N. Hawkins

“ When draughting the water, bear in mind that the greater the perpendicular lift the less the quantity of water which can be pumped, remembering that it is the pressure of the atmosphere which forces the water into the pump, and not any power exerted by the pump itself, which simply produces the vacuum. Thus, the nearer the surface of the water the greater the velocity with which it enters the pump, while the higher the pump the weaker the pressure and the less the quantity of water which enters it, and at a height of about 30 feet no water at all will go into the pump. ”

“ In density there is a great difference; water, which is the type of liquids, is 770 times as heavy as air, the type of gaseous bodies, while under the pressure of one atmosphere. A spiral spring only shows elasticity when it is compressed; it loses its tension when it has returned to its primitive condition. A gas has no original volume; it is always elastic, or in other words, it is always striving to attain a greater volume; this tendency to indefinite expansion is the chief property by which gases are distinguished from liquids. ”

“ The high-class turbine pumps of to-day are simply machines in which the water is given a velocity which is partially changed to pressure before discharge, and the pump is designed so that the well-known actions, outlined above, proceed along natural lines, which are, to use the common phrase, lines of least resistance. It is simply a question of careful design.
The modern pump causes the water to flow along paths naturally due to the forces acting and to guide the stream in such a way as to avoid the production of eddies and whirls within itself which so enormously cut down the efficiency. ”

“ Liquid Air is a marvelous result of compression. It liquefies at a pressure of 573 pounds per square inch, at the reduced temperature of -220° F.; at atmospheric pressure it boils at -312° F., at which temperature it can be handled like water. Air is the vapor of a liquid, and acts in its properties like the vapor of other liquids. Liquid air in color is like that of a blue sky on a cloudless day. ”

“ When the atoms or particles which constitute a body are so balanced by a system of attractions and repulsions that they resist any force which tends to change the figure of the body, they will possess a property, known by the name of elasticity. Elasticity, therefore, is the property which causes a body to resume its shape after it has been compressed or expanded.
Fig. 339.
Pressure exerted by Gases. Gases exert on their own molecules, and on the sides of vessels which contain them, pressures which may be regarded from two points of view. First, we may neglect the weight of the gas ”

“ Most air lift propositions are deep-well cases—that is, the water is lifted a distance greater than 25 feet; and just in proportion as the lift is increased do we get away from the aerated form idea, and so when the air pressure is greater than the head of water, a certain volume of compressed air is received into the eduction-pipe, the water in this pipe is at that time moving rapidly upward; that is, its momentum has been established. Hence the air takes up this velocity and goes upward with the water from the energy received from the elasticity of the air due to its compressor. ”

“ It is essential that the machinery relied upon for fire protection should at all times be ready for instantaneous and effective service; this, because both life and vast property interests are at stake, hence of all machines made, the modern steam fire engine is produced with a niceness of finish and accuracy of fit equaled by no other, when size is considered; it approaches towards the perfection seen in the mechanism of a fine watch. ”

“ Now, if the piston should be loaded with a weight, the pressure on the outside would be that due to the atmosphere, plus the weight, while the pressure from the inside is simply equal to atmospheric pressure; thus the piston is forced to descend, but as the air inside of the cylinder has no means of escape, the volume it fills being diminished, its pressure rises until the pressure under the piston balances that above it. ”

“ A pipe fitter is one who fits pipes together, or applies pipes, as to an engine or pump. A pipe fitter uses all the tools already described and in addition several others, as stretched lines, the spirit level and plumb-bob; he also uses special devices to aid in special cases; these are sometimes invented by himself and sometimes belong to “the trade-lore” transmitted in the long and varied operations of every successful shop. A pipe fitting is a piece, as a coupling, a valve, etc., used for connecting lengths of pipe or as accessory to a pipe. ”

“ The particular feature that makes steam valuable in producing a vacuum is the fact that when it is condensed, it decreases 1600 times in volume and except for this small quantity of water and some vapor which even cool water gives off in a vacuum, a perfect vacuum would be established and it is only necessary to draw off the condensed steam and vapor by proper apparatus to enable the vacuum to be maintained which the condensation has created. The apparatus for doing this is called the air pump and the reservoir in which this condensation takes place is called the condenser. ”

“ By the aid of pressure and of low temperatures, the force of cohesion may be so far increased in many gases that they are readily converted into liquids, and we know now that with sufficient pressure and cold they may all be liquified. On the other hand, heat, which increases the vis viva of the molecules, converts liquids, such as water, alcohol and ether or gas into the aëriform state in which they obey all the laws of gases. The aëriform state of liquids is known by the name of vapor, while gases are bodies which, under ordinary temperature and pressure, remain in the aëriform state. ”

“ It must be dense enough and hard enough to resist all the working strains and influences that are likely to act upon it. The jointing of a steam pipe must resist the temperature of the steam, the water it carries with it, the changes of temperature when the pipe cools during intervals of work, and the strains due to the weight of the pipe, and also the internal pressure of the steam. If it expands differently from the metal in the pipe, it must be sufficiently elastic to compensate for this expansion, otherwise it will leak each time the pipes cool down. ”

“ It happens at times that a pump, with the full pressure against which it is expected to work, resting upon the discharge valves, refuses to lift water for the reason that air within the pump chamber is not dislodged, but only compressed by the motion of the plunger. It is well, therefore, to arrange for running without pressure until the air is expelled and water follows. This is done by placing a check valve in the delivery pipe, and providing a waste cock in the discharge chamber to be closed after the pump has caught water. ”

“ There are other evils sometimes inherent in hard waters above the mere production of a crust. Some waters contain a great deal of soluble magnesia salts, together with common salt. When this is the case there is a great probability of corrosion, for the former is attacked by steam at high pressure in such a way that muriatic acid fumes are produced, which seriously corrode the boiler, and what is far worse, passes with the steam into the engine, and sets up corrosion in the cylinders and other delicate fittings with which the steam comes in contact. ”

“ The elasticity of air and other aëriform fluids is that property by which they are increased or diminished in extension, according as they are compressed. This property exists in a much greater degree in air and other similar fluids than in any other substance. In fact, it has no known limit, for, when the pressure is removed from any portion of air, it immediately expands to such a degree that the smallest quantity will diffuse itself over an indefinitely large space. And, on the contrary, when the pressure is increased, it will be compressed into indefinitely small dimensions. ”

“ In winter, if no heater is attached to the engine, the room must be kept warm, to insure against frost.
The machine should be started gradually, but before doing so the engineer ought to satisfy himself that the joints and connections in the suction hose are air tight, that the discharge gate is open, the churn valve closed, that the fire has been properly attended to, the cylinder cocks open, the exhaust nearly closed, and all the bearings and journals well oiled, and the wheels properly blocked, especially if the engine is standing on a grade. ”

“ Uniting with the body of water in the combining tube, it imparts to it a large share of its speed, and the body of water thus set in motion, operating against a comparatively small area of boiler pressure, is able to overcome it and flow into the boiler. The weight of the water to which steam imparts its velocity gives it a momentum that is greater in the small area in which its force is exerted than the boiler pressure, although its force has actually been derived from the boiler pressure itself. ”

“ Air stored under pressure in a reservoir can be used expansively, in an ordinary steam engine returning an equivalent amount of work that was required to compress it—less the friction.
The admission of the air being through a single tube, it creates a constant flow of air in one direction only, thus filling the cylinder at each stroke with air at atmospheric pressure. This movement gives a momentum to the air which causes it to fill the cylinder to its fullest extent at each stroke. ”

“ European centrifugal pumps with their small impellers and consequent high speed of rotation, are especially liable to this repelling action, and very often are wholly inefficient from this cause. One maker who claims a high duty for his pumps, attaches a screw at the sides of the impeller to coax the water into the pump, and the idea is a good one if the difficulty is not otherwise provided for. In this way a pump can be made of smaller diameter for a given duty, but it is commonly inferior to a larger one for the same work.”—Industries. ”

“ It takes less power to feed into the bottom of a tank than it does into the top, on account of the weight of water in the tank. The bottom of the tank holds up all the water except the column directly over the opening of the delivery pipe, so that the additional pressure on the pump is due only to the depth of water in the tank, not to the size of the body, and it is impossible to feed into the top without increasing the height of the column fully as much. ”

“ Lack of space forbids following, as could be done, the growth of the modern steam fire engine from these primitive beginnings to its present high point of excellence and widely extended use. Wherever civilized men are gathered into towns and cities there can be found this admirable mechanism affording protection to both life and property. ”

“ A hydraulic dredge consists mainly of a centrifugal pump with its driving engine and boiler, and hoisting machinery for handling suction pipe and boat; the pump in operation creates a strong suction flow in the suction pipe, sufficient to pick up the material and draw it into the pump, from which it is again delivered through the discharge pipe any distance to point of delivery, and can at same time be elevated to reasonable heights. Sand, mud, silt, etc., are readily picked up by the suction force only, but where material is packed it must first be agitated. ”

“ A tank is an artificial receptacle for liquids, thus: a tank engine is one which carries the water and fuel it requires, thereby dispensing with a tender; tank-iron or steel is common plate used in building tanks. Steel is cheaper than sheet-iron. A cistern is primarily a natural reservoir—a hollow place containing water; more commonly an underground reservoir or tank. Closed pressure tanks are usually cylindrical shells similar to a horizontal steam boiler, having bumped or rounded heads to save bracing. Closed pressure tanks are used extensively in connection with hydraulic elevators ”

“ The foot piece, or nozzle, which regulates the admission of air to the discharge pipe at the point where the air comes in contact with the water, thereby makes it possible to carry air at full pressure to the end of the air pipe, and utilizes the energy due to the velocity of the discharged air.
After a well is once regulated or balanced there is but little occasion to move the adjusting wheel or valve, the starting and stopping of the flow of any particular well being accomplished by means of an ordinary valve or plug cock on the air pipe at or adjacent to the well. ”

“ A vacuum is defined very properly as an empty space; a space in which there is neither steam, water or air—the absolute absence of everything. The condenser is the apparatus by which, through the cooling of the steam by means of cold water, a vacuum is obtained. ”

“ To deal properly with this subject the science of chemistry must be largely drawn upon; chemically pure water is that which has no impurities, and may be described as colorless, tasteless, without smell, transparent, and in a very slight degree compressible, and, were a quantity evaporated from a perfectly clean vessel, there would be no solid matter remaining. Now, in dealing with the impurities inside a boiler, it is to be observed that in no sense do they change the essential nature of water itself. ”

“ Should the water being delivered by the main pumps be unsuitable for feeding the boiler, this valve must remain closed, and a supply from a barrel or tank introduced through the connection provided for that purpose.
When feeding the boiler, it is a good plan to occasionally feel the pipe leading from check to boiler with the hand, as one can tell by this means whether the pump is feeding properly. If feeding all right, the pipe will be cool. If the pipe is hot, the pump is not feeding properly, try the pet cock.
Always keep a good torch, ready for use, in the fuel pan. ”

“ In case the pump or engine works more rapidly than is intended the oil is pumped into the chamber, EE, faster than it can escape through the outlet at, C, and the piston, GG, is forced upward, raising the lever, L, with its weight, and throttling the steam. In case the pump runs more slowly than was intended, a reverse action takes place, the weight on the end of the lever, L, forces the piston, GG, down and more steam is admitted. As the orifice at, C, can be increased or diminished by adjusting the screw at, N, the governor can be set within reasonable limits to maintain any desired speed. ”

“ A compressor is a machine usually driven by steam by which air is compressed in a receiver so that its expansion may be utilized as a source of power at distances where an ordinary engine could not be conveniently used. ”

“ The fluidity of air invests it, as it invests all other liquids, with the power of transmitting pressure; fluidity is a necessary consequence of the independent gravitation of the particles of a fluid. ”

“ When the air piston draws in a charge of air, the air fills the cylinder at atmospheric pressure, or a little below, and on the return stroke of the piston it has to be compressed to the same pressure as in the receiver before it can lift the delivery valve, and as the valve is held to its seat by a spring, and also by its own weight, the pressure has to be considerably above that of the receiver before the valve will lift. ”

“ It can excite no surprise that London should have been almost wholly destroyed in the great fire of 1666, when such were the machines upon which the inhabitants chiefly depended for protecting their property and dwellings. ”

“ The power required to work pumps, of whatever construction, is saved: the exhaust injector doing the same work by the condensation of waste steam.
The waste steam, in passing through the injector, heats the feed-water to a temperature of about 190° F. The condensation in the injector of so large a quantity of waste steam reduces256 back pressure considerably, and necessarily increases the power of the engine.
It is not uncommon for these injectors to form a vacuum of a half-inch of mercury within the exhaust pipe, which of course helps the engine to that extent. ”

“ When a pump fails to start after standing for some time it should be primed by filling the barrel with water and starting the pump slowly. If after priming it fails to raise water, the suction pipe should be examined and also the plungers and the valves. If the plunger packing has become dry and hard, merely filling the water end with water will not at once remedy the trouble because the packing must be thoroughly soaked before it will work properly.
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Pumps should be packed with the same care and consideration as is used with the best steam engines. ”