AERFERRISI

Impianti e ricambi per il riscaldamento e il condizionamento di ambienti

Impianti di termoventilazione per ospedali

Another sector with important applications of the Aerferrisi heating system is the sector relevant to hospitalization rooms and accessory rooms in hospitals. Hygienic and health needs require that single or multiple-bed wards are ventilated and at the same time heated with the appropriate air change. This air change must be perfected with air filtering and humidification, so that room conditions may lead to a state of wellbeing. Aerferrisi’s technical service has remarkable experience in devising solutions for these special systems, and will share it with any heat technicians who will ask for information. The starting principle is that the air circulating in the hospital units has to change constantly, without ever recurring to air recovery, which could negatively impact the healing process of patients; so, the starting principle is to heat with a total air change, using as a means for conveying heat the same air used for the renewal. The system’s functional scheme consists of delivering to the wards the air coming from the conditioner that has treated the air taken from outside, which has been filtered, heated to the right point, and humidified. The delivered air goes out partly through the imperfections of doors and windows (about 10%) and the rest goes back towards the corridor or entrance, where it will be collected by a proper air extractor and then expelled, having ventilated in the mean time the unhealthy rooms (bathrooms, laboratories, ward kitchens, etc.). By properly regulating the air volume let in by the conditioner and the volume of air expelled by the air extractor, a proper aerothermic balance can be established. We now want to address heat technicians about the methods of searching for system data and therefore choosing the right size of the machines, whose task will be to fully satisfy requirements. If we call:

Q=Cd / [( ti - ta ) x 0,3 ] = Cd / ( 7,5 - 10 )

the replacement calories are: Cr = Q x 0,3 x ( ta - te )

therefore the total calories will be: Ct = Cd + Cr

The inlet air conditioner will thus have the air flow (Q) and return the total calories (Ct) required by these formulas, while the air extractor will have to have an air flow of Qe = 0.9 Q, with a 10% expected air loss. By regulating the inlet volume of air in every room, the desired temperature conditions will be obtained. Therefore, it is good to use thermostatic vents, and better if they are inserted on the air expulsion from the wards; thus, the overpressure of the rooms compared to the outside will always be guaranteed, and this will avoid unpleasant draughts of external air. An example will clear this concept used by Aerferrisi in searching for the data for aerothermic elements. Let us consider a hospital unit consisting of a whole storey, in which there are 6 wards for multiple 6 bed hospitalization, and 2 bed wards; with other accessory rooms, the total volume to be treated is 2,000 cu m. The relevant Cd value is 40,000 cal/h:

Q = 40.000 / 7,5-10 = 4.000- 5.350 mc/h

if the external temperature is -5°C and the internal temperature is +20°C, the replacement calories are:

Cr = 4.000-5.350 x 0,3 x [( 20 - (- 5 )] = 30.000-40.000 and so the total calories will be Ct = 70-80.000.

The machine must therefore be able to have a maximum air flow of 5,350 cu m/h an a calories yield of 80,000 cal/h. The air extractor will have to have a maximum air flow of 4,800 cu m/h. In the case of single wards, these will be treated individually with the help of primary air delivery from the clinically established air change. This principle also applies to summer air conditioning. The given examples respectively represent the two possible solutions that are today repeated in the creation of systems in hospitals. Aerferrisi Technical Service is rich in experience, acquired in time through the realization of many applications.

TECHNICAL SHEET

Aerferrisi srl   Via Vittime di Bologna, 14 - 10156 Torino - Tel. 011/2740283 Fax 011/2740284   P.I. 00501690010   info@aerferrisi.com  www.aerferrisi.com