Along with air, various pollutants move along the channels of ventilation systems - dust, grease, soot, water vapor and other liquids. Most of the hazards are captured by filters, but some are deposited on the inner walls of the ducts and on the working surfaces of the equipment. In order to prevent the accumulation of pollutants, ventilation is cleaned with subsequent disinfection. The technology of work and the choice of detergents depends on the type of ventilated space.
The frequency of treatment activities
According to the requirements of sanitary standards, ventilation systems are cleaned according to the following schedules:
- offices, shopping centers and administrative buildings - annual cleaning of channels;
- production facilities - at least 2 times a year;
- healthcare and public catering organizations - once every 3 months (quarter);
- kindergartens, schools and other educational institutions - twice a year.
Note. Regulatory documents of the countries of the former USSR that regulate the procedure and frequency of ventilation maintenance differ little. Duct cleaning regulations are almost the same.
Regarding the frequency of treatment works in residential apartment buildings and private cottages, the standards do not impose strict requirements. But the draft check in chimneys and vertical shafts should be carried out by a specialized organization three times a year, which is not done in practice.
For owners of apartments and private houses, we recommend that you clean the canals annually, a maximum of 1 time in 2 years. Moreover, the outlet pipe, fan and hood hood without any problems served by their own hands.
Problems of unclean ventilation ducts
Ignoring the fire and sanitary requirements for the technical condition of ventilation systems leads to the following consequences:
- The accumulated dust is easily ignited by the slightest spark. Through a network of ducts, the flame can spread to several rooms.
- It is more difficult to set fire to fat, vegetable oil and soot, but with sufficient heat, the listed pollutants ignite and give off a lot of heat. Quenching is quite difficult.
- From fat and other deposits, increased resistance to air flow is created due to increased friction against the channel walls. The performance of the ventilation system is reduced.
- The accumulation of grease and soot can damage axial and duct fans, whose motors are in contact with the air flow. The reason is clogging and overheating of the windings.
- Inside the sewage layer covering the walls of the ducts, mold forms and various pathogens multiply.
In practice, exhaust ducts of apartment buildings and private houses are serviced quite rarely. It must be admitted that the risk of fire inside natural ventilation systems arranged in the thickness of concrete or brick walls is extremely low. But moistened dust and greasy deposits in any case worsen the natural draft in the pipes.
The ventilation systems of industrial facilities are cleaned more or less regularly, which is facilitated by inspections of inspecting services. In private cottages, where modern forced-air and exhaust ventilation with mechanical motivation is designed, the frequency and quality of service depends entirely on the owners.
Methods for removing contaminants
At the moment, ventilation and air conditioning systems are cleaned in three ways:
- mechanical removal of dirty plaque from vertical channels;
- dry air duct cleaning;
- combined foam washing.
Reference.Ventilation systems of hospitals, schools, offices and food enterprises are subject to mandatory disinfection. Antiseptic treatment is carried out in the process or after cleansing the walls of the channels.
The first option is practiced for punching the vertical shafts of multi-storey buildings. Climbing to the roof, the performer lowers a kettlebell with a metal ruff or brush inside the duct. A layer of dirt and grease is torn off from the brick (concrete) walls mechanically, waste is scattered in the mine’s “pocket” or is scrapped in the apartment through the opening.
The remaining two options are more effective because they are implemented using modern technology. The equipment allows you to work on industrial air ducts of any configuration and various laying methods. Completely disassemble ventilation is not required.
Applicable tools and equipment
We offer to consider a set of treatment equipment from the famous Finnish manufacturer Pressovac:
- video camera for internal inspection of air ducts;
- brushing machine with electric or pneumatic drive;
- vacuum installation;
- filtering unit;
- compressor (used in conjunction with a pneumatic brushing machine);
- spray bottle for disinfection of the ventilation system.
The brush device is a flexible shaft 6–40 meters long, connected to an electric motor or pneumatic drive. The rotating shaft is placed inside a strong shell; a brush of the required shape is fixed at the end.
The vacuum unit is a powerful fan with a capacity of up to 15,000 m³ / h, sucking debris from the channel. Further, the flow is directed to a filtering machine, where particles of pollutants are captured.
In addition to the main equipment, the kit includes accessories:
- brushes of various shapes and stiffness;
- corrugated pipes connecting units with air ducts;
- caps for lateral branches of ventilation ducts;
- vacuum discs used in circular pipes;
- shaped elements and inspection hatches for additional insertions into the channels.
Information to homeowners. In addition to the listed accessories, the company sells 3–6 m long mini-shafts plus brushes for small section air ducts. The device is connected to a conventional electric drill, which allows you to independently clean the ventilation in apartments and private houses.
Detergents and disinfectants
Professional cleaning of air ducts from fat and other harmful deposits is carried out using specialized chemicals:
- aggressive alkaline compositions for washing channels with a foam method;
- neutral powder blast remover with soft blasting.
Explanation. Blasting is a procedure similar to sandblasting of pollutants. Only instead of sand, finely dispersed chemical powders are used that do not damage the zinc coating of the ventilation duct. The technology is effective, but quite expensive.
Alkaline products are sprayed inside the ducts in advance or in the process of purification. Under the influence of the reagent, fats and soot decompose, the precipitate is washed off with water.
The type and concentration of disinfectant antiseptics is selected according to the results of a study of samples (the so-called washings). The latter are taken at the stage of inspection or primary cleaning of the ducts and sent to the laboratory.
Technology for cleaning ventilation systems
At the first stage, a treatment plan is drawn up. We study the ventilation scheme, determine the connection points of the machines, the points of setting the plugs and the amount of installation work.
Note. In the process of servicing the ventilation system, you can not do without a partial disassembly and reassembly of the elements. Example: to connect the pipe from the vacuum pump, you need to remove the inspection hatch or disconnect the shaped part of the duct.If hatches are not available at the required points, the installers cut openings in the channels and put airtight covers.
In addition to air channels, the following ventilation elements are cleaned:
- receiving and exhaust devices - grilles, diffusers, umbrellas of local exhausts;
- fire retardant and non-return valves, adjusting dampers;
- heat exchangers for heaters, recuperators and central air conditioners;
- fan parts in contact with the air stream - impellers, turbines;
- grease filters designed for regeneration (recovery).
Equipment and ventilation are also cleaned externally. Cell, pocket and bag filters are completely replaced. Upon completion of work, the organization draws up an act approved by the customer.
The technological operation of dry cleaning the air duct network looks like this:
- The vacuum machine is connected by a hose to the main air line, usually next to the fan. Long collectors of large diameters are divided into sections of the estimated length, comparable with the performance of the machine.
- A second corrugated pipe connects the filter unit to the vacuum fan.
- Along the entire length of the serviced area, ventilation grilles are removed, branches of a smaller diameter are disconnected. The holes are tightly closed with plugs.
- The operator of the brushing machine, wearing a protective suit and respirator, extends the flexible shaft with the cleaning tool into the channel on the other hand. To remove fat, an alkaline reagent is pre-sprayed there.
- Both units are started and the duct is cleaned. Dust and soot removed from the walls by a rotating brush are sucked in by a vacuum unit. Dirty air is supplied through the pipe to the filter unit, which traps all particles.
- The operation is repeated in subsequent sections in the same way.
Note. If the ventilation system is correctly designed, you do not have to disconnect the air ducts. On the branches from the collector there will be dampers that can be covered.
Conclusion
It should be understood that work on cleaning and disinfection of ventilation and air conditioning systems is carried out only by specialized companies that have permits and trained personnel. Third-party brigades and private individuals are not allowed to service the ventilation networks of industrial and office buildings. In order not to interrupt production processes, the bulk of the work is performed in the evening or at night.