METHOD OF PRODUCING AN INSULATED EXHAUST DEVICE
A method for producing an exhaust gas aftertreatment or acoustic device ( 20 ) having a maximum operating temperature T MAX . The method includes the steps of (a) providing a blanket ( 40 ) of silica fiber insulation material having a weight percentage of SiO 2 greater than 65%; (b) calcining the insulating material by heating the blanket ( 40 ) so that all of silica fiber insulation material is raised to a temperature T greater than T MAX (where T is less than the melting temperature of the silica fibers of the blanket); and (c) securing the blanket ( 40 ) on the device ( 20 ) after the calcining step. The blanket is encapsulated in a covering ( 50 ) prior to the calcining step whereby the blanket is batting in the covering, with the covering between the blanket and the device being a selected one of wire mesh or siliconized fiber glass.
1 . A method of providing external insulation for an exhaust gas aftertreatment or acoustic device having a maximum operating temperature T MAX , the method comprising:
providing a blanket of silica fiber insulation material having a weight percentage of SiO 2 of greater than 65%;
calcining the blanket by heating all of the silica fiber insulation material to a temperature T greater than T MAX , wherein T is less than a melting temperature of the silica fibers of the blanket;
encapsulating said blanket in a covering before the calcining step whereby said blanket is batting in said covering; and
securing the blanket around an outermost surface of the exhaust gas aftertreatment or acoustic device after the calcining step;
wherein said covering between said blanket and said exhaust gas aftertreatment or acoustic device is a selected one of wire mesh or high temperature textile.
2 . The method of claim 1 wherein T is at least 1.05×T MAX .
3 . The method of claim 1 , wherein said high temperature textile is a selected one of siliconized fiber glass or straight woven glass fiber.
4 . The method of claim 1 wherein during the calcining step the blanket is in an uncompressed state.
5 . The method of claim 1 wherein T MAX is within a range of 300° C. to 1100° C.
6 . The method of claim 1 , wherein the securing step comprises installing the blanket so that the blanket encircles a core of the device through which the exhaust gas passes.
7 . A method of providing external insulation for an exhaust gas aftertreatment or acoustic device having a maximum operating temperature T MAX , the method comprising:
providing a blanket of silica fiber insulation material having a weight percentage of SiO 2 of greater than 95%;
calcining the blanket by heating all of the silica fiber insulation material to a temperature T greater than T MAX , wherein T is less than a melting temperature of the silica fibers of the blanket;
encapsulating said blanket in a covering before the calcining step whereby said blanket is batting in said covering; and
securing the blanket around an outermost surface of the exhaust gas aftertreatment or acoustic device after the calcining step;
wherein said covering between said blanket and said exhaust gas aftertreatment or acoustic device is a selected one of wire mesh or high temperature textile.
8 . The method of claim 7 wherein T is at least 1.05×T MAX .
9 . The method of claim 7 , wherein said high temperature textile is a selected one of siliconized fiber glass or straight woven glass fiber.
10 . The method of claim 7 wherein during the calcining step the blanket is in an uncompressed state.
11 . The method of claim 7 wherein T MAX is within a range of 300° C. to 1100° C.
12 . The method of claim 7 , wherein the securing step comprises installing the blanket so that the blanket encircles a core of the device through which the exhaust gas passes.
13 . A method of providing external insulation for an exhaust gas aftertreatment or acoustic device having a maximum operating temperature T MAX , the method comprising:
providing a blanket of silica fiber insulation material having a weight percentage of SiO 2 of greater than 65%;
calcining the blanket in an uncompressed state by heating all of the silica fiber insulation material to a temperature T greater than T MAX , wherein T is less than a melting temperature of the silica fibers of the blanket and is at least 1.05×T MAX and T MAX is within a range of 300° C. to 1100° C.;
encapsulating said blanket in a covering before the calcining step whereby said blanket is batting in said covering; and
securing the blanket around an outermost surface of the exhaust gas aftertreatment or acoustic device after the encapsulating step;
wherein said covering between said blanket and said exhaust gas aftertreatment or acoustic device is a selected one of wire mesh or high temperature textile.
18 . The method of claim 17 , wherein said high temperature textile is a selected one of siliconized fiber glass or straight woven glass fiber.
19 . The method of claim 17 , wherein the securing step comprises installing the blanket so that the blanket encircles a core of the device through which the exhaust gas passes.