What component of a keg helps to apply pressure needed to dispense beer?

The component that helps to apply pressure needed to dispense beer from a keg is the Sankey valve. This specialized valve allows the introduction of gas into the keg, which creates pressure that pushes the beer from the keg to the tap. The Sankey valve is commonly found in commercial kegs and is designed to provide a secure connection for gas and liquid flow.

While other components may play critical roles in the beer dispensing system, they do not directly apply the necessary pressure for beer extraction. The thermostat, for instance, regulates the temperature of the beer but does not influence the pressure. The spear is a part of the keg's inner structure that facilitates beer flow but cannot apply pressure by itself. The coupler, which connects the keg to the dispensing system, is essential for operation and safety, but it acts in conjunction with the Sankey valve to allow gas to enter and push beer out of the keg. Therefore, the Sankey valve is the key element in providing the required pressure for dispensing beer.