Automated system for controlling the sealing of aerosol packings

Abstract

When producing aerosol-based preparations, the quality of aerosol packing (AP) is determined mainly from the results of testing the hermetic sealing.The control of the latter by the bubble method in a hot water bath does not meet the present industrial requirements as the aqueous medium causes active corrosion of the AP body while the test consumes much power, and control is subjective.The Dzerzhinsk branch of Nizhegorodsk Polytechnical Institute designed automated system AKG-Gs for testing valve airtightness in seamless AP. The sensitive element of halogen leak detector GTI-6 was used as a gauge for detecting the gas-phase leak from the AP. The possibility and advantage of using such a gauge was examined in [i-3].Considering the fire and explosion hazard of the industry, the gauge is made with an explosion-proof shell, is hazard-free, and ranked IExdPVT4 safety class [4]. The measuring block together with the gauge is set up outside the hazardous building.In view of the possible loss of gauge sensitiveness, control is effected in two stages: in the first stage, APs with large leakages are detected and discarded and, in the second, testing is done to the required sensitiveness level.Correspondingly, the device consists of two blocks: a block with low control sensitiveness set up directly on the conveyor and a highly sensitive block with a rotor-type module having eight platforms.Control at each stage is effected by two gauges operating alternately.The gauges in the sensitive second block are activated after detecting and discarding defective ones in the first block.A jet of clean air is blown onto the low-sensitive block to restore the sensitiveness of the idle gauge.To reduce the fluctuations of background signal and restore the sensitiveness of the gauge rapidly after contact with the coolant leaking from defective APs, the electrical circuit of the leak detector has a follow-up system that suppresses slow deviations of background signal from the zero line by controlling the filament current of the sensitive element.Threshold values of background signal variations causing filament current fluctuations are controlled.In view of atmospheric contamination of the building with the coolant, the sensitive elements in the second block are partly isolated from the ambient environment by a shell of organic glass under which clean air is blown at a slight excess pressure. Figure 1 shows the layout of the equipment.APs 1 on conveyor 7 enter the low-sensitive block 2. In case of rejection, the output signal of leak detector GTI is compared with the given value by the liminal device LD and, when in excess, is transformed into a pneumatic signal in eiectropneumatic converter (PC) and reaches pneumatic cylinder 3. The rejected ones are automatically dumped into bunker 4 by pneumatic cylinder 3. The control sensitiveness at this stage is 0.5 m3"Pa/secoGood ones continue to move on the conveyor to highsensitive block 5 where they are held by sprocket 8 and, holding on to turnstiles block 9, travel to position I on rotor 6. As t...