Tunnel washer
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A tunnel washer, also called a continuous batch washer, is an industrial laundry machine designed specifically to handle heavy loads.
As the name implies, the device consists of a long metal tube called a tunnel. A huge metal spiral called an Archimedes screw runs down the center of the tunnel, dividing it into sections called "pockets". As the screw rotates, linen is forced from one end of the tunnel to the other. Since the screw is made of porous metal, laundry can move through the washer in one direction while water and chemicals are forced through in the other. Thus, the linen moves through pockets of progressively cleaner water and fresher chemicals. Soiled linen continuously goes into one end of the tunnel while clean linen moves continuously out of the other.
Since their introduction in the late 1960s, tunnel washers have become progressively more reliable. Though extremely expensive, they are now common in major hotels, hospitals and other high-volume laundry departments.
At the start, one of the machine's major drawbacks was the necessity of using one wash formula for all items.
Modern computerized tunnel washers can monitor and adjust the chemical levels in individual pockets, effectively overcoming this problem.
