manuale_EMERITUS_4.0_(MULTI_LANGUAGE)

22 6 HYGIENE Great attention has been paid to this aspect in order to offer a product which can guarantee absolute reliability. The main aspects which set this product apart are: • The sprayed water has been carefully treated and purified. The formation of deposits and biofilm is excluded providing that the machines are correctly cleaned and maintained. The risk of bacterial contamination is therefore reduced to the minimum on condition that the plant is correctly operated • Water drag-out by airflow has been eliminated. The air, after passing over the surfaces of the exchanger, is expelled into the atmosphere by the fans. To obtain this result, a solution has been adopted which injects the water at the temperature of the mains supply upstream of the heat exchangers and checks in all operating conditions that the ratio of air quantity to water quantity is always greatly above the values of saturation. • Water supplied to the Spray system is drinking water and therefore by definition is not contaminated by bacteria (l egionella ,…) which could damage health. • Water in the ramps of the Spray system could, if the system is not used, heat up in the sun. Specific tests undertaken at the I stituto Zooprofilattico di Pavia (Italy) have demonstrated clearly that water treated in accordance with LU-VE specifications contains no proliferation of Legionella Pneumophila . • Special UV lamps which guarantee sterilization of the water have been installed in the complete system in order to avoid any bacterial contamination present in the supplied drinking water. • The adiabatic panels are supplied with water which is mains drinking water or water from the recovery tank; in either case, the water has not been stagnant and is in any case below 25°C (where Legionella bacteria are in active). The water which runs through the adiabatic panels in not recirculated. • Complete drainage of the entire system with time scheduling and setting selected by the user. Management of machine standstill and hygiene for sprayed dry coolers and condensers The VDI 2017-2 code of practice concerning hygienically sound operation necessitates the management of machine standstill for the spray system of the units, as follows: The management of machine standstill describes the provisions necessary to protect components of the system from stagnation and consequent hygiene risk. Particular attention is drawn to the circumstance where, from a hygiene point of view, it is preferable to rinse off components instead of draining the system completely. Draining exposes the system to the penetration of microbiological contaminants. With rinsing, the potential contamination is expelled before it is formed. In principle, there are two types of standstill, which are in any case treated in an identical manner in the LU-VE standstill management method: • interruption of operation: complete or partial rest of max. 4 weeks • standstill: uninterupted period of inaction of the system of more than 7 days. It is also necessary to take into account the treatment of the supplied water, given that the VDI 2047-2 code of practice contains the obligation that softening systems and the membrane must be regenerated or rinsed out after max. 3 days. As these systems are self- regenerating or rinsing through their own controller, it is not necessary to follow any special procedure, it is only necessary to guarantee the water and electricity supply. In this way the period for the management of machine standstill is defined and the procedures for the management of standstill must be carried out once every seven days minimum. The procedures differ for winter and summer operation. In winter operation it is necessary to drain all the components at risk of frost formation. In this case it is not possible to perform the complete rinsing out of the system. LU-VE recommends a temperature limit of 8°C. The annulment of winter operation (or empty plant) can occur starting from a relatively high hysteresis (minimum 5K above the +8°C mentioned above) or with the first activation of the spray system. In summer operation all components can be rinsed out. It must be ascertained that the entire water content of the system is substituted at least once. As reference, LUVE recommends a rinsing out period of 15 minutes. If the system has lengthy tubing, this value should be checked and if necessary modified. LU-VE recommends rinsing as part of standstill management every 24 hours. To ensure a proper operating it is necessary to inspect and to clean regularly the adiabatic panels, the distribution system, the pump and the water tank.