US2697216A - Signaling device - Google Patents

Description

8Q, 14, 154 C, K, LEE 2,697,216 SIGNALING DEVICE Filed Feb. 11, 1953 a d z 0 23 b w l/ e SUPPLY /a Q Z; 601 =v fi POWER }5U/PL7 J 7b Moro/Q INVENTOR. COLIN K. LEE BY United States Patent Oflice 2,69 7,2 l 6 Patented Dec. 14, 1954 SIGNALING DEVICE Colin K. Lee, Webster Groves, Mo., assignor to Monsanto Chemical ompany, St. Louis, Mo., a corporation of Delaware rr a ion February 11, 1953, Serial No. 336,269 10 Claims. or. 340-444 This invention relates to a telltale or overflow detector for warning of overflow of receptacles, for recording when overflow has taken place, for purposes of keeping records and for purposes of safety, and the like and more particularly relates to a. telltale device which clearly establishes that hoppers, tanks, bins and the like have been filled to overflow and material has been lost, contaminated, or that hazardous conditions have been created.

In the filling of such receptacles as tanks, bins, hoppers and the like, the overflow of the veyed vto such able because of its toxicity, corrosiveness or cost, because exceedingly strict inventory accounts must be kept on the material, or because overflow would create a hazard to the safety and well being of the workmen, or would otherwise create a dangerous condition which could not be detected unless the fact of overflow could be established. For example, where ethyl alcohol is employed in industry as a process solvent or reactant, or a product diluent or for any other industrial use, exceedingly accurate inventory records must be maintained. Not only must the alcohol in storage be accounted for, but also that amount consumed in process must be accurately known. Ethyl alcohol is frequently pumped from storage to a weighing tank where other an overflow of the alcohol. The evidence of overflow in such cases readily disappears by evaporation or merely by flushing the evidence down the drain. Or if the tank has an overflow trap, gutter or the like connected to a waste discharge line, the evidence is disposed of very neatly. Such unknown losses of ethyl alcohol are undesirable.

An additional example where the overflow of a material is undesirable is in the use of concentrated aqueous of such caustic materials as sodium hydroxide. The concentrated solution of sodium hydroxide not only creates corrosion problems but also creates hazards for plant personnel.

Usually weigh tanks, hoppers, and bins employed in industry are open to the atmosphere and, because they are ordinarily movable, they generally do not have traps, gutters and the like to convey away any overflow. Ac cordingly telltale, warning or detecting devices which will present positive evidence of overflow are quite useful.

A primary object of this invention is to provide a telltale device for positive indication of overflow.

Another object is to provide a telltale device whose warning or signal cannot be shut off before the overflow condition has been noted and remedial action taken.

It is also an object of this invention to provide an inexpensive telltale device containing simple electrical circuits.

Further objects and advantages of this invention will appear from the disclosure which follows and the attached drawing illustrating a preferred embodiment of this invention.

In the accompanying drawing:

is a diagrammatic illustration of a typical electrical circuit embodying the invention and used in conjunction with this invention.

The telltale device of this invention is so constructed that a signal device such as a lamp, bell or buzzer operates as the pump fills the tank. However, when the tank overflows, a second signaling device operates and the first signaling device ceases to operate. The second signaling device operates alone and continuously until the condition of overflow has been discovered and remedial action taken. Only after replacement of a simple portion of the telltale circuit will the second signal device cease to operate.

With reference to the attached drawing:

There is attached to a scale upon which is a tank to be filled (neither of which are shown), a switch 10 containing a stationary contact 11 connected to telltale current supply main 3 at a and a movable contact 12 so coupled to the platform or beam of the scale that at a predetermined weight a slight excess over the capacity of the tank contact 12 engages contact 11. One end of the winding of field 13 about armature 14 is electrically 15a but insulated therefrom armature 14. Movable contact 15a engages contact points 16, 17 of the pump motor or control circuit during normal operation and movable contact 15 engages contact points 18, 19 when field 13 is energized. Movable contacts 15, 15a are mechanically connected but electrically separate. Switch 10, field coil 13, armature 14 and movable contacts 15, 15a constitute the circuit for energizing the overload circuit.

In telltale device circuit fuse 20 19. Overload circuit contact 18 is electrically connected to main 2 at g. Fuse 20, contacts 18 and 19 with the corresponding leads constitutes the overload circuit.

Resistor 21 is electrically connected to main 2 at c and to terminal [2; signal lamp 22 is electrically connected to main 2 at f, and to terminal e; signal lamp 23 is electrically connected to terminal 2 and to main 3 at d and terminal 2 is electrically connected to terminal I). Resistor 21, fuse 20, signal lamps 22, 23 together with the appropriate leads constitute the telltale device circuits.

For the telltale device of this invention to function properly it should be signaling devices 22 and 23. A very satisfactory telltale device can be readily constructed by using a 1.0 amp. fuse or fuse 20, a 1.0 watt neon lamp for each of signal devices 22, 23 and a 500 ohm resistor for resistor 21.

More specifically the preferred telltale device comprises a fuse of a size to be within the carrying capacity of contacts 15, 18 and 19 and large enough to exceed the current passed by the resistor 21, connected in parallel with a low-power-consuming neon lamp. With this parallel circuit in turn connected in series to a second parallel circuit containing a low-power-consuming resistor and a low-power-consuming neon lamp. Also to this compound circuit there is an overload circuit connected to said fuse to remove the resistance in series with the fuse when the condition of overflow occurs.

The telltale device of this invention and its operation will be described in detail with respect to the filling of a tank on a scale by pumping a liquid into said tank from storage. To fill the tank the pump motor is started by switch 30 thereby energizing the motor circuit and a portion of the telltale circuit. While pumping, current flows through telltale supply mains 2, 3 through fuse 20 of 1 amp. capacity and through resistor 21 and neon lamp 22 since the fuse passes suflicient current for both the resistor and the lamp. When overflow takes place movable contact 12 engages contact 11 energizing coil 13, moving armature 14 and thereby opening the motor circuit shutting off pump motor and closing the overload circuit at contact points 18 and 19. The overload circuit is energized throwing the full voltage on fuse 20 causing fuse 20 to burn out and thereby disrupting the flow of current through path abs and putting neon lamp 22 and resistor 21 in parallel with each other and in series with neon lamp 23. The current in the telltale circuit now must flow through path debs and def which includes both neon lamps and resistor 21 causing neon lamp 23 to burn since the current which can flow is limited by what can pass through neon lamp 23 and this current is divided between lamp 22 and resistor 21 inversely as their resistance. Lamp 22 having a greater resistance than resistor 21 receives a lesser amount of the current passed by lamp 23 and hence will not light. Lamp 23 continues to burn until fuse 20 is replaced. Thus when fuse 20 is in a locked unit and the key to the lock is kept within the control of a'production supervisor this fuse cannot be replaced Without the condition of overflow being noted.

The importance of the relationship of the resistance of resistor 21 and lamps 22, 23 is readily apparent from the above. After the fuse has burned out, the current flowing through the telltale device circuit must first go through lamp 23 and then will follow the path of least resistance remaining in the telltale device circuit. Since the resistance of resistor 21 is but a fraction of that of lamp 22 most of the current passing through lamp 23 will not go through lamp 22 but instead will pass through resistor 21.

When lamps 22 and 23 are of a different color, for example, lamp 22 green and lamp 23 red, it will be a sim ple matter to detect whether the pump is running, green light burning, or overflow has occurred, red light burning, by the color of the lamp burning. Many modificacations of the above described telltale device are readily apparent. For example, a signal bell such as the doorbell or a buzzer can be used as signaling device 23 in place of a neon lamp. When such devices are employed for signaling device 23 it is essential that the resistance of resistor 21 should be a fraction of that of the signaling bell or buzzer. In general the resistance of resistor 21 should be that fraction of the resistance of signaling device 23 equal to the fractional amount of current which is just below that required to operate the signal device 23. Usually lamps, bells, buzzers and the like which can be used as inexpensive signaling devices will not function on a current flow less than about to of their operating current. Thus, if the resistance of resistor 21 is 1 to or less, preferably to of that of signaling device 23, the telltale device of this invention will function as hereinbefore described.

The telltale circuit as the drawing indicates comprises a number of circuits. The first circuit that which operates under normal conditions contains a fuse in series with a signal device and a resistor which are in parallel. When current flows in this circuit, enough current will flow through the signal device to permit it to function at its rated capacity and the remainder of the currnt will go through the resistor device since the resistance of the resistor is much less than that of the second signal device. Likewise the total current flowing through said signal device and reslstor will flow through the fuse. When the fuse path is destroyed by the overload circuit, the current in the telltale device circuit mi ht go through both the second signal device and the resistor. However, since the resistance of the resistor is much less than that of either of the signal devices, current will preferentially flow through the resistor and not through the first signal device. Thus the current path is limited to the series circuit containing the resistor and the second signal device. From the foregoing it is apparent that the telltale device of this invention can be readily assembled from inexpenslve electrical parts. The compound circuit of the preferred telltale device is sufliciently simple so that it can be assembled in a single compact unit.

What is claimed is:

1. An arrangement of circuits for an electrical signaling device for positive indication of a condition of overfillmg of a receptacle comprising a first circuit having an electrically actuated signaling means with a shunt fuse; connected in series with said first circuit with respect to a current source a second circuit having an electrically actuated signaling means with a shunt resistance of less than the resistance of either signaling means in said first and second circuits; and a normally open third circurt having a means responsive to said condition of overfilling to close this circuit, said third circuit being connected with respect to said first and second circuits so as to destroy said shunt fuse in said first circuit and to constitute a shunt circuit only for said second circuit when said overload circuit is closed.

2. The arrangement of circuits of claim 1 Wh 6 each signaling means is a neon lamp.

rather than the other signal 3. An electrically operated device for positive indication of a condition of overflow when a weighable receptacle is being filled, compfising a first circuit having an electrically actuated signaling means with a shunt fuse; connected in series with said first circuit with respect to a current source, a second circuit having an electrically actuated signaling means with a shunt resistance of less than the resistance of either signaling means in said first and second circuits; and a normally open third circuit containing a closing means therefor linked to said receptacle and responsive to a predetermined weight thereof, said third circuit being connected with respect to said first and second circuits so as to destroy said shunt fuse and to constitute a shunt circuit only for said second circuit while said third circuit remains closed, the signaling means in said first circuit being actuated by the shunting of said second circuit while said third circuit is closed, and the shunt resistance shunting the signaling means in said second circuit when said third circuit is opened and before replacement of said shunt fuse.

4. The device of claim 3 wherein is a lamp.

5. The device of claim 3 wherein each signaling means is a neon lamp.

6. The device of claim 3 wherein each signaling means is a neon lamp and the shunt resistance in the second circuit is from to V of the resistance of either neon lamp.

7. The device of claim 3 wherein each signaling device is a neon lamp rated at one watt, said shunt fuse has a capacity of one ampere and said shunt resistance has a 500 ohm resistance.

each signaling means 8. In a filling apparatus, the combination of a pump I motor circuit, a scale and an electrically operated device for positive indication ofa condition of overflow when a weighable receptacle is being filled, comprising a first circuit having an electrically actuated signaling means with a shunt fuse; connected in series with said first circuit with respectto a current source, a second circuit having an electrically actuated signaling means with a shunt resistance of less than the resistance of either signaling means of said first and second circuits; and a normally open third circuit containing a closing means therefor linked to said receptacle and responsive to a predetermined weight thereof, said third circuit being connected with respect to said first and second circuits so as to destroy said shunt fuse and to constitute a shunt circuit only for said second circuit while said third circuit remains closed, the signaling means for said first circuit being actuated by the shunting of said second circuit while said third circuit is closed, and the shunt resistance shunting the signaling means in said second circuit when said third circuit is opened and before replacement of said shunt fuse.

9. In a filling apparatus, the combination of a pump motor circuit, a scale and an electrically operated device for positive indication of a condition of overflow when a weighable receptacle is being filled, comprising a first circuit having a neon lamp with a shunt fuse; connected in series with said first circuit with respect to a current source, a second circuit having a neon lamp with a shunt resistance of from to the resistance of either neon lamp in said first and second circuits; and a normally open third circuit containing a closing means therefor linked to said receptacle and responsive to a predetermined weight thereof, said third circuit being connected with respect to said first and second circuits so as to destroy said shunt fuse and to constitute a shunt circuit only for said second circuit while said third circuit remains closed, the signaling means for said first circuit being actuated by the shunting of said second circuit while said third circuit is closed, and the shunt resistance shunting the signaling means in said second circuit when said third circuit is opened and before replacement of said shunt fuse.

10. In a filling apparatus, the combination of a pump motor circuit, a scale and an electrically operated device for positive indication of a condition of overflow when a weighable receptacle is being filled, comprising a first circuit having a neon lamp rated at one watt with a shunt fuse of one ampere capacity; connected in series with said first circuit with respect to a current source, a second circuit having a neon lamp rated at one watt with a shunt resistance rated at 500 ohms; and a normally open third circuit containing a closing means therefor linked to said scale and actuated at a predetermined weight thereon, said third circuit being connected with respect to said first and second circuits so as to destroy said shunt fuse and to constitute a shunt circuit only for said second circuit While said third circuit remains closed, the neon lamp in said first circuit being actuated by the shunting of said second circuit While said third circuit is closed, and the shunt resistance shunting the signaling means in said second circuit when said third circuit is opened and before replacement of said shunt fuse.

Number 5 1,373,242 2,159,751 2,402,312 2,468,676 2,547,526 10 2,621,240

UNITED STATES PATENTS Name Date Hellman Mar. 29, 1921 Saul May 23, 1939 Burch June 18, 1946 Liben Apr. 26, 1949 Hilliard Apr. 3, 1951 Kemper Dec. 9, 1952

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