Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
293 words
A method for replacing a coolant containing PCB in an electrical induction apparatus having a tank containing said coolant, an electrical winding and porous solid cellulosic electrical insulation immersed in said PCB-containing coolant with a substantially PCB-free high boiling dielectric permanent coolant to convert said electrical apparatus into one in which the rate of elution of PCB into said coolant is below the maximum allowable rate of elution into the coolant of an electrical apparatus rated as non-PCB, said solid porous electrical insulation being impregnated with said PCB-containing coolant, said method comprising the steps of: (a) draining said PCB-containing coolant from said tank to remove a major portion of said PCB-containing coolant contained by it; (b) filling said tank with an interim dielectric cooling liquid that is miscible with said PCB, is sufficiently low in viscosity to circulate within said tank and penetrate the interstices of said porous solid electrical insulation, and is capable of being readily separated from said PCB; (c) electrically operating said electrical induction apparatus and continuing said electrical operation for a period sufficient to elute PCB contained in said PCB-containing coolant impregnated in said porous solid insulation therefrom into said interim dielectric cooling liquid; (d) thereafter draining said interim dielectric cooling liquid containing said eluted PCB from said tank; (e) repeating the cycle of steps (b), (c) and (d) when the rate of elution of PCB into said interim dielectric cooling liquid exceeds 0.55 ppm of PCB per day based on the weight of said permanent dielectric coolant; and (f) filling said tank with a substantially PCB-free permanent coolant selected from the group consisting of high boiling, high viscosity, silicone oils, synthetic ester fluids, poly-alpha-olefin oils and hydrocarbon oils so as to reclasify said electrical apparatus to non-PCB status.
Claim 2
Independent Claim
293 words
A method for replacing a coolant containing PCB in an electrical induction apparatus having a tank containing said coolant, an electrical winding and porous solid cellulosic electrical insulation immersed in said PCB-containing coolant with a substantially PCB-free high boiling dielectric permanent coolant to convert said electrical apparatus into one in which the rate of elution of PCB into said coolant is below the maximum allowable rate of elution into the coolant of an electrical apparatus rated as non-PCB, said solid porous electrical insulation being impregnated with said PCB-containing coolant, said method comprising the steps of: (a) draining said PCB-containing coolant from said tank to remove a major portion of said PCB-containing coolant contained by it; (b) filling said tank with an interim dielectric cooling liquid that is miscible with said PCB, is sufficiently low in viscosity to circulate within said tank and penetrate the interstices of said porous solid electrical insulation, and is capable of being readily separated from said PCB; (c) electrically operating said electrical induction apparatus and continuing said electrical operation for a period sufficient to elute PCB contained in said PCB-containing coolant impregnated in said porous solid insulation therefrom into said interim dielectric cooling liquid; (d) thereafter draining said interim dielectric cooling liquid containing said eluted PCB from said tank; (e) repeating the cycle of steps (b), (c) and (d) when the rate of elution of PCB into said interim dielectric cooling liquid exceeds 0.55 ppm of PCB per day based on the weight of said permanent dielectric coolant; and (f) filling said tank with a substantially PCB-free permanent coolant selected from the group consisting of high boiling, high viscosity, silicone oils, synthetic ester fluids, poly-alpha-olefin oils and hydrocarbon oils so as to reclasify said electrical apparatus to non-PCB status.
Claim 3
Dependent Claim
29 words
Method as claimed in claim 1 wherein the interim dielectric cooling liquid is trichlorobenzene, tetrachlorobenzene or mixtures of same and the permanent coolant is a dielectric silicone oil coolant.
Claim 4
Dependent Claim
30 words
Method as claimed in claim 1 or 2 wherein each step (c) is continued for 20 days to 1 year or 30 to 120 days or 45 to 90 days.
Claim 5
Dependent Claim
62 words
4 . Method as claimed in claimsl to 3 wherein, when carrying out step (d) of the previous cycle and step (b) of the next succeeding cycle,the interim cooling liquid is drained from the top of the tank while fresh chilled interim dielectric cooling liquid is fed into the bottom of the tank and while electrical operation of the apparatus is continued.
Claim 6
Dependent Claim
54 words
Method as claimed in claims 1 to 4, wherein the steps (d) and (f) are carried out by feeding the PCB-free permanent coolant into the bottom of the tank while removing the interim dielectric cooling liquid in the tank from the top of said tank, and while electrical operation of the apparatus is continued.
Claim 7
Dependent Claim
40 words
Method as claimed in claimslto 5, wherein the tank is provided with heat insulation in order to raise the temperature of the interim dielectric cooling liquid contained by it during each step (c) while electrically operating said electrical induction apparatus.
Claim 8
Dependent Claim
29 words
Method as claimed in claims 1 to 6, wherein the interim dielectric cooling liquid in the tank is heated during step (c) while electrically operating the electric induction apparatus.
Claim 9
Dependent Claim
44 words
Method as claimed in claims 1 to 6 wherein during step (c) the interim dielectric cooling liquid is removed from said tank, heated and returned to said tank while maintaining sufficient interim dielectric fluid in said tank and electrically operating said electrical induction apparatus.
Claim 10
Dependent Claim
33 words
Method as claimed in claimsl to 8 wherein the interim dielectric liquid is more volatile than the PCB and is separated from the contained PCB by distilling off the interim dielectric cooling liquid.
Claim 11
Dependent Claim
59 words
Method as claimed in claimsl to 8 wherein the interim dielectric cooling liquid containing PCB eluted from the solid insulation is drawn off from the tank as a slip stream while electrically operating the electrical induction apparatus adding fresh interim dielectric cooling liquid substantially equivalent to the amount of PCB-containing interim dielectric fluid drawn off in the slip stream.
Claim 12
Dependent Claim
26 words
Method as claimed in claims 1 to 10 wherein the tank is flushed with a solvent for the PCB following step (a) and before step (b).
Claim 13
Dependent Claim
24 words
Method as claimed in claim 11 wherein the flushing solvent is the same liquid as the interim dielectric cooling liquid used in step (b).
Claim 14
Dependent Claim
18 words
Method as claimed in claim 11 wherein the flushing solvent and the interim dielectric cooling liquid is trichlorobenzene.
Claim 15
Dependent Claim
22 words
Method as claimed in claimsl to 12 wherein the interim dielectric cooling liquid is 1,2,4-trichlorobenzene or a mixture of trichlorobenzene and tetrachlorobenzene.
Claim 16
Dependent Claim
21 words
Method as claimed in claims 1 to 14 wherein the permanent coolant employed to fill the tank is a silicone oil.
Claim 17
Dependent Claim
56 words
Method as claimed in claim 15 wherein the permanent coolant used in step (f) is a silicone oil having the following formula: (CH 3 ) 3 SiO (CH 3 ) 2 SiO n Si(CH 3 ) 3 wherein n is a number of such value providing a viscosity of about 50 mm 2 /s at 25°C.