US2063373A - Low water safety device for boilers - Google Patents

Description

Dec. 8, 1936. |=|NDLEY 2,063,373

Low WATER SAFETY DEVICE FOR BOILERS Filed June 9, 1932 4 Sheets-Sheet l 7b ELEc TR/CALLY CONTROLLED AUTOMATIC TUEL SUPPLV as v 5 29 55 6 INVENTOR HOWARD J FNDLEY ATTO EY.

Dec. 8, 1936. H. J. FINDLEY LOW WATER SAFETY DEVICE FOR BOILERS Filed June 9, 1932 4 Sheets$heet 2 INVENTOR. HOWARD J FTNDLEY ATT Dec. 8, 1936. J FlNDLEY 2,063,373

LOW WATER SAFETY DEVICE FOR BOILERS Filed June 9, 1932 4 Sheets-Sheet 3 111 insu/a/ion I 4 121 71 I 1 gnu/011011 INVENTOR. HOWARD J T/WDLEY Dec, 8, 1936.

H. J. FINDLEY LOW WATER SAFETY DEVICE FOR BOILERS Filed June 9, 1932 4 Sheets-Sheet 4 INVENTOR. HOWARD J. F Y

W ATT NEY.

Patented Dec. 8, 1936 PATENTIXOFFICE LOW WATER SAFETY DEVICE FOR BOILERS Howard J.

The Bishop &

Findley, Cleveland, Ohio,

Babcock Mfg. C'ompany,

land, Ohio, a corporation of Ohio assignor to Cleve- Application June 9, 1932, Serial No. 616,346

8 Claims.

. This invention relates to safety apparatus for boilers and the like, and relates particularly to boilers having automatic electrically actuated fuel supplying apparatus and to automatic devices for shutting down a fuel supply whenever the water in the boiler, due to any cause, reaches a predetermined low level.

As is well known, the continuous firing of a boiler after the water level. therein has reached a certain low level, may result in injury to the boiler and associated apparatus, and in some cases wherein the pressure release apparatus is inadequate, may result in an explosion and damage to the apparatus and destruction of property.

Heretofore various devices operating upon the principle of a float, actuated by the attainment of a low water level, have been proposed to effect corresponding control of fuel supplying apparatus, but such devices have practical disadvantages which have prevented general use. Among such defects are responses of such apparatus to changes of pressure as well as of water level, thus cutting off the fuel supply to the boiler at various levels, fluctuating with the pressure, and not at a substantially constant level.

In a low water cut-out designed to terminate the fuel supply to the boiler when a predetermined low water level is reached it is desirable that, after the fuel supply is cut off, it cannot be reestablished until the cut-off is manually reset, and further, that it cannot, be manually reset until the boiler has been filled to a point substantially above the low water level.

It is an object of my invention, therefore, to provide an improved apparatus for shutting down the fuel supplying apparatus of a boiler upon the occurrence of a water low a predetermined low level.

Another object of my invention is to provide an improved low water cut-out for boilers or the like, wherein after the fuel supply to the boiler has been cut off, it cannot be reestablished until the boiler water has been raised to a point substantially above the predetermined low level point.

Another object of my invention is to provide a low water cut-out for boilers or the like, wherein after the fuel supply to the boiler has been stopped it cannot be reestablished until the water level has been raised to a point'substantially above a predetermined low level point and the device has been manually reset.

Another object of my invention is to provide in a low water cut-out for boilers and the like, a relatively sensitive actuating mechanism which will be relatively unefiected by variations in temperature of the boiler water.

Another object of my invention is to provide a low water cut-out for boilers and the like, wherein a switch controlling the fuel supply molevel therein to or beboiler.

tor will be positively actuated at a predetermined point.

Another object of my invention is to provide a low water cut-out for boilers or the like, provided with external, adjustment means encased in a removable housing whereby the device may be easily and quickly adjusted as desired.

Another object of my invention is to provide a low water cut-out for boilers and the like, which is relatively inexpensive to manufacture and may be efficiently assembled.

Other objects of the invention and the invention itself will become more apparent to those skilled in the art to which my invention appertains by consideration of the accompanying description and drawings, wherein- Fig. 1 is an elevational view of a boiler provided with an automatic fuel supply, wherein a preferred embodiment of my invention is employed to shut off the fuel supply to the boiler when a predetermined low water level is reached;

Fig. 2 is a medial vertical sectional view of the embodiment of my invention illustrated in Fig. 1;

Fig. 3 is a side elevational view.of the embodiment of my invention illustrated in Fig. 2;

Fig. 4 is a perspective view partially in section of a portion of the switch mechanism shown in Figs. 2 and 3;

Fig. 5 is a modification of my invention generally similar to that shown in Figs. 1, 2, and 3;

Fig. 6 is a vertical sectional view of another modification of my invention;

Fig. '7 is a side elevational view of the modi fication of my invention shown in Fig. 6;

Fig. 8 is a vertical sectional view of a modification of my invention generally similar to that illustrated in Figs. 6 and ,7;

Fig. 9 is a fragmentary view of a switch casing which I may employ in connection with the modifications illustrated in Figs. 6 and '7;

Fig. 10 is a fragmentary sectional view taken from the plane I!) of Fig. 6.

Referring to Figs. 1, 2, and 3, wherein I show a preferred embodiment of my invention, the device for cutting off the fuel supply to the boiler when a predetermined low water level has been reached is generally indicated at l and will hereinafter be termed the low water safety cut-out.

The low water cut-out is connected to a conventional boiler 2, by pipes 3 and 4 which are in communication with the boiler water where.- by the level of water in the pipe 3 or the low water cut-out I will be the same as within the The pipe 4 preferably is connected to the lower portion of the boiler thus minimizing any tendency of surging in the boiler to be communicated to the low water cut-out and thereby trip the device before the predetermined level is reached,

An electrically controlled fuel supply apparatus (not shown) is supplied with current from mains 5, the flow of current to the fuel supply apparatus being controlled by a switch 6 mounted on the low water cut-out I.

The low water cut-out casing comprises a preferably cast iron cup-shaped base I, and a confronting cup-shaped preferably cast iron head 8 having interposed therebetween sealing washers 99 and an annular preferably sheet metal ring to. The cup shaped base I flares generally outward from the bottom thereof and terminates upwardly in a generally inwardly extending flange ll, faced as indicated at l2 to provide an engaging face for the lower sealing washer 9, but at l3 the wall of the base does not flare outwardly but extends generally vertically from the bottom of the cup shaped base 1 and engages the inner edge of the flange I I, thus providing a generally flat wall portion.

The base 7 has centrally disposed at the bottom thereof an outwardly extending, interiorly threaded boss 14 which threadedly engages the pipe 4. The head 8 is provided at the top thereof with an inwardly extending, interiorly threaded boss l6 adapted to sealingly engage the pipe 3, and is further provided with a horizontally extending, internally threaded boss I! and a diametrically disposed aligned aperture 18. The head 8 which flares generally outwardly from the top thereof, is provided with a boss is which thus provides a generally vertical planar surface in the wall thereof. The base I and the head 8 may be secured together in any suitable manner such as by providing spaced outwardly extending lugs l and 15A having aligned apertures therein whereby they may be secured together by bolts 25 and nuts 25A.

A sleeve provided with a stepped shoulder 2| and a relatively thickened tubular threaded end 22 is sealingly and rigidly secured within aperture l8 of head 8 by means of a sealing ring 23 which is compressively disposed intermediate the shoulder 2| and a faced boss 24 on the inner wall of the head 8 by a nut 25 engaging the threaded end 22 of the sleeve 20. One end of a bellows 26 which is composed of a suitable metal is sealingly secured to the shoulder 2| of the sleeve 20 and is axially positioned thereon by the end of the bellows telescopically engaging the said shoulder.

A flanged bushing 21 threadedly engages the boss I! of the head 8 and compressively engages a sealing ring 28 intermediate an inwardly extending face 29 of boss I! and a flanged shoulder 30 of the bushing 21. A second bellows 3| is sealingly secured to the shoulder 30 by brazing or the like and the bellows are sealingly secured together at-the confronting ends thereof as indicated at 32 and are also secured to an axially disposed switch actuating rod 33 and externally of the bellows they are secured to the downwardly extending pin 34. The switch actuating rod 33 is fulcrumed about a pin which is disposed within an aperture provided therefor in the rod 33 and is secured to the sides of the sleeve 20 preferably by flanging over the ends of the pin which are projected through the tube.

A bellows 36, concentric with pin 34 has the bottom thereof 3! closed and at the upper end is sealingly secured to the under side of the sheet metal ring in by any suitable means such as brazing. The lower end of pin 34 is sealingly secured to the bottom 31 of the bellows 36 preferably by projecting a shouldered end therejected to the of through a centrally disposed aperture in the bottom 31 and flanging the end over to sealingly grip the edges of the aperture intermediate the flanged head and the shoulder of the pin.

The portion of the housing above annular ring [0 together with the interior of the bellows 36 is effectively sealed from the portion of the housing below ring l0 and exterior of the bellows, except for a communicating passageway established as follows. The head 8 is provided with a channel portion 8a integral with its inner wall, and a similar channel portion Ia communicating therewith is formed in base 1, and after the casing is initially filled, the water level therein may be kept substantially at the top plane of passage 8a. Normally the bellows 36 being subsame hydraulic pressure above and below ring ID will be uninfluenced thereby. When the level of water drops below the ring I 0 the bellows 35 will remain full and at a predetermined low level the difference in pressure inside and outside of the bellows 36 will be sufficient to expand bellows 36 downwardly to trip the switch mechanism.

Both ends of the horizontally disposed bellows 26-3l are open to the atmosphere and will be in communication therewith at all times. At the same time bellows 26 and 3| are also effectively sealed against escape of water therethrough and to prevent the entry of water to the interior thereof; and each bellows 26 and 3| neutralizes the collapsing tendency exerted by the other due to pressure in the casing 8! thereby preventing axial or transverse binding action on the pin 35 by rod 33. As the bellows 36 moves downwardly, it will move the aflixed pin 34 downwardly and thus rock upwardly the outer end of the rod 33 fulcrumed about pin 35 in sleeve 20.

A means is comprises a spring 38 secured to the end of rod 33 preferably by projecting an end of the spring through an aperture provided therein, the other end of the spring being secured to a screw 33 threadedly engaging a preferably sheet metal bracket 40 secured to the boss IQ of the head 8 by a screw 4|. A look nut 42 locks the screw 33 in any adjusted position.

It will thus be seen that by rotating the screw 39 and regulating the tension of the spring 38 the bellows 36 may be calibrated to rock upwardly the outer end of rod 33 when a predetermined water level exteriorly of the bellows is reached.

Two fixed contacts 43 of the switch 6 only one of which is shown are disposed in spaced relation in a suitable insulating element 44, which in erably has embedded therein a generally L- shaped supporting member 46 which engages the under side of flange H and abuts the outer face l3 of the head I and is preferably provided with threaded apertures adapted to engage the screw 45, whereby the insulating element 44 and the contacts 43 therein may be rigidly supported.

A movable contact bar 49 of suitable conducting material (see Figs. 2 and 4) is centrally apertured whereby it may be rockingly seated on a shoulder 41 of a guide pin provided with a reduced threaded end 48 and 9. preferably hexagonal head 41a. The insulating element 44 is provided with a hexagonal recess terminating in a reduced co-axial circular aperture within which the guide pin is slidingly disposed with the head 41-41 thereof engaging a normally compressed spring 58 which encircles the pin and at its opposite end seats against the bottom of the hexagonal recess in insulating element provided with a generally rectangular base 5i grooved to accommodate bar 49 and having a stem 52 is telescoped over the reduced end 48 and is locked therewith by a washer 53 and a nut 54 which threadedly engages the pin end. The guide pin is thus prevented from rotating relative to insulating element 44 and the contact bar will normally be held in springpressed relation with the fixed contacts 43 and will be prevented from moving laterally thereto but will be permitted to wipingly engage the fixed contacts thereby minimizing any tendency towards arcing or the like.

A locking bar 55 generally rectangular in shape is provided at the upper end thereof with a flanged end 58, and adjacent the other end provided with a generally oval shaped aperture 51. The locking bar 55 is pivotally mounted as indicated at 58 and has a spring 59 oppositely reacting upon the outer wall of flange II and the inner face of the locking bar which tends to rotate the bar around the pivot 58 in a counterclockwise direction. The stem 52 of the guide pin is disposed within the aperture 51 of the locking bar and the bar on rocking counter-clockwise engages the washer 53 and by continued movement opens the switch contacts.

It will be observed that as the bar 55 is rotated in a counterclockwise direction, it will move the movable contact 49 outwardly from the fixed contacts and thereby break the circuit to the fuel supply apparatus.

The operation of the lower water safety cut-out is as follows. As the water level in the boiler drops there is a corresponding drop in the bypass 3--4 and when the water exteriorly of the bellows 36 and below ring l8 reaches a predetermined level, the weight of the water within the bellows causes the bottom of the bellows and the affixed rod 34 to drop sufficiently to actuate the switch actuating rod 33. This outer end of the rod which pivots around the pin 35 is thereby lifted due to the combined action of the bellows 38 and the tension spring 38. As the switch actuating rod 33 is raised above the tip 58 of bar 55, the bar rocks in a counterclockwise direction due to the pressure exerted thereagainst by the spring 59 thus locking the rod 33in raised position, and breaking the contact between the fixed contacts 43 and the movable contact 49 and thereby shutting off the fuel supply to the boiler.

It will thus be seen that when a predetermined low water level is reached in the boiler that the fuel supply to the motor will be automatically cut off.

The switch mechanism is preferably provided with a casing 63 which is generally cup shaped and is apertured at the bottom thereof as indicated at 64 to engage spaced lugs extending from the bottom of base l3 of head I. The top of the cup shaped casing is provided with spaced apertures within which are disposed screws 65 engaging the head 8 and thereby rigidly securing the switch casing to the low water cut-out casing. The bottom of the casing 53 is provided with an aperture 68 through which the lead wires are fed to engage a terminal 81 connected to the fixed contact by a bar 88.

element 44. A preferably fibre supports a bellows In order to provide a means of forcing the bar 55 in a clockwise direction so that tip 58 thereof may disengage the end of switch actuating rod 33, a push button 68 is slidingly disposed in an aperture in casing 63 and has a head 83A thereon normally held in engagement with the inner wall of the casing by an L- haped resilient member 8! secured to casing 63. When the push button is forced inwardly the member 81 forces bar 55 in a clockwise direction.

If at this time water has been added to the boiler and has risen in the cut-out casing above the level of the bellows 36 so that the rod 33 is no longer held in counter-clockwise position. pushing of the button 88 and rocking of the bar 55 clockwise will permit the end of rod 33 to fall in front of the bar and retain it in switch operable reset condition. If, however, sufficient water has not been added, the rod 33 will not drop in front of the bar 55 and the switch cannot be reset.

It will be noted that the low water safety cutout which I employ is relatively unaffected by variations in the temperature and pressure of the boiler water, that it is positive in operation and operates at an adjustably variable predetermined water level, that it can only be reset manually, and that it cannot be manually reset until the water in the boiler has been raised above the danger low level point.

In Fig. 5 I have illustrated a modification of my invention which is similar in operation and construction to the form illustrated in Figs. 1, 2, and 3 with the exception that I have employed a float 18 as the actuating element for the rod 34 rather than the bellows 38 previously used.

An element H is secured to the horizontal bellows preferably by brazing and is provided with a threaded stem 12 which engages a threaded collar secured to the float. A lock nut 13 is preferably provided whereby the float may be locked in any adjusted position.

Referring to Figs. 6 and 7 I have shown another modification of my invention wherein I employ a sheet metal casing and have altered the type of switch and the actuating mechanism slightly. In this modification I preferably employ a sheet metal case comprising the cup 88 grooved as indicated at 8| along the rim thereof, and the cap 82 having the peripheral edges of the cap disposed within the groove 8| and sealingly secured therein preferably by welding. The casing is provided with aligned apertures substantially axially thereof in the bottom of the cup and in the cap wherein are afiixed apertured pipe elements 83 preferably by welding as indicated at 84.

To ensure additional rigidity the portion of the pipe element 83 indicated at 83A is preferably previously formed as a reduced sleeve thus providing a shoulder against which the peripheral edges of the apertures in the cap and bottom of the casing abuts, and are then flanged over to generally form a tongue and groove structure which is sealed by the welding process. The pipe elements 83 are preferably hexagonalls shaped whereby they may be rotated to threadedly engage the elements 83 with the pipes 3 and 4 illustrated in Fig. 1.

A flanged ring 85 is weldingly secured to the cup 88 substantially centrally thereof and in turn 86 secured thereto preferably by welding, the bellows being provided with a relatively stiff bottom 81. Horizontally disposed bellows 88 and and have a coaxially disposed ring 89 are sealing ly secured'together 90 secured thereto preferably by welding, and are sealingly secured to the casing walls at the opposite ends.

A pin 9| disposed axially of the casing is sealingly aflixed to the bottom of the bellows 86 and is provided with a threaded stem at the upper end thereof adapted to engage a cap 92 which is weldingly secured to the bellows 88 and 89 after the bottom 81 of the bellows has been adjusted through the medium of the pin 9| to the desired position.

A sleeve 93 is rigidly secured to the casing wall by a nut 94 and a lock washer 95, the sleeve being threadedly engaged with an integrally threaded flange 96 of the casing wall. The nut 94 also secures a bracket 9'! to be later described. A rod i 01 is fulcrumed within the sleeve 93 by a pin 98, and loosely engages the ring 90 at one end and at the other end is secured to a tension spring 99. The spring 99 is afiixed at its opposite end to the bracket 97.

The bracket 9! is preferably formed of sheet metal and in side elevation is clearly shown in Fig. 6 and is generally of constant width. It is secured to the casing wall by any suitable means such as riveting. Upstanding ears I are pro- Vided to support a pin IOI about which a. switch lever I62 fulcrums.

The switch lever I02 is apertured to loosely surround a contact guide I03. The contact guide I 03 comprises an insulating portion I04 in the apertured lever and a generally box shaped insulating member I09, at one end of the insulating portion I04 and an insulating washer I08 on the other end, adapted to engage the top face of the switch lever I02. The insulating member I09 is provided with a transverse recess within which is rockingly disposed a movable contact bar H0. The guide element is preferably provided with a reduced cylindrical portion threaded at the end thereof, thus providing a shoulder upon which the bottom face of the movable contact bar II 0 loosely seats.

The element I03 is preferably tubular whereby it may be telescoped over the reduced cylindrical stem of guide element I05 and secured thereto by a nut III which engages the threaded end thereof. The movable contact bar I I 0 will thus be permitted to rock longitudinally when engaging fixed contacts i I2 (only one of which is shown) rigidly secured in an insulating element I06 in spaced relationship and thus make a very desirable wiping engagement when contacting therewith. The fixed contacts II2 extend through the insulating element I06 and have generally L-shapedterminal brackets II3 secured thereto preferably by flanging over the contact ends projected through apertures in the bracket.

Terminals II4 adapted to engage leads from the mains 5 threadedly engage the bracket H3. The insulating element I06 is rigidly secured to the bracket 9! preferably by screws II5.

A spring II 6 encircles the pin IOI and has one end secured to the switch lever I02 and the oppo-' site end secured to the bracket 91 whereby the switch lever will rock in a counter-clockwise contact opening direction, when the right hand end c the rod 101 is pivotally raised out of engagement therewith.

A generally rectangular cup-shaped casing II! is provided with spaced apertures at the top thereof adapted to engage pins IIB integrally secured to bracket '91 and at the bottom provided with spaced threaded apertures whereby it is secured to the base of the bracket 91 by screws II 9, thus being easily removable when it is desired to ad- 'municating just the switch mechanism. The casing is flared outwardly to provide a pocket I20, whereby the switch lever may be rocked clockwise manually to reset it. The casing is slotted above the pocket and an upper edge I 2| thereof acts as a stop to limit the upward movement of the switch lever when in the contact disengaged position. The casing is preferably slotted below the pocket I20 whereby the word on" marked on a downwardly extending lug I24 of the switch lever will indicate when the circuit is closed.

A sheet metal segmental wall I34, Figs. 6 and 10, concentric with and spaced inwardly from the inner wall of cup 80 has the ends thereof flared outwardly whereby they may be sealingly secured to the wall of cup 80 preferably by welding. The bottom edge of segment I34 seats upon and is sealingly secured to the ring 85 near the peripheral edge of an aperture I35 provided in flanged ring 85 thus providing a passage from the portion of the cup above ring 05 to the portion below for reasons previously described.

With this arrangement, when the water falls in the casing cup, the water inwardly radially of the segmental wall I34 will all be supported by the bellows so that a relatively great gravitational force for operating the cut-oil switch is provided.

Referring to Fig. 8 I have shown a modification of my invention generally similar to that illustrated in Figs. 6 and 7 but wherein I employ a float I30 which threadedly engages the cap 92 by a stem l3I substantially centrally positioned in the upper face thereof. The float I30 will function in the same manner as the bellows 06 to actuatethe switch mechanism when a predetermined low water level is reached.

Although'I-have shown and described embodiments of my invention I contemplate that numerous and extensive departures may be made therefrom without departing from the spirit and scope of my invention and the appended claims.

Having thus described my invention what I claim is:

1. In a low water device for electrically actuated apparatus, a housing, connections establishing in the housing levels of water under pressure, an element in the housing movable responsive to changes of water level independently of pressure therein, contacts disposed externally of the housing and controlled by movement of the movable element to be actuated upon occurrence of water level below a predetermined level, by a contactoperating means projected through a perforation in the wall of the housing, means isolating said contact operating means from pressure within the housing and manual means for operating the contacts, said means beinginefl'ective to maintain the contacts operated except upon restoration of level in the housing above the predetermined low level.

2. In a device of the class described, a housing adapted to be connected to acontainer to establish in the housing levels of water in the container. a movable element in the housing movable responsive to changes of water level therein, a perforation in the wall of the housing, a tubular bellows element sealed at its end to the periphery of the perforation to seal the same and cominteriorly with the atmosphere through the said perforation, an elongated element extending axially through the perforation and outwardly of the housing and pivotally supported upon the housing wall, and inwardly of the tubular bellows being connected to the inner wall thereof, and the outer wall of the bellows being connected to the movable element whereby movements of the movable element may be communicated to the external portion of the elongated element, a cup bellows supported by the housing and connected to the said movable element and adapted to move it upwardly or downwardly in response to changes of water level in the housing, and switch contactsexternally of the housing operable by said externally projecting portion.

3. In a device of the class described, a housing adapted to be connected to a boiler to establish in the housing levels of water in the boiler under pressure, a movable element in the housing movable responsive to changes of water level therein independently of boiler pressure, a perforation in the wall of the housing, a tubular bellows element sealed to the walls of the housing at the periphery of the perforation and communicating interiorly with the atmosphere through the said perforation, an elongated element extending axially through the said perforation and outwardly of the housing and pivotally supported upon the housing wall, and inwardly or the tubular bellows being connected to the inner wallthereof, and the outer wall of the bellows being connected to the movable element whereby movements of the movable element may be communicated to the external portion of the elongated element, switch contacts externally of the housing operable by said externally projecting portion, said switch contacts comprising spaced insulated fixed contacts rigidly supported externally of the hous-' ing and an insulated movable contact adapted to wipingly engage said fixed contacts.

4. In a device of the class described, a housing adapted to be connected to a boiler'to establish in the housing levels of water'in the boiler, a movable element in the housing movable responsive to changes of water level therein, a perforation in the wall of the housing, a tubular bellows element sealed at one and upon the inner wall of the housing and at its opposite endsurrounding the periphery of the perforation and sealing the same and communicating interiorly with the atmosphere through the said perforation, an elongated element extending axially throughthe perforation and supported upon the housing wall, and inwardly of the perforation, extending into the tubular bellowsand connected to an intermediate inner wall portion thereof, and the outer wall of the bellows at an intermediate portion thereof being connected to the movable element whereby movements of the movable element may be communicated to the external portion of the elongated element, a bar fulcrumed externally of the housing in spring-pressed relation with the external portion of the elongated element at a predetermined water level position of the elongated element, fixed contacts rigidly supported externally of the housing, movable contacts adapted to engage the said fixed contacts and operable by said bar, and manual means for forcing the said bar to engaged relationship with the elongated element and against the tension of the spring.

5. In a device of the class described, a housing adapted to be connected to a boiler to establish in the housing levels of water in the boiler, a movable element in the housing movable responsive to changes of water level therein, aligned perforations in the walls of the housing, tubular bel-'- lows element sealed at opposite ends to the'peripheries of the perforations and communicating interiorly with the atmosphere through said perforations, an elongated element extending axially through one of the perforations and outwardly of the housing and pivotally supported upon the housing wall, and inwardly of the housing being connected to an intermediate inner wall portion of the bellows, the outer wall of the bellows at an intermediate portion thereof being connected to the movable element whereby movement of the movable element may be communicated to the external portion of the elongated element, a spring adjustably engaging the elongated element whereby the relative effects thereon of the movable element may be altered, and switch contacts externally of the housing operable by said externally projecting portion.

6. In a device of the class described, a housing adapted to be connected to a boiler to establish in the housing'levels of water in the boiler, a movable element in the housing movable responsive to changes of water level therein, a tubular bellows element sealingly engaging the housing walls at each end and interiorly communicating with the atmosphere, an elongated element in the bellows element extending axially thereof and outwardly of the housing and pivotally supported upon the housing wall and inwardly connected to the movable element through the bellows wall and adapted to be moved by the movable element,

switch contacts disposed externally of the housing operable by an externally projecting portion of the elongated element, an insulating element rigidly secured externally of the housing, spaced fixed contacts secured to the said insulating ele- 'ment, a guide pin slidingly mounted in the insulatengagement with the fixed contacts, a bar pivotally mounted externally of the housing loosely engaging the'movable contact guide and normally engaging the external portion of the elongated element and adapted to disengage the fixed immovable contacts when in an engaged position with the said elongated element.

7. In a liquid-level-responsive switch device, a walled housing adapted to have liquid levels established therein under pressure, a switch, movable switch operating means, and meansisolating the operating means from pressure in the housing to cause it to actuate the switch independently of pressure in the housing upon a change'of liquid level in one direction, and means to normally prevent restoring of the switch upon change of liquid level in the other direction inde-v pendently of pressure in the housing, and adjustable means externally of the housing to ad just the level at which the switch is actuated.

8. In a liquid-level-responsive switch device, a walled housing adapted to have liquid levels established therein under pressure, a switch, movable switch operating means, and means isolating the operating means from pressure in the housing to cause it to actuate the switch independently of pressure in the housing upon a change of liquid level in one direction, manual means externally of the housing for restoring the switch, means to normally prevent restoring of the switch upon change of liquid level in the other direction independently of pressure until a predetermined liquid level is obtained, and means externally of the housing for adjusting thelevel at which the switch is actuated.

HOWARD J. FINDLEY.

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