FIG. 50. ANOTHER TEST SHOWING FRICTION LOSS DUE TO VELOCITY.
This indicates, first, that a much lower friction loss will result with the use of larger hose than is the case with the smaller size. Note, also, that the difference in the final vacuum at the hose cock is much more uniform when the larger-sized hose is used in varying lengths. Since it is desired to maintain a constant vacuum at the renovator at all times and it is also desirable to be able to vary the length of hose to suit the conditions of the work, while it is not convenient to vary the vacuum at the hose cock, much more uniform results will be possible when larger hose is used. If the smaller hose is used in varying lengths and a practically uniform vacuum is maintained at the hose cock, the quantity of air and the vacuum at the renovator will vary. If 1-in. hose is used and the vacuum at the hose cock be maintained at 10 in. mercury, the air quantities and vacuum at the renovator will be approximately:
TABLE 7.
Air Quantities and Vacuum at Renovator with 1-in. Hose
and 10-in. Vacuum at Hose Cock.
| Length of Hose, feet. | Vacuum at Renovator, in. hg. | Air, cu. ft. | H. P. at Hose Cock. | ||
|---|---|---|---|---|---|
| 100 | 4 | ¹⁄₂ | 29 | 0 | .80 |
| 75 | 5 | 32 | 0 | .885 | |
| 50 | 6 | ¹⁄₂ | 34 | 0 | .94 |
| 25 | 7 | ¹⁄₂ | 37 | 1 | .02 |
From this it is evident that the vacuum within the renovator will be increased above that necessary for economical cleaning. It will require somewhat more effort to push the cleaner over the carpet and also a slightly greater expenditure of power at the hose cock to operate the cleaner with a short than with a long hose. However, the author does not consider that either the increase of effort to push the renovator or the increase of power will be sufficient to prohibit the use of 1-in. hose with the Type A renovator.
If we use 1¹⁄₄-in. hose with Type A renovator and maintain a vacuum of 6 in. of mercury at the hose cock, the resulting vacuum and air displacement at the renovator will be:
TABLE 8.
Air Quantities and Vacuum at Renovator with 1¹⁄₄-in. Hose
and 6-in. Vacuum at Hose Cock.
| Length of Hose, feet. | Vacuum at Renovator, in. hg. | Air, cu. ft. | H. P. at Hose Cock. | ||
|---|---|---|---|---|---|
| 100 | 4 | ¹⁄₂ | 29 | 0 | .43 |
| 75 | 4 | .7 | 30 | 0 | .445 |
| 50 | 5 | .0 | 33 | 0 | .448 |
| 25 | 5 | .4 | 35 | 0 | .518 |
This table shows a more uniform degree of vacuum at the renovator with the varying length of hose, but the greatest difference is in the horse power required at the hose cock to accomplish the same results at the renovator.