Vacuum chamber

“ Practically every physician advocates it, and it is compulsory in some towns and cities. Deaths have occurred from it, but they are very infrequent.
Vacuum.—The perfect vacuum, which it is impossible to produce, is space without air or atmosphere. Vacuums are made by pumping all the air out of a receptacle or chamber. In a vacuum, everything falls at the same rapidity, as there is nothing to buoy it up, a feather descending as rapidly as lead shot. ”

“ Examine the tube for vacuum by noting the sound the mercury makes when allowed to roll gently about in the large chamber. If it makes a clear, metallic click, the vacuum is good; but, if the sound is dull and the mercury sluggish in moving, the vacuum is either partially or wholly destroyed. ”

“ By this means it is possible to have several janitors working at the same time on different floors of the building, and each will be independent of the others in his control of the vacuum; although one man may finish and turn off the switch on his floor, the pump will not be stopped if the vacuum is still required by workers on other floors. ”

“ Directly behind the pulpit is a small closet containing a friction wheel, by means of which, should the electric light fail for any reason, every gas jet in The Temple can be lighted from dome to basement.
For cleaning the church, a vacuum plant has been installed, which sucks out every particle of dust and dirt. It does the work quickly and thoroughly, in fact, so thoroughly it is impossible even with the hardest beating to raise any dust on the covered chairs after they have been cleaned by this process. ”

“ The auxiliary slot or vacuum breaker permitted air to enter the cleaning slot even when the renovator was placed on a surface plate, and, owing to this feature, a high degree of vacuum never existed within the renovator. It was always [28] easy to operate and did not damage the carpet. Owing to the wide slot, articles of considerable size could be picked up, and there was always an abundance of air passing through the renovator to produce a velocity in the hose and pipe lines sufficient to carry any heavy articles picked up. ”

“ However, if the exhauster be of such characteristics and the hose and pipe lines be so proportioned that there is practically [65] a constant vacuum in the renovator, regardless of the quantity of air passing, and provided this vacuum is not allowed to exceed 5 or 6 in. of mercury, no disastrous effects will be experienced in cleaning light-weight fabrics with a straight-slot renovator having a cleaning slot not over 1⁄4 in. ”

“ It is, therefore, necessary for the exhauster to be capable of handling 140 cu. ft. of air or 70 cu. ft. of air per renovator in order to do effective carpet cleaning when carpet renovators and brushes are used in conjunction.
When two floor brushes are used with the above arrangement of pipe and hose, the vacuum must fall considerably or [113] the air quantity be greatly increased. However, the reduction in vacuum will not result in serious loss in efficiency when only brushes are in use. ”

“ The party gazed in silence and wonder for a moment at the collossal creation of the human mind, and then turned and followed their guides up a long flight of stairs to a large room under the center of the huge dome.
It was a marvelous room, filled with an intricate complication of ingenious apparatus. Upon one side was banked series after series of vacuum tubes, mounted upon long panels of shining bakelite. Another wall was completely hidden by a huge switch-board, studded with a seemingly endless array of switches, control knobs, rheostats and levers. ”

“ If the displacement pump be run at constant speed, every change in the quantity of air exhausted will cause a change in the vacuum produced. This will result in inefficient operation and may result in undue effort being necessary to operate the renovator and in excessive wear on the carpets. ”

“ In a school house containing four class rooms, where the janitor cleans the play rooms and corridors during the school period, as can be readily done with a vacuum cleaner since there will be no dust scattered about to fill the air and render it unsanitary, the class rooms can easily be cleaned in one hour by one operator. The author considers that one sweeper capacity for each six to eight rooms is ample for a large school. ”

“ When a brush or floor renovator is used on the furthest outlet from the vacuum producer at the same time that carpet renovators are being used on outlets nearer the vacuum producer, the larger quantity of air passing the brush will tend to reduce the vacuum at the hose cock to which the carpet renovator is attached and thereby impair its efficiency. ”

“ They produce about 1 in. of mercury at the carpet renovator when operated on an ordinary carpet. When small-sized upholstery renovators are used, a much higher vacuum is possible. When operated with bare floor renovators or brushes, the quantity of air exhausted is not much over 20 cu. ft. per minute and they make very inefficient bare floor and wall cleaners, but will do thorough carpet and upholstery cleaning provided a small enough renovator is used. ”

“ Therefore, the most effective and economical renovator should be that which gives the highest vacuum with the least air passing.
FIG. 23. TESTS SHOWING EFFICIENCY OF DIFFERENT TYPES OF RENOVATORS AT DIFFERENT DEGREES OF VACUUM.
If the degree of vacuum within the renovator be carried to an abnormally high degree, there will be a tendency for the renovator to cling so close to the carpet that its operation will be difficult and the wear on the carpet rapid. ”

“ In this case a 3-in. pipe will give a slightly greater friction and will be sufficient.
Unfortunately, it is rarely possible to locate the vacuum producer in as favorable a point as that given in the illustration, but an effort should always be made to select a location as nearly central to all risers as possible. The basements of modern office buildings are generally crowded and the space assigned to the mechanical equipment is limited and owing to the necessity of ventilation, the vacuum producer is generally located near the outside of the building. ”

“ Since this renovator has a wider cleaning slot than the Type A carpet renovator, and, as it is used with the same vacuum producer, hose and pipe lines, a considerable degree of vacuum will be produced under same, especially when operated on polished floors, where the conditions are nearly the same as we observed with Type A carpet renovator operated on linoleum. With the wider slot, the effort to move these renovators becomes too great for easy operation. ”

“ This makes it necessary for some one to make a tour of the building in order to close the valve which is open before the system can be efficiently operated. If the vacuum producer is designed to operate several renovators simultaneously, it may not be discovered that there are any valves open and a considerable amount of power will be wasted. ”

“ As we continue to follow the dust-laden air in its passage toward the vacuum producer we next encounter that portion of the conduit which is permanently and rigidly fixed in place in the building; namely, the pipe line, its fittings and other appliances. ”

“ While the head against which these pumps will be required to work, when assisted by the vacuum in the condenser, is much less than the total lift from low tide water to the entrance into the condensing chambers, they are so designed as to be ready to deliver the full quantity the full height, if for any reason the assistance of the vacuum should be lost or not available at times of starting up. ”

“ There is no trouble at all about installing the stationary vacuum cleaner after the building is erected, but naturally it is less expensive to put it in during the building and when planned for ahead than it is to put pipes through a house after it is built. ”

“ When the head of the excavation is very far from the entrances, or when the mountain is too high to allow excavation by shafts, it is quite impossible to secure good natural ventilation, especially during the spring and autumn months, and the engineer has to resort to some artificial means by which to supply fresh air to the workmen.
Artificial Ventilation. —Artificial ventilation in tunnels may be obtained in two different ways, known as the vacuum and plenum methods. ”

“ A vacuum cleaner might show in a technical test a tremendous vacuum and when used on the carpet the nozzle be so constructed as to mitigate the power of the suction so created and, therefore, be ineffectual as a cleaner. Therefore, the salesman can talk glibly to the uninformed about [51] vacuums and tests and never say “but our nozzle is so large or so high or so low that the air intake is bad.”
Too much vacuum often makes the machine heavy by sucking too heavily upon the carpets. ”