Laundry engineering for healthcare Part 2

In this, the second of three articles on laundry engineering for healthcare, we look in more detail at the opportunities for achieving good quality healthcare linen, efficiently and on time, by taking the right decisions with equipment selection and the way in which it is operated and maintained.

Washing

Washer extractors are generally more expensive to operate than tunnel washers (in terms of energy, water, chemicals and labour), so any plans for the future should take this into account. It is quite possible to achieve the same quality standards and decontamination performance from tunnels as from extractors, provided they are set up and operated correctly. This applies equally to small modern designs of tunnel for the small laundry. Where a laundry is still employing washer extractors to see out their useful life, attention should be paid to follow advice to minimise the operating cost until they can be phased out (see Dec 2020 issue (minimising water costs) and Mar 2022 (minimising energy costs)).

Tunnel washers deliver the highest output at the lowest cost, if they are operated steadily and continuously with the minimum of manual intervention. To achieve this, it is necessary to sequence loads so that there is never a ‘tumbler hold’, whilst the entire washing line idles until a tumble dryer comes free and the press can be cleared to take the next transfer. Modern computer-controlled tunnel programmes are well able to divert work for the ironer to a single tumbler for example, keeping the others for longer, full-dry cycles.

Keeping the tunnel going continuously also requires elimination of frequent recourse to Engineering to solve technical issues. Wherever an issue crops up more than two or three times a week, it is essential that a team gets onto it and removes the cause permanently. This then shapes the preventative maintenance plan for the unit, so that the interruptions disappear entirely. The worst type of recurring issue is unexpected tunnel blockage. This can be caused by accidental feeding of two loads into the front compartment before the first has transferred.

Where a healthcare laundry is operating only one tunnel, with pre-wash sorting, and whites and coloured sharing this, then it may prove impossible to avoid putting a run of empty pockets after a run of coloureds. It is worth getting the cost accountant to calculate accurately the annual cost of this in terms of wasted water, energy and chemicals, because this might accelerate the decision to operate with at least two tunnels. Until then, the high cost of running empty pockets can be minimised by batching-up loads of coloureds so that there are only one or two changes to whites during the shift or even the day – even though this might not be easy and may require significant changes elsewhere.

Disinfection

For healthcare textiles and increasingly hospitality and workwear items, cleanliness and presentation have to be accompanied by assured disinfection. For many years, implied thermal disinfection (holding a wash temperature of at least 71C for at least 3 minutes plus mixing time) was deemed adequate for achieving a 5 log10 kill (that is reducing the concentration of viable micro-organisms by a factor of at least 100,000). Modern thinking is rapidly challenging the adequacy of this (because, for example, an overloaded washer extractor might show 71C in the sump but could demonstrably fail to reach this in the centre of the load).

The European Norme EN 14065:2016 is achieving widespread adoption, because this allows a variety of disinfection techniques, but requires the laundry to institute adequate checks to assure that disinfection is consistently achieved. It overcomes the shortcomings of implied thermal disinfection and equally importantly, it allows for chemical disinfection. This can reduce at one stroke the increasingly high cost of energy requirements of the old methods and makes a very significant contribution to combatting climate change. Validation of disinfection can be carried out by batch, daily or weekly ,in-house, by engineering and production staff using a variety of methods. Less frequent checks use swabbing of finished goods and laundry surfaces (especially laundry barrows, for example), to produce swabs which can be analysed for key pathogens. There are special control test pieces which the laundry can process once through the main wash process, followed by laboratory analysis, which give the log reduction in micro-organisms that has actually been achieved.

All this has led to wash temperatures coming down towards 40C, which has offered significant benefits in quality and presentation of staff uniforms, with reduced creasing in the wash. It is also leading to phasing out of the central boiler on many plants, with this being replaced by direct gas firing of tumble dryers and gas-fired thermal oil heaters local to the ironers.

Moisture removal

Efficient moisture removal after washing still offers significant opportunities in many plants, because squeezing out an extra one or two percent offers major energy saving and capacity increases downstream in ironing and drying. It is from five to fifteen times more expensive in energy terms to use heat to dry the moisture than it is to squeeze it out. It really pays to get the engineering and production teams working on this together (see LCN Mar 2022 issue). All it requires is attention to detail in every washer extractor programme and at the membrane press. The key factors are spin speed and spin time in the washer extractor and the time at maximum pressure at the membrane press. The team may need training in the technique for measuring accurately the moisture retention after pressing or spinning.

There are now engineering solutions to most nuisance noises which a laundry might generate. The engineering team will normally be able to dampen vibration effects at the floor mountings. The external vents from the washer extractors and the tumble dryers (and even tunnel finishers) can now be fitted with special silencers, not unlike those used on a motor vehicle internal combustion engine and based on similar principles.

Minimising manual handling

Operatives wheeling barrows from point to point should be minimised in a modern, high-volume, high productivity healthcare laundry. Just as work could enter the sorting area on a conveyor, so the work leaving the tumble dryers after the tunnel washer could be taken by conveyor to the next station, depending on classification. The conveyors from the dryers could bring the textiles to waist height to avoid stooping to lift and they could be delivered to the correct ironer, for example, at the correct height for the operator to take them for feeding.

The final conveyors into the packing area should enable correctly sized packages of finished goods to be slid across onto the packing out delivery cages with the minimum of lifting and with no walking or carrying. Vacuum systems to take batches of moist uniforms pneumatically from the tumblers to the finisher will eliminate any need for barrows to be pushed manually. These are big changes, but they are essential if the modern laundry is to achieve the high throughput needed with no clutter or jams.

Tumble drying

The ‘tumbler hold’ problem, which is the bugbear of so many laundries, can almost always be solved by getting the correct sequence of classifications into the tunnel washer, by optimising the dryer termination points (usually by automating these) and by setting conditioning times correctly. These areas should be looked at before any consideration of buying an additional dryer.

The tumbler is a useful device for breaking down the ‘cheese’ of textiles from the membrane press, but if the textiles are going forward for ironing or tunnel finishing, the time in the tumbler should be limited to no more than is required to break the cheese. It is false economy to try to speed the ironer or the finisher by a few minutes’ partial drying in the tumbler, because this has a thermal efficiency of only around 50%, whereas the ironer and finisher are much more economical.

Automatic end point detectors for the dryers are now an absolute essential and at present energy costs they pay for themselves in only a few months. However, they do need to be set up correctly and cleaned of oil and lint regularly.

The actual moisture retention should be monitored on a regular basis and maintained at the correct level above zero. It is important to avoid any risk of taking work to bone dry (and beyond!), because this wastes considerable energy and causes progressive greying.

Plastic bags in the tumblers are a disaster and should be treated as such by management at all levels, with strong reaction if throughput falls because of blocked perforations in the cage. The need for automatic and efficient clearing of the lint screens in the outlet air stream is widely recognised, but it is almost as important to have a regular daily or weekly check on the inlet air screens, because progressive blockage here will steadily reduce throughput.

Where noise is a major issue for patients or neighbours, especially during the evening and overnight, then consideration should be given to fitting silencers around the exhaust ducting. Modern systems are very effective and frequently solve nuisance problems at reasonable cost.

Conclusion

This is the second instalment of a three-part series on ‘Laundry Engineering for Healthcare’. In our February UK issue, we shall be looking at the advice which the laundry engineer is well placed to offer to laundry management in order to achieve those elusive objectives: high productivity, low operating cost and assured disinfection. The opportunities are there in most laundries and the prizes are really worthwhile.