Nov. 19, 1946. F. M. PATTERSON 2,411,457 LOW WATER ALARM Filed May 17,- 1944 '24 4/ )W70/MEMS. Patented Nov. 19, 1946 l2,411,457 UNITED STATES PATENT OFFICE 2,411,457 Low WATER ALARM Frank M. Patterson, Pitman, N.` J. Application May 1v, 1944, serial No. 535,964 6 Claims. (c1. 11s-_109)` 'i The present invention relates to steam pres~ sure equipment and more particularly to a low water alarm for steam boilers and the like. Some of the objects of the present invention are: to provide an improved apparatus for re sponding to low water levels of a boiler as an indication thereof, or as a means for assuring prompt regulation of such level; to` provide a simple and sure means of protecting a boiler from low water conditions; to provide a device wherein an axially movable shaft is arranged to be shifted under a low water level to operate an alarm; to provide means including a rotating propeller within the boiler or water column for causing an alarm to sound When'the boiler level drops to a predetermined low; and t0 provide other improvements asv will hereinafter appear. In the accompanying drawing, Fig. 1 repre Z limits provided by the annular box 28 encircling, the section 2'! and providing the necessary end clearances. . For housing the turbine 24, a closure cap` 30 iits about the turbine and has threaded connec tion with the. body I8. This cap 30 also forms a bearing 3l for the end of the shaft and is made pressure tight by a gland 32.. Steam is led to one side of the turbine 24 by a port 33 leading from' ’ the interior of the column II', while an exhaust port 34 is provided at the opposite side of the turbine chamber. ` » For sounding an alarm when the boiler level reaches low water, a bell 35 is mounted upon the cap 30 to be in the path of the clappers 25 when - the latter are in alarm, position, asV will beA ex plained. 1 For bringing the` bellclappers 25 into striking sents a longitudinal section of a low‘water alarm relation to` the bell 35, a plunger 36 having a cone embodying one form of the present invention; 20' shaped end is pressed against the end of the Fig. 2 represents a` sectional detail on line 2-2 shaft I8 by a coil spring 3l bearing at. one end of Fig. 1; Fig. 3 represents asection on line 3--3 against a. collar on the plunger‘and atV the other of' Fig. 1; and Fig. 4 represents a side elevation endA against` a» follower' 38 formed` as. a` part of a of the device as installed on the water column of feed screw 4B' threaded through a supporting arm a boiler. 4‘I and operated by a knurled. head 42. Referring to the drawing, one form of the In operation of theA device. the steamA pressureA present invention is shownl illustratively as used maintains: theV turbine 24: rotating and as >long as. as a low water alarm for boilers, though the the propeller 23 is operating in the water in the invention is not limited to the specific use since boiler it will shift and hold the shaft I8 (to the it is applicable to feed water regulators, high and 30 right as seen in Fig. 1) in a position overcoming low water alarms, steam traps, drainers and other the pressure of the spring 3l so that the clappers pressure equipment. As shown, the device com 25 are removed from the path of the bell 35. prises a body I 0 arranged to be attached in leak When the level of the water falls below the proper proof relation to the side of a water column low point the propeller is then operating in a II of a boiler I2, at a point in alinement with 35 steam area and its thrust becomes ineffective to the low water level. Bolts I3 secure the body I8 overcome the spring pressure, and the latter then to the column II and a gasket I4 is interposed shifts the shaft I8 (to the left as seen in Fig. 1) between the parts to make the joint pressure and the clappers I8 now strike the bell 35 and tight. The body IU has an extension I5 projecting sound the alarm. through an opening I6 provided in the column I I, 40 It will now be apparent that a complete unitary and through which a bore Il extends axially low water indicator has been devised wherein through the body I0. This bore I 1 forms a journal a positive and certain indication of a water level for a shaft I8 passing therethrough and projecting is obtained at all times and under all conditions. at both ends thereof. This shaft I8 is lubricated It should be noted that the propeller operates and maintained pressure tight by a gland 20 of to maintain the device ineffective as long as the suitable packing material arranged to be forced level is above the danger point but when the into place by a supply duct 2| and feed screw 22. level falls below such point the propeller being in The end of the shaft I8, which enters the column a steam area can no longer overcome the pres Il, has a screw propeller 23 keyed thereon while sure of the thrust spring whereupon the latter the opposite end mounts a turbine 24 and a pair 50 actuates suitable alarm or other mechanism to of bell clappers 25, the latter being carried by result in the dangerous condition being corrected. spring arms 26. The turbine 24 is mounted upon While the turbine is here shown as driven by a square section 2'I of the shaft I8 to transmit steam it can, as an alternative, be driven by a motion to the shaft I8 but the arrangement is small electric motor or other means, as will be such that the shaft I8 can slide axially within 55 understood. 2,411,457 , ' _, l.; 4 It will be understood that the device of the tion when said level falls to bring said propeller invention can be applied to any tank or vessel having two mediums therein of different densi ties which produce different reactions upon the rotatable member of the device. Furthermore, the shaft of the rotatable member can be ar ranged vertically‘in the tank or vessel to be ver into the steam space of the boiler, and means operated Joy said shaft in alarm position to oper ate said indicator. 4. In a low Water alarm for boilers, a screw propeller in a vessel subject to boiler pressure, a body attached exteriorly to said vessel, a shaft rotatably and slidably mounted on said body tically adjustablefor determining the level of for mounting said propeller, said shaft being the medium of greater density. In this form a paddlecan ¿be used instead of a propeller and l0 moved by the propeller-in one direction when immersedA in water, a spring for >moving said the differenceV in resistance between rotation in’ shaft in the opposite direction when the pro the two mediums taken as a measure of the liquid peller is in the steam space, means for continu level. By using an electrical' circuit an amme ously rotating said shaft by fluid pressure Within ter could indicate the variation in load when 15 the boiler regardless of level fluctuations, and passing from one medium to another.> _ means `operated by the shaft for indicating a low Having thus described my invention, I claim: Water condition. l. In a low water alarm for boilers,.an indica- » 5. In a low water Ialarm for boilers, a screw tor, an axially movable shaft entering the boiler I " , propeller in a vessel subject to boiler pressure, at a selected low water level, means for con tinuously rotating said shaft by fluid pressure 20 a body attached eXteriorly to said vessel, a shaft rotatably and slidably mounted on said body for within the boiler'regardless of level fluctuations, mounting said propeller, said' shaft being axially f means operated by said shaft when the level moved by the propeller »in one direction when> falls below lsaid selected low water level for actu immersed in water, a spring for moving said ating said indicator, and means reacting to» the water in the boiler to normally render said indi 25 shaft in the opposite axial‘direction when the> propeller is in the steam space, means for con cator operating means ineffective at levels above tinuously rotating said shaft by fluid pressure said low Water level. ' within the boiler regardless of leve-l fluctuations, 2. In a low water alarm for boilers, an indi " cator, an axially movable shaft entering the boiler means operated lby the shaft for indicating a at a selected low water level, means for continu 30 low Water condition, and means forming pressure tight joints for said shaft and housing. , _ ously rotating said shaft by ñuid pressure Within > the boiler regardless of level fluctuations, means operated by said shaft when the level falls below said selected low water level for actuating said indicator, and means comprising a screw propel ler on the shaft in the boiler to normally render said indicator operating means ineffective at lev els Iabove said low water level. 3. In a low water alarm for boilers,` an indica 6. In a low water alarm for boilers, an indi cator, an axially movable shaft entering the boiler at a selected low level, a' turbine keyed on said shaft, means actuated by boiler pressure for con tinuously operating said turbine to rotate said shaft, a screw propeller on said shaft and Within the boiler to react against the Water in the boiler to maintain said shaftV in a position,correspond tor, an axially movable shaft entering the boiler 40 ing to a safe water level, a spring -for movingk at a selected `lovv level, means fo-r continuously said shaft to an alarm position when said level rotating said shaft by fluid pressure within the falls below said selected low level tor bring said boiler regardless of level fluctuations, a screw4 pro propeller into the steam space. of the boiler, and peller on the shaft within the boiler reacting means operated by said shaft in alarm position against the water to maintain said shaft in a 45 to operate said indicator. n ‘ position corresponding to a safe water level, a spring for moving said shaft to an alarm posi FRANK M. PATTERSON. .