—As no tests of cleaning an actually dirty carpet were on record, quicksand having been used in the Institute of Technology tests, it was necessary to first clean some carpets that had been soiled in actual daily service in order to obtain a standard with which to compare the results in removing various substances, which it was intended to try as a substitute for dirt. A carpet which had been in actual use for a number of years on the floors of the old United States Mint building, in Philadelphia, and receiving the ordinary amount of cleaning, was procured. This was a Brussels carpet with a glue-sized back, containing about 20 sq. yds. It was divided into three approximately equal parts.
An indicator was attached to the vacuum pump for taking air measurements, and it was found that there was considerable leakage of air into the system through the connections to the separators and at other points, therefore the pump was operated with 22 in. of vacuum in the separator and a card taken with all outlets closed and the amount of leakage noted. During the tests this degree of vacuum was always maintained in the separators and pipe lines and the vacuum in the renovator was varied throughout the tests by throttling the hose cock. This manner of making tests gave a practically constant leakage which was deducted from the quantities shown by the indicator cards taken with the renovators in operation.
As the writer had already made many tests of the efficiency of various types of vacuum pumps as air movers under various degrees of vacuum, and as the capacity of the pump available was far in excess of that required to operate one renovator, no attempt to obtain the efficiency of the plant as a unit was made. Instead, the vacuum at the hose cock was adjusted until the degree obtained was what the writer had found to be within the limit obtained in practice. The resulting vacuum at the renovator was then noted.
Each piece of carpet was cleaned during six periods of one minute each, using a different vacuum at the tool for each piece of carpet. The carpets were weighed at the beginning of the test and after each one-minute period. At the conclusion of these tests each carpet was cleaned until no change of weight occurred after two minutes’ cleaning. They were then considered as being 100% clean and this standard was made a basis for computing the percentage of dirt removal. A renovator of Type C was used in these tests.
Shortly afterward a similar test was made on a dirty carpet of 4.6 sq. yds. area, using a renovator of Type F. This carpet was also a Brussels, with glue-sized back, which had been in use in the shoe department of a large department store in Hartford. These carpets contained approximately 2 oz. of dust per square yard, none of which was visible on the surface, and they were probably as clean as the average carpet after being gone over with a carpet sweeper or after a light application of a broom.
TABLE 1.
Cleaning Tests of Dirty Carpets.
| Type of Renovator. | A | C | F | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Vacuum in renovator, in. Hg | 2 | 4¹⁄₂ | 1 | 2¹⁄₂ | 4 | 3¹⁄₂ | ||||||
| Air exhausted, cu. ft. per min. | 16 | 27 | 24 | 37 | 44 | 59 | ||||||
| Material removed, per cent. of total, 1 min. | 50 | 60 | 37 | 39 | 47 | 35 | ||||||
| Material removed, per cent. of total, 2 min. | 72 | 81 | 52 | 59 | 63 | 55 | ||||||
| Material removed, per cent. of total, 3 min. | 85 | 90 | 59 | 66 | 71 | 69 | ||||||
| Material removed, per cent. of total, 4 min. | 90 | 95 | 61 | 72 | 83 | 77 | ||||||
| Material removed, per cent. of total, 5 min. | 93 | 98 | 66 | 75 | 87 | 84 | ||||||
| Material removed, per cent. of total, 6 min. | 95 | 100 | 67 | 82 | 90 | 89 | ||||||
| H. P. per ounce dust | 0. | 037 | 0. | 147 | 0. | 045 | 0. | 116 | 0. | 252 | 0. | 261 |
| Ounces dust per minute | 1. | 9 | 2. | 0 | 1. | 34 | 1. | 64 | 1. | 8 | 1. | 78 |
| H. P. at renovator | 0. | 07 | 0. | 29 | 0. | 06 | 0. | 19 | 0. | 45 | 0. | 475 |
As the sizes of the carpets used in making the tests were not always the same, allowance has been made for this variation by using, in the case of Type F renovator, instead of the true time, a calculated time which allows each renovator the same time for cleaning 1 sq. yd. of carpet. For instance, in the case of the small carpet cleaned with Type F renovator, an interval of 60 × 4.6 ÷ 6, or 46 seconds, was taken as equal to one minute’s cleaning of the carpet with types A and C renovators. Such interval is stated and plotted as one minute in the [table] opposite, which gives the results of cleaning dirty carpets with the three types of renovators.
Type A Renovator Most Efficient on Dirty Carpets.
—The results of the tests of the three types of renovators, each when it was operated with the highest vacuum under the renovator, are plotted in [Fig. 17] in order that a ready comparison may be made. This curve indicates that Type A renovator does more effective cleaning in less time than either of the other two types tested.