[The problem of the measurement of relative humidity in the disinfecting dryceaning process (author's transl)].
One of the most important conditions for obtaining reproducible microbiological results by disinfecting drycleaning is a control of the relative humidity of the drycleaning bath. An apparatus called "Wasserkontroller" (see Fig. 1) had been recommended as a device for the determination of the relative humidity. It consists of a special cylindrical casing into which the sensor of a hair hygrometer has been introduced. In contrast to electric instruments, this apparatus has the advantages of rigidity, simple adjustment, and above all of a low cost price. In practice, however, the "Wasserkontroller" proved to be a failure, since it indicated false values at times. In the studies published and discussed in the present paper, the causes for the malfunction of the hair hygrometer, in the device mentioned were determined. It could be observed that a malfunction of the hair hygrometer mainly occurred when the hairs fixed in the sensor were moistened by the drycleaning bath or by the drycleaning solvent (perchloroethylene), respectively. Then the hair hygrometer is no longer capable of reacting sufficiently to the fluctuation of the relative humidity of the bath. On the basis of the experimental results obtained instructions are given for the employment of hair hygrometers in drycleaning and for the design of the device casing: 1. The hair hygrometer has to be protected inside the device casing against a contamination by the bath or the condensing drycleaning solvent. 2. The inlet pipes to the device casing and the casing itself have to be protected against loss of heat as well as against the influence of heat sources. Temperatures of drycleaning bath and device should be balanced. 3. The inlet pipes to the device should be provided with a flowmeter or a flow detector, respectively. 4. The outlets of the device should be connected directly with the drum filled with the drycleaning bath. 5. The device has to be constructed in such a way that no infiltrated air may be sucked in. 6. The hair hygrometer has to be cleaned and to be adjusted at suitable time intervals. Provided that the technical requirements are met, hair hygrometers may also be considered as reliable measuring instruments in the practice of drycleaning.
D003020:Clothing; D004203:Disinfection / Q000295:instrumentation; D005069:Evaluation Studies as Topic; D013242:Sterilization / Q000295:instrumentation
Zum Problem der Messung der relativen Feuchte in der desinfizierenden Trockenreinigung