A valve assembly comprising: a valve body including a seat, with the seat defining an outlet for venting a tank; a float disposed inside the valve body and movable between a first position and a second position relative to the valve body; a support coupled to the float and movable with the float between the first and second positions; and a sealing member attached to the support and having a base abutting the support, with the sealing member having an engagement portion supported by the base to define a space between the engagement portion and the support to allow movement of the engagement portion between an initial position when the float is in the first position and a displaced position when the float is in the second position, with the engagement portion spaced from the seat when in the initial position, and with the engagement portion engaging the seat when in the displaced position such that the space decreases in size and the engagement portion deforms about the seat to cover the outlet, wherein the float includes an attachment member, and wherein the support includes a coupler engaging the attachment member to movably couple the support to the float, characterized in that: the support has a first side and a second side opposing the first side, with the base abutting one of the first and second sides (56, 58) of the support, the support defining a first hole through the first and second sides (56, 58) such that the space is in fluid communication with inside of the valve body to equalize pressure between the space and inside of the valve body when the engagement portion moves between the initial and displaced positions. a valve body including a seat, with the seat defining an outlet for venting a tank; a float disposed inside the valve body and movable between a first position and a second position relative to the valve body; a support coupled to the float and movable with the float between the first and second positions; and a sealing member attached to the support and having a base abutting the support, with the sealing member having an engagement portion supported by the base to define a space between the engagement portion and the support to allow movement of the engagement portion between an initial position when the float is in the first position and a displaced position when the float is in the second position, with the engagement portion spaced from the seat when in the initial position, and with the engagement portion engaging the seat when in the displaced position such that the space decreases in size and the engagement portion deforms about the seat to cover the outlet, wherein the float includes an attachment member, and wherein the support includes a coupler engaging the attachment member to movably couple the support to the float, characterized in that: the support has a first side and a second side opposing the first side, with the base abutting one of the first and second sides (56, 58) of the support, the support defining a first hole through the first and second sides (56, 58) such that the space is in fluid communication with inside of the valve body to equalize pressure between the space and inside of the valve body when the engagement portion moves between the initial and displaced positions. the support has a first side and a second side opposing the first side, with the base abutting one of the first and second sides (56, 58) of the support, the support defining a first hole through the first and second sides (56, 58) such that the space is in fluid communication with inside of the valve body to equalize pressure between the space and inside of the valve body when the engagement portion moves between the initial and displaced positions.