By Dave Burnham, EDRO Corp.
Many times when loading a washer extractor, not much thought is given to the fact that how a machine is loaded will affect proper processing of the goods. But incorrect loading does affect the goods being processed. Let’s see how.
There are four controlling factors to consider when gauging the effectiveness of the wash process. They are:
• Mechanical action
• Chemical type and concentration
• Temperature
• Time
Mechanical action is one of the most important variables affecting wash results. Within the laundry process, mechanical action is controlled by the loading practices used for a given size and type of washer.
• Loading varies with fabric and machine type
• Loading affects soil removal, fabric strength and excessive wrinkling
• Loading influences the costs for labor, chemicals, water and energy
Washer loading is stated as pounds of fabric per cubic foot of cylinder volume. Water and soil amounts vary in soiled fabric from almost zero to a large percentage of the fabric weight. To provide consistent standards, washer-loading factors are calculated on the weight of clean, dry fabric processed.
The established conventional loading factor over recent years has been between 5 and 6 pounds (clean dry weight) of cotton fabric per cubic foot of cylinder volume.
In the past, calculations for pounds of fabric per cubic foot were based on 100% cotton textiles. However, many of today’s textiles contain lighter synthetic fibers, resulting in lighter weight fabrics.
Because of this, the same amount of weight of polyester blended or 100% polyester textiles should not be loaded for 100% cotton textiles.
Many washer manufacturers, in an effort to market their laundry equipment, “stamp” washing machines with a poundage-capacity figure for laundering 100% cotton. This figure is often misinterpreted, causing many operators to overload machines.
Overloading
Overloading is not beneficial to good laundry performance because it decreases mechanical action. This happens because there is no room in the cylinder for the load to tumble. Detergents and chemicals cannot be distributed properly and the tightly packed textiles hamper dilution and lower soil removal, resulting in poor mechanical action and poor-quality laundering with an increase in stain count. If a washer is overloaded, the items in the center of the basket remain dry and soiled.
Extra water levels are required for each operation and longer consecutive rinses may be needed to remove loose soil chemical supplies remaining in the load. If these supplementary steps are not employed, loads may need to be rewashed.
Laundry operators are encouraged to compare and load washing machines on the basis of cubic foot capacity. The volume – in cubic feet – of a washing cylinder can be computed from the following equation:
(PI) R2 (radius of cylinder) x depth of cylinder / 1728 = cubic content of cylinder
Underloading
Underloading can also yield poor performance. With underloading you have agitation, but the water level is intended for a greater volume of goods. This “softens” the drop in the cylinder by having the load falling into the wash liquor instead of against the cylinder ribs. Excessive costs are incurred with underloading due to the chemical concentration being intended for a larger load leading to an increase in costs per pound of laundry.
Underloading a washer can be expensive, not only in terms of water, utilities, chemicals and manpower, but also in replacement of linen. Underloaded washers tend to damage linen by breaking down fibers. Chemical concentrations, temperatures and mechanical action that are greater than what a load dictates contribute to this.
Some fabrics, however, MUST be underloaded due to their bulk as compared to their weight. Garments that contain polyester blends are usually loaded at 3.5 to 4.5 pounds per cubic foot. This minimizes wrinkling and subsequently provides easier finishing.
A washing machine’s loading figures should be based on equivalent clean, dry textile weight. Laundry operators looking to load machines on the basis of soiled weight must utilize a reliable method to convert clean, dry weight to soiled weight for each individual plant classification.
The ratios differ depending upon individual plant conditions. Therefore, it is necessary that ratios be determined for each individual plant by weighing soiled loads and comparing the soiled weight to the clean weight for the same load after processing. If proper soil sorting is practiced, the ratio (soil weight/clean weight) could be consistent and need only be periodically determined.
Washer-extractor loading guidelines:
• Load the machine to 90% of its rated capacity
• Ensure all water levels are set correctly
• Carry out a visual check of the wash wheel. After the load is saturated with water, and the wheel is rotating clockwise, the linen should “break” from the 11am position to the 4pm position. This provides the necessary mechanical action for soil removal
With the correct water levels set, this method should permit the necessary flushing and rinsing of linen, as well as maximizing chemical performance yielding clean goods.
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Need help planning your laundry operation? EDRO has a Laundry Planning Guide to help you get all you can out of your laundry in the most efficient manner. In this guide you will find:
• Definitions of terms you need to know
• Information / charts for laundry necessities including water consumption, boiler & gas data
• A guide to sizing the right equipment for your application
• A handy Facility Check List that will allow you to keep important data in one place
You can find the guide here: EDRO’s Laundry Planning Guide
