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Publication numberUS838823 A
Publication typeGrant
Publication dateDec 18, 1906
Filing dateOct 22, 1904
Priority dateOct 22, 1904
Publication numberUS 838823 A, US 838823A, US-A-838823, US838823 A, US838823A
InventorsWilliam I Thomson
Original AssigneeSafety Car Heating & Lighting
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Low-water alarm.
US 838823 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

PTBNTED DEG. 18, 1906.






Application filed Octbl' 22| 1904. Serial H0. 229.590.

To alt whom it may concernl Be it known that I, WILLIAM I. THOMSON,

residing at Newark, in the county of Essex,

State of 'N ew Jersey, have invented certain new and useful Im rovements in Low-Water Alarms, of which tliie following is a full, clear, and exact description.

My invention relates'particularly to a low- Water alarm for a hot-water car-heating system; but it will be understood that the invention, with slight changes in the details ofthe constructiomcan be utilized in other situations'.` It must be understood, therefore, that the invention is not limited to hotwater heating systems, but for the purpose of convenience, clearness, and conciseness I shall describe the invention as applied to a hot-water heating system for cars, making reference to the Baker system as an example of a system with which my invention can be incorporated.

My invention has for its further obj ect to provide means in alarm systems generally whereby upon the occurrence of an alarm a test -may not the contingency for which the alarm has been provided has happened or Whether some defect exists in the system by reason of which a false alarm may have been given.

In the' accompanying drawing I have shown a diagrammatic view, partly in sectionalV detail, of a low-water alarm and circuit connections embodying m Invention.

As is Well known, t e Baker heating sy tem for heating cars consists, in the main, of

Va stove supplied with a coil of pi e within the fire-pot en of an expansion rum on the roof or above the stove and connecting by a riser with the upper end of the coil, and a system 'of pipes extending from the expansiondrum down to the Jdoor of the car and under the seats. This circuit of ipes is iilled with salt water or brine up to the overflow of the eXpngsion-drum, which is then closed tightly.

' en the water becomes heated in .the normal operation of the system and expands, the whole syst em is subjected to ressures up to two hundred or three hundredp pounds per square inch. Under these circumstances aleak 'often occurs in some out of the way e made to ascertain whether' or Patented Dec. 18, 1906. y

and the spray and the alarm is not given' when it is most needed. This same corrosive action constitutes an objection to alarms with hinged or sliding parts which ares upposed to move when the water recedes, but which in reality'become covered vwith salt and rust, generally stick, and are consequently unreliable.

In the construction in which my invention is embodied and which is shown in the drawings there are no moving parts or floats. An iron plate'is held about one inch above the bottom of the drum upon a suitable rod and insulated from the drum, and the circuit of a relay is completed through the salt Water in the drum, so that so lon as the Water-level remains high enough in t e drum the relay will hold the alarm apparatus out of action. When the water recedes, the circuit is opened, thereupon causing the relay to release its armature to complete a local circuit and ring a bell to call the porters attention to the fact that the fire orsteam in the reot ofthe stove or the transfer-heaters must be shut off. The relay and its battery may be placed in an convenient position andthe relay connecte in the electric system of the cars, just like an additional ushbutton in the ordinary call-circuit for t e porter of the car. i

In the drawing I have shown, by way of example, one embodiment of the completeVY invention wherein means for testing are provided, the closed-circuit alarm system proper being combined with an open-circuit testing system, which may be of any desired character, but which may convenientl be the ordinary call-circuit of the car, Which being ICO in constant use is constantly under supervision, whereas the alarm-.circuit bein used only in emergencies is not under-suc rigid observation.-

,Having described my invention in general terms, I will proceed to describe the specic embodiment shown in the drawings.

In the drawing, a is a section of the castt l: t E.

riser-pipe b ofheghxot-water heating system,

which also includes a smortransfer-heater. (Not shown.) The descending ieg c of the same circulating system leads from the drum.

An iron plate d is su ported a shortdistance .above the bottom o the tank upon an iron rod c, which screws into the iron studj. This stud f is provided with a shoulder g, insulated from a screw-plug h by means of a mica washer i and a fiber sieeve j, suitable lead washers k being used, if desired. The iron studf is further provided with in ica and iron washers Z m, respectively, anda plurality of.

nuts o for effecting electrical connections.

An ordinary pipe-cap p, screwed over the` plug, protects `the connectionv from the weather, and awire q, connected to the stud, leads through a hole in the casting or plug 71. to the relay 1^. The relay 1 is connected by a wire s to one contact t of a suitable knifeswitch or other desired switch t. The other contact t2 of the switch is connected by wire u with one pivotal connection of the switch A wire y connects one contact z with one pole of the battery fu, and a wire 2 connects the other pole of the battery v with the contact w3 of the switch x. The other pivotal connection w* of the switch :z: is connected by a wire w to the pipe c or any other pipe or part in electrical connectionwith the cast-iron drum c. The circuit connections just described are those of the closed-circuited alarm system roper.

The local circuit o? the relay is as follows: A wire 1 leads from the contact t* of the switch t to a bell 2, thence by battery 3 to wire 4 to the back Contact 5 ofthe relay armature,6 which is connected by wire 7 to the contact t3 of the switch t.

The operationo the apparatus so far described will be readily understood. So long as the iron plate (Z is .immersed in the water the batterycircuit fv will be complete and the armature 6 will be held against its front stop.8. Then the water recedes below the iron plate, the relay-circuit is thereby broken and .the armature 6 will swing against the back-stop, elcsing the local`bell-circuit and giving the alarm. It will be obvious, however, that as the battery o is constantly on closed circuit it 'will eventually fail, and this too would cause the alarm to be given.

y In order to provide means for readily determining whether or not the alarm has been roperly given or whether or not the battery lias failed, I connect one pole of the battery 3 by a wire 9 to the contact at of the switch a: and the other pole of the battery 3 by wire 10 with another contact :c5 of the switch This battery 3 being on open circuit will be constantly in condition for action, and when the alarm is given in order to make the required test the switch :c may be swung from thc contacts I? ac3 to the contacts :c5 zu, thereby inserting the battery 3 into the main alarm-circuit. lf the alarm has been given by' reason of a failure of the battery and the 7o circuit is otherwise complete, the armature of the relay will be drawn up and the bell will cease ringing. If, however, the circuit is broken at any ,point-Tior instance, if the liquid-level in the drum is below the electrode or contact d-no current will low through the, main alarm-circuit from the battery 3 and the bell 2Vwill continue to ring, thus indicating positively that the water is low in the drum. 8o

The object of making the plate a and the rod e of iron is to prevent making an electric battery, which would of. course occur if'the drum-casing and the plate d were of different metals. The lead washers f on eachsideof the mica washer i', is to make a tight joint.

It is quite di'iicult to make an insulated joint tight when subjected to two hundred or three hundred pounds pressure; but I have found that a thin sheet of leadon the sides of the 9o mica will eifectually make a tight joint.

Having described-my invention, what I claim, and desire to secure by Letters Patent, is

l, In a system of the class described, in combination, a receptacle adapted to contain a liquid, a relatively insulated terminal within said receptacle adapted to be electrically connected therewith by saidliquid, indicating means, a source of electric current Ioo adapted to be placed in circuit with said indicating means, means adapted u on connection between said terminal an said receptacle being broken to complete said'circuit through said indicating means, a source of electric current within said last-mentioned means, and means adapted to substitute said lir'st mentioned for said last-mentioned source of current.

2. In a system oi the'class described, in Ilo combination, a circuit comprising normally closed circuitbreaking means and a source of current, a second circuit comprising indi-- eating means and a source of current, means adapted upon said first-mentioned circuit being broken to complete said second circuit, and means adapted to substitute said second source of current for said first source of current in said first circuit.

3. In a system of the,class described, in combination, a metallic receptacle adaptedv to contain a saline liquid, a relatively insulated terminal of a similar metal within said receptacle and normally projecting within said liquid, a circuit comprising said terminal I 25 and a source of current, a second circuit comprising indicating means and a source'o'f current, means adapted upon said first circuit becoming broken to close` said second circuit.

and operate said indicating means, and 13o vmeans .adapted to substitute said second source of current for said first source in said st circuit. 4. In a system of the class described, in combination, a metallic receptacle adapted to containa saline liquid, a relatively insu- With by said liquid, a circuit comprising said terminal and a sourceo current, indicating means, means adapted to render Operative said indicating means on said circuit becoming broken, a second source of current, and means adapted tO substitute said second for said first source of current in sr id circuit.

n a system of the class described, in combination, a metallic receptacle adapted to contain a saline liquid, a terminal of a similar metal within said receptacle and nor-l mally connected therewith by said liquid, ini means, and means a second for said irst source of current inv said 35 first circuit.

apted to substitutesai A WILLIAM 1. THOMSON. Witnesses:



Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2534381 *Nov 10, 1948Dec 19, 1950David SebastianHydraulic brake level indicator
US3352989 *Oct 22, 1965Nov 14, 1967De Leonardis Michael JElectrode assembly for insertion in a fluid container
US3626400 *Oct 8, 1968Dec 7, 1971Gen Motors CorpSelf-checking fluid level indicators
US3910118 *Jan 18, 1974Oct 7, 1975Gerdts Gustav F KgProbe for controlling the level of electrically conductive liquids
US6587050Jul 24, 2001Jul 1, 2003Eaton CorporationOscillator activated continuity testing switch
US6653846Sep 14, 2001Nov 25, 2003Eaton CorporationMultifunction circuit continuity and sensor tester
US20060264260 *May 7, 2006Nov 23, 2006Sony Computer Entertainment Inc.Detectable and trackable hand-held controller
Cooperative ClassificationG08B29/14, Y10S200/30