Maintenance in air conditioning systems

The lack of a culture of prevention, care and cleanliness, inexperience in design, inadequate facilities, maintenance failures, little or no training of technicians, improvisation of trade and negligent acts in their ways of use prevent the proper functioning and long life of air conditioning systems

The growing development of data centers in Mexico and their increase in energy consumption pose a major challenge for air conditioning manufacturers, for whom the biggest challenge is to find efficient cooling solutions in high-density data centers.

Making the guarantees valid would not be necessary if the operating specifications of the air conditioning systems were met in a timely manner. After the relevance and accuracy of the engineering design, one of the most important is to provide maintenance service in a timely manner. To this is added to address a series of problems of a human nature: little or no training of some technicians, lack of updating in new procedures, as well as possible acts of negligence on the part of employees who do not know how to take care of the equipment.

Some of the most common problems have their origin in the culture of non-prevention, as José Antonio Pérez, head of the Supervision Department of the total maintenance company, points out in an interview.

"Many times, employees themselves damage equipment, wet engines or burn them. We have seen it during the maintenance service to cold rooms, when checking bearings, bushings and bearings. Sometimes, they leave the doors open or are blocked by excess ice, and this prevents air circulation. Particularly, in industrial kitchens, where there is a lot of human traffic, equipment gets dirty much faster and usually the kitchen staff does not have basic knowledge for a good use of the equipment."

In his opinion, the responsibility for providing maintenance services is always relative. "It depends on the people. When one deals with the direct user there is no major problem because he does take care of the equipment and takes efficient measures. On the other hand, when we have dealt with restaurant chains, we realize that the staff does not really care, even damaging the equipment on purpose.

"A couple of years ago we were working with a well-known hamburger chain and we realized that, which makes me think that, as an induction, they should have an employee training unit. However, there is none; that is, in reality no one knows and no one gets involved. They don't know anything about anything."

The maintenance of the equipment is not a mere protocol between user and manufacturer. Any heating, air conditioning and ventilation system is subject to periodic reviews and preventive, corrective or predictive services, as the case may be.

"With the preventive service, air conditioning or refrigeration equipment is prevented from being out of service. Basically, during our visit we checked the mechanical part (motors, blades, bearings) and the electrical part (elevators, wiring). In the corrective we change some spare parts that have concluded their useful life; we correct that, repair and restart the equipment", specifies José Antonio Pérez, who adds: "In an air conditioning, cooling, cooling or conservation system, one of the aspects that we take care of the most is to avoid a malfunction of the fans, whether evaporators or condensers, because from there other problems are generated, such as excessive freezing. That is what you have to take care of: that the engines are not close to the range that comes out of good operation. We check the bearings and know that cleaning the coils and exchangers is indispensable."

To make a guarantee effective, the expert suggests hiring a maintenance service at the same time as the purchase of the equipment. "In the end, it comes out cheaper because it doesn't result in severe damage." The number of services that will be performed to the air conditioning systems will depend on where they are installed, the hours they are used per week or if the place where they operate is a critical environment, with a lot of dust, too much humidity or tartar, as it happens on the coast.

Finally, says Antonio Pérez, the managers of the teams are often the employees. "They know if there was an electric shock or how this or that problem originated. During our inspection visits we check what is wrong and this is how we also detect hidden defects that we will have to repair."

Extending the useful life of the equipment and keeping the operating mechanism in optimal conditions would be ideal. "In this lies the importance of performing constant maintenance services to air conditioning and refrigeration equipment, or to those that provide some function, electrical or mechanical. This is a very important point; the next thing is to obtain the maximum benefit and performance, in addition to optimizing the costs of corrective actions, "suggests the engineer Luis Eduardo Roldán, director of Fri-Rold.

"In the case of air conditioning systems, it is imperative to achieve a healthier climate. Always, in the area of the evaporator contaminants are concentrated, such as dust, and that is transmitted to the areas to be heated. Remember that there are bacteria that die with temperature and others that reproduce at higher or lower temperatures. In some businesses and homes, they are choosing to install additional systems to control bacteria and make the air cleaner, such as ozonators. Some teams already have them integrated."

Regarding the change of filters, the frequency of replacement will depend on the type of filters with which the system is working. "There are bacteriological equipment in a new area and the filters need to be changed every four to six months; in the event that they have mesh filters (only for particle retention), we recommend performing three maintenances per year."

Engineer Roldán points out that it is not common for mesh filters to be changed, they are only washed. "Maintenance times depend on the areas where the equipment is installed. There are very clean areas where the first maintenance can be done every six months and the subsequent ones every year; do not forget that this will depend on the conditions in which the teams are found".

"Of course, abuse is commonplace. This happens because sometimes, during maintenance, users are present and see what is done and how it is done. We leave them; that is, it is not about deceiving anyone, but about doing a good job, and if they are present they can realize the quality of the work. However, in houses where domestic service is available, many times, to save the cost of maintenance, they themselves indicate to their staff what to do: 'raise it there, remove the filters, cut it with a brush'. Anyway... it has happened that they buy canisters of compressed air and they do the work alone."

Maintenance work ensures that the equipment is kept in the best condition and operates efficiently for a long time

Once a report of temperature failures has been received and the equipment is checked, it turns out that the staff finds the equipment very clean on the outside and totally full of dust inside. "We disassembled and found the turbines full of dust. The fact that untrained people want or try to maintain equipment is a sure sign of breakdown. There are sensor bulbs that at a certain moment we have seen that set them aside or are not cleaned correctly, and produce a false reading. Those are the results: temperature alteration."

Specialist in the management of air conditioning for buildings, industrial refrigeration and the area of rapid freezing, considers it essential to offer training to those responsible for the handling of the equipment.

"On many occasions they move the control and deprogram the system. And since they think that making a call can generate some cost, they do not call; in this way they omit the maintenance service. We always explain to the end users what the scope of the warranty is, the rights they have when contracting the installation service and the maintenance costs, along with a delivery letter, where we specify everything in writing."

For engineer Joel Rubio Márquez, from the company Diseño Ingeniería y Mantenimiento Industrial, preventive maintenance is essential for air conditioning systems to work efficiently. "These devices operate by heat transfer mechanisms, mainly in the evaporation and condensation coils. The accumulation of dirt significantly decreases caloric transfer. Cleaning allows them to operate at their maximum efficiency by reducing electricity consumption."

He comments that "within the preventive maintenance service, refrigerant leaks are corrected in threaded joints or service valves. This operation is especially important because there is no refrigerant that does not affect the ozone layer. Therefore, it is essential to eliminate leaks.

"The preventive service helps to verify and correct, also, the operation of controls, elevators, contactors, transformers, and eliminate false contacts that decrease the life of the equipment and increase the consumption of electrical energy. Maintenance work eliminates vibrations, lubricates bearings, bad odors, disinfects evaporation coils, cleans and unclogs drains and, in general, keeps the equipment operating efficiently for much longer."

Maintenance periods depend on the use of the equipment

• Comfort air conditioning for residential or commercial use. It is recommended to give service every three months

• Air conditioning for hospitals. Requires monthly, semi-annual and annual maintenance routines

• Air conditioning for computer sites. Due to its intensive use, it requires monthly maintenance

• Conservation or freezing chambers. Due to its intensive use it is convenient to do monthly maintenance

"On many occasions, the user complains because the system works all the time and does not 'cool'; then, we went to check the equipment and found it completely dirty, with the separation between fins of the coils filled with earth and the evaporator frozen by the low air flow due to the clogging of earth. Once the service is concluded and with the equipment working at full load, the user who complained that the equipment did not cool is surprised at the amount of 'cold' it is giving."

Engineer Rubio emphasizes that periodic maintenance is essential for equipment that has filter banks, since when saturated they restrict the flow of air to the evaporation coil and, when they are oversaturated, they can throw the dirt that they are supposed to retain.

"We must remember that filters retain everything from dust and particles to microorganisms, in the case of HEPA. That is why it is important to take basic safety measures when removing them: in addition to safety glasses and gloves, you have to use a mask for fine powders."

Of course, there are extreme cases: "We had the opportunity to review a piece of equipment that had the evaporation coil frozen and presented a return of liquid refrigerant to the compressor (in this case it was scroll); it was turned into a real block of ice, except for the head. The bag filter and HEPA filter were completely blocked, so not enough airflow reached the evaporation coil. This caused freezing and completely blocked the airflow, which caused the refrigerant not to evaporate and only a fraction in liquid state reached the compressor.

"On some occasions, we have found minisplit equipment in multi-story buildings that, due to distance limitations, the condensers are installed in poorly ventilated adapted rooms, which causes the equipment to be protected by high pressure. The required airflow is in the order of 750 CFM per ton of cooling. Because of this, it has been necessary to install a ventilation system that provides that airflow.

"Currently, we are starting to see variable refrigerant volume (VRV) equipment, even in simple minisplit systems, which allow us to have longer distances between condenser and evaporator, up to 50 meters vertically and more than 100 meters horizontally. These systems already work with the refrigerant R-410A, which, due to its high pressure, must have a more careful handling, especially having manifolds and using hoses specified for the refrigerant."

Types of maintenance

The engineer Rodrigo de Bengoechea, Professor of the Faculty of Engineering of the UNAM, mentions that the maintenance of any equipment or system should be understood as the series of activities necessary to ensure that they operate under the best possible conditions; it is in itself to optimize the operation of a computer or system.

Maintenance should be divided into several categories:

1. Routine or preventive

If the computer or system is considered to be functioning normally, the following operations will be performed:

1.1. Cleaning of equipment and parts. The condenser and evaporator must be perfectly clean to ensure good heat transfer and avoid contamination and overheating in the equipment

1.2. Lubrication to the mechanisms that require it: bearings, chumaceras, bushings

1.3. Review and change of filters in package units, air handlers, fan & coils, minisplits. Dirty or poor filters hinder airflow and decrease equipment efficiency

1.4. Filter dehydrator. Normally no importance is given to the dehydrator in air conditioning equipment; it is often clogged by dirt inside the system and is very easy to check: if it is "cold" it is covered; you must have the temperature of the liquid line when operating normally. If it is clogged, it will need to be replaced (you have to know how to do it; it is not so easy)

1.5. Review of amperage and voltage of compressors, pumps and fans. it is important to check the "tightening" of contactors and starters, as they often loosen and cause false connections

1.6. Work log. It is very important that you keep a log of the maintenance work done on the equipment, as it will be the history of the changes and repairs made. If no operation was performed, it should also be noted

2. Corrective

At some point it will be necessary to carry out major repairs, changes of engine, compressor and fan blades. These changes will stop the operation of the equipment or system. It is necessary to foresee the parts or spare parts that will be required so that the strike is in the shortest possible time. You can not have in the maintenance workshop all the parts, but the most critical or frequent: blades, filters, refrigerant, bearings

Some parts are not repairable by maintenance personnel; for example, semi-hermetic compressors and motors. A specialized workshop should be used to repair them; depending on the place, it will be necessary to have a compressor, a motor and valves in perfect condition to make a change

3. Predictive

From a careful analysis of the logs of the equipment it is possible to predict when it will be necessary to replace a component and thus program it to obtain the spare parts and perform it at the most opportune moment

Incipient failure is usually very easy to determine. It is the point of warning that the equipment will fail in a considerably short time. Examples: metal-metal noise in car ballasts, squeaking of bands in generator, water pump and excessive noise in marksmanship.

Preserving human life

The proper functioning of air conditioning systems not only responds to questions of comfort, health and well-being of people who work in offices, hotels, restaurants or hospitals, or those who live in air-conditioned buildings. Specialized research units, for example, require exceptionally precise designs and optimal facilities. There can be no error here. The slightest margin could lead to local infections, even a pandemic, and lose your life.

Biosecurity is a matter of life and death. Working in biocontainment work does not only concern excellent engineering designs and maintenance services, it implies performing practices as delicate as preventing the dissemination in the environment of highly infectious agents, which must remain in total secrecy.

This is attested by biologist Gonzalo Salgado, researcher at the National Institute of Respiratory Diseases (INER) of the Center for Research in Infectious Diseases (CIENI). With more than a decade of experience in biosecurity, design and supervision of work, equipment, validation, maintenance and setting of biocontainment laboratories, he has specialized in the management of infectious microorganisms.

"The first biosafety laboratory was opened at CIENI in 2004, with many design, construction and equipment errors. This is important to say, because throughout these years we have worked to solve them. To this day we have seven level 2 biosecurity laboratories and one level 3 biosecurity laboratory, which allow us to manipulate infectious agents of respiratory transmission."

Professor of the workshop on HIV and pathogenesis of AIDS of the degree in Biology, in the Faculty of Sciences of the National Autonomous University of Mexico, Salgado warns about the risk of transmitting diseases to laboratory personnel, maintenance or those who are in constant contact with the operation of the property when the specific parameters of construction and management of facilities and equipment are not met, including maintenance service.

"Laboratory-associated deaths are well documented in the United States. From this derives the need to propose international policies that promote changes in the design of research laboratories and special rooms for patients with contagious diseases or for patients who must be protected from normal environmental conditions, such as AIDS patients. "

According to the specialist, the levels of biosecurity will depend on the danger of the agent and the type of transmission in question – whether by management of reservoirs, by respiratory or sexual route – which will determine the type of infrastructure required.

"Those of us who are dedicated to biosecurity are at constant risk, obviously because we are in daily contact with pathological agents and laboratory animals. For this reason, infrastructure is essential so that the rest of the risk factors are perfectly controlled."

The specific characteristics of pathological agents will make it possible to delimit laboratory practices and techniques, personal protective equipment and infrastructure. "All this does not remain only in the infrastructure; it's just the first part. It's one thing to have a lab and another thing entirely to operate it. Our experience tells us that air conditioning is one of the essential issues that must be addressed, as it is one of the factors that allow human life to be preserved."

Type A biologist of INER, Gonzalo Salgado has been operating the laboratory of this research center for nine years. "I can say that, after all this time, the biggest challenge has been to achieve continuous operation of the air conditioning system. At this point the experience and capacity of the engineers is very important. They are the first to know what they are working for and understand the implications of a biosafety laboratory; that is, they are not exempt from being infected by everything we handle there.

"Of course, the type of maintenance must be highly specialized. Engineers, as well as people designated for the service, will need to have a lot of knowledge and training in this regard. It would be deadly to attempt improvised procedures. It should not be lost sight that the operational issues of a containment laboratory are based on these characteristics and before taking projects of this type engineers should read, inform and educate themselves in each and every one of the issues that biosecurity includes. There are a lot of excellent courses abroad, but there are already very good ones in Mexico."

The expert defines biocontainment as the action of preventing the agent being worked with within the laboratory from leaving. "The amount of infectious a patient can have, compared to what we handle in the lab, is radically low. We handle strains of HIV that are 10,000 times more pathogenic and can transmit the disease more quickly than by contagion from an infected individual."

According to the Biosafety Manual, developed by the World Health Organization (WHO), biocontainment applies specifically to biosafety levels 3 and 4.

"Level 1 is considered basic; it is a teaching laboratory similar to that of high school. Level 2 are laboratories more aimed at diagnosis. In level 3 laboratories, specialized diagnoses are made for diseases that are a little dangerous and for which a cure is needed; especially local diseases, such as Ebola. Level 4 are units of dangerous pathogens; here, the practices are increasing their degree of dangerousness. Also, protective equipment varies at each of these levels."

Within the same laboratory there are levels of containment that the equipment must have. Most of the work is carried out in the biosafety booths and in incubators where there are special controlled environments.

If it is taken into consideration that biosecurity hoods are the main site where these agents are handled, "laminal flow hoods are not the same as the hoods of conventional air conditioning systems. We use centrifuges, which help us drive the components of liquids. Most of this equipment generates aerosols and, if an accident occurs, they can spread throughout the interior of the laboratory if they do not have the right conditions. In addition, alternate sites are required to store instruments and work materials.

"The maintenance of biosecurity hoods is not carried out precisely inside, because, when entering directly into the laboratory, the lives of the personnel in charge of carrying it out would be put at risk. It is convenient, therefore, to have an emergency maintenance zone and another specialized in waste, interacting as complementary areas."

What Gonzalo establishes as a rule for a biosafety laboratory is that the injection system must be independent of the extraction system. From his experience, he assures that there can be no recirculation in the air handlers. "Some models are injection with filtration," he says.

There should never be the presence of toxins. In some areas, the air entering the laboratory is clean because it has passed through HEPA filters; this air is then extracted through a separate fan with directional reflux.

"The ventilation system should be insulated and used only for the laboratory; it has to be a unique laboratory system and necessarily use high-efficiency HEPA filters designed to remove particles up to 0.3 microns and capture 99.2 percent of particles. It is advisable to change these filters every year for the decontamination of the laboratory and operations.

"You always have to control the mechanical and electronic systems. The system has to be controlled through ducts and the airflow must be direct: from clean areas (where we change our street clothes) to dirty areas (where we are handling the agent). Before entering the laboratory, we will have to verify that the pressure marked by the pressure gauge is negative."

The important thing in biosecurity laboratories is that most of the spaces where respiratory transmission agents are handled must have a bag in-bag out system. The intention is to distribute the infectious particles from the volume of air handled by the systems. Not all biosafety laboratories require this system; only the spaces where we work with infectious agents. HIV research is one example. The design of the laboratory will depend on the type of research being done; therefore, there can be no generic laboratories. They have to be laboratories prepared for any mishap, including accidents at work.

"All this changed my perspective of what the design of a laboratory is; for example, the number of air change times per hour will reflect the volume of air removed in percentage. Approximately 90 percent of the air is removed within a room in 12 minutes with two air changes per hour; 99.9 percent is removed in 35 minutes with two air changes per hour.

"From the moment of drawing the design, it is very important to plan how the operation and maintenance processes will be carried out, and what will be done so that the balancing can be carried out automatically and continuously; that is, to conserve the negative pressure that falls continuously by voltage wires. As there is no emergency plant, temperature control must be maintained."

Transforming ideas into reality

If one considers one of the principles of engineering: to transform ideas into reality, the pertinent thing in these times is to conceive engineering designs that give optimal response to the current conditions of environmental temperature. A good executive design should include the management of each of the project requirements.

"The times in which the Latin American Tower was built are no longer the same," says engineer Rodrigo Ruiz Hinojosa, who directs the company Mereti in Puebla, dedicated to the sale of spare parts and equipment for air conditioning and refrigeration systems. "If we look at the building, the window airs peek out of the façade because when the Tower was built it was never thought that so many air conditioning systems would be needed. Today, air conditioning is the first thing to think about; that is, in the comfort of people who work or live in large buildings."

Despite the advance of engineering and the high degree of technical specialization, in some localities, the members that make up the productive sector in the Mexican Republic still lack optimal maintenance services for their air conditioning and refrigeration equipment. Therefore, for them it is not possible to provide an excellent state of conservation to perishable products.

Flowers, vegetables, legumes, meat and dairy need certain conditions of humidity and cold for their conservation to be optimal; all the more so, those of export quality. However, this was not what Pedro Viveros Perea, from the sales area of Grupo Mereti, observed.

"Days before the celebration of Muertos, several colleagues of the company and I traveled to Chiapas to a livestock expo and we realized that it is a totally discovered market. We look at the needs of users in that area and notice that they are very neglected. Most producers and ranchers lack advice on refrigeration chambers and air conditioning. Generally, none of them are supported with engineering projects according to the current needs of technology, hygiene and care of their products. Chiapas is a more or less tropical area, and there is a lot of fruit that needs to be refrigerated immediately after being harvested."

A serious problem pointed out by Pedro Viveros is the presence of a large number of people dedicated to offering maintenance services, "specialization work" in refrigeration chambers without a hint of specialization. Those who offer this service are technicians who do not have training and do not follow an adequate procedure for the installation of cameras that are really necessary and provide the exact intensity of cold that the products require.

"There is exotic fruit that needs to be very well refrigerated. Worst of all, many producers are extremely disoriented, they are not aware that their products are not receiving proper care. They usually rent the famous termokin: trailer boxes with cooling systems. The problem is that when meat or fruit is transported for sale it already goes to a point very close to decomposition.

"The treatment they give when harvesting their fruit or when they kill the cattle is not adequate. I would say that meat remains out of refrigeration for a long time. All this happens when you do not have good commercial and engineering advice on projects, whether refrigeration or air conditioning. Under those circumstances, there is always a risk of spoiling the business."

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