter 5, Conclusion, there are fewer summaries of the programmable mixers studied in this paper, and it is recommended that this section be added.

Comments on the Quality of English Language

It has basically met the journal's quality requirements.

Author Response

Comments 1: The abstract section needs to summarize what is being researched in this paper, not all of it is the current state of research.

Response 1: Thank you for pointing this out. I manage to modify the entire abstract, as follows: In the present paper, the use of programmable microprocessors to develop a computerized stand for the preparation of a mixture of flammable/toxic/explosive gases in order to obtain mixtures at concentrations in explosive range, is presented. The operating principle of the stand being based on the mixing of two volumetric flow, controlled with the help of microprocessors, where gases are stored and circulated at atmospheric pressure through cylindrical injectors, driven by stepper motors so that the gas circuit does not require valves. The exit of the stand is a homogenization chamber, with agitator and sensor to confirm the desired concentration of the mixture. This automated stand eliminates mechanical, electric or pneumatic valves from the gas circuits, avoiding elements with high mechanical resistance suitable for high pressures/depressions, removing the possibility of the return of the gas flow, without sensitivity to sudden pressures variations.

Comments 2: In section 2.4, it is stated that the programmable mixer eliminates the disadvantages of the known methods, and its principles can be appropriately described.

Response 2: Yes. Some known methods are pointed here. The programmable mixer described in this paper eliminates the disadvantages of the known stands and methods, methods at national and international level to obtain gas mixtures are with mechanical valves, with electric valves, with the help of flow regulators, or by indirect reading the concentration of the gas of interest through measuring the concentration of oxygen, as well as by applying the law of partial pressures, allowing to obtain homogeneous mixtures at high precision concentrations, elimination of mechanical, electrical, or pneumatic valves from the gas circuit, that are susceptible to negative influence the mixture concentration, avoidance of elements that are suitable for high pressures / depressions and eliminating the possibility of gas flow return.

Comments 3: The title of chapter 3 does not correspond to the contents therein, and it is suggested that it be changed.

Response 3: Indeed, here is a proposal of the modified title. Experiments

Comments 4: Whether the pictures in chapter III could be properly labelled.

Figure 1. Computerized gas mixing stand to produce mixtures at desired concentrations

Figure 2. Two cylindrical injectors driven by two stepper motors controlled by microprocessors

Figure 3. A new vision of an improved computerized stand for the preparation of a mixture of flammable / toxic gases

Comments 5: The font size of the figures in figure 3 is suggested to be a bit larger for readers' convenience.

Response 5: Without using acronyms, I increased the font inside figure 3.

Comments 6: In Chapter 5, Conclusion, there are fewer summaries of the programmable mixers studied in this paper, and it is recommended that this section be added.

Response 6: With sincere thanks, another relevant mixer is presented below.

Following some documentary research other works are relevant, such as a flammable gas dispenser, for determining the parameters involved in combustion, explosion and detonation processes, consisting of a cylindrical glass tube, U-shaped with water, having a shorter, closed dosing arm that is connected by an elastic hose, equipped with shut-off valve at the test chamber and a buffer arm, having the same diameter, longer, open and provided with a glass level.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The main topic of this research is the development of a programmable system capable of generating mixtures of flammable, toxic and explosive gasses with acceptable accuracy, especially in the explosive range between the lower explosive limit (LEL) and the upper explosive limit (UEL). The aim is to develop a system that can produce these mixtures with an accuracy of 0.1 percent by volume and is suitable for experiments and safety applications. The authors make this clear in the introduction and emphasize the need for accurate gas mixtures for experiments and safety applications. Although the work represents a significant advance in the field of programmable gas mixing systems, there are several areas where it could be improved.

The originality of this research lies in the innovative use of a programmable system that eliminates the need for traditional mechanical, electrical or pneumatic valves that are prone to failure. Instead, the system uses stepper motors and a microcontroller for precise control. This novel approach bridges the gap of inaccuracies associated with conventional gas mixing methods. While the manuscript discusses the relevance of these innovations, it should further address how this system compares to certain existing technologies and highlight the practical benefits and potential applications in industry and experimental research.

The manuscript contributes to the topic of automation systems by presenting a detailed design and implementation of a new gas mixing system. A mathematical algorithm for gas concentration calculations is presented and the system is demonstrated. However, the manuscript could be improved by comparing the results more explicitly with the existing literature and explaining how it advances current technologies and methods. Adding a section with a comparative analysis would strengthen the manuscript by contextualizing its contributions in the broader field. Also missing is a detailed literature review of existing research and methods. This should be included to better position the study in the current academic landscape.

The methodology is sound, but there are areas that can be improved. Specific details about the open-source board, microcontroller, hardware specifications including stepper motors, and software used for programming are missing and should be included for a complete understanding of the system. System accuracy is explained, but gas sensors typically have a margin of error that should be explicitly stated. Stating the expected errors and discussing the sensor specifications would provide more transparency and reliability.

The results section of the manuscript is not entirely adequate, as it contains detailed descriptions of materials and methods that should be presented separately. The authors describe the components of the system, how they work and the mathematical algorithms in the Results section, which should be part of the Materials and Methods section. This distracts from the actual results and data analysis and makes it difficult to focus on the results of the experiments. To improve clarity and organization, the Materials and Methods should be clearly outlined in their respective sections, and the Results section should be devoted exclusively to the presentation of experimental results, data, and relevant analyzes. This separation improves the readability of the manuscript and allows for clearer and more effective communication of results.

The discussion section of the manuscript currently contains detailed descriptions of the experimental results and specific data points that should be moved to the results section. The discussion should focus on interpreting the results, explaining their significance and relating them to existing research. It should emphasize how the results contribute to the field, compare the results with previous studies, and discuss similarities or differences. In addition, the discussion should address the limitations of the study and make suggestions for future research. Figures 5 through 9 should not be part of the discussion but should be included in the results section to ensure that all experimental data are properly organized and presented in the appropriate sections. The discussion section should also include thorough and clear explanations of Figures 11 through 15, explaining the conditions, the phenomena observed, and their significance.

The section on the conclusions contains several points that were not dealt with in the earlier sections of the manuscript. For example, the complexity of indoor explosions and the influence of turbulence are discussed in the conclusions, whereas these topics are not covered in detail in the results or discussion sections. The use of Schlieren and Shadowgraph techniques is mentioned but not discussed in detail in the Methods and Results sections. Furthermore, although the conclusions refer to the calibration of the mathematical models and simulations, these models and their calibration processes are not described in detail. The conclusions should be consistent with the results and discussion and ensure that all points are supported by detailed explanations and data.

The references cited in the paper are appropriate and cover a range of basic and recent studies relevant to gas explosions and mixing systems. However, more recent references and studies should be included, especially those that directly compare similar programmable gas mixing systems or mention more recent methods used in other similar studies.

The tables and figures are well organized and illustrate the possibilities of the system. The authors should reconsider the need for Figures 5 through 9; the recorded methane values could be better presented in a tabular format.

 

Comments for author File: Comments.pdf

Author Response

Comments 1: While the manuscript discusses the relevance of these innovations, it should further address how this system compares to certain existing technologies and highlight the practical benefits and potential applications in industry and experimental research.

Response 1: Thank you for adding such a detailed approach to the manuscript. Allow me to point some of the most relevant benefits of the system: The main advantages of the computerized gas mixing stand are obtaining homogeneous mixtures at high precision concentrations, no mechanical, electric or pneumatic valves in gas circuits, no elements with high mechanical resistance, the system operates at atmospheric pressure, concentration at a high rank, concentration checking at the exit of the stand.

Comments 2: Specific details about the opensource board, microcontroller, hardware specifications including stepper motors, and software used for programming are missing and should be included for a complete understanding of the system. System accuracy is explained, but gas sensors typically have a margin of error that should be explicitly stated.

Response 2: Yes, some details are pointed here. Section 2.6 was renamed as Arduino used as open-source platform to program the mixer. Arduino was the best decision here, in order to make the gas mixer programmable. This board is an open hardware that can be used in any applications and comes with various benefits for the user, such as: digital pins/analog pins arranged in a specific pattern, in order to fit into most Arduino compatible devices, power connect for the device itself and low voltage for connected components, a microcontroller, that allow programming of the board, in general Atmel controllers, like ATmega8, ATmega168 and so on. Serial connector and a variety of other small components (oscillator, voltage regulators). Section 2.7 was added with the name Software used to run the mixer.

Comments 3: System accuracy is explained, but gas sensors typically have a margin of error that should be explicitly stated.

Response 3: Indeed, I inserted a new section. Inside chapter 4 I added a sub-section called 4.1 Measuring device with ethane detector with details.

Comments 4: Figures 5 through 9 should not be part of the discussion but should be included in the results section to ensure that all experimental data are properly organized and presented in the appropriate sections. The discussion section should also include thorough and clear explanations of Figures 11 through 15, explaining the conditions, the phenomena observed, and their significance.

Response 4: I assume that the new rearrangement of pictures 5 through 9 (renamed as 11, 12 ,13 ,14, 15) inside the chapter 5 Conclusions will bring more content to the manuscript.  Discussion section was rearranged with a sub section called 4.2. Controlled explosions with an explosive air/gas mixture obtained from the computerized stand, that explains with more details the Figures 11 through 15 (renamed now as Figure 17, 18, 29, 20, 21).

Comments 5: The use of Schlieren and Shadowgraph techniques is mentioned but not discussed in detail in the Methods and Results sections.

Response 5: In Materials and methods, a new section was introduced that explains the role of Schlieren technique. 

2.6.        Capturing the flame front with Schlieren technique

Shadowgraph and Schlieren techniques are used in aeronautical engineering to see the flow about high-speed aircraft and missiles, as well as in combustion research, ballistics, explosions, and in the testing of glass. In principle, they are ideal for the identification of flow patterns. Schlieren photography, we know that is a visual process used to photograph the flow of fluids of varying density. As mentioned, the Schlieren process was invented to study supersonic motion, widely used in aeronautical engineering, to observe and record the flow of air around objects. The role of this method is changing due to the increasing use of computational fluid dynamics, which reduces the need for all such experimental fluid flow measurement techniques. A basic Schlieren system uses light from a single collimated source shining on, or from behind, a target object.

Comments 6: The authors should reconsider the need for Figures 5 through 9; the recorded methane values could be better presented in a tabular format.

Response 6: With sincere thanks, the recorded methane values are now presented in tabular format with display thumbnail.

 

Author Response File: Author Response.pdf