Fifty years ago, the laundry manager would have relied on soap and metasilicate to achieve good washing performance, tinkering with time, dosage and temperature to achieve an adequate result at reasonable cost.
Now the launderer has a range of different types of chemicals available and the laundry engineer has a critical role to play in helping the plant to use these safely and correctly without unexpected hazards or fabric damage.
Washed away
Bleach dosing can dissolve the machine. When pressed, a washing machine salesman will quickly reassure a potential customer that all the critical components of the machine are made from stainless- steel. Why then is rapid component failure such a problem?
First, a great many critical components are not made of stainless and there are several types of washer extractor in use in the rental sector which include aluminium components. Aluminium dissolves in an alkali environment and the hotter and stronger the wash liquor, the more rapidly the damage occurs.
This has become an acute problem in some areas where sodium hydroxide is being used to build the wash alkalinity. When this comes into contact with an aluminium door component, for example, not only does the aluminium dissolve but it creates bubbles of hydrogen gas with potentially devastating effects.
Of course, modern designs of washing machine have carefully eliminated aluminium components but there are plenty of examples on older models.
So is stainless-steel the ultimate solution? Unfortunately not. There are many grades of stainless and many washing machine components are made from 303 stainless which is quite vulnerable when compared with the rather more expensive 316 grade.
For example, injecting neat 15% sodium hypochlorite bleach as delivered into a 303 stainless soap hopper will give progressive dissolving of the metal with ugly black metallic residues coming away and passing into the main cage itself. If sodium hypochlorite bleach is being injected into a tunnel washer the best piping to use is suitably reinforced plastic tubing rather than any metal substitute.
Joint corrosion
This particular problem was highlighted by corrosion at the welds and in internal components which occurred in many continental tunnel washers in the days when manufacturers did not pay enough attention to weld materials. It was found that iron released from washing machine components in this way successfully catalysed the breakdown reaction between bleach and cotton to produce weak linen which went into holes and frayed very easily.
Modern machines are made of high grade stainless and as much attention is paid to the weld metal and welding rods as to the machine components themselves.
Of course, mixing laundry chemicals can be a recipe for disaster and current changes at the back end of tunnel washers require expert advice and assistance from the soap supplier before the laundry manager and engineer start to dabble.
Risky mix
The main risk concerns the possibility of mixing an oxidising bleach, such as sodium hypochlorite, with an acidic sour. When this happens chlorine gas is produced. Chlorine is excellent at neutralising the bacteria that develop when children wee in swimming pools, but in higher concentrations it is lethal; hence its widespread use in the trenches of the Western Front during World War I.
If the bleaching and souring system is designed by the soap supplier, this type of problem will not arise because soap suppliers tend to be expert chemists, well able to avoid this type of hazard. It is only a problem for the experimental and inquisitive!
Copper piping is excellent for domestic central heating and brass fittings can resist the effects of towns’ water, borehole water and sea water quite well.
However, copper and brass are rarely appropriate materials for piping modern strong laundry liquors around tunnel circuits because they will be readily attacked. If the piping is damaged in this way, trace amounts of copper and other metals entering the laundry liquor. One would be forgiven for thinking that these trace amounts would have little effect. Unfortunately, that is not the case.
Metals of this type act as catalysts. (A catalyst is the vital ingredient in a chemical reaction which is not consumed by the reaction itself, but which promotes the chemical breakdown of other items – cellulose in cotton, in particular, can be affected.) Some launderers are finding that, even with minimal bleaching injected into the correct compartment, they are getting accelerated fabric breakdown. This results in a high level of customer complaints about holes, tears and frays, and an unacceptable amount of ragging of damaged stock.
What implications does this have for the engineer? First, modern laundry chemicals and laundry liquors must be handled, wherever possible, by pump from drum delivery or by automatic powder handling from a sack-fed hopper.
In many cases, soap suppliers will meet some or all of the cost of this but if they will not, then a small laundry is generally best advised to install automatic dosage progressively and move away from operator handling and its obvious risks. Now that effective systems are generally available, a factory inspector will take a dim view of any incidents involving chemical splash.
Personal protection
Where it is essential for the engineer to handle chemicals for maintenance purposes correct personal protective equipment (PPE) must be used. Gloves, face visor and possibly overalls will be needed and these have to be a good fit. They should be stored in a convenient place and kept clean and ready for use.
Finally, storage of laundry chemicals requires a separate risk assessment that identifies adequate controls to minimise potential problems. This means arranging to store bleach containers out of direct sunlight to prevent chemical breakdown. It also means keeping separate those chemicals which could react together to create a serious hazard (such as bleach and sour).
Chemicals should be kept in their original containers with the warning hazard label clearly visible and the top securely fastened. Containers should not generally be stacked one on top of another and staff should be able to reach containers without having to pull them down from a great height and without having to lift them in an awkward manner.
An excellent guide to the preparation of risk assessment of this type is given in the Health and Safety Management Guidelines published by the TSA.
Tightening regulations
The range of different chemicals is growing and next year we will see a considerable tightening of effluent control regulations. This means that there will be further increases in the complexity of laundry detergents with a possible significant reduction in alkalinity.
Unfortunately this is coming at a time when certain enzyme products (those containing subtilisins) are coming under strong scrutiny and stringent controls, so the future will be interesting, to say the least.
Of course, the laundry engineer is best placed to cope correctly with these changes so that laundry chemicals do the job for which they are purchased while maintaining the integrity both of the products being washed and the machinery in which they are processed.
