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Mozzanica offers its customers a collection of documents to provide useful assistance on the updating of safety regulations.

The American Henry S. Parmalee is considered the inventor of the first automatic sprinkler, patented in 1874.

Just four years later Frederik Grinnell improved on Parmalee's idea by introducing what became known as the Grinnell sprinkler.

Since then automatic sprinkler systems represent the most popular fire prevention solution worldwide thanks to their simplicity and intrinsic effectiveness.

In 1812 the progenitor of today's flood and sprinkler systems was designed and installed by William Congreve at the Theatre Royal in Drury Lane in the United Kingdom. A water supply fed a network of perforated pipes. These systems (which soon spread to textile factories) needed to be activated manually and acted on the entire area to be protected. Even now, today's flood and water spray systems use water in large quantities and, unlike sprinklers, act simultaneously across the entire protected space. Unlike the Congreve system which exploited gravity and perforated pipes, today, thanks to the force of pumps and control of the delivery through appropriate nozzles, these systems can switch off or contain a fire until the arrival of emergency teams, but also prevent it from spreading, cooling the surrounding environment. They are in fact used where the propagation speed of a fire can be high and where highly effective intervention is required from the very first stages. In particular, the cooling action is particularly effective in safeguarding the resistance of the structures, especially if they are metallic (typically they are used to cool tanks which, if overheated can generate the phenomenon of BLEVE - boiling liquid expanding vapour explosion due to softening of the structural components).

A fire needs fuel, heat and comburent. The water mist systems act on the first two elements. They are able to generate a very fine mist of water, with drops of tens or hundreds of mm in diameter. By absorbing heat in proportion to the contact surface, the drops, expanding by heating, remove energy from the fire, hinder the contribution of comburent and absorb radiant heat. The water mists have been used in fire-fighting since the 1880s but it was only a hundred years later that water mist technology became established and was used in fixed extinguishing systems. Perfectly eco-compatible, it is a technology that economises on the use of extinguishing agents (using flow rates from one tenth to one hundredth less than sprinklers) and, in proportion to the nebulisation rate, minimises wetting (and related damage). This means that water mist systems are suitable for situations in which the available water reserves are limited (for example on the top floors of very tall buildings) or where, for reasons of weight and compatibility, the distribution system must have a minimal impact (pipes of just 15 -20 millimetres make the system particularly suitable for ships and areas of artistic interest). Terrestrially, the main uses are the protection of engine rooms, ordinary risk residential areas and data centres.

The use of carbon dioxide as an extinguisher is closely linked to the spread of electrification. It was in particular the Bell Telephone Company that, since 1914, stimulated the search for an electrically non-conductive chemical to extinguish fires on its telephone switchboards.

The Walter Kidde Company developed, for these requirements, the first portable CO 2 extinguisher and in the 1920s automatic systems that used carbon dioxide were already available.

In 1928 the first NFPA standard for carbon dioxide extinguishing systems began to take shape. Colourless, odourless, non-corrosive, electrically non-conductive, carbon dioxide does not participate in combustion reactions and, therefore, if it is poured onto flames, it moves oxygen (and the vapours that can be ignited) away from these thereby extinguishing them.

Released from refrigerated or compressed storage at high pressure, the gas also expands, cools down, strikes the materials involved in the flames and removes their energy, thereby acting on two of the vertices of the fire triangle (even if the main action is to remove comburent from the reaction).

Typically used in closed rooms, these systems can also be employed in open environments, exploiting localised applications and leveraging on the discharge time and the dynamics of carbon dioxide which, denser and heavier by 50% than the surrounding air, can create blankets that flood the protected spaces.

A CO2 system does not cause damage to structures, furnishings or to protected assets and does not leave residues or decomposition products; naturally present in the air, carbon dioxide has no application limitations and costs that may be related to the use of other gaseous extinguishing agents.

CO2 systems have a good gas penetration rate in the areas to be protected and are effective on a wide range of flammable and combustible materials.

The Montreal Protocol, which entered into force on 1 January 1989, banned substances that threaten the ozone layer, including halogenated extinguishers, and prompted the search for new environmentally friendly agents, otherwise known as clean agents. The alternatives that exploit the same principle as the systems previously in use, the so-called "in kind" systems - use halocarbons extinguishing agents (halogenated hydrocarbon gases) or inert gases. Unlike some of those "not in kind” ones, which are based on different approaches (water-mist, foam, aerosol, etc.), they allow a fast and clean action resulting in the immediate resumption of activities after the intervention. All clean agent systems act on the oxygen available for the combustion reaction by diluting and/or "removing" it from the flame due to the difference between the various specific gas weights and by chemical-physical means, increasing the heat capacity of the atmosphere contained in the protected volume, which hinders heat propagation. Unlike inert gas systems, halocarbons also act chemically, capturing oxygen through the free radicals that are released via the decomposition of the extinguishing agent.  Used for the protection of spaces where sufficient gas sealing can be achieved and, also for reasons of cost/benefit, gas systems are in particular used where it is not possible to use water (data centres, archives, electrical substations , libraries, warehouses and technical areas with personnel present).

Water, the most economical and effective extinguisher, on some fires, is inadequate or even harmful, as in the case of flammable liquids. For this reason foam extinguishing systems have been developed. An advantage of the foam is that in it a person can breathe; the air contained in the bubbles has the same mixture as the free one. Otherwise he can't do the fire. The wetting and cooling capacity of the foam is the main feature that determines the extinguishing effect; increasing the wetting effectiveness of the water, less can be used and greater resistance to the re-ignition of the flames.

In terms of removing heat from the fire, the efficiency of a foam system depends on the quality of the air bubbles; the smaller they are, regular, compact and numerous, the larger the heat exchange surface, the higher the extinguishing efficiency. In contact with the flames, the water contained in the bubbles converts into steam, increasing its volume by about 1700 times. Occupying the space, the vapor expels the air and lowers the concentration of oxygen to less than 7.5%, abundantly below the threshold necessary for the fire to sustain itself. Simultaneously with the effect of "suffocating" the water, vaporising absorbs heat, cooling the materials involved in the fire.

For those persons involved in fire prevention, the fire triangle is the starting point for any approach to protection or prevention. However, barely two decades ago, a fire was tackled from the perspective of limiting the probability of ignition, separating the fuel from the comburent through dust, foams, gas or water or saturating the rooms with inert gases.

There is actually another approach to prevention: reducing oxygen below a threshold that does not allow combustion to sustain itself. The theory is simple, and was known since Lavoisier, at the end of the 18th century, discovered the role of oxygen in combustion processes. However, the development required not only theoretical concepts but technologies, materials and management techniques that have only recently become available.

In particular it was in Germany, in the 2000s, that the ignition thresholds for the different materials finally began to be identified. A substantial difference between caution and prevention is that the second must act continuously. Maintaining a constant hypoxic atmosphere in an environment, i.e. one in which oxygen does not exceed 15% of the mixture, requires many aspects to be addressed simultaneously.

Firstly, it is necessary to have devices that act on the gases present, segregating some and increasing the concentration of others; in turn these systems must be guided by analysis and continuous control of the air parameters. But this is not enough; building waterproofing techniques are required for the premises together with air exchange systems that allow "perimeter control".

An extremely important system, which must guarantee the correct functioning of all the slave systems. Installing a new pumping station requires careful study, appropriate risk assessment and correct analysis of the customer's situation. Technology and engineering must combine for the best result.

The pumping station is the most important element of any water fire-fighting system, it is the heart of the system itself, essential to guarantee the use of water at the correct pressure and at the most suitable flow rate, required by the fire-fighting systems used.
Its reliability and efficiency is therefore essential for the protection against all risks.
In the design phase it is essential to analyse not only the pumps but also the characteristics of the room in which they will be installed, both in masonry and in prefabricated structure, and the characteristics of the connected water supply.

Prevention is better than cure; the fire-fighting strategy also includes aspects that may at first sight appear to be less relevant than the large-scale highly technological systems. A good practice, stimulated by a sign, rather than a fire-resistant division can do a lot to prevent a fire from igniting or, at worst, from spreading.

Mozzanica introduces in the sector new innovative digital solutions for advanced maintenance that are able to combine normal maintenance activities with "IoT” (Internet of Things) systems, for the integrated management of safety, choosing to operate according to Company 4.0 dictates.

Wars, especially modern ones that involve huge masses of people, one of the many consequences - often tragic - have the ability to uproot brilliant minds from the most disparate sectors and confront them with issues that probably would never have attracted their attention. This is what happened in 1943 to Conrad Hal Waddington. Evolutionary biologist, paleontologist, geneticist, embryologist, philosopher, poet and painter, Waddington was not particularly interested in aviation but with the outbreak of the Second World War he found himself enlisted in the Royal Air Force (RAF).

Aged forty, when he became scientific advisor to the Commander-in-Chief of the Coastal Command, Waddington was already an established scientist but fighting the German submarine threat more effectively seemed to have little relevance to his studies on epigenetics. Waddington and his colleagues developed a series of surprising recommendations that challenged the conventional military wisdom of the time in terms of attack tactics but what we remember him for here was his observation concerning the fact that of the 40 B-24 "Liberators" of the Coastal Command only half were flying in search of German U-boats while the other 50% was systematically grounded largely undergoing maintenance or waiting for it, whether planned or unplanned.

Adopting the methods that had already challenged his established beliefs, Waddington applied statistics and observed that scheduled preventive maintenance at very intense cycles was harmful, increasing the frequency of failures after the interventions. As with surgery, maintenance had to be performed no more than necessary otherwise risking reducing safety and reliability. The proposed solution was to increase the time interval between scheduled maintenance cycles and to eliminate all preventive maintenance activities that could not be proven effective. 

The safety of a ship is a matter of great responsability and commitment. Each risk must be evaluated

Work with us; join our team. You will acquire new knowledge and Mozzanica will gain new energies, abilities and new perspectives, yours.

SICUREZZA 2019
International Security & Fire Exibition
Fiera Milano (Rho)

VI ASPETTIAMO AL NOSTRO STAND T02 PADIGLIONE N°5

The Frenchman Alexis-Marie de Rochon and the Italian Marsilio Landriani had noticed, in the second half of the eighteenth century, that not all the components of light, which Newton's prism had decomposed a hundred years earlier, carried the same amount of heat but it took almost another century before William Herschel provided a systematic explanation to the phenomenon. Herschel was looking for a way to observe the sun through a telescope, experimenting with filters - coloured glass - and when he moved the thermometer he was using to measure the heat of different regions of the visible spectrum, in the dark region beyond the red end of the spectrum, he discovered that the heat, instead of decreasing, continued to increase. 

The German musician who had emigrated to the England of George III and the self-taught astronomer, Herschel, to whom we owe the discovery of Uranus and, following his appointment as the royal astronomer, made a number of very important contributions in the description of the Milky Way; in fact he had just discovered infra-red (which he called "thermometric spectrum"). It might be assumed that thermography found its origins here. In reality, stressing the concept a little, the first uses of the heat emitted by a body - to understand how this was working - date back to ancient Egypt; already in 400 BC, doctors used to spread a thin layer of mud over a patient's body and would then observe the different drying rates.

From doctors in the shadow of the pyramids to the discovery of Hershel, not only were the measurement techniques refined, but also the diagnostic capacity, managing to relate the heat detected to the cause of the heat itself. The first half of the twentieth century saw noticeable improvements in infra-red imaging thanks to the introduction of infra-red-sensitive photographic films. During the Second World War and the Korean War infra-red was used for a variety of military applications, such as detecting troop movements. Companies such as Texas Instruments, Hughes Aircraft and Honeywell developed detectors for the US military, but these were extremely expensive. 

Complex projects, specific environments, high demands, unexpected events, technicians to be coordinated…
For all above-mentioned just one interlocutor: Mozzanica.

Mozzanica has created over 900 systems, 1,000 maintenance systems and has had installed 30,000 fire extinguishers, 8000 hydrants and 5,000 doors. In addition, it boasts a fleet of mobile workshop units with 17 technicians available 24 hours a day, 4 operating branches and coverage across the national territory.

A pump creates a pressure difference between the outgoing and incoming flows; if this difference - known as prevalence - is proportional to the thrust that the pump imparts to the fluid and therefore to the energy used for this work, it is clear that the greater the flow rate, or the quantity of fluid on which to distribute the effort, the lower the head. The correlation between flow rate and head can be represented in a graph in which the heads are placed in ordinate and the abscissa in flow; keeping the pump rotation speed constant, for each flow rate value, the head has values​which, when combined, represent a curve, called the characteristic curve.

The ideal curve of a pump for a fire extinguishing system should be as flat as possible, i.e. a situation in which the head remains relatively insensitive to changes in flow rate. The reason is easy to understand when considering the fact that the supply request, during the operation of a fire extinguishing system, can vary significantly - for example, depending on how many sprinkler heads open - and this cannot happen at the expense of pressure and of the quantity of water that is supplied, which could result in an unpredictable action on the flames (the flow rate and pressure required by the fire system must be guaranteed even when the water supply is at its minimum level). Although the pump operates along all the points of the curve just described, there is an area in which the efficiency - that is, the ratio between the power made available and the power usefully employed to carry out the work of pushing the fluid - is maximum.

There, the hydraulic forces inside the pump balance. Imbalanced forces can cause the pump shaft to bend or flex. Some factors, in fact, such as the degree of opening of valves along the pipes, the increase in the roughness of the pipeline, the variation of the pressure in the tank or the level of the liquid in the case of an open tank, etc., can cause variations in the operating point. The pump rotation speed (the shape of the characteristic curve essentially depends on the type of impeller) and the deposits in the pipes can also affect the pump operating point.

The cause and effect of an imbalanced pump are also the cavitation phenomena - dependent on the energy that the liquid must have in the inlet section of the impeller, to continue its journey inside the impeller itself. In case of an overly low discharge pressure, bubbles formed by the gases dissolved in the water can be released, creating cavities in the liquid. These gases, if dragged through the pump, can reach areas of greater pressure, undergoing condensation/dissolving phenomena with energy release.

The gas particles implode and create micro-jets against the pump walls. The damage that phenomena of this type can cause is the fall in the characteristic curve of flow-rate and head of the pump which can result in non-priming of sufficient liquid. The vibrations transmitted to the pump and from this to the piping can exceed the structural resistance of the system (wear of the bearings and thrust bearing, with consequent breaking of the motor shaft and of the impeller) or can wear it (causing corrosive phenomena against blades and impeller discs, of the shaft liner and other parts of the pump). Such damage increases the inefficiency of the pump and the problems can self-propagate until the pump is no longer usable.

Water temperature, altitude and pressure drops created by suction butterfly valves, curves and flow direction changes are variables that affect the delivery flow characteristics and with respect to which an incorrect system calibration can be derived from the analysis of pump performance curves. For this type of analysis, a volumetric ultrasonic flow meter is used. This is a non-invasive, ultrasonic investigation technique. Each fluid has its own characteristic speed with which sound propagates inside it.

By applying transducers to the outside of the duct where the fluid passes, and noting their relative position, an ultrasound train is emitted which passes between the two points. The path that the sound takes depends on the position of the sound input points, the material and the geometric characteristics of the duct into which the fluid passes, the type and density of the fluid, all known variables upstream. The transit time also depends on the direction of the flow and its speed, variables that make it possible to derive the characteristic curve.

Machining and assembly faults, the corrosive phenomena of cavitation or slag accumulation, but also the simple construction tolerances of the individual elements, cause rotating machines to lose balance.

The first symptoms of this are vibrations and noise; the analysis of these "markers" in the case of a fire pump, during its operation, can tell a lot about its performance and condition and the coupling with the motor. Vibrations begin before overheating occurs critically, noises betray inefficient consumption and impurities of lubricants.

Typically, noises and vibrations can be related to fluid passing through the pump, the mechanical parts or the vibration of the pump structure itself (generally much less energetic than the first two types).

The first type of vibration is generally attributable to cavitation phenomena; the rapid vaporisation and condensation of fluids, in areas of abnormally low pressure, create micro-bubbles that collapse "shooting" very high pressure microjets onto the pump body. Friction and turbulence of the fluid reduce efficiency and the microjets, added together, can cause extremely harmful vibrations that can lead to misalignment of the shafts or wear of the bearings as well as problems in the supports and bearing parts of the pump body, of the bases, fatigue of the materials with consequent breakages, etc.

Fortunately, these phenomena leave a clearly detectable acoustic signature which allows a maintenance engineer to intervene early.

Even sudden changes in fluid speed (think of the starting of a fire alarm system) can create vibrations, noises and consequently harmful stresses to the components of the system. Varying suddenly the inertia of a fluid, which is not particularly compressible (sudden stops or flow starts, sudden changes of direction) can create pressure peaks that exceed the structural resistances of gaskets, membranes, valves, etc. or that, if repeated, can wear them out prematurely. In this case also, the acoustic investigation can detect these phenomena or analyse them with an appropriate level of detail.

To conclude, vibrations that individually might be negligible can mutually cancel each other out but also, more dangerously, enter into resonance and accumulate. The overlapping of

vibrational frequencies, for example, generates the so-called beat, detectable as a rhythmic variation of the volume - becoming exponentially more harmful.

It is therefore evident that it is not enough to measure the level of the vibrations and instead a thorough analysis of the spectrum is necessary. Vibrational analysis is a very broad and widely standardised non-destructive field of investigation, both from the point of view of the equipment necessary for the analysis, and for the modes (choice of reading points, acceptance criteria as well as acceptable vibration levels set for the various rotating machines, residual imbalance) and finally for the specific skills of the person performing the measurement.

Keeping safety on board always efficient

Pump and motor misalignment is one of the main causes of breakage and premature wear of bearings, joints and seals and produces excessive vibrations, noise and increases in coupling temperature.

Misalignment is considered to be the cause of a percentage that is between half and two thirds of the failures of the rotating equipment.

From the loosening or breaking of the foundation and coupling bolts, these are a prelude to greater damage such as the premature failure of gaskets and even of the shaft

Alignment of the motor pump is essential because it minimises the misalignment forces acting on the bearings and the seals of the gaskets, minimises the wear of the joint and in addition lengthening the life of the components. Increasing of the time between failures and reducing vibrations also has benefits in terms of efficiency, reducing energy costs.

Larger motors are usually coupled directly to their loads with rigid or flexible couplings; the former do not compensate for misalignment of the motor while the flexible ones tolerate small amounts of misalignment and can also partially reduce the vibrations transmitted from one appliance to another.

However, coupling flexibility is not the solution to misalignment as it transmits stresses to the motor and to the bearings and/or to the pipes connected downstream of the motor.

The alignment of the motor pump involves re-alignment of the central lines of the shafts between a motor and a pump, through the use of lifting bolts or via lever bars, hammers or other tools.

For correct alignment, however, it is necessary to use alignment tools such as selection indicators or laser alignment tools. 

The causes of misalignment include sedimentation of the base after prolonged operation, insufficient tightening of the bolts or installation errors.

The diesel engine coupled to a fire-fighting push unit must be able to operate continuously at full load with power compliant with precise standards (ISO 3046) even in unfavourable environmental conditions (the standard also provides for a temperature of 5°C in the engine room). For this to happen not only must the motor be appropriately designed and installed but it must also undergo punctual and professional maintenance.

The UNI EN 12845 standard distinguishes the maintenance activities to be carried out by the operator of the fire prevention system from those to be entrusted to competent and qualified technicians. Among the latter, a prominent place is undoubtedly reserved to periodic maintenance of the diesel engines associated with the pumps.

In fact the pumps must be driven by motors (electric or diesel) that are capable of supplying the pumps with the power required for the various characteristic curves.

Firstly, the technician must make sure that the engine is clean and dry (the rooms where the thrust units are housed may be underground, at risk of moisture condensation or even flooding). For a diesel engine to work, on request, this must obviously have sufficient fuel in the tank to guarantee sufficient operating time (the duration of the water supplies depends on the level of risk - light, ordinary or high risk). Fuel storage is in fact regulated both with regard to the structural characteristics - tank, pipes, etc. - and with reference to the installation conditions and the level verification instruments. Particular attention must be paid to all these aspects during maintenance.

The lubricating liquids must retain suitable quality and quantity characteristics, as must the circuits that guarantee their recirculation. Similarly the cooling circuits and liquids must be checked and guaranteed to ensure compatibility with operation of the engine. For this purpose, careful maintenance is not limited to checking that the engine is maintained but also involves the conditions of the premises in which it will operate, which may be a discriminating factor on the cooling capacity; although this characteristic is a design choice it is possible that subsequent interventions may alter the design conditions, altering the envisaged cooling capacity. In some cases, a system of forced air extraction from the engine rooms could be provided; this system therefore becomes a critical element to be placed under adequate maintenance.

The maintenance technician also checks the condition of the battery electrolyte, the charging circuit and the general correct operation.

According to a replacement program, the technician checks and replaces the oil, diesel and air filters. and inserts a new filter cartridge, if necessary. All the tests performed must be able to be recorded and compared, from year to year.

As this is a highly reliable system but in any case subject to malfunctions, a redundant logic must be provided which protects against any missed start-up of the diesel engine and therefore, as part of the maintenance program, a failure test must also be provided to verify that the alarm and back-up systems intervene correctly.

During operation the engine must be able to release the exhaust fumes; the ducts intended for this purpose must comply with precise construction and installation standards but must also maintain, over time, the characteristics of adequacy (for example, the exhaust terminals must be appropriately protected against atmospheric events and equipped with a protection grid and must comply with precise distances from the external reference plane and from windows and doors. It is not unthinkable that, especially in an industrial context in frequent plant reorganisation, the conditions around the pump rooms may change; a competent maintenance person knows how to detect these possible variations.