WHAT WENT WRONG
Recognising and resolving machine problems
Readers might want to cut out this article and keep it handy for when a puzzling problem develops in the future, say Roger Cawood and Richard Neale
The advance of automation As a society, over the years, we have become accustomed to the ever-increasing degree of automation. However, it will be obvious that for the foreseeable future, vehicles of all types will still need some form of human input to monitor their performance, together with fuelling and maintenance, if they are to operate safely and reliably. The same applies to drycleaning machines which today, in terms of their operation, place little demand on the operator compared to the early 1960s when, at the end of the day, the shutdown procedure for machines could take an hour, requiring the operator to redirect solvent flows around the machine, as and when necessary, before reconfiguring the machine for the following day. Today the limited operator training on automated machines often leaves very many operators with little or no fundamental understanding of how the solvent levels and condition, or interaction of the various machine components and steam and filter pressure etc can adversely affect the automated operation of the machine or the quality of the cleaned product.
Solvent levels
It may come as a surprise to many that by far and away the most common and easily resolved problem encountered on drycleaning machines is insufficient solvent in the machine! In our view this is often in the mistaken belief that the less solvent there is in the machine, the less it will use. Excluding leaking tanks, spillages and a small amount of solvent lost during still cleaning, the vast majority of solvent usage is from vapour escaping and therefore the less solvent and the more air there is in a tank, the more vapour there is in the tank to escape. If solvent usage is an issue, the first step is to ensure that the machine is topped up to above the minimum levels recommended by the machine manufacturer. In our experience, depending on machine capacity, it is not
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uncommon to find that a machine needed up to 50 litres or more of solvent to restore the correct working solvent levels. The next step should be the inspection of the cage, button trap, air filter and still door seals to ensure they are in good condition – also check that the doors are correctly adjusted and forming a good seal in terms of pressure; at this point it would be a good idea to ask your engineer to carry out a thorough check for vapour leaks while the machine is in operation.
Insufficient solvent in the machine can easily result in a number of serious problems which leads to a build-up of fatty acids, colour and other soluble impurities in the solvent, incomplete removal of soiling and stains, greying and cage marks. Greying caused by redeposition of soiling from dirty solvent or inadequate detergent. In order to maintain the base tank solvent in good condition, a minimum of 2.5 litres of solvent per kg of work cleaned needs to be distilled.
Routine maintenance Regular maintenance is absolutely vital, both to the efficient and safe operation of your machine and, just as importantly, to the quality of cleaning that it delivers. Typically, lack of attention to the cleaning of the button trap, lint screens and the still, and failure to respond to prompts for filter cleaning or rises in filter pressure, will inevitably lead to an increasing risk of the following problems: Blocked button trap, leading to cage marks, incomplete soil removal, fabric damage, extended drying times and solvent retained in garments. This can result in staff being exposed to high solvent vapour concentrations.
Damaged or blocked lint screens, leading to linting, incomplete drying, blocked air cooler and air heater, and the build-up of lint and debris on the inner surfaces of the machine.
Dirty still, causing slow distillation;
CHECK LIST: The solvent levels in the machine need to be checked at least on a weekly basis
the still should be cleaned as soon as distillation starts to slow. Slowness can lead to overfilling of the still, foaming and a ‘blackover’, contaminating the water separator and possibly the distilled solvent tank. This problem, if not observed by the operator, can easily lead to catastrophic greying and possibly shrinkage due to the carryover of water, detergent and soiling into the distilled solvent.
Filter cleaning – while some machines prompt the operator when a filter clean programme is needed, others may require a response by the operator in relation to the manufacturer’s maximum recommended filter pressure and require the operator to do a filter clean. Repeated, excessive filter pressure will reduce solvent flow, and compact soiling onto the discs. This will also damage them, allowing breakthrough of particulates that will progressively impact on soil removal from the cleaned work and the solvent, resulting in greying.
Serious machine faults, some of which require an immediate response from the operator.
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