Chapter X: Part 10

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Now screw up the stuffing-box nut (having previously removed the packing), then move the valve and stem so that the small port at right of valve will be open 1/16 inch and make a scratch upon the stem close to stuffing-box nut. The valve should then be moved in the opposite direction to open the other small port 1/16 inch and make a second scratch upon the valve stem next to stuffing-box nut. Prepare joint and replace steam chest on cylinder. To square the valve, slacken the screw in crosshead and move the latter to the end of stroke with edge of crosshead flush with the end of guide, then set the valve stem so that the first scratch is flush with the face of nut, same as when the scratch was made. Tighten screw in set screw under valve rod dog and move the crosshead to the opposite end of stroke, and note the position of second scratch. If it does not come to the position in which it was made, _split the difference by slackening the set screw under valve rod dog and move the valve rod to equalize the travel of valve_.

In replacing steam chest on cylinder, cover the opening with a thin board, or piece of sheet iron, before turning it over to prevent the valve from dropping out of place.

This slide valve has a fixed travel and _the process of setting is precisely the same as for that upon a steam engine with a plain slide valve_.

SMITH-VAILE SINGLE PUMP.

The accompanying sectional view of steam end of the “Smith-Vaile” exhibits some very novel features. So far as the piston and cylinder in this pump are concerned they are not unlike the average first class pump, but with this difference. It has only one set of cored ports, B, B. The supplemental ports, C, C, are drilled.

The main valve, A, is a slide and is moved by a valve piston, D. Almost all the valve pistons as now made are simply plugs turned accurately to fit the holes in the chest and without any means of adjustment to compensate for wear. After these valve pistons become worn they have to be replaced with new ones, but there is a period between the time when the valve piston becomes so leaky as to render the action of the pump uncertain and the time when the worn valve is replaced by a new one that the pump is very wasteful of steam.

The valve piston in this pump is provided with packing rings, E, E, which compensate for wear of these parts so that this valve is expected to do efficient service long after a slow valve. The supplemental valve, F, has a reciprocating rotary motion which is communicated to it by the rock arm, G, and pitman, H, connecting with the crosshead, I, secured to the piston rod. It will be observed that the piston rod, J, and the rod, K, of the water end are separated so that should either one give out through wear or accident it can be replaced without sacrificing both, as would be the case if they were solid in one piece. This supplemental valve, F, in general appearance very closely resembles the “Corliss” valve, and its action is somewhat similar, in controlling the action of the valve piston, which will be understood from the engraving without further description. These pumps all have removable water ends and can be rebored or otherwise manipulated without disturbing the steam end of pump. The cylinder can be separated from the foot by removing the bolt, M.

The duplex pump is also shown in the accompanying engraving, where, A, A, represents the steam cylinders, secured to the foot, B, by bolts, as previously described.

The usual slide valves have been replaced by piston valves, C, in this instance and are provided with removable seats, D, D.

These piston valves have packing rings, E, E, also to compensate for wear and the valves are cast hollow to reduce their weight as much as possible consistent with good workmanship, also to serve as ports for steam admission. When these valve seats become worn they may be easily removed and rebored or replaced by new ones, as desired. It will be observed that these ports are very short to reduce the clearance as much as possible, and to secure a more satisfactory cushion. Each valve is operated by the rock arm connected with the opposite engine in the usual way.

THE DUPLEX
PUMP

THE DUPLEX STEAM PUMP.

_The word duplex_ means two fold, or double, and has a wide application, as the duplex lathe, the duplex watch, etc., hence, the well-known duplex-pump is one in which _two direct acting pumps are placed side by side_ and so connected that the steam piston of one operates the valve of the other. See Fig. 300.

Fig. 301 shows one of the smallest manufactured patterns of this type of pumps. Its dimensions are as follows: 2-inch diam. steam cylinder; 1-1/8-inch water cylinder; 2-2/3-inch stroke. Its capacity is .044 gallons per revolution; rev. per minute, 80; gallons per minute, 3.5. Steam pipe, 3/8-inch; exhaust pipe, 1/2-inch; suction pipe, 1-inch; discharge, 3/4-inch. Floor space occupied, 1´ 9″ × 7″ wide; requires 1/2 H.P.

The valve motion (see Figs. 302, 303) of one cylinder is communicated or produced by the piston of the other through the medium of rocker arms and links. By means of the small lost motion of the levers the pistons have a slight pause at the end of each stroke, which allows the water valves to seat quietly, thus preventing any slam or jar.

With this arrangement, as one of the steam valves must always be open, there can be no dead point, thus removing the liability of the pump to stick. The simplicity of the duplex movement is at once evident, each valve is dependent upon its counter part, and both directly control the action of the steam, which is supplied through one simple throttle valve.

NOTE.—Of the effect produced by the steam-moved direct-acting pump of
much greater capacity it may be said there are now in use pumps of
this class, exerting over 250 horse-power, delivering five million
gallons of water in twenty-four hours through main pipes, say thirty
inches diameter and fourteen miles long, without the use of an air
chamber, and which do their work so quietly, steadily, and gently,
that a nickel coin set on edge on the extreme end of the pump would
not be overthrown by any jar or motion of the pump while it was doing
this work.

_The adoption of the Worthington design of duplex pumps_, has been well nigh universal, especially so since the expiration of the earlier patents. Nearly all leading manufacturers now make “duplex pumps.” Single, compound and triple expansion.

Compounding consists of adding a second steam cylinder on the end of the high pressure in use, both using the same piston rod, the steam from the boiler being first used in the smaller cylinder, and at the end of the stroke of the piston being exhausted behind the piston of the larger cylinder on its return stroke. In this way the measure of the expansion of the steam used, was the relation of one cylinder to the other.

By this arrangement a much smaller steam cylinder, for using the high pressure steam, could be adapted to do the same work, for in addition to the pressure of steam working full stroke in the small cylinder, was to be added the pressure of the steam being expanded in the large cylinder.

In addition to this, for large compound and triple expansion engines was added the further economy realized by attaching a condenser to form a vacuum in the large steam cylinders.

Adapting these newer improvements in the marine engine coupled with what had previously been accomplished in the direct-acting steam pump, they were at once brought up in size, capacity, and economy alongside the previously constructed rotative pumping engines.

The history of the invention of this pump is given on pages 69 and 70; to these pages a careful attention is advised, as they briefly describe also the fundamental principles of its operation. This form of steam pump has been so long and generally in use that the valve mechanism is already familiar to most engineers.

The simplicity of both its theory and its practical application obviates the necessity of devoting very much space to its consideration. The final improvement made by Worthington in connection with the steam duplex pump was in the adaptation of triple expansion in its steam ends.

THE WORTHINGTON DUPLEX PUMP.

The illustrations, Figs. 302 and 303, are sectional views of one side, or half, of the Worthington steam pump, showing two different designs. They illustrate the interior arrangement of the pump. The valve, as may be seen at, E, is an ordinary slide valve; the motion of this valve is controlled by a vibrating arm, F, which swings through the whole length of the stroke. The moving parts are always in contact, which ensures smooth and even motion.

_This valve motion is the prominent and distinguishing characteristic of the Worthington duplex pump._ Two steam pumps are placed side by side and so combined that one piston acts to give steam to the other, after which it finishes its own stroke and waits for its valve to be acted upon by the other pump before it can renew its motion. This pause allows the water valves to seat quietly, and removes any harshness of motion. As one or the other of the steam valves is always open, there is no dead point, and therefore the pump is always ready to start when the steam is admitted.

_In the plunger and ring pattern_, Fig. 302, there is a double-acting plunger, B, working through a deep metallic ring bored to fit the plunger. The plunger is located some inches above the suction valves, leaving a _settling chamber_, into which any foreign substance may fall out of the way of the wearing surfaces. Both the plunger and ring can be taken out and either refitted or, when necessary, renewed. The valves consist of small discs of rubber, or other suitable material, and are easily accessible through convenient handholes. This pattern is recommended where the liquid to be pumped contains small quantities of grit or foreign material, or where there is an unusually long or high suction lift.

_In the piston-pattern pump_, Fig. 303, there is a packed water piston, G, working in a brass-lined cylinder, H. Both the suction and the discharge valves are located above the water pistons, so that the pistons may be at all times submerged. This pattern is recommended where the liquid to be pumped _contains no grit or foreign material_.

Fig. 304 _shows the Worthington Admiralty pattern boiler feed pump_ which is designed to meet the requirements of the United States Bureau of Steam Engineering for steam boiler pressure up to 250 lbs. to the square inch. The ordinary slide valves are replaced by piston valves with outside, adjustable, lost-motion links, making it possible to readily adjust the stroke. The water end is made of composition, gun metal, or cast-iron, as desired. When made of cast iron the water end is brass-fitted throughout.

TABLE OF SIZES, CAPACITIES, ETC.

===========+===========+========+=================
| | | Horse-power
| | | of Boiler based
| | | on 45 pounds of
| | | water per hour,
| | | which this
Diameter of|Diameter of| Length | pump will
Steam | Water | of | supply at
Cylinders | Pistons | Stroke | slow speed.
-----------+-----------+--------+-----------------
4-1/2 | 2-3/4 | 4 | 170
5-1/4 | 3-1/2 | 5 | 280
6 | 4 | 6 | 470
| | |
6 | 4-1/2 | 6 | 590
7-1/2 | 5 | 6 | 670
9 | 6 | 6 | 960
| | |
7-1/2 | 4-1/2 | 10 | 800
9 | 6 | 10 | 1400
10 | 7 | 10 | 2200
| | |
12 | 8-1/2 | 10 | 3200
12 | 9-1/4 | 10 | 3800
14 | 10 | 15 | 4800
-----------+-----------+--------+-----------------

===========+===========+========+======================================
| | | Sizes of Pipes for
| | | Short Lengths
| | | To be enlarged as
| | | length increases.
| | +-------+---------+---------+----------
Diameter of|Diameter of| Length | | | |
Steam | Water | of | Steam | Exhaust | Suction | Delivery
Cylinders | Pistons | Stroke | Pipe | Pipe | Pipe | Pipe
-----------+-----------+--------+-------+---------+---------+----------
4-1/2 | 2-3/4 | 4 | 3/4 | 1-1/4 | 2 | 2
5-1/4 | 3-1/2 | 5 | 1 | 1-1/2 | 2-1/2 | 2-1/2
6 | 4 | 6 | 1-1/2 | 2 | 4 | 3
| | | | | |
6 | 4-1/2 | 6 | 1-1/2 | 2 | 4 | 3
7-1/2 | 5 | 6 | 1-1/2 | 2 | 5 | 4
9 | 6 | 6 | 2 | 2-1/2 | 5 | 4
| | | | | |
7-1/2 | 4-1/2 | 10 | 1-1/2 | 2 | 4 | 3
9 | 6 | 10 | 2 | 2-1/2 | 5 | 4
10 | 7 | 10 | 2 | 2-1/2 | 6 | 5
| | | | | |
12 | 8-1/2 | 10 | 2-1/2 | 3 | 6 | 5
12 | 9-1/4 | 10 | 2-1/2 | 3 | 6 | 6
14 | 10 | 15 | 2-1/2 | 3 | 8 | 6
-----------+-----------+--------+-------+---------+---------+----------

===========+===========+========+=========================
| | |
| | | Approximate Space
| | | Occupied
| | | Inches
| | +--------+-------+--------
Diameter of|Diameter of| Length | | |
Steam | Water | of | Height | Depth | Width
Cylinders | Pistons | Stroke | | |
-----------+-----------+--------+--------+-------+--------
4-1/2 | 2-3/4 | 4 | 38 | 18 | 23
5-1/4 | 3-1/2 | 5 | 46 | 22 | 29
6 | 4 | 6 | 50 | 23 | 32
| | | | |
6 | 4-1/2 | 6 | 50 | 23 | 32
7-1/2 | 5 | 6 | 54 | 28 | 33
9 | 6 | 6 | 57 | 27 | 36
| | | | |
7-1/2 | 4-1/2 | 10 | 66 | 28 | 33
9 | 6 | 10 | 68 | 27 | 36
10 | 7 | 10 | 77 | 34 | 40
| | | | |
12 | 8-1/2 | 10 | 86 | 39 | 44
12 | 9-1/4 | 10 | 86 | 39 | 44
14 | 10 | 15 | 110 | 36 | 50
-----------+-----------+--------+--------+-------+--------

A notable feature in this pump is the location of the exhaust passage; _this opening is underneath the cradle_—or the part that the pump rests upon—just forward of the steam cylinders. The flanges of the steam end and cylinders and the steam chest cover have been made heavier than the regular and strengthened to withstand the higher pressures.

Fig. 305 is a sectional view of a larger size duplex pump than the one shown in Fig. 302. The plunger, B, packing is identical, but the number of water valves is double; access for cleaning the suction chamber, C, is had by removing the hand hold plate at the side and in the center. The discharge valves are reached through the hand hold at D.

SETTING THE VALVES OF THE DUPLEX PUMP.

_The following rule applies to nearly all duplex pumps of the Worthington type._ The valves are usually of the common “^D^” valve type, working on the cylinder iron, or bronze seats, and suitably “set.” Sufficient cushion at the end of each stroke is provided by separate valves in the ports.

RULE.—1, _Locate the steam piston in the center of the cylinder_, Fig. 305. This is accomplished by pushing the piston to one end of its stroke against the cylinder head and marking the rod with a scriber at the face of the stuffing-box, and then bringing the piston in contact with the opposite head; 2, _divide exactly the length of this contact stroke_. Shove the piston back to this half mark, which brings the piston directly in the center of the steam cylinder, F; 3, _perform the same operation with the other side_; 4, _place the slide valves_, which have no lap, _to cover all the ports_, E; 5, _pass the valve stem through the stuffing-box and gland_. The operation of placing the pistons in the center of their cylinders will bring the levers and rock shafts in a vertical position; 6, _screw the valve stem through the nuts_ until the hole in the eye of the valve stem head comes in a line with the hole in the links, connecting the rocker shaft; then put the pins in their places; 7, _adjust the nuts on both sides of the lugs_ of the valves to leave about 1/4″ or 1/8″ loss motion on each side.

This process of adjustment being performed with both cylinders, the steam valves are set. In short the travel of the two valves is simply equalized.

DUPLEX OIL PUMPS.

The pattern of pump shown in Fig. 306, is especially designed for use in connection with hydraulic lifts and cranes, cotton presses, testing machines, hydraulic riveting and punching machines, and hydraulic presses of all kinds. Also for _oil pipe lines_ (see Table, page 341), mining purposes, and such services as require the delivery of liquids under heavy pressures.

There are four single acting outside packed plungers, which work into the ends of the water cylinders, the latter having central partitions; each individual valve has its own cover or bonnet. The arrangement of compound steam cylinders is shown. The water valves are easily accessible, and are contained in small chambers, capable of resisting very heavy pressures. The general arrangement shown in the engraving is subject to numerous alterations, according to various requirements, _but the general characteristic of four outside packed plungers is in all cases preserved_.

SPECIAL DUPLEX PUMP.

(_Outside packed Plunger Pattern for High Pressure._)

TABLE.

==========+==========+========+====================+============
| | | |
Steam | Water | |Capacity in Gallons,| Strokes per
Cylinders.| Plungers.| Stroke.| per Stroke | Minute,
| | | each Plunger. | each
----------+----------+--------+ | Plunger.
Ins. | Ins. | Ins. | |
----------+----------+--------+--------------------+------------
| | | |
16 | 5 | 12 | 1.02 | 50 to 100
16 | 6 | 12 | 1.47 | 50 „ 100
16 | 7 | 10 | 1.66 | 50 „ 100
16 | 7 | 18 | 3.00 | 40 „ 80
16 | 8 | 12 | 2.61 | 50 „ 100
16 | 8 | 18 | 3.91 | 40 „ 80
16 | 9 | 12 | 3.30 | 50 „ 100
18-1/2 | 7 | 12 | 2.00 | 50 „ 100
18-1/2 | 7-1/2 | 12 | 2.30 | 50 „ 100
18-1/2 | 8 | 18 | 3.91 | 40 „ 80
18-1/2 | 9 | 18 | 4.95 | 40 „ 80
18-1/2 | 10 | 12 | 4.08 | 50 „ 100
18-1/2 | 10 | 18 | 6.12 | 40 „ 80
20 | 8 | 12 | 2.61 | 50 „ 100
20 | 8 | 18 | 3.91 | 40 „ 80
20 | 9 | 12 | 3.30 | 50 „ 100
20 | 9 | 18 | 4.95 | 40 „ 80
20 | 10 | 12 | 4.08 | 50 „ 100
20 | 10 | 18 | 6.12 | 40 „ 80
----------+----------+--------+--------------------+------------

==========+==========+========+=============+============
| | | Capacity of |
Steam | Water | | Both |
Cylinders.| Plungers.| Stroke.|Cylinders, in| Steam Pipe.
| | | Gallons, |
----------+----------+--------+ per Minute. +------------
Ins. | Ins. | Ins. | | Ins.
----------+----------+--------+-------------+------------
| | | |
16 | 5 | 12 | 102 to 204 | 2-1/2
16 | 6 | 12 | 147 „ 294 | 2-1/2
16 | 7 | 10 | 166 „ 332 | 2-1/2
16 | 7 | 18 | 240 „ 480 | 2-1/2
16 | 8 | 12 | 261 „ 522 | 2-1/2
16 | 8 | 18 | 312 „ 625 | 2-1/2
16 | 9 | 12 | 330 „ 660 | 2-1/2
18-1/2 | 7 | 12 | 200 „ 400 | 3
18-1/2 | 7-1/2 | 12 | 230 „ 460 | 3
18-1/2 | 8 | 18 | 312 „ 625 | 3
18-1/2 | 9 | 18 | 396 „ 702 | 3
18-1/2 | 10 | 12 | 408 „ 816 | 3
18-1/2 | 10 | 18 | 490 „ 980 | 3
20 | 8 | 12 | 261 „ 522 | 4
20 | 8 | 18 | 312 „ 625 | 4
20 | 9 | 12 | 330 „ 660 | 4
20 | 9 | 18 | 396 „ 792 | 4
20 | 10 | 12 | 408 „ 816 | 4
20 | 10 | 18 | 490 „ 980 | 4
----------+----------+--------+-------------+------------

==========+==========+========+==============+==============
| | | |
Steam | Water | | |
Cylinders.| Plungers.| Stroke.| Exhaust Pipe.| Suction Pipe.
| | | |
----------+----------+--------+--------------+--------------
Ins. | Ins. | Ins. | Ins. | Ins.
----------+----------+--------+--------------+--------------
| | | |
16 | 5 | 12 | 3 | 4
16 | 6 | 12 | 3 | 5
16 | 7 | 10 | 3 | 6
16 | 7 | 18 | 3 | 7
16 | 8 | 12 | 3 | 7
16 | 8 | 18 | 3 | 8
16 | 9 | 12 | 3 | 8
18-1/2 | 7 | 12 | 3-1/2 | 6
18-1/2 | 7-1/2 | 12 | 3-1/2 | 6
18-1/2 | 8 | 18 | 3-1/2 | 8
18-1/2 | 9 | 18 | 3-1/2 | 8
18-1/2 | 10 | 12 | 3-1/2 | 10
18-1/2 | 10 | 18 | 3-1/2 | 10
20 | 8 | 12 | 5 | 7
20 | 8 | 18 | 5 | 8
20 | 9 | 12 | 5 | 8
20 | 9 | 18 | 5 | 8
20 | 10 | 12 | 5 | 10
20 | 10 | 18 | 5 | 10
----------+----------+--------+--------------+--------------

==========+==========+========+==========+====================
| | | |
Steam | Water | | Discharge| Water Press.
Cylinders.| Plungers.| Stroke.| Pipe. | Pump End will
| | | | stand, in lbs., per
----------+----------+--------+----------+ square inch.
Ins. | Ins. | Ins. | Ins. |
----------+----------+--------+----------+--------------------
| | | |
16 | 5 | 12 | 3 | 450
16 | 6 | 12 | 4 | 450
16 | 7 | 10 | 5 | 300
16 | 7 | 18 | 6 | 450
16 | 8 | 12 | 6 | 300
16 | 8 | 18 | 7 | 450
16 | 9 | 12 | 7 | 250
18-1/2 | 7 | 12 | 5 | 250
18-1/2 | 7-1/2 | 12 | 5 | 300
18-1/2 | 8 | 18 | 7 | 450
18-1/2 | 9 | 18 | 7 | 250
18-1/2 | 10 | 12 | 8 | 250
18-1/2 | 10 | 18 | 8 | 250
20 | 8 | 12 | 6 | 450
20 | 8 | 18 | 7 | 450
20 | 9 | 12 | 7 | 250
20 | 9 | 18 | 7 | 250
20 | 10 | 12 | 8 | 250
20 | 10 | 18 | 8 | 250
----------+----------+--------+----------+--------------------

A test of the superiority of this method of moving, and controlling long columns of fluids under extreme heavy pressures was made at the time of the introduction of long pipe lines _for conveying oil from the wells to the seaboard_.

NOTE.—After trying various kinds of pumps for forcing the oil through
these long pipes, and after having a succession of disasters in the
way of burst pipes, and leaking joints, it was decided to test the
efficiency of the direct-acting duplex steam pump. These pumps were
placed in the various stations along the pipe lines, and after a
continued service of many years, have shown their perfect adaptation
to that exceptionally hard service. These pumps convey the oil over
mountains where at times the coupled lines have been over one hundred
miles long between the pumps, and where the pressure on the plunger
of the pump sometimes rises to 1,500 lbs. per square inch.

J. F. HOLLOWAY.

COMPOUND DUPLEX PUMPS.

(_With The Deane Switch Valve._)

The application of this valve is shown in Fig. 307, on the opposite page. It can be attached to any regular Compound or Triple Expansion Pump, and if not in use does not in any way impede the regular running of the machine.

The Deane switch valve is a device by which compound low service pumps may be converted into powerful fire pumps. This appliance consists of a valve of such construction that steam may be allowed to enter the cylinders as usual for compounding, or may be diverted by simply moving a lever, when all four cylinders receive steam at boiler pressure, each exhausting independently to the atmosphere. The change makes each steam cylinder available for its maximum power, all four cylinders develop their full power, and its effect can be utilized in powerful fire streams.

It should be borne in mind in justice to the manufacturers that the Deane switch valve is not to be classed with the ordinary two or four-valve arrangement, which, while admitting initial steam to the second cylinders, develops no power in the first, or, as it is sometimes arranged, uses initial steam in all four cylinders and develops less power than if the second cylinders were used independently.

This valve is recommended by the Insurance companies, and compound duplex pumps fitted with the Deane switch valve will be accepted in place of the Underwriter pump of similar capacity. This valve is also frequently used where two widely differing water pressures are required for other purposes than for fire protection.

Every machine is subject to rigorous tests before leaving the factory, including a 300-pound test of the water cylinders. Every pump is guaranteed to be in full accordance with the specifications.

UNDERWRITER FIRE PUMPS.

The Insurance Companies have issued detailed specifications for the construction of fire pumps to be known as Underwriter Fire Pumps. They have agreed that such pumps with their specified attachments be recognized as the approved type, and that pumps built and fitted up less perfectly be not approved in future installments.

_The wide experience and systematic methods_ of the Insurance Companies place them in position to give valuable suggestions as a result of their observation and experiment, and these are embodied in carefully drawn regulations issued by their Engineering Department.

The specifications are very exacting in every particular, entering into _the design, material, and workmanship in minute detail_. They call for a number of fittings and attachments not usually furnished, and a most rigid test at the factory before shipping, and by the Inspecting Engineers of the Insurance Companies after the pump is installed, which secures for the purchaser the certainty of having a machine which beyond any reasonable doubt can be relied upon to do its full duty when emergency arises calling for its use.

There are a few quite important features not found in pumps of usual construction. The pumps are composition fitted throughout, the water cylinder bushings and plungers and linings to stuffing-boxes are of composition, the piston and valve rods, made unusually heavy, are of Tobin bronze. The mixture of the copper and tin composing the plungers and bushings varies for the two so as to prevent their cutting. Owing to the very high speed at which these pumps are liable to be run during a fire, all the working parts are made excessively strong, and the valve area and water passages are larger than usual. The interior of each Underwriter pump is treated with a rust-proof coating, and every precaution taken so that the pump will start instantly after an indefinite period of disuse.

Figs. 307 and 308 exhibit two somewhat varying but acceptable forms of the duplex steam pump.

_Among the attachments included in an outfit_ for the underwriter pump may be mentioned: an elbow or tee for the suction connection with a large suction air chamber, a set of brass priming pipes with special gate and check valves for the same, an automatic water pressure relief valve fitted to a cone and overflow pipe, a steam gauge and a special water gauge with duplex spring, each of which in the Underwriter Pump is mounted on an ornamental plate rigidly attached to the machine.

Straightway hose valves for the proper number of streams are placed in the neck to a very large discharge chamber, and there is also a large discharge opening for connection to the system of hydrants and sprinklers.

A stroke pointer is attached which travels between graduations marked on the yoke, indicating the length of stroke which pump travels, a one-point sight feed cylinder lubricator, a capacity plate with enamelled face giving instructions for operating, etc., is attached to each machine.

SPECIFICATIONS
OF THE
National Board of Fire Underwriters
FOR THE MANUFACTURE OF
STEAM FIRE PUMPS
AS RECOMMENDED BY THE
National Fire Protection Association.

EDITION OF 1904

THE NATIONAL STANDARD PUMP.

This pump is merely a pump of the well-known “duplex” type, built in a very substantial manner, and with certain improvements suggested by the experience of inspectors with Fire Pumps.

The principal points of difference between the National Standard Pump and the ordinary commercial pump are:

_1st. Its steam ports and water passages and air_ chamber are made
much larger than in common trade pumps, so that a larger volume of
water can be delivered in an emergency without water hammer.

_2nd. It is “rust proofed” that it may start instantly_ after disuse,
by making its piston rods and valve rods of Tobin Bronze, instead of
steel; its water pistons, stuffing boxes and rock-shaft bearings of
brass, instead of cast iron. Its valve levers are made of steel or
wrought-iron forgings, or of steel castings.

_3d. The following necessary attachments_ are all included in the
price of the “National Standard Pump,” viz.:—a vacuum chamber, two
pressure gauges, a relief valve, a set of brass priming pipes, 2 to 6
hose valves, a stroke gauge, a capacity plate, an oil pump, a sight
feed lubricator and a cast-iron relief-valve discharge-cone.

_By reason of the larger ports, passageways and pipes_, its larger
number of valves, and the added attachments, and general superior
construction a “National Standard” pump costs more than a common
trade fire pump, but the cost per gallon which these pumps can
_deliver in an emergency_ by reason of their large passageways, etc.,
is no greater than for the old style of fire pump and is well worth
this extra cost.

_Finally it should be remembered that these specifications_ cover
only the outlines of the design, and that all pumps built under them
are not of equal merit, for certain of the pump factories possess
a broader experience and better shop facilities than others, and
that the responsibility for first-class workmanship and strength of
materials rests on the pump manufacturers, and not on the insurance
companies.

_We advise that all contracts call for strict conformity to the
National Standard Steam Fire Pump specifications of the National
Board of Fire Underwriters._

UNIFORM REQUIREMENTS.

The following specifications for the manufacture of Steam Fire Pumps, developed from those originally drawn by Mr. John R. Freeman, are now used throughout the whole country, having been agreed upon in joint conference by representatives of the different organizations interested in this class of work. They will be known as “The National Standard,” and have been up to this time adopted by the following associations: Associated Factory Mutual Fire Insurance Companies, National Board of Fire Underwriters, National Fire Protection Association.

NATIONAL STANDARD SPECIFICATIONS FOR THE MANUFACTURE OF STEAM FIRE PUMPS

1. WORKMANSHIP.

_a._ The general character and accuracy of foundry and machine work must throughout equal that of the best steam-engine practice of the times, as illustrated in commercial engines of similar horse-power.

This refers to strength of details, accuracy of foundry work,
accuracy of alignment, accuracy of fits, quality of steam joints and
flanges, construction of steam pistons and slide-valves, etc., and
does not apply particularly to exterior finish.

2. DUPLEX ONLY.

_a._ Only “Standard Duplex pumps” are acceptable.

So-called “Duplex” pumps consisting of a pair of pumps with
“steam-thrown valves” actuated by supplemental pistons are not
acceptable.

Experience shows that duplex pumps are more certain of starting after
long disuse. The whole power of the main cylinder is available for
moving a corroded valve or valve rod, whereas on a single pump with a
“_steam-thrown_” valve no such surplus of power is available.

Further, the direct acting duplex has the great advantage over a
fly-wheel pump of not suffering breakage if water gets into steam
cylinder.

3. SIZES OF PUMPS.

_a._ Only the four different sizes given on the next page will be recognized for “National Standard” pumps.

The multiplicity of odd sizes of “Trade Pumps” is confusing, and
different makers have, in the past, estimated the capacity in gallons
according to different arbitrary standards.

NATIONAL STANDARD PUMP SIZES.

======================+=======+===============================
| Ratio | Capacity
Pump Sizes. | of | At 100 lbs.
| Piston| at Pump.
------+-------+-------+ Areas.+----------+--------+-----------
Steam.| Water.|Stroke.| | Number of| Nominal| Actual
| | | | 1-1/8 in.| Gals. | Gals. Per
| | | | Streams. | Per |Min. as per
| | | About | | Minute.| Art. 4.
------+-------+-------+-------+----------+--------+-----------
14 × 7 × 12 |4 to 1 | =Two= | =500= | 4830
14 × 7-1/4 × 12 | | | | 520
----------------------+-------+----------+--------+-----------
16 × 9 × 12 |3 to 1 | =Three= | =750= | 8060
----------------------+-------+----------+--------+-----------
18 × 20 × 12 |3 to 1 | =Four= | =1000= | 9990
18-1/2 × 10-1/4 × 12 | | | | 1050
----------------------+-------+----------+--------+-----------
20 × 12 × 16 | 2-3/4 | =Six= | =1500= | 1655
| to 1 | | |
----------------------+-------+----------+--------+-----------

NATIONAL STANDARD PUMP SIZES.(continuation)

======================+===============+================
| [B] Boiler |
Pump Sizes. | Power | Full Speed.
| Required |
------+-------+-------+------+--------+-------+--------
Steam.| Water.|Stroke.|Horse | Steam | Rev. |Piston
| | |Power.| Pres. | Per |Travel
| | | |at Pump,|Minute.|Feet Per
| | | | lbs. | |Minute.
------+-------+-------+------+--------+-------+--------
14 × 7 × 12 | 100 | 40 | 70 | 140
14 × 7-1/4 × 12 | | | |
----------------------+------+--------+-------+--------
16 × 9 × 12 | 115 | 45 | 70 | 140
----------------------+------+--------+-------+--------
18 × 20 × 12 | 150 | 45 | 70 | 140
18-1/2 × 10-1/4 × 12 | | | |
----------------------+------+--------+-------+--------
20 × 12 × 16 | 200 | 50 | 60 | 160
| | | |
----------------------+------+--------+-------+--------

[Footnote B:

This boiler power is required for continuous running at full speed
and pressure. It is, however, often best to put in a larger pump than
the existing boilers could drive at full capacity, as a _small boiler
will drive a 750-gallon pump at the 500-gallon speed with very nearly
as good economy as it can drive a 500-gallon pump at full speed_. The
pump then does not have to be changed when the plant is enlarged and
the boiler power increased.

A steam piston relatively larger than necessary is a source of
weakness. It takes more volume of steam, and gives more power with
which to burst the pipes if the throttle is opened wide suddenly
during excitement.

It has been common to make all fire-pumps with water plunger of
only one-fourth the area of steam piston, with the idea that pump
could thereby be more readily run at night, when steam was low. The
capacity in gallons is thus reduced 25 per cent. as compared with a 3
to 1 plunger on the same steam cylinders.]

_b._ The above sizes of steam and water cylinders and length of stroke have given general satisfaction and will now be considered as standard.

Often, especially with large pumps, “4 to 1” construction is a
mistake, and gives no additional security, although the pump might
start and give a few puffs with 30 lbs. of steam on banked fires;
because, if any pump of whatever cylinder ratio draws 50 or 100
horse-power of steam from boilers with dead fires, it can run
effectively only a very short time (ordinarily, perhaps, 3 to 5
minutes), unless fires are first aroused to make fresh steam to
replace that withdrawn.

Steam pressures stated above must be maintained _at the pump_, to
give full speed and 100 lbs. water pressure. Pressure at boilers must
be a little more, to allow for loss of steam pressure between boiler
and pump. Pumps in poor order, or too tightly packed, will require
more steam.

The boiler horse-powers above are reckoned on the A. S. M. E. basis
of 34-1/2 lbs. of water evaporated from and at 212 degrees Fahrenheit
as the unit of boiler horse-power. From 12 to 15 square feet of
water-heating surface in the boiler is commonly assumed necessary for
the generation of one horse-power.

Smaller boilers than called for above, if favorably set, and having
excellent chimney draft, can sometimes be forced to nearly double
their nominal capacity for a short run, as for fire service.

_c._ _250 gallons per minute is the standard allowance for a good 1-1/8-inch (smooth nozzle) fire stream._

A so-called “Ring Nozzle” discharges only three-fourths as much water
as a smooth nozzle of the same bore, and is not recommended.

From fifteen to twenty automatic sprinklers may be reckoned as
discharging about the same quantity as a 1-1/8-inch hose stream under
the ordinary practical conditions as to pipes supplying sprinkler and
hose systems respectively.

4. CAPACITY.

_a._ Plunger diameter alone will not tell how many gallons per minute a pump can deliver, and it is not reasonable to continue the old time notion of estimating capacity on the basis of 100 feet per minute piston travel.

_b._ The capacity of a pump depends on the speed at which it can be run, and the speed depends largely on the arrangement of valves and passageways for water and steam.

_c._ _It is all right to run fire-pumps at the highest speed that is possible without causing violent jar, or hammering within the_ _cylinders. Considerations of wear do not affect the brief periods of fire services or test, hence these speeds are greater than those allowable for constant daily duty._

_d._ Careful experiments on a large number of pumps of various makes at full speed, show that in a new pump with clean valves, and an air-tight suction pipe, and less than 15 feet lift, the actual delivery is only from 1-1/2 to 5 per cent. less than plunger displacement. This slip will increase with wear, and for a good average pump in practical use, probably 10 per cent. is a fair allowance to cover slip, valve leakage, slight short-stroke, etc.

_e._ Largely from tests, but partly from “average judgment,” and recognizing that a long stroke pump can run at a higher rate of piston travel in lineal feet per minute than a short stroke pump, and that a small pump can make more strokes per minute than a very large one, the speeds given in the preceding table have been adopted as standards in fire service for direct acting (non-fly-wheel) steam pumps, which have the large steam and water passages herein specified.

_f._ Rated capacity is to be based on the speed in the preceding table, correcting the plunger displacement for one-half the rod area and deducting 10 per cent. for slip, short-stroke, etc.

Men sometimes ask why, (if they can run a pump smoothly so as to get
a delivery of 1,000 gals. per minute,) we should not accept as “a
thousand gallon pump,” irrespective of its suction valve area or its
exhaust port area or the size of its cylinders.

To this we reply that _when new and favorably set_ almost any pump
built according to these specifications can run at a much greater
delivery than here rated, but when lift is unusually high or suction
pipe long, or when the pump takes its suction under a head, no pump
can be run so fast as on, for instance, a 5-foot lift. A solid
foundation is also a great and indispensable aid in running a pump
fast.

Standard 500-gallon pumps have often delivered 800 gallons, and
1,500-gallon pumps have delivered 2,000 gallons; but some margin must
be allowed for unfavorable conditions and for deterioration as a pump
grows old, or for the absence of an expert to get its utmost duty.

5. CAPACITY PLATE.

_a._ Every steam fire-pump must bear a conspicuous statement of its capacity securely attached to the inboard side of air chamber, thus:—

NATIONAL STANDARD FIRE PUMP

16 × 9 × 12

CAPACITY
750 GALLONS PER MINUTE, OR
3 GOOD 1-1/8-IN. SMOOTH NOZZLE
FIRE STREAMS

FULL SPEED
70 REVOLUTIONS PER MINUTE

NEVER LET STEAM GET BELOW
50 POUNDS, NIGHTS, SUNDAYS
OR AT ANY OTHER TIME

The name “Underwriter” has been largely used for a considerable time
to designate the type of pump covered by the principal features of
these specifications. While our preferences are against the use of
this word as designating any piece of apparatus objections will not
be raised at the present time to its being continued on name plates
in place of the words “National Standard,” if manufacturers so desire.

_b._ This plate must have an area of not less than one square foot, and must be made of an alloy at least two-thirds aluminum and the remainder zinc. The letters must be at least one-half inch in height, plain and distinct, with their surfaces raised on a black background and buffed off to a dead smooth finish.

The name of pump manufacturer may also be placed on this plate, if
desired.

_c._ A smaller plate of composition must be attached to steam chest bearing the size of pump, the shop number, and the name of shop in which the pump was built.

6. STRENGTH OF PARTS.

_a._ The maker must warrant each pump built under these specifications to be at time of delivery, in all its parts, strong enough to admit of closing all valves on water outlet pipes while steam valve is wide open and steam pressure eighty pounds, and agree to so test it before shipment from his works.

_b._ The pump must be warranted so designed and with such arrangement of thickness of metal that it shall be safe to instantly turn a full head of steam on to a cold pump without cracking or breaking the same by unequal expansion.

7. SHOP INSPECTION.

A systematic shop inspection must be given to each pump to ensure completed workmanship, and to prevent the use of defective parts, improper materials, or the careless leaving of foreign matter in any part of the cylinders or chests.

Several instances have occurred in which chisels, bolts, or core
irons have been found in steam chests or steam cylinders. This
has resulted in a serious crippling of the pump and in some cases
requiring repairs to be made before the pump could be used for fire
purposes.

THE STEAM END.

8. STEAM CYLINDERS.

_a._ These must be of hard close iron with metal so distributed as to ensure sound castings and freedom of shrink cracks. The following are the minimum thicknesses acceptable:

14″ Diam. 7/8″ thick
16″ „ 15/16″ „
18″ „ 1″ „
20″ „ 1-1/8″ „

_b._ The inside face of the steam cylinder heads and the two faces of the piston must be smooth surfaces, fair and true so that if the piston should hit the heads it will strike uniformly all around, thus reducing to a minimum the chances of cramping the piston rod or injuring the pump.

_c._ All flanged joints for steam must be fair and true and must be steam tight under 80 lbs. pressure if only a packing of oiled paper 1/100 inch thick covered with graphite were used. Jenkins, “Rainbow” or equivalent packing of not exceeding 1/32 inch original thickness is acceptable. Oiled paper is not acceptable as a final packing, as it burns out.

For size of steam and exhaust pipes, standard flanges and bolting, see Art. 39.

The specifications originally required machine facing for all these
surfaces. The art of machine molding from metal patterns with draw
plates, etc., has, however, attained such excellence in certain
shops, that in regular practice “foundry faced” cylinder heads and
piston faces can be made true and fair, and steam joints can be made,
tight under 80 lbs. pressure with a packing of oiled paper only 1/100
inch thick.

Under proper assurance that this precision can be obtained in regular
practice at the shop in question, foundry finish may be accepted on
cylinder heads and piston faces, steam chests and steam-chest covers.

In the case of _built-up pistons_, of separable form, it must be
conclusively shown that the boring and finishing are carried on by
such methods as will ensure the faces of pistons being exactly square
to the piston rod and exactly parallel to the cylinder head.

In the case of _solid pistons_ the two faces must be machine faced,
as proper parallelism cannot well be obtained by foundry methods.

Ordinary foundry finish secured by the old methods and wooden
patterns is not acceptable and acceptance of any foundry-finish can
only be secured after a special investigation of shop practices.

_d._ Heads at both ends of cylinder must be beveled off very slightly over a ring about one inch wide, or equivalent means provided to give steam a quick push at piston, should it stand at contact stroke.

9. BOLTS AND STUDS.

_a._ The stress on bolts or studs in connection with steam cylinders must not exceed 7,500 lbs. per square inch under a test pressure of 80 lbs. steam, disregarding such initial strain as may be due to setting up. (Compute pressure area out to center line of bolts.)

No stud or bolt smaller than 3/4 inch should be used to assemble parts subject to the strain of steam pressure as smaller bolts are likely to be twisted off.

10. YOKE.

_a._ The steam cylinders and water cylinders must be connected by such a form of yoke as requires no packing, a metal to metal joint at this connection being considered necessary. The piston-rod stuffing box heads should concentrically fit the counter-bore of the yoke.

If packing is put into these joints, there is a chance of the steam
and water ends getting out of alignment and leaking at the joint
between cylinders and yoke.

11. STEAM PORTS.

_a._ The area of each exhaust steam passage, at its smallest section, must not be less than 4 per cent. of the area of the piston from which it leads.

This is a large increase over the size heretofore common, but
indicator cards which we have taken from pumps of several different
makes indicate this to be one of the points in which improvement
is most needed to accommodate the high speeds at which fire pumps
are always supposed to run, and this unrestricted exhaust aids very
materially in giving steadiness to the jet of water.

_b._ Each admission port must be not less than 2-1/2 per cent. of area of its piston, and to avoid wasteful excess of clearance, these passages should not be bored out larger in interior of casting than at ends or passage.

_c._ The edges of the steam-valve ports must be accurately milled, or chipped and exactly filed to templets, true to line, and the valve seat must be accurately fitted to a plane surface, all in a most thorough and workmanlike manner and equal to high-grade steam-engine work.

_d._ To guard against a piston ring catching in the large exhaust ports, these ports must have a center rib cast with cylinder at cylinder wall. See also Art. 13 _d._

12. STEAM-CLEARANCE SPACE.

_a._ Clearance (including nut-recess, counter-bore, and valve passages) must not exceed 5 per cent. for contact stroke or about 8 per cent. for nominal stroke (_i. e._, contact stroke should overrun nominal stroke not more than one-half inch or not less than one-fourth inch, at each end).

_b._ The clearance space between face of piston and cylinder head must be reduced to smallest possible amount, and these contacting surfaces be flat, without projections or recesses other than the piston rod nut and its recess.

Some makers, with the idea that a fire pump need not be economical,
have not taken pains to keep these waste spaces small.

Securing small clearance costs almost nothing but care in design, and
is often of value, since at many factories boiler capacity is scant
for the large quantity of steam taken by a fire pump of proper size.

13. STEAM PISTONS.

_a._ May be either built up or solid, as maker thinks best.

It is believed that “solid” (cored) pistons with rings “sprung
in,” are for fire-pumps much preferable to built-up pistons, since
follower bolts _do_ sometimes get loose.

_b._ Piston must not be less than four inches thick between faces. If solid, walls should be not less than 1/2 inch thick, and special care should be given to shop inspection to determine uniformity of thickness.

_c._ If built up pistons are used, involving follower bolts, such bolts must be of best machinery steel, with screw thread cut for about twice the diameter of the bolt and fitting tightly its whole length.

_d._ The width of each piston ring must exceed the length of the large exhaust port by at least 1/4 inch.

This is to avoid the possibility of piston ring catching in the port.

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Pumps and Hydraulics, Part 1 (of 2)Chapter X: Part 10

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