Electric cartridge heater with metal sleeve adapter

In combination:

• an electric cartridge heater having a metal sheath of a predetermined outside diameter and adapted to have its exterior wall surface closely fit the wall of a bore in a mass to be heated,
• means for adapting said cartridge heater to fit in heat transfer relationship within a bore of a larger diameter, comprising metal sleeve means having an inside diameter to provide an inside wall surface to closely fit the sheath exterior wall surface, and having an outside diameter to provide an exterior wall surface to closely fit the wall surface of said larger bore,
• said cartridge heater being produced in a minimum sheath lenght and various longer sheath lengths,
• said sleeve means being formed as multiple sleeves of equal length,
• each sleeve having a length equal to said minimum sheath length, and for heaters having longer than minimum sheath length said sleeves being disposed serially in end-to-end abutting relation between facing wall surfaces of said sheath and said bore in number to cover said longer sheath length, and
• each sleeve being of continuous cross-section and of constant thickness and uniform diameter throughout its length whereby hot spots between a sleeve and a cartridge heater are minimized.

In combination:

• an electric cartridge heater, having a metal sheath of a predetermined outside diameter and adapted to have its external wall surface closely fit the wall of a bore in a mass to be heated,
• and a kit of at least two sleeves to accompany said cartridge heater and to adapt the same to fit in heat transfer relationship within bores of larger diameters, each sleeve having an inside diameter to provide an inside wall surface to closely fit over the sheath wall surface,
• and said sleeves having predetermined different outside diameters to closely fit the wall surface of larger bores having inside diameters complementary to said different outside diameters,
• each sleeve being of continuous cross-section and of constant thickness and uniform diameter throughout its length, whereby hot spots between a sleeve and said cartridge heater are minimized.

In combination:

• an electric cartridge heater having a metal sheath of a predetermined outside diameter and adapted to have its external wall surface closely fit the wall of a bore in a mass to be heated,
• and sleeve means for adapting said cartridge heater to fit in heat transfer relationship within a bore of larger diameter, said sleeve means having an inside diameter providing an inside wall surface to closely fit over the sheath exterior wall surface, and having an outside diameter providing an exterior wall surface to closely fit within the wall surface of said larger bore,
• said sleeve means being of continuous cross-section and of constant thickness and diameter throughout the length thereof to minimize hot spots between the sleeve means and cartridge heater,
• and said sleeve means being formed of pressed iron powder to serve as a low-cost, non-load bearing, thermal transfer mass transversely and longitudinally filling the space between said sheath exterior wall surface and the wall surface of said larger bore.