US1654679A

US1654679A - Low-water alarm

Info

Publication number: US1654679A
Application number: US758148A
Authority: US
Inventors: Harry W Coddington
Original assignee: Individual
Current assignee: Individual
Priority date: 1924-12-26
Filing date: 1924-12-26
Publication date: 1928-01-03
Anticipated expiration: 1945-01-03

Description

Jan. 3, 1928.

' H, w. C(ODDINGTON LOW WATER ALARM Filed Dec. 26. 1924 2 Sheets-Sheet Sum: 11* oz SW01 new H. W. CODDINGTON ,Jan. 3, 19

LOW WATER ALARM Fi led Dec. 26. 1924 2 Sheets-Sheet 2 4 Patented Jan. 3, 1928.

untrue STATES HARRY W. COD'DINGTON, OF ROANOKE, VIRGINIA.

' LOW WATER ALARM.

Application filed December 26,1924. Serial No. 758,148.

This invention relates to low water alarms of the thermostatic type and has among its objects to provide an improved device whereby the enginemen may be advised when the water in a steam boiler reaches a dangerously low stage. A more specific object is to provide a thermostatically operated low water alarm having a maximum operating range for a given change in temperature, also to provide a low water alarm convenient to manufacture and easy to maintain in serviceable condition. A still iurtlierobject is to provide a low water alarm espe ially' adapted for use on locomotive boilers where the conditions of service are severe. With these general and other more specific objects in view, the invention consists of the formation, combination and arrangement of parts as will be herein described and finally claimed.

In the accompanying drawings which show a preferred form. of the invention,

Figure 1 is an organization view showing a low water alarm constructed in accordance with the principles of the "present invention. This figure shows the alarm in side elevational View and as attached to the shell of an ordinarylocomotive boilersv Figure 2 is a fragmentary, longitudinal," sectional view through the boiler end of the alarm. Figure 3 is a fragmentary, transverse, sectional view through a portion of the opposite end of the alarm, this view being taken substantially on the line 3+3 of Figure 1. Figure iis a transverse, sectional view through one end of the expansion element, the view being taken on the line H of Figure 2. 'Figure 5 is a transverse horizontal sectional view through the boiler fitting of the device, this view being taken substantially on the line 5 5 of Figure 2. Figure 6 is a transverse sectional view taken througlranother portion of the expansion element, this view being taken substantially on the line (36 of Figure 1. Figures 7 and 8 are respectively a transverse vertical sectional view and a fragmentary side elevational view of the tube portion of the expansion element, these views showing a modified form of the bracketv which supports the fulcrum .rod. Figure 9 is a plan view sbowin' the upper portion of the boiler. titti which the expansion elementis attached. .The'scale of Figure l-is somewhat reduced over the scale of the re maining figures.

Before, proceeding with a description of the device as illustrated in the drawings, it will first be mentioned that many difliculties and limitations are met in the construction of thermostaticlow water alarms, particularly those intended for use onlocomotive boilers. The differences in'temperature that are available and upon which operation depends are small. Every means is resorted to in orde' to obtain an increase in the thermal range, a gain of even a few degrees being sought after, and sometimes spelling the difference between a successful and an unsuccessful devioe. This will be better understood when it is remembered that a locomotive is exposed to a wide range ofclimatic conditions; is sometimes housed, again is exposed to rain or snow. Thedevice should be capable of being applied to and adjusted upon a cold boiler, not in moon that boiler over a wide range of steam pressures and corresponding steam temperatures, whether the locomotive be standing tion, and must then be certain of-operation or running at high speed. The air temperaunmistakably to announce a condition of actual low water, it is of no less importance that it shall not soundfalse alarms as from merely a surge that momentarily uncovers the tell tale portion of the device. Delicate thermal and mechanical problems are involved in the construction of any thermostatic low water alarm, where a limited temperature change and almost mlcroscopic. ex-

pansive movement must be utilized; andthe problems are, as statedfeven greaterv for losound from the stage of the water.

comotiveservice. The benefits derived from the various features of the present invention will be more clearly understood by having in mind these peculiar operating conditions.

Referring now to the drawings the shell of the boiler is denoted by the numeral 1.

At any suitable point, preferably ust above the point where itis desired to indicate a critically low stage of water, the shell of the boiler is provided with an opening 2, the upper or outermost portion of this opening being beveled as indicated at 3. Seated from the exterior against this beveled portion of the opening is a ball faced ring at which is interiorily threaded, as indicated at 5, .and into which is screwed a bushing 6. This bushing" may extend inward? y slightly within the steam cavity of the boiler, and is in turn interiorly threaded to accommodate a threaded drop pipe 7 which is connectedthereto. The exterior surfaceof the lower end of the bushing 6 formed with faces as indicated at 8 to accommodate the j awsof a wrench or other tool for screwing "it firmly into the ring l from the under side of the latter. After screwing the drop pipe 7 into the bushing 6 the uppermost end of the pipe may be beaded over as indicated at 9 to prevent unscrewing, and the pipe 7 may be welded to the bushing as indicated at lOto effectively seal the threaded connection and prevent the loss of the vacuum within thecavity of'the alarm. The drop pipe 7 will be carried down to the level where it is desired that the alarm shall Mounted upon the upper surface of the ring i is a special boiler fitting 11. A plurality of studs 14 are screwed into the shell of the boiler and the. upper ends of these studs extend through suitable openings in a bottom flange 15 of the fitting. The fitting 11 may, by means of the studs 14, be clamped firmly against the ring at, the upper face of the ring t and the bottom face of the fitting 11 being machined to constitute a flatsteam tight joint 12. lhe upper surface of. the ring l is also preferably provided with a machined cylindrical extension 13 which is preferably arranged concentric with the bore of the ring t, this cylindrical. portion comprising a dowel adapted to seat within a suitablyformed recess in the base of the fitting 11. By the 1ntmJ-engagcment ot the said recess and the dowel the fitting 11 is prevented from slippage with respect to the ring at and the dowel and recess may also comprise a portion of the'steam tight joint between these two elements.

It has been found desirable to construct low water alarms of this type with the drop pipe indirectly connected to the fitting 11 inthe manner shown, as the proper length of the drop pipe can be more accurately dete mined and set than with co utruction other types. It has also been found easier to keep steam tight joints by this construction inasmuch as the ring 4 may be made of one kind of material, the fitting 11 of another kind if desired, and the bushing 6 of still another kind of material. It has also been found easier to align the anxious parts in service'when the ring 4t is made separately from the fitting 11 as illustrated.

It has already been pointed out that the available movement of the free end of the. expansion element is very small, being in clude the use on the same of tools oflprecision in connection with the mounting of the alarm. A peculiar use and advantage of the construction just described resides accordingly in the fact that the alarm may be thereby more accurately mounted upon the rough boiler, inasmuch asthe drop pipe unit and the fitting 11 may be adjusted with respect to each other and the joint face'12-13 at. the ring 4 may be slightly angled by'aecurate machine tools, so that by a slight rotation of the drop-pipe unit, the outer endof the mechanism may be brought into 'deiicate alignment, irrespective of boiler irregularh ties. r

The fitting 11 has a substantially cylindricatcavity 16 arranged in vertical. alignment with the drop pipe! and in direct open communication, through the cavity of the drop pipe 7, with the steam or water space of the boiler; This cavity extends upward for the full height of the fitting 11 and at the upper extremity is nrnrmally closed by means of a screw plug 17. Just below the top of the fitting the cavity 16 has a lateral branch '18 which is inciined sligl tly upward from the horizontal, and to the outer end of this branch is connected the sloping expansion element 19. the cavity of the expansion element being in open 'tluid conununication with the cavities 16'and 18. The plug 1'7 i ll baffle 21.

of the same.

' nee 1,619 I 3 the connected cavities above the openings 22. This baflle also serves to retard the fall of water from the expansion element in cases where the lower end of the drop pipe is momentarily uncovered, as by a surge of water in a locomotive boiler. Located slightly belowthe baffle 21 area plurality of inwardly extending stops or shelves 23 formedupon the interior wall of the fitting 11. These are provided in order toprevelnt the disk 21 from dro 'iping to a position where the top of. the bushing. 6' might be blanked off in case the stem 20 should break. It will be noted in Figure 5 that in the present embodiment there are three of these shelves whereas there are but two of the openings 22. By making the number of shelves different from the number of openings,.the openings-can never simultaneously register with all'of the shelves and the disk will thereby be pre. vented from ever dropping past the shelves whileat the same time the shelves can never seriously interfere with the passage of steam and the slow passage of water through one or more of the openings 22.

It has been found by experiment that a battle arranged at the location and in they manner just described is especially effective in preventing undue soundings'of the alarm from surges. Its e'liiciency in this respect is due to the fact that when the water attempts to drop back suddenly through theopenings 22, a localized'vao'uum tends to form in the space'immediately above the Also, under certain circumstances steam becomes trapped in the portion of the chamber 16 that lies above the baffle 21, thus forming a seal for the waterin' the expansion element. i r i By integrally connecting the baffle 21 to the plug 17 it will be seen that when the plug is rotated in the unscrewing direction the battle will. be similarly moved.

of the fitting, it 'will'be'broken loose from the same and propelled outwardly through the incrustation by the rotatlon and retraction boilerend of the expansion element 19. For

this purpose this end of the fitting is bev eled as indicated as at .24. Themain portion of the expansion element is formed of a metallic tube with a collar. 25-brazed or otherwise secured upon the outer periphery The endv of the tube is expanded aroundythe end of this collaras shown, at 26 and the metal of the tube. at the portion QS'lhGIGOf is then machined off to form, withthev bevel 24, a steam tight joint. Aspanrier nut'27 is threaded upon the exterior surface of the branch of the fitting 1.1 and by means of thisfspanner nut fere" with the baffle.

7 Accordingly if the baffle should be scaled to the interior.

of three disks 29 which are substantially of the same diameter as the interior of the cavity of the tube portion'of the expansion element. These dlsks are spaced somewhat fromelach other andare connected by means of suitable stein portions. Eachdisk is provided with an upper and a lower opening 30", these openings being designed and arranged to permit of the ready flow of steam to lill the cavity of the expansion element but to retard the return of water from the cavity of the expansion element to the boiler. It has been found preferable to rigidly and permanently affix this bafliein the boiler end of the expansion element. It has also been found permissible to do so inasmuch as it is not necessary'to provide for means at the boiler end of the expansion element to wash out andv cleanse the interior of the. tube as scale and sediment do notlodge within it to any great extent in ordinary usage. It is accordingly preferable to mount these disks permanently in the lower end of the expansion element and to furnish expansion elements fitted with the baffles as a single man-. ufactured unit; This construction also permits of the use of the stem 20 to connect the baffle 21 to the main portion of the plug 17 as the presence, of the stem does not inter It has beenfound necessary. to occasionally wash out the drop pipe 7 and for this reason the opening in the fitting. 11, normally closed by the plug 17, is maintained in alignment with they bore I of the tube 7. When the plug 17 is un screwed, the baffle 21 which is connected thereto bythe stem 20 iswithdrawn at the same time and direct access is had to the cavity of the drop pipe 7.. I

It will be noted in Figure 9 that index figures. or match marks are provided on the. top surface of the. plug 17 and onv the top edge of the adjacent'portion of the tilting 11. It is the intention thatthe plug 17 shall be screwed into the fitting until the mark on the plug matches with the marks on the top of-the fitting. This'will insure the openings 2210f the bafile 21 standing in a transverse direction with respect to the line of the expansion element 19. At the same time, the baffle 28 is fixed in the tube portion of the expansion element in such manner that the openings 30 of the disks 29 will lie in vertical arrangement. Considering the channel of the vmember 11 and of the branch thereof, the holes 30 in the "upper disks are out of axial alignment with the holes 22 ofthe disk 21 This arrangement still. further breaks up the local circulation andciency has been found to be increased a greater amount than by the addition of extra discs 29 to the bafli'e 28, as the rlghtangled arrangement of battles breaks up the direct path of circulation of the water between the expansion element and the boiler, thereby resulting in a decreased temperature of the water within the expansion tube. And by arranging the openings 22 out of axial alignment with the openings 30 a still greater difference in temperature is obtained and the range of the alarm very materially increased.

It should be understood that while the isolated water inthe expansion tube is sometimes referred to as being chilled, this expression is relative only, for in fact the water in the expansion element under the most favorable conditions is many degrees higher in temperature than the surrounding atmosphere and often not many degrees below the boiler temperature. The steam engineer is aware that the temperature of the water inside of the boiler is the same as that of the steam itself. The drop pipe 7, being and between the several connected cavities of the low water alarm causes the isolated water in the expansion element to remain at a temperature closely approaching that of the steam unless means are introduced to break up and hinder such circulation. The provision of the bafiie 21, and particularly the arrangement of the apertures 22 thereof with respect to the apertures 30 in the discs of the baflle 28 has been found to be particularly effective in this respect, due to the fact that the water is compelled to follow a spiral course in its circulation and sets up cross currents in the space next above the battle 21. which tend to equalize the temperature of thc'water in this space, resulting in a break up of the general thermic circula- 7 tion and causing a reduction in the temperature of the water in the expansion tube 19.

The outer end of the expansion element 19 comprises a terminal fitting 31. A portion of this fitting at 32 has a square external contour and this is arranged to rest in and to be supported by a jaw-shaped opening 33 in a bracket 34. The bracket 34 is shown as attached to the'shell of the boiler by means of studs 35, with any suitable leveling means such as melted babbitt poured into the crevice between the bracket and the shell of the boiler,this being indicated at 86. The ex pansion element 19 is demountably' attached to the fitting 11 as heretofore explained, and

accordingly it may, when detached from the fitting 11., be lifted outof the jaw-shaped opening of the bracket 34. In order to prevent undesired lifting ofth'e outerend of the expansion element, either by hand or during the operation of the devlce, a yoke member 35 is provided. The member 35 1s attached to the bracket 34 by means of small bolts 36 and the member-35 is arranged to embrace the outer end of the terminal fitting 31 as indicated in the drawings, to form an upper guide for the same. The yoke must, of course, be removed from the bracket 34c before the expansion element can be lifted out of the jaw-shaped opening. Thefoutermost end of the fitting 31 may be, closed by a plug 37. A test pipe 38-witl1 a test valve-39 may be led out from the plug 37. The jaw of the bracket 34 forms a means to prevent injury to the expansion element when it is necessary to unscrew the plug 37. The main portion of the expansion element is usually formedof a relatively soft-mate rial such as a copper tube of relatively li ht gauge, and should the plug 37 be ditiic ult to unscrew, the tube portion of the exp'an-- sion element might be injured except for the protection of the jaw engagement of the outer end of. the element with the bracket 34.

The yoke member 35 is provided in order to prevent undesired lifting of the outer end of the expansion element. It has been found that in the absence of such guiding means a part of the available movement is lost, being expended in lifting of the outer end of lllll the expansion element] The squared outer guide comprises means to prevent injury to the tube 19 when the plug 37 is unscrewed. At the same time the removable yoke member 35 makes it possible to readily'disassemble the device, and also conserves the available movement as heretofore mentioned by direeting it in the desired direction. and preventing rising of the outer end of the expansion element. 7

Low water alarms of this type are actuated by thermal expansion and contraction of the expansion element. As long as the open lower end of the drop pipe 7 is submerged the drop pipe itself, the fitting 11, the tube portion of the expansion element 19, and the terminal portion 31 thereof will all be filled with water. This water is isolated from the water of the boiler and with the introduction of the baffles near the boiler end of the expansion element as heretofore" described, local circulation willbe practicali iy prevented, so that the water in the expansion element will be at a considerably lower temperature than the water within the boiler.

As soon as the. lower end of the drop pipe v 7 is uncovered, the water in the'expansion element will tend to fall back into the boiler,"

and if the lower end remains uncovered for a short period of time the water will all leave the expansion element and it will be replaced by steam of a temperature corresponding to the boiler pressure. sion element 19, and a portion ofthe fitting 11, will accordingly lengthen in response to the thermal change and, as the fitting 11 is rigidly connected to the boiler shell, whereas the outer end or" the expansion element is free to slide longitudinally in the bracket 34, it will'be seen that the outer end of the expansion element will move in response to the lengthening out the parts. This movement is taken advantage of to actuate an alarm lever which is pivot-ally attached to the terminal fitting 31 at 41. This feature of the device is not new, but in the past it has been the practice to fulcrum the leversuch as l0 directly upon the bracket 34:. :The result of this has been, that, considering the device to have been fitted up and adjusted with the boiler cold, which is the usual practice, much of the expansive value of the expansion .ele-' ment has been lost, inasmuch as the shell of the boiler lengthens when the. boiler is fired up and theshell becomes heated. A feature or the present invention is to overcome this defect and at the same time to increase the range of the expansion element The general principle involved in correcting the defeet is to arrange a fulcrum for the lever .40 which will not be afi'ected by the expansion and contraction of the boiler shell. To do this for a boiler of the type shownit is desirable to carry the fulcrum back as near to the boiler end of the expansion element 19 as practical. 'In the present embodiment, the fulcrum point for the lever is indicated at 4:2. Extending from the point 12 to the fitting 11 is a tie-rod 43 having a suitable jaw at the fulcrum end and beingthreaded into a bracket 14 of the fitting 11 at the opposite end. Inasmuch as the fitting 11 is in efiect H a portion of the expansion element, its expansion and contraction being efiective to actuate the lever 40, the same as though it were an integral part of the expansion element, it will be seen that the fulcrum thus described is in effect located upon or-attached to the boilerend of the expansion element.v The rod 43 is preferably guided from the tube portion of theexpansion element by means of a guide 45. This prevents vibration of the rod 43 when the locomotive is in operation. It Wlll accordingly be seen that whereas the bracket 3 1 supports the outer end of the expansion element, the lever 40 is in turnsupported, not by the bracket 84, but'by the expansion element through the connection 11,- and' that when the point 41 moves to the left (see- Figure 1) in response to lengthening of the'partsthepoint 42' will not be similarly affected and the result will be a downward movement of the extreme The expan-- 'filled with steam;

The pipe indicated at 52 beneath the whistle is for drainage purposes only. When the water level is restored and the trapped'steam in the expansion element. 19 and the con nected chambers has condensed, water from the boiler will be drawn up into thevarious contract and the, lever 10 will be retracted, permitting the valve 18 to closethereby shutting off the'alarm.

By means of the test valve 39 the device may be tested for complete operation. By opening this valve for a few seconds the chilled water willbe blown out of the expansion element and connected parts and the connected passageways will be filled with hot water from the boiler, which being at sub stantially the same temperature as the steam, the entire device will be actuated the same as though the passageways were actually The pipe 38 preferably discharges into the ash pan. j

" In Figures 1 and 6 the guide for the rod 43-is shown as entirely surrounding the tube of the expansion eleinent and brazed or otherwise rigidly secured thereto. In thebrazed orotherwise formed upon the-tube;

The ends or another suitable portion ofthe guide may contact with this feather to insure the guide be ng in proper position to receive the rod I have thus described a preferred form of my invention. Other embodiments are contemplated, within the scope of the appended claims, without departing from thespirit' thereof. g

What is claimed is: 1. A low water alarm of. the thermostatic type, the same including in combination with a steam boiler, a fitting attached to the boiler, said fitting having a passageway therein, an. expansion element in fluid communication with one'end of said. passageway, a drop pipe connected to and infiuid communication with theother end of said passageway, the samebeinglarrangedin axial alignmentwith said passageway,.said drop pipe extending within the. steam; and water connected passageways. -As this isolated water cools the expansion element will again space of the boiler and terminating in an I open lower end defining the critical stage I of the water, and a: baille arranged across the said passageway of the fitting, the battle lying above and in line with the said drop pipe. 7 a

2. A low water alarm of the thermostatic type, the same including in combination with a steam boiler a fitting attached to the boiler, said fitting having a passageway therein, an expansion element in fluid communication with one end of said passageway, a drop pipe connected to and in fluid communication with the other end of said passageway, said drop pipe extending within the steam and water space of the boiler and terminating in an open lower-end defining the critical stage of the water, a bafiie arrangedacross said pas-- sageway, the baflie lying above and in line with'the said drop pipe, a clean-out opening in the fitting above and in line with the baffle, and a member adapted to normally close said opening, the baffle being attached to said closing member. 7

3. A low water alarm of the thermostatic type, the same including in combination with a steam boiler a fitting attached to the boiler, said fitting having a passageway therein, an expansion element in fluid communication with one end of said passageway, a droppipe connected to and in fluid communication with the other end of said passageway, said drop pipe extending within the steam and water space of the boiler and terminating in an open lower end defining the critical stage of the water, a battle arranged across said passageway, the baffle lying above and in line with the said drop pipe, a cleanout opening in the fitting above and in line with the baffle, a member adapt ed to normally close said opening, the bafile being attached to said closing member, and means'formed on the interior wall of the fitting comprising an emergency support for said baffle. I

4. A low water alarm of the thermostatic typeincluding, in combination with a boiler,

a boiler fitting having a cavity in fiuid commnnication with the steam and water space of the boiler, an expansion element connected to the fitting and extending laterally "therefrom, the same being in open fluid communication with the cavity of the fitting, a battle in the expansion element near the'said fitting, and a bafiie in the cavity of the fitting, the said baffies being arranged in planes substantially at right angles to each other.

5. A low water alarm of the thermostatic type including, in combination with a boiler,

therein, some of the openings being arranged out of line, axially of the passageway, with others thereof.

6. In a low water alarm of the thermostatic type, the combination with a steam boiler of a drop pipe adapted'to' extend within the steam and water space thereof, a collar secured to the upper end of the drop pipe, the said collar being arranged to eo-ope erate with the boiler shell to form a steamtight joint, a fitting removably mounted upon the collar, and an expansionelement extending laterally from said fitting and removably secured thereto, said fitting oomprising a fluid connection between the drop pipe and the expansion element.

7. In a low water alarm of the thermostatic type, the combination with a steam boiler of a drop pipe adapted to extend within the steam and water space thereof, a collar secured to the upper end of the drop pipe, the said collar being arranged to cooperate with the boiler shellto form a steamtight joint, a fitting removably mounted upon the collar, an expansion element extending laterally from said fitting and removably secured thereto, said fitting comprising a fiuidconnection between the drop pipe and the expan sion element, and means connected to the shell of the boiler adapted to clamp the said fitting to the collar and the collar against the boiler.

8. A low water alarm of the thermostatic 1 type including in combination with a steam boiler a drop pipe extending from the exterior of the boiler into the steam space thereof and having an open lower end defining the a removable baflie arranged across the cavity of said hollow fitting above and in line with said drop pipe, and a normally closed cleanout opening in the fitting above and in line withthebafile. V p I ,7

9. A low water alarm of the thermostatic type including in combination with a boiler a fitting attached thereto,an expansion element demountablyattached to the fitting, a support bracket for the outer end of the expansionelement, the same having a recess formed therein adapted to receive the expansion element, and a removable, member secured to the bracket and engaging the end of the expansion element, the walls of said recess and the said member being arranged to guide the expansionelem-ent. r

' 10. A low water alarm of the thermostatic type including in combination witha boiler a fitting attached thereto, an expansion ele ment demountably attached to'the' fitting, a V 7 support bracket for the outer end of'the expansion element, the same having a non-cirfluid communication with said hollow fitting, V

eular recess formed therein adapted to re-- pansion element being of co-operating noncircular cross section, and removable means attached to the bracket and overlying the expansion element, the same being adapted to oo-operate with the outer end of the expansion element to hold the same against rising 1 from normal position Within said recess.

In testimony whereof I aflix my signature.

HARRY W. CODDINGTON;