A buffer tank is a storage tank used on the cold user side of an air-conditioning system. The tank is used as storage to cover peak loads or in situations when a surge in demand exceeds the capacity of the cooling system.The buffer tank is a container in which the cooled medium can be stored.A buffer tank is typically used when there is a variable cooling requirement. In such applications the tank is used as storage to cover peak loads or in situations when a surge in demand exceeds the capacity of the cooling system.