The Rotrex Vacuum Cleaning System.

It is an acknowledged fact, experimentally verified, that it is impossible to entirely separate dust from air. Therefore, any system, whether it relies upon separating tanks or not, cannot prevent dust and grime from passing to the pump. Pumps with internal metallic contact, either piston or rotary, are likely to be damaged and worn by the scoring action of the dust, which, combined with the lubricating oil which such pumps require, may form in them an abrasive vitreous mass.

Since dust cannot be kept out of the pump, the latter should, if possible, be made to provide for it. Such a pump would have no internal metallic contact and would be so made as not to require oil as a lubricant. One solution of this problem is to be found in a rotary pump having a watersealed clearance. Such a pump cannot be worn by dust and does not require oil as a lubricant. In addition, if it is combined with a submerged screen, the meshes of which are just exceeded by the pump clearance, the pump does not require any dust separation whatever. Instead, the soluble material passes into solution and is discharged from the pump direct to the sewer as a stream of discolored water, while the insoluble parts collect at the screen.

The Rotrex system employed by the Vacuum Engineering Company, 25 Madison Ave., New York City, comprises these features. The apparatus is so constructed that dust and solid matter is drawn into a submerged saturating chamber, into which, due to the vacuum, a very small flow of water is maintained. The dust passing through this water becomes dissolved; the mixture is carried through the pump and automatically discharged direct to the sewer in the form of discolored water, this cycle being clearly shown in the accompanying illustration, showing a typical installation. Broad patents cover this feature, which embodies a principle essentially different from that underlying other methods.

This company has also developed a line of tools embodying some interesting operating characteristics. For instance, difficulties in the use of vacuum cleaning tools in classrooms have recently been summarized as follows:

1. The correct manipulation is not possible within the space available.

2. Nearly 80% of the dust in classrooms occurs beneath the bench where the pupil is continually scraping his or her feet.

3. This part of the floor is acknowledged to be one of the most difficult surfaces which a vacuum cleaning tool is called upon to sweep.

4. Until now, no tool on the market was capable of sweeping these sections completely; they were simply left unswept.

In an effort to meet the difficulties here enumerated a unique tool having a modified ball and socket joint has been developed by the company, and is shown herewith. A feature of this tool is that its handle is able to assume any angle necessary beneath a bench or desk, while, through a special contrivance, the operator may rotate it on the floor at will by means of the handle without disturbing its correct position. This latter feature is obtained through the use of the studs BB.

Another tool has an unusual arrangement of its wearing felts, which form dust ducts in the sides at the three corners so that the dust travels along the side of the triangle to a corner where it meets the inrushing air and passes to the pump. This tool is especially useful in reaching corners.

A tool that prevents the surface dust from being pushed along in advance of it is also shown, and is called the Perfect bare floor sweeper. The felts have openings in front and rear, as well as narrow dust ducts to the ends. The front and rear ducts direct the dust to the central orifice, and any movement in the way of a push or pull serves for its operation. This tool is equipped with a swivel joint for the raising and lowering of the handle.

This company has also developed an interesting connection for use between the tool and handle. It consists of two split rings, the rings being split in opposite directions so that any leakage in the lower ring is baffled by the upper one. This connection is now applied to all of its tools and has been found to give no trouble through sticking, while the dimensions allow for free turning of the handle in the tool. The upper or jamb ring screws down against a square shoulder in the shank,

preventing it from holding the split rings rigid.

AUXILIARY AND INCIDENTAL USES OF THIS SYSTEM.

As a means of removing water from any point of the building, in the event of the sprinkler system becoming accidentally operative, causing a flood, or in the event

NEW TYPES OF VACUUM CLEANING TOOLS.

of water from any other cause, such as leakage, causing a similar condition, and finally in case of fire, after the sprinklers have performed their function, the Rotrex system can be brought immediately into play to remove this water before it has run down to floors beneath. It can perform this service continuously, and, in addition, the apparatus is always available for this use and requires no valve or other adjustments at the machine in order to handle the water. In the event of this service being necessary, hose lines from the different outlets are concentrated to the point in question, and the water is removed and passed directly to the sewer.

The Rotrex system, by reason of its ability to handle air or water, or both, can, in the event of the failure of the sump pump, be used through its hose line to discharge this water direct to the sewer as one of its normal uses.

Its service for withdrawing obstructions in the drainage system of wash bowls, etc., by the connection thereto of a hose line, is likewise within the province of its use.

The Rotrex pump discharges all water direct to the sewer, or soil line, without any extra handling by additional pumps, and the operation of sweeping and discharging to sewer in solution is continuous and automatically performed.

awarded to the Rotrex system are the Railway Exchange Building, St. Louis, Mo., 24-sweeper plant; Hotel Biltmore, New York, 10-sweeper plant; Adams Express Company Building, New York, 12-sweeper plant.

The Challenge System of Vacuum Cleaning. Vacuum cleaning is the modern method of removing dust and litter. It is the natural complement of our own sewage systems of garbage removal. It is the final step in sanitation and removes a class of waste matter the dangers of which have until recently been underestimated.

The Challenge vacuum cleaning system, manufactured by the Creamery Package Mfg. Co., of Chicago, Ill., has been designed with a view of providing an efficient system that shall be simple, free from complications and of extreme durability. The vacuum producer, an exterior view of which is shown in Fig. 1, consists of a centrifugal exhaust fan, with horizontal bearings, mounted on the vacuum chamber in which is located the dust receptacle, and directconnected to an electric motor, or by belt to other source of power. It is built in eight sizes, for from one to six sweepers. Fig. 2, showing a No. 2 Challenge machine in sectional elevation, is representative of all sizes. Especial attention is called to the simplicity of the machine, a feature absolutely necessary to continuous satisfactory

service in residences, and most desirable in larger installations. By a unique device the vacuum and air displacement are regulated to the desired point for maximum efficiency. This feature is patented.. The bearings of the fan and also of the motor are the well-known S. K. F. Swedish ball bearings and run in a continuous oil bath, insuring perfect lubrication. There are no belts, chains, pistons, cams, valves, thrust bearings, metal surfaces in sliding contact, or other complications that cause wear, trouble and waste of power.

The Challenge is based on the principle of displacing a large volume of air with a sufficient vacuum to effect thorough cleaning. The vacuum at the tool is sufficient to draw in fine dust and dirt, while the large size openings and pipes permit free passage of large coarse litter. The piping used is 221⁄2 in. diameter or larger, according to number of tools used simultaneously. All openings are 2 in. diameter.

The advantage of large diameter piping and hose in vacuum cleaner work with respect to clogging, while important, is secondary to the reduction in power consumption.

It is well established that for efficient cleaning there is required 80 cu. ft. of air per minute at the tool for each tool in use. Using this as a standard, the following comparison of vacuum loss with pipe and hose of certain sizes will illustrate the saving in power through the use of larger pipe and hose.

In a single sweeper installation using 100 ft. of pipe and 50 ft. of hose, displacing 80 cu. ft. per minute, the vacuum loss is:

Total vac. loss. ins.13.927

VACUUM MACHINE.

5.106

0.8305 The above totals show the vacuums which it is necessary to produce at the machine in addition to the vacuum employed in useful work, i. e., cleaning, under different working conditions. Power consumed in overcoming line loss is much greater in small conduits than in the large ones.

The Challenge is a system for regular daily use. To carry out this idea the tools are designed to clean carpets and rugs, hardwood floors, walls and ceilings, radiators, upholstered furniture.

There are special devices for dusting smooth surfaces, cleaning crevices, nooks, corners and all sorts of places difficult of access. The floor and carpet tools are wide, so that a large floor or rug can be gone over and thoroughly cleaned in a short time, a feature that contributes greatly to its daily usefulness.

The Challenge machine has a large gal

FIG. 3.-DUST RECEPTACLE OF CHALLENGE SYSTEM.

vanized steel dust receptacle in the base of the machine. The receptacle, which holds several bushels, is easily removed for emptying. Fig. 3 illustrates this feature. Another advantage, especially for residence use, is that when desired the machine may be had with separable shaft connection so that the motor may be quickly disconnected from the fan and used to drive washing machines and other household appliances.

An Insulating Material Composed of Countless Shells.

An interesting description of the principal element used in the manufacture of Nonpareil high pressure pipe covering, which is made by the Armstrong Cork Co., of Pittsburgh, was given by H. W. Prentis, Jr., manager of the company's publicity department, in an address at the recent convention of the National District Heating Association.

"Ages ago," he said, "there existed in the waters that covered the greater part of the surface of the earth, thousands of different species of microscopic plants, known as diatoms. These little plants possessed the power of forming skeletons or shells for themselves of practically pure silica, from the water in which they made their home. When death ensued, the organic matter quickly decayed and was dissolved by the water, the insoluble skeletons of silica sinking to the bottom. In the course of thousands of years, great deposits of these minute skeletons were formed, many of which are found today high and dry above the sea. Some of the beds are hundreds of feet thick, and the white chalk-like material of which they are composed is called, appropriately, diatomeous earth.

Under the microscope its peculiar structure can be clearly seen. Countless bil

lions of tiny skeletons, each one hollow and filled with air.

For many years the heat insulating value of this earth was well known, but no method was available by which it could be bonded together in the various forms requisite for insulating purposes. This problem was finally solved, however.

As the earth is removed from the quarries or mines, it is stacked up in the open or under sheds and allowed to dry out thoroughly. It is then loaded into cars and shipped to the factory, where it is placed in storage. The first step in the manufacturing process is to reduce the earth to powder by passing it through several grinding machines. It then drops down to the mixers, where asbestos fibre is added. Then by means of an ingenious machine, the plastic mass is run into molds of the proper shape and thickness. After having been removed from the molds, the sections are placed in the driers, where they are allowed to season for a number of days. Finally, after being trimmed, sawed and