Embodiments described herein relate to a valve assembly for an endoscopic device and methods of using the same. The valve assembly can be disposed in a receptacle and operably coupled to a gas inlet port, a gas outlet port, a water inlet port, and a water outlet port. The valve assembly can include a valve stem defining a first channel, a second channel, a third channel, and a fourth channel fluidically coupled to an adjustable sealing member. During at least one of insufflation, irrigation, and lens cleaning, communication of gas between the gas supply and the water outlet port is prevented when gas is communicated through the fourth channel via the first channel and the third channel such that the gas exerts a sealing pressure on the adjustable sealing member.
