With a vacuum of 2 in. of mercury in the renovator and 20 cu. ft. of air passing, the vacuum at the hose cock will be:
TABLE 16.
Vacuum at Hose Cock, with 2-in. Vacuum
at Type A Renovator.
| Size of Hose, In. Diameter. | Length, in Feet. | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| 100 | 75 | 50 | 25 | ||||||
| Vacuum at hose cock, in. hg. | |||||||||
| 1 | 4 | 3 | .5 | 3 | 2 | .5 | |||
| 1 | ¹⁄₄ | 2 | .6 | 2 | .45 | 2 | .3 | 2 | .15 |
In this case the increase in vacuum at the renovator would not be objectionable as, with 4 in. vacuum at the hose cock, the vacuum at the renovator would never reach the standard used with the former deductions and the volume of air passing could, therefore, never reach 29 cu. ft. Any increase, due to the use of shorter hose, would, therefore, be an advantage in its approach toward the standard set for the larger plants. Therefore, we will assume that a vacuum of 4 in. mercury will be maintained at the hose cock with 1-in. hose and a vacuum of 2¹⁄₂ in. at the hose cock with 1¹⁄₄-in. hose.
The renovators for bare floor work will be the felt-covered type and will be opened at the ends just sufficiently to limit the vacuum within the same to 2 in. mercury when operating with 25 ft. of hose. This will require the passage of 40 cu. ft. of free air per minute when 1-in. hose is used and 35 cu. ft. when 1¹⁄₄-in. hose is used. The horse power at the hose cock will be 0.39 H. P. with the 1-in. diameter hose and 0.17 H. P. with the 1¹⁄₄-in. hose. Here again we see that the 1¹⁄₄-in. hose is the more economical to use.
If bristle brushes are used with this system at the same time that carpet renovators are in use, the quantity of air which will have to pass them, in order to maintain the vacuum on the system at the proper point to do effective cleaning with the carpet renovators, will be:
TABLE 17.
Air Quantities When Bristle Bare Floor Renovators
Are Used in Conjunction with Type A
Carpet Renovators at 2 in. Hg.
| Size of Hose, In. Diameter. | Length of Hose, in Feet. | ||||
|---|---|---|---|---|---|
| 100 | 75 | 50 | 25 | ||
| Free air, cu. ft. per minute. | |||||
| 1 | 30 | 36 | 42 | 60 | |
| 1 | ¹⁄₄ | 41 | 48 | 60 | 80 |
The use of these brushes in plants of more than one-sweeper capacity would require the use of an exhauster of greater capacity than is required for either the carpet or the bare floor renovator. Where the plant is of but one-sweeper capacity, the quantity of air that would pass these brushes, were the plant of proper capacity to serve the carpet and floor renovators, would not be sufficient to do effective work, as was explained in [Chapter IV]. In such cases, this arrangement should be prohibited.
A system of the type just described is what has been termed by the author as a “small volume” plant in [Chapter IV].