| Size of Hose, In. Diameter. | Length, in Feet. | ||||
|---|---|---|---|---|---|
| 100 | 75 | 50 | 25 | ||
| Free air, cubic feet per minute. | |||||
| 1 | 36 | 43 | 54 | 74 | |
| 1 | ¹⁄₄ | 49 | 56 | 68 | 94 |
| 1 | ¹⁄₂ | 68 | 78 | 94 | 130 |
These figures show a considerable reduction from those obtained with the brush type of floor renovator, particularly when the larger sizes of hose are used, and considerable reduction can be made in the capacity of the exhauster and still obtain the best results when using carpet renovator and bare floor renovator simultaneously.
The horse power at the hose cock required to operate these felt-faced floor renovators with different sizes and lengths of hose are:
TABLE 15.
Horse Power Required at Hose Cock to Operate
Felt-Covered Floor Renovators in Conjunction
with Type A Renovators.
| Size of Hose, In. Diameter. | Length, in Feet. | ||||
|---|---|---|---|---|---|
| 100 | 75 | 50 | 25 | ||
| Horse power at hose cock. | |||||
| 1 | 1.0 | 1.19 | 1.49 | 2.05 | |
| 1 | ¹⁄₄ | 0.72 | 0.83 | 1.0 | 1.39 |
| 1 | ¹⁄₂ | 0.79 | 0.93 | 1.13 | 1.56 |
In this case, the 1¹⁄₄-in. hose is the most economical size to use, as was the case with the brush renovators. However, the advantage over the 1¹⁄₂-in. hose is not as great as with the brush renovator.
With this type of renovator, the manufacturer has some control over the length of hose which the operator will use in connection with the bare floor renovator, as he may open the ends of the renovator just sufficiently to produce 2 in. of vacuum under same with, say, 50 ft. of hose. Then, if the operator should attempt to use the renovator with 25 ft. of hose, it will stick and push hard and he will soon learn that a longer hose is necessary.
Conditions for Plant of Small Power.
—For locations where it is desirable to sacrifice efficiency somewhat to reduction in the amount of power required, as in residences, the Type A carpet renovator may be used and the vacuum under the same reduced to 2 in. mercury, which will still do effective cleaning, but at a slower rate, as was shown by tests in [Chapter III]. This requires not exceeding 20 cu. ft. of free air per minute.
With this quantity of air the velocity in the hose must be considered as, in order to have a clean hose at all times, it is necessary to maintain a velocity in the hose of not less than 40 ft. per second. Referring to the diagram, [Fig. 48], it will be seen that this velocity will not be obtained in any hose larger than 1¹⁄₄ in. and this is, therefore, the largest size which can be used. In all the former cases the velocity was so much in excess of this minimum that its consideration was not necessary.