As the vacuum cleaning system must be capable of cleaning surfaces of a widely variable character many forms of renovators are necessary. Of the various surfaces cleaned the author considers that carpets and rugs comprise the most important, as well as the most difficult to clean effectively, so that the carpet renovator will be considered first.
The Straight Vacuum Tool.
—Various forms of carpet renovators have been and are in use by manufacturers of vacuum cleaning systems. The first type of renovator to be considered is that having a cleaning slot not over 12 in. long, with its edges parallel throughout its length, and not over ³⁄₈ in. wide, with a face in contact with the carpet not over ³⁄₈ in. wide on each side of the slot. This form of renovator is illustrated in [Fig. 11] and is designated by the writer as Type A. The first of these renovators was introduced by Mr. Kenney and, as finally adopted by him, was 12¹⁄₂ in. long, with ⁷⁄₈-in. face and with a cleaning slot 11¹⁄₂ in. long and ⁵⁄₃₂ in. wide. This form of cleaner was termed the “straight vacuum tool” and is used today by many manufacturers. Slight modifications in its form and dimensions were made in some cases, as in the one manufactured by the American Air Cleaning Company. In the one used in all tests by the writer on type A renovators, the slot was reduced to 10 in. long and ¹⁄₈ in. wide and the face of the renovator was slightly rounded at the outer edges, leaving very little surface in contact with the carpet.
FIG. 11. TYPE A, THE STRAIGHT VACUUM TOOL.
FIG. 12. TYPE B, WITH WIDE SLOT AND WIDE BEARING SURFACE.
A renovator of this type is easily operated over any carpet even when a considerable degree of vacuum exists within the renovator itself. It has met with favor when used with the piston type of vacuum pump without vacuum control, as was the case with the earlier systems. However, when a very high degree of vacuum occurs within the renovator it has a tendency to pull the nap from the pile of the carpet.
Soon after the introduction of this form of renovator, some users of same, particularly in San Francisco, complained that while the renovator effectively removed the dust from carpets it failed to pick up matches and other small articles and preliminary or subsequent cleaning was necessary in order to remove such litter.
To overcome this difficulty Mr. Kenney increased the width of the cleaning slot to nearly ¹⁄₂ in., with the result that when a high degree of vacuum existed within the renovator, which often occurred where no vacuum control was used, it stuck to the carpet, rendering its operation difficult and, at the same time, doing great damage to the carpet. Hence, its use with the piston type of vacuum pumps was abandoned.