Machine monitoring and routine maintenance

10 August 2022



Take care of your drycleaning machine and you will avoid a myriad of problems, write Roger Cawood and Richard Neale


Perchloroethylene machines 

Your machine lies at the heart of your business and is therefore a key factor contributing to your success. In the event of a serious breakdown or, say, bad odours in the cleaned garments, you can be in real trouble. The majority of cleaners only have one machine, so it makes good business sense to have a strategy in place to deal with a worst-case scenario. Establishing a ‘help each other’ relationship with another cleaner is a good way of planning for this eventuality.

Computerised control of the operation of the modern drycleaning machine has led to a much-reduced need for detailed operator training, but operators still need to have a sound understanding of good solvent management, how the machine works and the need for a flexible approach to its operation. Unfortunately, many of today's operators are taught to perform routine maintenance procedures such as a filter clean, at a specified time or day of the week without reference to the actual condition of the machine, with the operator being unaware of really critical issues, such as filter pressure, distillation rates and solvent flow rates or even the relevance of the filter pressure gauge. Sooner or later, this type of regimented approach will lead to things going pear-shaped, with the first indication of a problem being issues such as bad odours in the cleaned garments, poor cleaning, dirty sweals on garments or incomplete drying, by which time some garments might already have been returned to customers in an unsatisfactory condition.

While a fixed routine maintenance programme may work reasonably well for low, steady workflows, during busy periods the need for routine maintenance such as still-cleaning and filter-cleaning is increased and becomes a variable requiring close monitoring and flexibility by the operator.

Looking after your machine

The following routine maintenance and monitoring regime, see opposite, is an example of the minimum of what should be expected from a competent operator.


Solvent and solvent management

It is vital that your drycleaning solvent contains correctly balanced stabilisers and inhibiters to counteract acidity and maintain solvent stability throughout repeated drycleaning cycles. It is therefore important to always purchase a good quality branded solvent, rather than economising on cheaper, recycled products which can cause serious internal machine corrosion.

Failure to maintain correct solvent levels and insufficient solvent in the machine is one of the most common operator problems. Running solvent levels down to the absolute minimum (and in some cases below), leads to insufficient distillation, with the attendant risks of unpleasant odours in the cleaned garments, greying, colour build-up in the solvent and sweals/marks in the cleaned items. Always make sure solvent levels in the machine tanks are kept at or near the recommended maximum for your machine.

In order to maintain the stability of the solvent, it is important to top up frequently and on a regular basis, say once a week, depending on the workload. This will ensure that stabilisers and other vital additives will be regularly replaced, and concentrations consistently maintained.

Filter maintenance

The quality of your cleaning depends very much on the solvent flow rate through the disc filter; this in turn is dependent on filter pressure - the higher the filter pressure the lower the flow rate. It is therefore important that the operator monitors the filter pressure and operates the Filter Maintenance programme before filter pressure reaches the machine manufacturer's recommended maximum. 

The risk here is that during busy periods (because of pressure of work, or because a filter clean is not scheduled till, say, the following day), the maximum filter pressure may be exceeded by a considerable margin. Ultimately this will lead to damaged filter discs, a blocked filter, poor quality cleaning and a risk of serious greying (because of redeposition of particulate soiling) to say nothing of the engineering cost involved in removing the filter internals and cleaning and replacing any damaged filter components. 

Distillation ratios

Soluble impurities such as oils, greases, tars and some dyes released from garments during cleaning have to be controlled until removed by distillation. If allowed to build up in the working tank solvent, they may cause discolouration and/or unpleasant odours in the cleaned items. To ensure soluble impurities do not accumulate to levels which present a risk to cleaning. Industry research has confirmed that the normal cleaning programme on your machine should be structured so that it delivers between 112 - 136 litres of distilled solvent per 45kg of cleaning, or around 3 litres per kilogram

The actual volume of solvent distilled needs to be calculated against your machines rated capacity and using the Normal Cleaning 2 bath Programme.

So, for a 20kg machine, to maintain the working tank solvent in good condition, a good ballpark figure to aim for would be around 60 litres of solvent distilled when using the Normal Clean programme.

It is important to regularly monitor the distillation rate (how fast the solvent in the still is returned to the distilled tank ) to ensure that distillation is completed by the end of the drying cycle.

Still maintenance

As soluble impurities build up in the still, the solvent boils more slowly; the operator needs to be very much aware of this, to ensure that the still is cleaned/pumped out before the distillation rate becomes unacceptable.

During busy periods. when consecutive loads are being cleaned, if only 60% or less, say, of the solvent in the still has been returned to the distilled tank, then there will probably be insufficient solvent available to adequately clean the next load. There is also a risk that there may be insufficient capacity in the still to accommodate all the solvent from the next load.

The water separator

Over a period of time small amounts of debris accumulate in the water separator and at the solvent/water interface, making it necessary to drain and clean it to avoid the risk of contamination of the distilled solvent with moisture and particulates. In the event of unstable distillation, or an overfilled still causing a “blackover”, the separator will be contaminated with detergent and soil; it will therefore be necessary to close down the machine and thoroughly clean the separator.

Any sign of a greenish/blue discolouration accumulating on the water separator sight glass or in the water layer needs to be investigated as this is a sign that the still condenser coil is starting to corrode. If the coil perforates, the solvent in the machine may be contaminated with water.

The recovery head

During drying, the air filter screens located in the recovery head can collect a surprising amount of lint and they must be removed and cleaned frequently. When pile fabrics, in particular, are cleaned it will always be necessary to clean the filter screens at the end of drying.

In order to avoid the build-up of lint in the air cooler, it is important that the operator continually inspects the lint screens for signs of wear and damage and checks the condition of the seals, which should form a snug fit in the recovery head. If lint bypasses the lint screens, it will progressively build up in the air cooler (thus extending drying times) and will require costly maintenance by the engineer to rectify the problem.

The button trap basket

The operator needs to check the basket every load. The perforations in the basket are very small and are easily blocked by debris and dirt; this is not obvious if the basket is left in situ, so it needs to be removed at least on a weekly basis and held up to the light to check its condition. Provided the basket is dry, any blocked perforations can be easily cleared with the steam gun.

It is also important, when the basket has been removed, that where there is a dip control mechanism inside the button trap. it is checked to ensure it is not obstructed by debris.

Detergent container

Drycleaning detergents play an important role in enhancing soil and stain removal but, just as importantly they also take into solution small amounts of free moisture from the garments and from spotting products/procedures. The control of moisture in drycleaning systems is critical: too much free moisture increases the risk of felting (and shrinkage) in animal hair textiles. Conversely, the tiny amount of moisture held in solution by the detergent considerably improves the potential for the removal of water-based staining and reduces static charges in the cleaned items.

It is not at all unusual to find the detergent container is in fact empty, so it is very important that the operator regularly checks the level of soap in the container and replaces it before it runs dry. When replacing the container, care needs to be taken to ensure the injector feed pipe is placed correctly and that the end of the pipe is actually resting on the bottom of the container.

  • If you have problems you would like the authors to examine please send with a good quality, high resolution (300dpi/1MB at least) pic of the item to
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Diagram showing the key components of an SED compliant drycleaning machine
On many machines it’s difficult to see solvent levels – make sure, use a torch
Monitor your filter pressure - don’t let this to happen to you
This filter was found to be completely solid with debris and had clearly not been cleaned for many months
Don’t take chances. This separator could soon be putting garments at risk
Check lint screens frequently for signs of wear
Hold the basket up to the light. If the perforations become seriously blocked it can result in lint and dirt being deposited on garments


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