US 2343440 A
Description (OCR text may contain errors)
March 7, 1944. o. E. ANDRUS DOMESTIC WATER HEATER 5 w d n A E n n r 0 Filed May 15. 1941 max;
r Patented Mar. 7, 1944 norms-no warm mum v Orrin 1:. Andrus, Altadena, Calil'., as'signor to a. o.
Smith Corporation, Mil
. ration'of New York waukee, Wia, a corpo- Application May 15.- 1941,8erialNo. 393,606
4 Claims. (cree -197) This invention relates to a domestic water heater and more particularly to theprotectionofthe tank against corrosion.
It has been specifically appliedin the protecting 1' of vitreous enamel lined tanks from corrosion at or nearto the openings where a possible contactis established between the hot water and the metal ofthe tank. It utilizes theprinciple of' cathodic protection set forthin my co-pen'ding application, Serial No. 15,146, filed April 6, 1935,
v For the purpose of providing the cathodic protection referred to, a large zinc ring 10 is soldered or otherwise secured. to the washer l and extends out into the water in the tank, presenting a substantial area of surface exposure. 'zinc, other suitable anodic metals or alloys might be employed.
' The zincring I0 is in electrical contact with the walli of the tank throughthe washer 1,,lip
for Corrosion resistant metallic-structures, and
upon which Patent No; 2,267,361 wasg'rant'ed De-.
' cient tolast either for the life time of the tank,
: oruntil suitable replacement can-be made.
cember 23, 1941.
Th principal object of the'inven'tionlis' to pro-- vide a simple and economic means for establish ing the required electrical potential in the metalwall of the tank for preventing electrolytic-corof exposure of the metal rosion at possible points to the hot water.-
Another object of the inventionis. to provide,
exposure has a" tendency to effect a corroding adjacent to a pipec'onnection to the tank, a body-' of metal in electrical contact wit-h'the inetal of 'lated from the nipple 4 by employing a flanged the tank wall, and which has a higher potential in the presence of hot water as the electrolyte than th potential of metal of the tank thereby causing current to fiow toward the metal of the tank through the water.
5andnipple 4. The nipple 4 is usually of stain-- less steel or othernon-corrodin'g material.
The size of the zinc washer l0 should be sufll- It "ispreierable not to have too much surface exposureof the nipple adjacent the zinc since such away or dissolving of the zinc. To this end, it is preferable to galvanize the washer. l and the nipple 4including' lip 5 withzinc so that they present substantially the same surface potential as the zinc ring [0.1 If desired, the pipe 3 may be insuconnection utilizing the principle of my Patent Fig. 2 is an elevation taken from inside the No. 2,179,476, granted November 14, 1939.
The wall I is, protected from corrosion by reason of the counter electromotive force set up at the surface of any exposed area of the wall, tending to counteract the flow of current resulting from the chemical reactions of corrosion. By counteracting such current flow, corrosion of the wall I is prevented.
In the process of establishing the counter potential a chemical reaction occurs at the surface of the zinc tending to corrode the latter.
The relative length of life of the zinc in any instance will vary with the impurities in the water, since different electrolytes result in diifer- Crider, Serial No. 335,998, filed May 18, 1940, j
which was issued as Patent No. 2,266,611 on December 16, 1941, and assigned to the same assignee as the presentapplication.
The nipple 4 has an inner lip 5 which is outwardly to provide a flange holding a packing ring, 6 in place around the nipple inside the curved outer edge '8 partially enclosing the edge of ring 6, and an oppositely curved inner edge 9 against which flange lip 5 presses.
cut potentials for the respective metals exposed,
and different rates of corrosion.
Instead of soldering. the zinc ring In to the washer 1, the ring might be threaded onto the inner end of nipple 4 or be otherwise secured to. the tank wall to provide the required protection.
Variousembodiments .of the invention maybe employed within the scope of the accompanying claims.
I claim: 1 v
'1. In a domestic water'heater, a tank .wall of when exposed to hot water and havingan open-.
ing therethrough for a pipe connection, means for connecting a pipe tothe wall at said opening, 'a' non metallic lining to protect the metal wall of the tank :from corrosion, a quantity of Insteadof to the tank wall by said connecting means, and zinc galvanizing material coating said pipe connecting means to prevent waste of the zinc from diilerences in electrical potential.
2. In a domestic water heater or the like, a tank wall of a metal cathodic to zinc subject to corrosion when exposed to the contents of the tank and having an.opening therethrough for a pipe connection, means for connecting a pipe to the well at said opening, a non-metallic lining to rotect the metal wall of the tank from corrosion, and a quantity of zinc secured to said connecting means on the inside of the tank and exposed to the fluid contents of the tank, said zinc being electrically connected to the tank wall by said connecting means.
3. In a domestic water heater or the like, a metal tank wall subject to corrosion when exposed to the contents oi the tank and having an opening therethrough for a pipe connection,
insideoi thejtank andexposed'to the water in j =the-:tank,=said zinc -being=electrically connected means for connectinsa pipe to the wall at said 1opening,-a non-metallic lining to protect the metal wall of the tank from corrosion, and a quantity of a metal anodic to the metal or said wall secured to said connecting means around said opening on the inside of the tank and exposed to the fluid contents of the tank, said anodic metal being electrically connected to the tank wall by said connecting means.
4. In a domestic water heater or the like, a metal tank wall subject to corrosion when exposed to the contents of the tank and having an opening therethrough for a pipe connection, means for connecting a pipe to the wall at said opening, a lining of vitreous enamel for said tank to protect the wall thereof from corrosion, and a quantity of a metal anodic to the metal of said wall secured to said connecting means around said opening on the inside of the tank and exposed to the fluid contents of the tank, said anodic metal being electrically connected to the tank wall by said connecting means.
ORRIN E. ANDRUS.