EQUIPMENT MANUFACTURING: KIM SHADY, LAUNDRYLUX CORP, NEW YORK, N.Y.
Loading capacity of washers and dryers is quite ambiguous. I was recently in a laboratory with multiple brands of washer-extractors. One of my objectives was to determine load size vs. rated capacity and the effects of under-loading.
The first laboratory result proved that based upon weight, you cannot load a washer beyond the rated capacity of the machine. In fact, it is difficult to place 50 pounds of dry terry cotton towels in a 60-pound washer. In nearly every machine tested, based upon weight, a machine will accept only 85% of the rated capacity. On some washers, because of the shape of the drum, only 75% is achievable. If you test poly/cotton sheets, the weight of the load is even less, as the polyester material has less weight for the amount of volume or space it takes in the wash wheel.
The lesson learned: Don’t expect the actual weight of a load to be equal to the rated capacity of the front-load washer-extractors.
The second laboratory test was to determine what happens when a small load (50% of capacity) is run in a washer. The results demonstrated the water used per actual pound of linen increased. Hence, it is more costly per pound to process. Also, the chemical dispenser did not know the load was smaller, again causing the cost per actual pound processed to increase.
Third result in the test was the washer’s ability to balance the load and advance the cycle to extraction. In some washers, there were multiple attempts to balance the load prior to extraction. This wasted time and water. In some cases, the washers never reached an acceptable balance level and the extraction speed was reduced, hence more residual moisture and longer drying times. As you can see, under-loading is expensive. And more loads per day must be processed, adding even more water, energy and labor costs.
We also tested load sizes in dryers. The objective was to determine drying time and energy cost for terry towels in a fully loaded, 60-pound-rated capacity washer in two different-sized dryers (capacities of 67 pounds and 83 pounds). The test results proved the larger dryer was faster and used less energy to dry the identical load.
At the end of the day, washers can’t be overloaded, while under-loading will significantly raise the cost per pound processed. Dryers can be overloaded, having the same effect on higher costs as under-loading washers.
At the end of the day, supervision and processes are critical. Unless, of course, the washers are smart enough to override human error!
HEALTHCARE LAUNDRY: SCOTT BEATON, KAISER PERMANENTE NORTHERN CALIFORNIA
One of the most important variables affecting wash quality results is mechanical action. Much of the mechanical action controlled by the laundry is affected by loading practices within a given size and type of washer.
Washer loading is expressed as pounds of fabric per cubic foot of cylinder volume. Loading varies with fabric type and with machine type. Overloading and under-loading can affect soil removal and fabric strength and create excessive wrinkling. It can also influence the costs for labor, chemicals, water and energy.
In order to provide consistent standards, load factors are normally based on the weight of clean, dry fabric processed.
Overloading is not conducive to good laundry performance. Supplies cannot be distributed properly throughout the load, and the tightly packed condition of the textiles impedes dilution, lowers soil removal, and results in poor mechanical action.
Additional water levels per operation and longer rinses may be required to remove loose soil and chemical supplies remaining in the load. If these additional steps are not employed, loads may require rewashing.
Overloading of continuous batch tunnel washers may result in jamming up the machine and halting production. Under-loading also can result in poor performance due to less mechanical action and can lead to excessive costs.
Some fabrics must be under-loaded because of their bulk as compared to their weight. Garments containing polyester blends typically are loaded at 3.5 to 4.5 pounds per cubic foot to minimize wrinkling and provide for easier finishing.
All in all, load weights should be determined for each individual plant per machine by weighing soiled loads and comparing the soiled weight to the clean weight for the same load after processing. If proper soil sorting is being practiced, the ratio (soil weight/clean weight) should be consistent by classification/machine and need only be recalculated periodically.
CHEMICALS SUPPLY: MARLENE WILLIAMS, ANDERSON CHEMICAL CO., LITCHFIELD, MINN.
Machine load sizes are designed to optimize machine performance, chemical use, fabric wear, and performance outcomes. There are prices to be paid for load sizes that vary widely from recommended protocols.
Under-loading of machines is largely a matter of wasted resources rather than performance outcomes. Running less-than-capacity loads results in additional loads needing to be run to accommodate total laundry weights. Waste in water (and expensive heated water), chemicals, and labor raise the cost per pound significantly when loads are not full.
Performance is typically not a problem when under-loading unless chemical use results in high foam generation during light loads. Extra foam can result in poor mechanical action with subsequent poor results. In front loaders, high foam levels can result in foam being forced into machine areas that are not typically rinsed. This foam residue, if not cleaned during special cleaning cycles, can provide food for bacteria and accompanying malodors.
Under-loading dryers can result in poor drying or no drying if dryer sensors do not recognize moisture amounts from small loads.
Overloading, on the other hand, is a self-defeating process. A myriad of problems results from overloading, including higher number of rejects, more rewash, lesser quality (lesser soil removal), and setting of stains.
Negative selection, i.e. removal of some stains while leaving other stains to be set in the dryer, is a function of overloading. Lack of mechanical action results in soils not being put into solution and carried away from fabric, excessive fabric wear in some areas of the machine as fabric does not move, and problems with inadequate dilution of chemical resulting in over/under-dosing of chemistry depending on overload dynamics.
Add more labor, chemical, water and time to rewash problem fabric and it becomes clear that running standard load sizes optimizes the laundry process.
Click here for Part 1!