ELECTRICAL HEATER WITH A CONTAMINATION-PROOF SEAL

摘要

An electrical heater comprising a heating element, a tubular metal sheath surrounding the heating element and spaced therefrom, insulation inside the sheath for electrically insulating the heating element from the sheath, and a closure closing one end of the sheath. A passaging extends through the closure in a direction generally lengthwise of the sheath. At least one power lead adapted for connection to a source of electrical energy extends through the passaging for conducting electrical energy to the heating element. The power lead includes an electrical conductor, a metallic sleeve surrounding the conductor, and insulation for electrically insulating the conductor from the sleeve. The conductor has a terminal portion electrically connected to the heating element. A seal between the closure and the sheath around the one end of the sheath seals against the passage of contaminants between the closure and the sheath. A seal between the power lead and the closure seals against the passage of contaminants through the passaging in the closure. The arrangement is such that the closure and the seals seal against the passage of contaminants into or out of the heater through the one end of the sheath.