VALVES AND COCKS.

The wordvalvecomes from the Latin—valva—a leaf, fold or valve of a door (as of a folding door).

A valve may act automatically so as to beopenedby the effort of a fluid to pass in one direction andclosedby its effort to pass in the other direction, as a clack valve; or it may be opened or closed by hand or mechanism, as a screw valve or a slide valve.In the glossaryat the beginning of this work, the word has been carefully defined and several illustrations have been given of various designs of the device which have come into general use.

Valves are of several classes.

1.Rotary; such ascocks,faucets,plug throttle-valves.

2.Lifting; raised clear from the seat by power beneath; such asball,conical,cup,safety,poppet.

3.Hinged; such asclack,butterfly.

4.Sliding; such as theslide,D,Bandbox.

5.Spring; such assome forms of safety-valves, Snifting and Relief valves.

6.Inverted-cup; such asquicksilver valve,air trap, etc.

7.Key; such as those of theorgan,flute, etc.

Other names are derived from peculiar shape, application, mode of actuation, etc.

A cockis a faucet or rotary valve usually taking its name from its peculiar use or construction, as:—

Blow-off cock,Cylinder-cock,Feed-cock,Four-way cock,Gage-cock,Oil-cock,Self-closing cock,Steam-cock,Stop-cock,Three-way cock,Try-cock,Water-cock, etc.Note.—The above classification is that made by E. H. Knight, Civil and mechanical Engineer, etc., and author of Knight’s Mechanical Dictionary. He adds: “The heart is created upon the principles of hydraulics, and is furnished with a valve. Harvey deduced the circulation of the blood from Aquapendente’s discovery of thevalves in the veins.”

Blow-off cock,Cylinder-cock,Feed-cock,Four-way cock,Gage-cock,Oil-cock,Self-closing cock,Steam-cock,Stop-cock,Three-way cock,Try-cock,Water-cock, etc.

Note.—The above classification is that made by E. H. Knight, Civil and mechanical Engineer, etc., and author of Knight’s Mechanical Dictionary. He adds: “The heart is created upon the principles of hydraulics, and is furnished with a valve. Harvey deduced the circulation of the blood from Aquapendente’s discovery of thevalves in the veins.”

As may be judged by the preceding paragraphs, giving the names derived from their mechanical and other uses of several only, of a great many varieties of valves, it were vain to attempt a complete list of these devices; it may be said however that the whole system of modern mechanism would be, almost, if not quite, a failure, if they were not used.

Hence, the student will do well to familiarize himself with the valve movements sure to be found in every combination of industrial and mechanical forces.

A few illustrations of the adaptation of valves of various designs to useful purposes now follow.—

A combined throttle and quick closing trip valveis shown in Fig.609, page 336; this is made by Schutte & Koerting Co., Philadelphia; this apparatus is designed to fill the requirements ofan emergency shut-off; the valve is balancedand operates as stop and throttle. The object of balancing the valve is to remove the strain from the spindle, so that its operation can be effected quickly and with the least effort. The piston above the valve is not tight fitting, and containsa small auxiliary or pilot valveattached to the spindle, which opens in advance of the opening of the main valve; thus the pressure above the piston and below the valve is equalized; little effort is now required to lift the main valve, at the same time the pilot valve, E, answers the purpose of a by-pass.

The several proportions are such that a slight over-pressure is maintained above the piston to give the valve, at all times, a tendency to close. This over-pressure should be but slight, and to regulate it at will there is (besides the leak around the piston)a separate steam admission above the piston, regulated by the plug, C.

Depending on the fit of the piston, this plug is opened more or less, or entirely closed, when valve is first put in operation, and then locked in that position.

Ordinarily the construction of this valve demands the application of a screw-spindle to actuate it;it is also made in angle form and can be placed with spindle upward or horizontal.In all positions, globe, inverted and angle valves, steam must always enter above the disc, viz., in the direction of the arrows.

Fig. 633.

The operation by lever is demanded when a valve is used as a quick emergency shut-off, either by hand or in connection with automatic appliance of governor, electrical cut-off or auxiliary, steam, air or hydraulic cylinder.

The valve itself is of the balanced form, except that in this valvethe spindle carries at the bottom a small piston or sleeve, F, shown in the figure. The valve is locked open by moving hand lever up till the catch on same engages with the lever, G, supported on the upright bar.

The valve being then open, steam pressure acts on the area of the piston, F, with continuous downward force, which will cause the valve to close as soon as the latch is released. Thus, by connecting the rod on the outer end of lever, G, with a hand lever, at any desired location, the operation is had without effort and promptly.

A pressure reducing valveis shown in outline and a side view in Figs.633and634; this is in effect a (Mason) pump pressure regulator and it is applicable for fire, tank, elevator, air and water works pumps, or any class of pumping machinery where it is necessary to maintain a constant pressure. The regulator may be quickly adjusted to any pressure desired by turning the key as shown in Fig.633.

The especial feature of this regulator is that the pressure chamber into which the water enters is entirely removed and separate from the steam and all working parts.

The long cylinder at the bottom of the regulator is a dashpot, the piston of which is connected with the main valve ofthe regulator, thereby preventing sudden and violent “jumping” of the pump when the pressure suddenly changes. These valves are made in all the pipe sizes; those up to and including 2-inch of the best steam metal; the largest sizes of cast iron, lined with steam metal.The springs are made of the finest tool steel, tempered.

Fig. 634.

The Mason Regulator Co., Boston, are to be credited with the following directions:

The regulator is placed in the steam pipe leading from the boiler to the steam pump and as near the pump as possible. The connection with the water system is made either from the tank or from the water system, at some little distance from the pump. Brass pipe should be used if possible, for this connection. The drip should be connected to some pipe where there is no back pressure. The steam from the boiler enters at the point marked “steam inlet from boiler,” and thence through the passage, X, through the port, which is kept open by the tension of the spring, 79, upon the auxiliary valve, 80. It continues down through the passage, Z, to the under side of the differential piston, 70, and raises the valve, 16, so that the boiler pressure is admitted to the pump through the passage marked “steam outlet to pump.” This starts the pump, which continues in motion until the required water pressure is obtained in the system and acts through the connection marked “water pressure inlet” on the diaphragm, 74. This diaphragm is raised by the excess of water pressure, and carries with it the auxiliary valve, 80, which closes the port for steam pressure. By the closing of this valve, the boiler pressure is shut off through the passage, Z, from the differential piston, 70, and the steam pressure from the boiler immediately closes the main valve, 16, so that no more pressure is admitted to the pump, which remains inactive until the water pressure in the system drops below the normal joint andrelieves the water pressure in the chamber, O, which causes the auxiliary valve, 80, to open again, and starts the pump as before described. The check valve, 71, which is placed in the bottom of the piston, 70, allows the pressure regulator to open easily, but stops the pump quickly. This is a great advantage, as the pump will not start with a jump, the moment the water drops. By changing the tension of the spring, 83, through the key stem, 85, the amount of water pressure can be regulated.

Fig. 635.

Mason water reducing valve.Fig.635is designed to reduce the water pressure from the street water mains to a low pressure, for houses and buildings. The body or valve portion is fitted with couplings, so that it may be easily attached to a pipe. That part of the valve above the diaphragm, and which comes in contact with the water, is made of the best steam metal, thus preventing corrosion. The long spring case is made of heavy iron pipe, at the end of which is an iron bracket, suitably drilled, so that the valve may be securely bolted either to the floor or to a beam overhead. The tension of the main spring is adjusted by means of a small rod inserted in a nut at the end of the spring case. The diaphragm is very strong and will hold several times the pressure required. The working of this regulator is very simple. The water enters through the inlet coupling, 45, and passes through the chamber, 68, into the low pressure side of the regulator, the valve, 43, being held open by the tension of the spring, 53. When the low pressure has attained the desired limit, which is also felt in the diaphragm chamber through the hole which communicates with the chamber, 68, it forces down the diaphragm and seats the valve, 43. When the pressure again drops in the system, the diaphragm is forced up by the spring, 53, and the valve, 43, again opens.

An automatic throttle valvefor a boiler feed pump is shown perspective and outline in Figs.636and637; this is a governor for the pump, controlled by the relative pressures of steam and water. It is known asMullin’s automatic controllerand is made at Seattle, Wash., and has the following features:

Fig. 636.

It is simply a balance valve and differential piston; it is in a class by itself, both as to its construction and operation in regulating feed water pressure in connection with steam boilers.

Fig. 637.

The initial steam pressure being on the ends of the valve, has access, through the neck, to the full area of the piston, andwill force it into a position that gives the full valve opening, where it will remain until overcome by water pressure from the pump, acting against the opposite side, which is of reduced area.

It is necessary in operating this valve to havean excess of water pressure over the steam pressurein the boiler. The excess of the water pressure is obtained by the reduction of the area of the water side of the piston—thus to illustrate—if the total area were 10 square inches, and the reduction was one inch or 10 per cent., it would require that the water pressure should be 10 per cent. greater than steam pressure, to give the same thrust on the piston, then until the water has reached a pressure 10 per cent. in excess of the steam, the valve would be held open, but thereafter it is held open only wide enough to admit steam to the pump to keep up this 10 per cent. excess pressure. Should the excess pressure attempt to rise above this, it immediately forces the steam valve nearly shut, thus nipping the cause of the rise, namely, too great a piston speed.

Note.—“In starting the pump, ‘stand by’ until it has caught suction, and accumulated nearly the correct water pressure, now open the valve on the pulse, or pressure pipe to the controller and open pump throttle wide, thus giving the controller free action.“Suppose the boiler pressure is 100 pounds, the water pressure will be 10 per cent. higher or 110 lbs. Carrying an even fire, with water at second gauge, feed valves properly set, the load suddenly increases, which pulls steam down to 99 pounds, the water does not remain at 110 lbs. as before, but is now 10 per cent. in excess of 90 lbs. or 99 lbs., thus in place of 10 lbs. excess water pressure there is but 9 lbs., which means there will be less water delivered through the feed valves, which will hardly ever have to be touched.“Next the load will lighten—steam will rise, and the excess pressure will automatically increase, thus restoring the water used at a time when it was most necessary to lighten the feed to temporarily favor the fire.“Suppose the load continues light, with good fires, steam rises to 110 pounds, the water will rise to 10 per cent. more pressure or 121 pounds, thus automatically giving more pressure to ‘feed up’ on high steam, and store away the heat that would be wasted by radiation, absorption, or perhaps blowing off.”

“Suppose the boiler pressure is 100 pounds, the water pressure will be 10 per cent. higher or 110 lbs. Carrying an even fire, with water at second gauge, feed valves properly set, the load suddenly increases, which pulls steam down to 99 pounds, the water does not remain at 110 lbs. as before, but is now 10 per cent. in excess of 90 lbs. or 99 lbs., thus in place of 10 lbs. excess water pressure there is but 9 lbs., which means there will be less water delivered through the feed valves, which will hardly ever have to be touched.

“Next the load will lighten—steam will rise, and the excess pressure will automatically increase, thus restoring the water used at a time when it was most necessary to lighten the feed to temporarily favor the fire.

“Suppose the load continues light, with good fires, steam rises to 110 pounds, the water will rise to 10 per cent. more pressure or 121 pounds, thus automatically giving more pressure to ‘feed up’ on high steam, and store away the heat that would be wasted by radiation, absorption, or perhaps blowing off.”

The water pressure will vary only as the steam pressure varies, always keeping the same per cent. of excess. The results are directly opposite to what would or does occur where feed water is delivered at a stated pressure. On a battery of boilers, during the cleaning of fires, the closing of feed valves on one, two or more boilers, does not affect the feed of those already set in the least, the pump will simply make less strokes necessary to properly feed the others.

The regulating is done by the feed valves at the boilers; if it is desired, all feeds may be closed, and the pressure will not rise, the pump will stop; if its plungers need packing it will be detected by the fact that the pump will creep, to keep up the required pressure. When feed valves are once regulated to admit the required amount of water, to replace the evaporation,they may be marked, and when in this position, they, with an even steam pressure, will always admit the same amount of water to the boilers.

It is understood that this valve is placed between the ordinary throttle valve and the pump.

Fig. 638.

Fig. 639.

The Bordo blow-off valveis shown in Figs.638and639; it consists of a brass or iron body which resembles the shell of a plug-cock, but with this difference, it has a sharper taper than the regular plug-cock; in this device the plug is usually made of brass—tinned on the outside. In process of making and whilehot a sheath of babbitt metal or its equivalent is cast upon the plug; the metals amalgamate and practically become one casting.

The parts of valve are as follows, 1, the body, 2, the plug, 3, the packing and lifting gland, 4, the lifting cam, 5, lock-nut, 6, two brass rings of equal size, with a special gasket between them—all as shown in the engravings.

The valve is operatedwith a wrench on the square of the plug. The lifting gland when adjusted is permanently held by a lock-nut. By releasing the lock-nut with the wrench and turning the gland to the left, the plug is lifted so that it will turn easily. When the lock-nut is moved up, the lifting cam (which couples the packing gland to the plug) can be pulled out; the gland is then free to be removed for repacking. In use the best method of handling is to open and close the valve slowly—never with a jerk.

Fig. 640.

The tendency toward higher pressuresteam boiler installation has made apparent the need of a blow-off, like this one described,made of strong material and correct in principle; in fact the high steam pressures now carried have almost made a revolution in boiler appliances.

The Fig.640represents two valves applied to the end of a blow-off pipe. The valve next to the boiler is open at all times excepting when the operating valve, next to the sewer is to be attended to for repairs, etc.

The table below isintended to correspond with the letters to be seen in the illustration, Fig.640.

Table.

SizeinInchesDiam.ofFlangeCentretoFaceCentretoBottomCentretoTopCentretoBottomDiam.of BoltCircleNo.ofBoltsDiam.ofBoltsThick.ofFlangeABCDEI141⁄221⁄241⁄241⁄221⁄831⁄441⁄211⁄1611⁄4523⁄451⁄851⁄421⁄233⁄441⁄23⁄411⁄2631⁄457⁄8623⁄441⁄245⁄813⁄16261⁄233⁄4771⁄433⁄8545⁄87⁄821⁄271⁄241⁄481⁄485⁄8457⁄843⁄41381⁄4591⁄21045⁄865⁄885⁄811⁄8

One cock of this pattern is usually employed, but to use two (as shown in the figure) is the best practice especially for high steam service.

Note.—It will be easily understood that the B. O. is an abbreviation; it stands for Bordo. The makers claim for the device that, 1, it will not stick or jam, 2, it keeps it seat under pressure, 3, it has full pipe area in ports, 4, it is easily adjusted to take up wear and, 5, it opens and closes with a quarter turn and with a very short wrench.

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