## Summary

The reliability of the technical manufacturing base of each state depends on the supplies of energies and drinking water in standard as well as extraordinary conditions. An extraordinary event or crisis situation can be caused by natural influences and anthropogenic events. Whereas in standard conditions, the supply of energies follows from contractual relationships, in case of extraordinary event it follows from a real situation that has occurred in the concerned entity of technical infrastructure. A common condition of technical–operational safety and manufacturing activity of all entities in standard and extraordinary situations is the reliability and continuity of water supplies for technological and sanitary purposes.

This article presents what the threats and natural and anthropogenic conditions that can disrupt or completely exclude manufacturing processes are and how these threats can be effectively coped with in the real environment.

## Keywords

Water ; Drinking water ; Water supply ; Industry ; Construction ; Manufacturing activity ; Safety ; Extraordinary event

## Introduction

Part of ensuring the operational safety and production reliability of each industrial entity is the supply of energies and water. If energy minerals (gas, coal, uranium and oil) have strictly defined functions in industrial entrepreneurial entities, then drinking water has a multipurpose role and has a variety of uses. It can be considered as primary precondition for activities of each industrial company, without exception. Without the supply of drinking water, any sanitary conveniences that must be part of manufacturing service buildings cannot be operated, meals to employees cannot be served and, in many cases, drinking water is used in technological manufacturing processes.

Inside water supply systems connected to public water supply systems act very often, especially in extensive industrial parks, as multipurpose sources of water for firefighting and are really a necessary precondition for ensuring the fire safety of the whole industrial park. From the above-mentioned facts it follows that water supply systems and industrial companies form one integral interconnected whole.

## Industry and its dependence on water supplies

Industrial companies and parks, see Fig. 1 , are usually connected to local water supply systems of towns and municipalities or, in specific cases, to water supply systems of group and regional water supply systems.

 Figure 1. Diagram of connection of the industrial park to the water supply system of local water supply system.

A common feature of each connection of industrial consumers of drinking water is the construction of a water delivery point for an inside water supply system. In the case of industrial parks with more water consumers, it is absolutely standard that the industrial park has one central measurement of water demand and many measurements of water depending on the number of entrepreneurial entities.

From the technical operational point of view, the reliability of drinking and firefighting water supplies for the inside water supply system of industrial park, especially at maximal water demand, depends on the dimensions of water service pipe, correct type of measurement system at the delivery point and optimum dimensions of pipes of the inside water supply system.

To achieve a balance between water demand and water supply, it is suitable to use mathematical modelling for the design of facility construction. The mathematical modelling of a piping system can be suitably used also in water piping reconstruction. This will guarantee the operator of the inside water supply system a sufficient overview of, e.g. water flow rates in specific parts of piping, hydrodynamic pressure depending on water discharge and delay in water at minimum operating mode.

The stated measures have economic effects not only on the initial costs of piping construction but also, and above all, on the permanent operating costs of water quality maintenance and water disinfections for the whole process of supply to all consumers.

## Mathematical modelling and its influence on operational reliability of water supply systems

The mathematical modelling of a water supply system is one of the most advanced methods for obtaining sufficient information about actual hydraulic parameters of the operating water supply system. So that the outputs of mathematical modelling may be realistic and exact, they have to be always calibrated before putting into operation, and for the use of the system, conditions have to be created.

### Conditions of mathematical modelling of a water supply system

Each model requires input data on nodes, pipelines, storage reservoirs and other subjects of the system. It is not difficult for the operator to transfer most of this information to the creators of the mathematical model. In the case of older water supply systems with a higher degree of pipeline incrustation, one of important conditions of modelling is the knowledge of roughness of the pipe inner walls. On the accuracy of this information the output value of modelling depends as well.

### Methods of water supply system calculation

For the successful mathematical modelling of local water supply systems of towns and municipalities and simultaneously also inside water supply systems of industrial parks, the following conditions must be fulfilled (Ingedult and Vyčítal, 1999  and Odula, 2001 ):

• Node condition : The sum of inflows, outflows and quantities demanded at each node of the water supply system must be zero.
 ${\displaystyle \sum _{i=1}^{m}(a_{ij}Q_{i})+G_{j}=0}$
( 1)

Qi – rate of flow in section i (m3  s−1 ), aij – expresses whether node j is the initial or final node of section i , Gj – quantity demanded from node j (m3  s−1 ).

• Loop condition : In each loop of the water supply system, pressures will be equalized. If we give the sign, which is identical with that of the direction of flow at the same basic orientation of the positive flow in the loop, to the head losses in the section, the sum of the head losses in the loop will be zero.
 ${\displaystyle \sum _{i=1}^{m}(b_{ik}h_{i})=0}$
( 2)

hi – head loss in section i (m), bik – expresses whether the given section i is part of loop k .

• Hydraulic condition : It describes a relation between head loss and flow rate in the section.
 ${\displaystyle h_{i}=k_{i}Q_{i}^{2}}$
( 3)

hi – head loss in section i (m),

 ${\displaystyle k_{i}={\frac {8}{g\pi ^{2}}}\lambda _{i}{\frac {l_{i}}{d_{i}^{5}}}}$
( 4)

li – friction factor, di – internal pipe diameter in section i (m).

For the calculation of a looped system, which consists of m sections and n nodes, we shall get s loops:

 ${\displaystyle s=m-n+1}$
( 5)
• Source path condition : The loss in the source path equals to the difference between height levels, free discharges, etc. of end nodes of the source path. If the number of pressure-dependent nodes is y , the number of source paths is equal to y  − 1
 ${\displaystyle \sum _{i=1}^{m}(c_{iy}h_{i})=H_{y}^{P}-H_{y}^{K}}$
( 6)

hi – head loss in section i (mm), ciy – orientation of sections of the source path, ${\textstyle H_{y}^{P},H_{y}^{K}}$ – level of pressure head at nodes at the beginning and at the end of the source path.

Diagrammatically for the needs of this article, particular key conditions used in the mathematical modelling of the water supply system are illustrated in Fig. 2 .

 Figure 2. Diagram of water supply system.

In Fig. 2 it can be clearly seen that a section can consists of:

• pipes, i.e. pipe section, or link,
• a pump, i.e. section with a pump,
• a valve, i.e. section with a valve.

In programming, another condition is distinguishing the following nodes of the water supply system:

• node with water demand,
• node with the inflow of water,
• water reservoirs or tanks.

An integral part of the assessment of hydraulic efficiency, reliability and safety of water supplies for industrial parks is the knowledge of risks that may threaten manufacturing processes.

### Safety risks of interruptions in drinking water supply to industry

Interruptions in the supply of water from public water supply systems cannot be eliminated in advance. On the contrary, it is necessary to consider them and to include them in emergency and crisis preparedness plans of entities for coping with extraordinary events. From a whole range of safety risks threatening the continuity of water supplies to industrial entities, it is necessary to take into account minimally the following events (Kročová, 2013 ):

• lack of water in the water source of a public water supply system,
• primary or secondary contamination of supplied drinking water,
• effects of natural influences on the water supply systems (floods),
• extensive water supply system accidents (landslides, etc.).

The above-mentioned and other risks are not however associated with the sources of drinking water and drinking water distribution systems at random. They have their own causes and rules. The risk of an unexpected extraordinary event can be actually reduced based on preventive safety risk analysis and suitably used methods. To other risks affecting the reliability of drinking water supply, construction operations in towns – existing and planned housing estates, network of streets, road traffic load, and others belong as well. These risks can be eliminated by a comprehensive approach that will interconnect planning processes especially in a built-up area (Peřinková et al., 2014 ).

## A system approach to the safety of drinking water supplies to industrial consumers

A system approach to an increase in the safety and continuity of drinking water supplies especially to the consumers that depend on direct supplies of water with usual parameters, to which unambiguously industrial consumers of the water belong, is one of the processes of safety planning in water management. It usually consists of safety risk analysis for the whole water supply system and its importance to various types of water consumers.

### Methods of safety risk identification and reduction

So that the analysis of safety risks may be efficient in practice, it must contain minimally the following range of problems and objectives:

• identification and definition of primary threats and consequences for the industrial entity concerned,
• identification of critical factors that can threaten the reliability and continuity of supplies of drinking and firefighting water from water supply systems for the determined purposes,
• example design solution for the emergency supplies of drinking water in extraordinary events or crisis situations to ensure the operation of technology of the manufacturing entity,
• example design solution for the emergency supplies of firefighting water for strategic demand points ensuring the fire safety of buildings of the industrial company.

The above-mentioned and other alternative measures however must not be only incidental, segment solution. They always must be based on an overall concept of safety of the manufacturing entity incorporated in a mind map, which is used as a basis for risk analysis that will be made with the use of a suitably chosen method (Bernatik et al., 2013 ).

## Discussion about the given problem

To the existing scientific knowledge of the rules of relationship between aquatic ecosystems and water use for human needs and industrial utilization, it is necessary to add new hypotheses on the influence of climate changes on the aquatic environment of the Earth. In professional circles of water managers, these problems are beginning to be discussed increasingly and solutions are beginning to be searched to find methods, means and ways suitable for reaction in actual conditions. Approaches and new solutions must be connected with results and conclusions of UN expert commissions, established for the purpose of 21st century climate change impact assessment. From the point of view of a multidisciplinary approach to water supply systems, in this area it is necessary to prepare, in the framework of safety education, a group of specialists for the management of institutions of various sizes and various degrees of complexity (Kavan, 2015 ).

## Conclusion

From the submitted article, markedly abridged in content, which presents the means to a substantial increase in the safety and continuity of drinking and firefighting water supplies to the industrial sector, it follows that the methods and ways of solving problems are published sufficiently in specialized literature. To ensure the continuous development of knowledge, it is however desirable to keep discussions about these problems not only on a national level, but minimally in the extent of solution for the whole moderate climate zone, where the majority of the states of Europe are there. The ever-changing needs of the society and also the continuous development of science and technology, with which the emergence of new safety risks and hazards is closely connected, affect dynamically the comprehensive solving of the given problems (Kavan et al., 2015 ).

## Conflict of interest

The author declares that there is no conflict of interest.

## References

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4. Kavan et al., 2015 Kavan, Š., Rathauský, Z., Cempírková, S., Trčka, M. New trends in education in the area of safety. In The Science for Population Protection, No. 2/2015, volume 7. MV–GŘ HZS ČR Population Protection Institute in Lázně Bohdaneč, ISSN 1803-568X.
5. Kročová, 2013 Š. Kročová; Contamination of water with noxious and hazardous substances; Inžynieria Mineralna, 14 (2) (2013), pp. 131–136
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Published on 05/10/16

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