MATERIAL SOLUTIONS
400. Cotton rich textiles (30:70 polyester/ cotton) have an even higher capability. So why do so many achieve only in the range 90 – 120 cycles?
One reason for poor textile life is the continued misuse of sodium hypochlorite bleach, which causes accelerated rotting of cotton fibres if used at the wrong concentration (more than 3ml per kg of dry textiles at 16% concentration) or too high a temperature (keep this below 60C, but the lower the better). Launderers who switch to an oxygen bleach often point out that it is not as effective on protein stains as sodium hypochlorite. This is quite true, but to remove protein stains with hypochlorite requires a strong dose, which is the cause of a great deal of unnecessary chemical damage and short textile life. Fatty proteins require the right emulsifier to remove and solubilise them, especially soiling such as fish oil or chicken fat on cotton rich. Oily proteins are strongly
attracted to the polyester fibres in cotton rich and they need the right emulsifier. One that is designed to take mineral oil off polycotton overalls will not work on food fats, although skilfully designed blends of different emulsifiers (able to tackle mixtures of widely differing oils and fats) are now available.
Low energy washing The change in permitted methods for disinfection of healthcare has taken place right across Europe and it is this which has opened the door for low temperature detergent systems. High temperature washing with plenty of alkali to saponify fats has worked well for over 100 years, but this is usually more costly; it takes time for the warm-up, and it absorbs valuable heat energy which is rapidly becoming unaffordable. Modern emulsifiers and blends of these make the old high temperature, high alkali systems
essentially obsolete, because these work at low temperatures without excessive alkali (helped sometimes by activators developed to accelerate low temperature effectiveness).
Low temperature washing has been one of the prime movers in the steady reduction of unit energy consumption (measured in kWh per kg dry weight of textiles) in the modern laundry. In the UK, the large laundry sector has reduced energy use by over 25% over a five-year period and this is still continuing. Market leaders are driving consumption below 1.0 kWh/kg textiles, an achievement considered beyond us only a few years ago.
Low energy ironing
Low temperature washing has been the main driver over the last 12 months, and this has rapidly become the norm to stand any chance of achieving acceptable prices and margins. Interest is now moving to cost-effective ironing and tumble drying. Minimum cost, high productivity ironing relies on two key objectives: to keep the ironer fed with sufficient work to keep it running continuously, aside from breaks, and to seek to consistently maximise bed coverage. These are now recognised as more important than trying to make the ironer run faster and still get the work dry (which usually raises quality issues and is difficult to maintain long term). Achieving continuous running means a scheduling system that keeps at least one batch ahead, without forming queues (which allow the work to dry and brown). It also means maintaining low and consistent moisture contents, with monitoring and control of time at pressure in the membrane press on CBTW lines (an area which has been sadly neglected in many plants) or optimising extraction spin speed and time. Shrewd operators have recognised the importance of maintaining maximum extraction of water vapour (by regular monitoring and optimisation of vacuum suction across every bed) and of achieving uniform roll- to-bed contact and pressure (by avoiding over-pressure and distortion of the springing).
REGULAR MONTORING: Simple dip slides provide even the smallest laundry with an inexpensive technique for daily or weekly monitoring of disinfection performance without a laboratory
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Low energy tumble drying The two key factors which have driven thermal efficiency of the tumble dryer have been a ruthless focus on consistency of load weights (with correct allowances now being made for the average moisture content of used towels), and the use
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