28 
In making a flange joint, the pipe should be flush with the face of the 
flange and the gaskets should be cut to match the interiors of the 
two pipes being connected. 
The location of taps or inlet valves for the connection of the hose 
lines deserves consideration. After the main branch lines are planned 
to reach all sections of the plant, the short leads or taps should be 
spaced or placed so that the greatest distance from any point on the 
floors or walls where the cleaning nozzles are to be used to the nearest 
tap is not greater than the effective working length of the hose to 
be used with the nozzles. Twenty-five and 50-foot lengths of hose 
are ordinarily used, although it is advisable to standardize on one 
length. The shorter hose is preferable, because of its greater port- 
ability and the heavy friction losses in hose lines. Care should be 
taken to place taps so that the hose can be attached for cleaning in 
pits or on balconies without climbing up or down to make the con- 
nection. Taps should also be arranged to eliminate the necessity 
of running the hose over or under conveyor belts, which may be in 
operation when the cleaning is being done. 
The selection of suitable hose for use with a vacuum-cleaning system 
depends to a certain extent upon the place where it will be used and 
the way in which it will be handled. A smooth interior helps to 
reduce friction losses, but the hose ordinarily used with vacuum- 
cleaning systems will not withstand the rough treatment received 
in an elevator or industrial plant. An attempt has been made to 
use metal hose, because the friction loss would be less than with 
rubber hose; but it wears out quickly. Moreover, it is heavy and 
difficult to handle. The spirally reinforced rubber hose stands up 
best under the rough treatment, but the friction losses with it are 
high. The development of a hose with a smooth interior, which is 
also capable of withstanding the rough treatment received around 
an industrial plant, will add to the general efficiency of the vacuum- 
cleaning system. 
The nozzle is the most important part of a vacuum-cleaning 
system. Nozzles of many kinds and combinations of brushes and 
nozzles have been tested. A satisfactory nozzle is one which will 
operate rapidly on a concrete floor or wall and gather up everything 
from grain and strings to pieces of concrete and even dust which 
has adhered to the floor because of dampness. The nozzle should 
rest on the floor in a natural operating position, so that the workman 
will not need to hold it at different angles to insure its successful 
operation. Bristles or a scraper may be necessary on some nozzles 
to loosen adhering material. A successful vacuum-cleaning nozzle 
has been designed and patented by the United States Department 
of Agriculture (fig. 23) . 3 
The collector or separator must be capable of handling large 
quantities of air and dust and heavier material. In some installa- 
tions, two separators or a collector and a separator are used. 
A partial separation in a collector or trap removes the heavy 
material, while the lighter dust passes on to a filter, where it is 
separated from the air, which passes on to the vacuum producer and 
is exhausted outside the building. Collectors and filters of several 
types are made. Some have a large expansion chamber, with 
3 J. O. Reed, "Improved Nozzle for Cleaners," published in American Elevator and Grain Trade, 
(August 15, 1924) vol. 43, no. 2, p. 113. 
