US2412977A - Flame sensitive device - Google Patents

Flame sensitive device Download PDF

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Publication number
US2412977A
US2412977A US51085143A US2412977A US 2412977 A US2412977 A US 2412977A US 51085143 A US51085143 A US 51085143A US 2412977 A US2412977 A US 2412977A
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Prior art keywords
flame
wire
sensitive device
device
coil
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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Inventor
Samuel G Eskin
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ROBERTSHAW THERMOSTAT Co
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ROBERTSHAW THERMOSTAT CO
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23QIGNITION; EXTINGUISHING-DEVICES
    • F23Q5/00Make-and-break ignition, i.e. with spark generated between electrodes by breaking contact therebetween
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23NREGULATING OR CONTROLLING COMBUSTION
    • F23N5/00Systems for controlling combustion
    • F23N5/02Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
    • F23N5/14Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermo-sensitive resistors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24COTHER DOMESTIC STOVES OR RANGES; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C3/00Stoves and ranges for gaseous fuels
    • F24C3/12Arrangement for mounting of control and safety devices
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12493Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771Transition metal-base component
    • Y10T428/12806Refractory [Group IVB, VB, or VIB] metal-base component
    • Y10T428/12826Group VIB metal-base component
    • Y10T428/12847Cr-base component
    • Y10T428/12854Next to Co-, Fe-, or Ni-base component

Description

Dec. 24, 1946-. S, G, E KlN 2,412,977

FLAME SENSITIVE DEVICE Filed Nov. 19, 1945 Chromz'zed y INVENTOR Samuel 6.51%?!) B Y I W 7 %M4/M 15 ATTORNEY Patented Dec. 24, 1946 FLAME SENSITIVE DEVICE Samuel G. Eskin, Pittsburgh, Pa., assignor to Robertshaw Thermostat Company, Youngwood, Pa., a corporation of Pennsylvania Application November 19, 1943, Serial No. 510,851

2 Claims.

This invention relates to electric circuit elements having the characteristics of largeresistance variation under temperature changes and, more particularly, to metallic flame sensitive resistors.

. Several metals and metal alloys have large positive temperature coefiicients of electrical resistivity rendering them valuable in various-circuit applications. These circuit elements may i be coils of wire, generally termed ballast resistors, and in order to utilize them to the fullest advantage it is sometimes desirable to expose them directly to the heat of a flame. In one application the coil is placed in the flame of a gaseous fuel burner and by its consequent change in resistance serves as a safety device to shut off the flow of fuel should the flame become accidentally extinguished.

Of the several alloys which disclose suitable electrical properties for the purpose described some will resist oxidation when exposed to the flame of burning natural gases. The usefulness of such materials is limited, however, by the corrosion to which they are subject when heated by manufactured gases containing sulphur. Various metallic and non-metallic coatings for metals are known which offer more or less protection against corrosion from sulphurous atmospheres but, in the particular services to which this application relates, it is of the utmost importance that the coated material retain the electrical re-. sistance properties which the uncoated material possessed.

It is an object of this invention to protect a metallic flame sensitive resistor from corrosion without adversely affecting its electrical resistance properties.

Another object of the invention is to permit the coated material to be bent or formed into a coil or other desired shape and to be repeatedly heated and cooled without cracking or peeling of the coating from the base material.

Another object of the invention is to permit formed coils of wire to be coated uniformly.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawing, wherein:

Fig. 1 is aschematic view of a safety system embodying the flame sensitive device of this invention; and

Fig. 2 is an enlarged sectional view of the device.

Referring more particularly to the drawing, the flame sensitive device It! is shown as exposed to the flame of a gaseous fuel burner 12 connected with a main fuel pipe I! through which the flow of gaseous fuel is controlled by an electromagnetically operated valve l6. As is customary in such devices, the electromagnetic valve l6 may be opened by energization of its coil 23 and closed by gravity upon deenergization thereof.

Electric current for operating the electromagnetic valve l6 may be supplied from line wires connected to the primary of a transformer IS. The valve circuit may be traced from the secondary of the transformer l8 by wire 20, wire 22, coil 23, wire 24, and wire 26 back to the secondary of the transformer I8. A control switch (not shown) may be incorporated in the described circuit to control the energization of the coil 23, as desired. In order to cause movement of the electromagnetic valve IE to closed position when the burner flame is accidentally extinguished, the flame sensitive device In is connected in shunt with the coil 23 by wires 28 and, connected with wires 24 and 22, respectively.

The flame sensitive device l may consist of a coil of wire from material having normally a relatively low resistance and a high positive temperature coeflicient of resistance. In this embodiment the device I0 is formed from nickelsteel wire containing about 70% nickel-30% I iron. The electrical resistance characteristics of the flame sensitive device in so formed are such that when heated by the flame of the burner l2 sufficient current will flow in the coil 23 to maintain the valve IS in open position, but when unheated by the burner flame, insufficient current passes through the coil 23 to maintain the valve IS in open position.

In the burner control apparatus described, the flame sensitive device It is used to determine whether the electromagnetic valve I6 is maintained in open position after running conditions have been established. In order to establish such conditions it is necessary that the valve l6 be initially moved to open position in order that fuel may flow to the burner l2 and the flame thereof heat the device ill to bring the'safety features into operation. Such movement of the valve [5 may .be accomplished by a manually operated lifting device 32 attached to the solenoid (not shown) of the electromagnetic valve l6 so that in the starting condition (while the flame sensitive device 10 is unheated by the burner flame) the valve l6 may be manually opened and maintained in such position until the flame sensitive device 10 becomes sufficiently heated to render such manual actuation unnecessary. It will be 2&19377 3 F apparent, however, that a constant burning pilot to which the device 90 would be exposed, or other arrangements known to the art, could be employed without affecting the scope of this invention.

As previously indicated, this invention is more.

particularly directed to protecting the flame sensitive element It from corrosion in the sulphur-.

ous atmosphere of the burner it without sacrifice. of the desired electrical resistance properties thereof. Accordingly, the nickel steel wire of which the device it is formed is provided with a protective coating which has been found to be highly resistant to corrosion in suiphurous atmospheres as may exist when manufactured gases are used as the fuel.

The protective coating for the device it) of this invention is applied by a process known as chromizing, whereby the nickel-steel underbody is surface-alloyed with chromium by a preferred method now to be described. The coil of nickelsteel wire forming the underbody of the flame sensitive device 50 is packed in a. mixture containing equal parts of ferrochrome and 60-mesh alumina and placed in a suitable furnace. No special surface treatment need be given the coil before the chromizing is started. -The atmosphere of the furnace is rendered non-oxidizing by the use of a gas such as hydrogen and hydrogen chloride. Heating of the coil is carried on for eight hours at 1000 C. which has been found sufficient to form a layer of adequate thickness. The duration of the treatment may, however, be varied in accordance with the thickness of surface layer desired.

A flame sensitive device it so treated has a surface coating in the form of a difiused layer integral with the nickel-steel underbody and the chromium content of the layer appears to decrease from the surface inwardly. The layer generally has a wall thickness from 0.0001" to 0.0002" and the device so formed shows excellent heat and corrosion resistance under severe conditions. The device also has the advantage of capability of being bent, wound or otherwise formed without cracking or peel= ing of the coating from the underbody and will undergo expansion and contraction with similar results. It appears, therefore, that while the exterior surface exposed to the flame of the burner i2 may consist of pure chromium, the general character of the coating consists of a chromium-nickel-iron alloy intimately bonded with the nickel-steel wire forming the underbody and.

having the characteristics of all metallic coatings formed by difiusion of metals.

The flame sensitive resistor thus formed is peculiarly adapted for the purpose described by reason of the retention of its electrical resistance properties substantially unchanged, although the uncoated nickel-steel wire which possessed such properties is new highly resistant to corrosion and heat under the severe conditions to which it is exposed. The invention thus serves the purpose of a fiamesensitive device for use in the burner control apparatus described in connection with Fig. 1 and will not only remain effective for a much greater length of time than an uncoated coil but will have none of the desired properties adversely affected by reason of the protective coating.

While the chromizing process has been outlined herein and satisfactory cells may be formed by use of such process, it will be apparent that the principles of this invention are not limited to flame sensitive devices produced by following the exact steps set forth. Other methods including,

variations of the described process may be em.- ployed to produce the desired difiused layer on a flame sensitive electrical resistor without depar-i ture from the spirit of the invention as set forth in the appended claims.

Iclaim:

1. A flame sensitive electrical resistor comprising a wire coil consisting of a chromium-free nickel-iron alloy of normally a relatively low electrical resistance value and a high positive temperature coefficient of resistance value having a chromium-containing layer integrally diffused with the surface thereof which is exposed to the flame, said layer being adapted to protect said wire from corrosion in sulphurous atmospheres resulting from the presence of the flame and without substantial alteration in the said electrical resistance value.

2. A flame sensitive electrical resistor comprising a wire coil consisting of about nickel-.- 30% iron alloy which is chromium-free and has normally a relatively low electrical resistance value and a high positive temperature coemcient of resistance value, said wire having a chromium containing layer integrally difiused with the surface thereof which is exposed to the flame, said layer being adapted to protect said wire from corrosion in sulphurous atmospheres resulting from the presence of the flame and without substantial alteration in the said electrical resistance value.

SAMUEL G. ESKIN.

US2412977A 1943-11-19 1943-11-19 Flame sensitive device Expired - Lifetime US2412977A (en)

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2800438A (en) * 1955-07-26 1957-07-23 Metal & Thermit Corp Chromium plating
US3055087A (en) * 1954-06-07 1962-09-25 Union Carbide Corp Carbonyl metal plated product
US3157585A (en) * 1959-12-18 1964-11-17 Gen Motors Corp Chromium plating
US3184331A (en) * 1963-12-16 1965-05-18 Du Pont Process of diffusion coating
US3312537A (en) * 1963-09-16 1967-04-04 Fibreglass Ltd Apertured body for the passage of molten glass
US3520043A (en) * 1966-06-17 1970-07-14 Johnson Matthey Co Ltd Self-regulating heating elements
US4284688A (en) * 1978-12-21 1981-08-18 Bbc Brown, Boveri & Company Limited Multi-layer, high-temperature corrosion protection coating
US8292879B2 (en) 2009-04-17 2012-10-23 Domain Surgical, Inc. Method of treatment with adjustable ferromagnetic coated conductor thermal surgical tool
US8617151B2 (en) 2009-04-17 2013-12-31 Domain Surgical, Inc. System and method of controlling power delivery to a surgical instrument
US8858544B2 (en) 2011-05-16 2014-10-14 Domain Surgical, Inc. Surgical instrument guide
US8915909B2 (en) 2011-04-08 2014-12-23 Domain Surgical, Inc. Impedance matching circuit
US8932279B2 (en) 2011-04-08 2015-01-13 Domain Surgical, Inc. System and method for cooling of a heated surgical instrument and/or surgical site and treating tissue
US9078655B2 (en) 2009-04-17 2015-07-14 Domain Surgical, Inc. Heated balloon catheter
US9107666B2 (en) 2009-04-17 2015-08-18 Domain Surgical, Inc. Thermal resecting loop
US9131977B2 (en) 2009-04-17 2015-09-15 Domain Surgical, Inc. Layered ferromagnetic coated conductor thermal surgical tool
US9265556B2 (en) 2009-04-17 2016-02-23 Domain Surgical, Inc. Thermally adjustable surgical tool, balloon catheters and sculpting of biologic materials
US9526558B2 (en) 2011-09-13 2016-12-27 Domain Surgical, Inc. Sealing and/or cutting instrument

Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3055087A (en) * 1954-06-07 1962-09-25 Union Carbide Corp Carbonyl metal plated product
US2800438A (en) * 1955-07-26 1957-07-23 Metal & Thermit Corp Chromium plating
US3157585A (en) * 1959-12-18 1964-11-17 Gen Motors Corp Chromium plating
US3312537A (en) * 1963-09-16 1967-04-04 Fibreglass Ltd Apertured body for the passage of molten glass
US3184331A (en) * 1963-12-16 1965-05-18 Du Pont Process of diffusion coating
US3520043A (en) * 1966-06-17 1970-07-14 Johnson Matthey Co Ltd Self-regulating heating elements
US4284688A (en) * 1978-12-21 1981-08-18 Bbc Brown, Boveri & Company Limited Multi-layer, high-temperature corrosion protection coating
US8523851B2 (en) 2009-04-17 2013-09-03 Domain Surgical, Inc. Inductively heated multi-mode ultrasonic surgical tool
US8372066B2 (en) 2009-04-17 2013-02-12 Domain Surgical, Inc. Inductively heated multi-mode surgical tool
US8377052B2 (en) 2009-04-17 2013-02-19 Domain Surgical, Inc. Surgical tool with inductively heated regions
US8414569B2 (en) 2009-04-17 2013-04-09 Domain Surgical, Inc. Method of treatment with multi-mode surgical tool
US8419724B2 (en) 2009-04-17 2013-04-16 Domain Surgical, Inc. Adjustable ferromagnetic coated conductor thermal surgical tool
US8425503B2 (en) 2009-04-17 2013-04-23 Domain Surgical, Inc. Adjustable ferromagnetic coated conductor thermal surgical tool
US8430870B2 (en) 2009-04-17 2013-04-30 Domain Surgical, Inc. Inductively heated snare
US8491578B2 (en) 2009-04-17 2013-07-23 Domain Surgical, Inc. Inductively heated multi-mode bipolar surgical tool
US8506561B2 (en) 2009-04-17 2013-08-13 Domain Surgical, Inc. Catheter with inductively heated regions
US8523850B2 (en) 2009-04-17 2013-09-03 Domain Surgical, Inc. Method for heating a surgical implement
US8523852B2 (en) 2009-04-17 2013-09-03 Domain Surgical, Inc. Thermally adjustable surgical tool system
US8292879B2 (en) 2009-04-17 2012-10-23 Domain Surgical, Inc. Method of treatment with adjustable ferromagnetic coated conductor thermal surgical tool
US8617151B2 (en) 2009-04-17 2013-12-31 Domain Surgical, Inc. System and method of controlling power delivery to a surgical instrument
US9549774B2 (en) 2009-04-17 2017-01-24 Domain Surgical, Inc. System and method of controlling power delivery to a surgical instrument
US9320560B2 (en) 2009-04-17 2016-04-26 Domain Surgical, Inc. Method for treating tissue with a ferromagnetic thermal surgical tool
US9265556B2 (en) 2009-04-17 2016-02-23 Domain Surgical, Inc. Thermally adjustable surgical tool, balloon catheters and sculpting of biologic materials
US9078655B2 (en) 2009-04-17 2015-07-14 Domain Surgical, Inc. Heated balloon catheter
US9107666B2 (en) 2009-04-17 2015-08-18 Domain Surgical, Inc. Thermal resecting loop
US9131977B2 (en) 2009-04-17 2015-09-15 Domain Surgical, Inc. Layered ferromagnetic coated conductor thermal surgical tool
US9265554B2 (en) 2009-04-17 2016-02-23 Domain Surgical, Inc. Thermally adjustable surgical system and method
US9220557B2 (en) 2009-04-17 2015-12-29 Domain Surgical, Inc. Thermal surgical tool
US9265553B2 (en) 2009-04-17 2016-02-23 Domain Surgical, Inc. Inductively heated multi-mode surgical tool
US9265555B2 (en) 2009-04-17 2016-02-23 Domain Surgical, Inc. Multi-mode surgical tool
US9730749B2 (en) 2009-04-17 2017-08-15 Domain Surgical, Inc. Surgical scalpel with inductively heated regions
US8932279B2 (en) 2011-04-08 2015-01-13 Domain Surgical, Inc. System and method for cooling of a heated surgical instrument and/or surgical site and treating tissue
US8915909B2 (en) 2011-04-08 2014-12-23 Domain Surgical, Inc. Impedance matching circuit
US9149321B2 (en) 2011-04-08 2015-10-06 Domain Surgical, Inc. System and method for cooling of a heated surgical instrument and/or surgical site and treating tissue
US8858544B2 (en) 2011-05-16 2014-10-14 Domain Surgical, Inc. Surgical instrument guide
US9526558B2 (en) 2011-09-13 2016-12-27 Domain Surgical, Inc. Sealing and/or cutting instrument

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