US2594465A

US2594465A - Electric heater

Info

Publication number: US2594465A
Application number: US72679A
Authority: US
Inventors: Lovfald Peer
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-01-25
Filing date: 1949-01-25
Publication date: 1952-04-29
Anticipated expiration: 1969-04-29

Description

April 29, 1952 P. LLOVFALD 2,594,465

ELECTRIC HEATER- Filed Jan. 25, 1949 IN V EN TOR.

Patented Apr. 29, 1952 UNITED STATES PATENT OFFICE ELECTRIC HEATER Peer Lovfald, Lincrcft, N. J.

Application January 25, 1949, Serial No. 72,679

1 Claim. 1

This invention relates to improvements in electric heaters and particularly it refers to an electric heater having low surface temperature and having so-called explosion-proof construction for use in oil refineries or other places where explosive or ignitible gases or materials are present.

Most present electric heaters suffer from a common defect in that their surface temperatures are too high. Even those which have totally enclosed elements often have surface temperatures way above the flash point of most volatile solvents such as acetone, benzene, naphtha, etc., as well as those of any number of combustible gas mixtures. It has, therefore, not been possible to use electric heaters in many places where such heaters otherwise would be highly desirable. In oil refineries, for instance, many heating installations are required where electric heating is the only practical solution. Due to the fact that the surface temperatures were too high, it was not always possible to install such heaters and yet obtain the highest standards of safety. My invention eliminates this difficulty and furnishes a heater with a low surface temperature which is safe for all such installations as above mentioned.

An important object of my invention is to provide an electric heater with low surface tem perature and with explosion-proof fittings.

A further object of my invention is to provide an electric heater within an explosion-proof metal housing of low cost and simple construction that will give long, safe and trouble free service.

Other objects and advantages of my invention will be apparent during the course of the following description.

In the accompanying drawing, forming a part of this specification, and in which like numerals designate like parts throughout the same,

Figure 1 is a side elevation in perspective of an electric heater embodying my invention,

Figure 2 is a longitudinal section taken along the center line, and,

Figure 3 is a transverse section taken along line 3-3 in Figure 2.

In the drawing, wherein for the purpose of illustration, is shown a preferred embodiment of my invention, the numeral 5 designates the heating element proper which is preferably of hairpin shape, as shown, and consists of a suitable resistance wire sealed in an outer steel tubing with a flexible insulating material capable of withstanding the temperature of the wire. The hairpinshaped heating element 5 terminates in the leadin wires 6 which are brazed to the wires of the insulated cable 1 which goes through the explosion-proof fittings 8 and 9 to the conduit ID.

The hairpin-shaped heating element 5 is cast into a metal tube II with metal fins 12. A disc of insulating material l3 closes one end of tube H. In a preferred embodiment the tube Il may be of steel with copper fins l2 while the metal [4 which is cast around the element 5 is aluminum which has a suitable melting point. The tube l l is supported at one end by the elbow l5 and rod is which has a flange l1 for fastening to the floor or wall. The other end of tube H is threaded into the reducer l8 which is connected to the fitting 8 by means of nipple IS.

A suitable housing of perforated or expanded metal is mounted over the finished heater as designated by numeral 26 in Figure 1. The sealing condulet or fitting 9 is filled with a suitable sealing compound which prevents any gas vapor or explosive mixture from entering the fitting surrounding the terminal connections. The fittings 8 and 9 are of sufficient strength to withstand an explosion on the outside without admitting any explosive gases, and sufficiently tight to prevent any sparks or flame to escape from inside the fittings and thereby ignite any combustibles outside same.

The operation of my invention is similar to that of any other electric heater. The differonce is to be found in the fact that due to the method of casting the hairpin element 5 in the metal [4 in tube H the radiating surface becomes very much greater. This is further enhanced by the metal fins 12 which act to cool the tube H and thereby still further reducing the surface temperature of same to a point where complete safety is achieved.

It is to be understood that the form of my invention, herewith shown and described, is to be taken as a preferred example of same, and that various changes in the shape, size, metals and materials used and arrangement of parts may be resorted to, without departing from the spirit of my invention, or the scope of the subjoined claim.

Having thus described my invention, I claim:

A low temperature explosionproof electric heater of the character described comprising, a finned tubular body threaded at both ends, a hairpinshaped electric heating element cast in aluminum into said finned tubular body, a mounting elbow placed on one end of said body, a thread reducer placed on the other end of said body where the leads from said heating element come out, and an explosionproof fitting threaded into said reducer.

PEER LOVFALD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,472,171 Haynsworth Oct. 30, 1923 1,591,141 Phillips July 6, 1926 2,317,426 Wilson Apr. 27, 1943 2,450,921 Smith Oct. 12, 1948 2,473,783 Brown, Jr June 21, 1949