A wall separates a first volume from a second volume and has a hole allowing passage between the first volume and the second volume. A wire passes through the hole, and a gasket surrounds the wire at the hole. The gasket includes a first section including a groove between a first flange and a second flange, the groove has an outer diameter matched to the diameter of the hole and the flanges have outer diameters greater than the diameter of the hole. A second section adjacent the first flange includes a tubular portion having a diameter less than the diameter of the hole and a tapered section smoothly transitioning from the diameter of the tubular portion to the diameter of the first flange. The gasket prevents flow of fluid through the hole between the first volume and the second volume.