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文章来源:http://www.iwuchen.com/  2016年03月15日  点击数:4366

Can the ventilation of GMP clean rooms beswitched off overnight?



The ventilation systems of clean roomsconsume a lot of energy, especially power for the ventilating fan,refrigerating capacity for cooling and dehumidification in summer as well asheating for warming and steam for humidification in winter. Therefore, thequestion comes up again and again whether one might switch off the ventilationof the rooms overnight or when they are not used in order to save energy.


It is not advised to switch off the ventilation systemcompletely, it is rather advised not to do it. Premises, pressure conditions,microbiology, everything would be out of control during that time. This wouldmake the subsequent measures for the restoration of the GMP-compliant statevery complex because each time a requalification would be necessary to reachthe normal GMP-compliant state.


But a reduction in the performance of the ventilationsystems (reduction of the air volume by reducing the performance of theventilation system) is possible, and is already carried out in some companies.Here too, however, the GMP-compliant state must be achieved prior to using theclean room again and this procedure must be validated.


For this purpose the following points must be observed:


The reduction can only be carried out so far that theclean room specific limits prescribed for the relevant case are not violated ingeneral. These limits have to be defined in each case for the operating statusand the reduction mode including permissible minimum and maximum values, suchas clean room class (particle count with equivalent particle size), productspecific values (temperature, relative humidity), pressure conditions (pressuredifference between the rooms). Note that the values in reduction mode have tobe chosen in such a way that the facility has reached the GMP-compliant statein due time before production begins (integration of a time program). Thisstate depends on different parameters such as building material and performanceof the system etc. The pressure conditions should be maintained all thetime, this means that a reversion of the flow direction is not allowed.


Furthermore, the installation of an independent cleanroom monitoring system is recommended in any case in order to constantlymonitor and document the above mentioned clean room specific parameters. Thus,the conditions of the area concerned can be monitored and documented at anytime. In the case of deviations (reaching of a limit) and in the individualcase it is possible to access the measurement and control technology of theventilation system and to carry out the relevant adjustments.


During the reduction attention should be paid toensuring that no unpredicted external interfering influences such as theentry of persons are allowed. For this the installation of a correspondingentry control is advised. In the case of an electronic locking system the entryauthorisation can be linked with the above mentioned time program as well aswith the independent clean room monitoring system so that entry is authorisedonly subject to compliance with the predefined requirements.


In principal, both states must be qualified first andthen requalified in regular intervals and the customary measurements for theregular operating status such as the recovery time measurement in case of acomplete failure of the facility must be carried out. In the case a clean roommonitoring system exists it is in principal not required - as mentioned above -to carry out further measurements at the start of operations after reductionmode if the procedure is validated. Special focus should be put on theprocedure of restarting since temporary reversions of the flow direction arepossible, for instance.


All in all about 30 % of the energy costs can be saveddepending on the mode of operation and the shift model but additionalinvestment costs might have to be offset.



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