Description: expansion tank is a welded steel container, there are a variety of different size specifications. The expansion tank is generally connected to the following pipes: (1) whether it will swell due to the water heating system, the increased volume of expansion into the expansion tank (and return trunk is connected). (2) exceeds a predetermined overflow pipe for excess water level within the tank is discharged. (3) the level tube used to monitor the water level inside the tank. (4) when the tank and circulation pipe may occur freeze expansion pipe, used to make the water cycle (at the bottom of the central location, and backwater roads connected to the tank). (5) for the sewage outfall. (6) water valve and float cabinets connected to the water level below the set value is to add water through the valve. For safety reasons, the expansion, the circulation pipe, the overflow pipe allowed to install any valve. Expansion tank for closed water circulation system, played a role in the balance of water and pressure relief valve to avoid frequent opening and automatic water valve frequent replenishment. Expansion tank to accommodate the expansion of water play a role, but also play a role in the makeup tank, expansion tank filled with nitrogen, able to accommodate a larger volume expansion of water, high and low pressure expansion tank can be used in parallel to the regulator system itself replenishment. The device control points are interlocked response, automatic operation, pressure fluctuation range, safe, reliable, energy-saving, economic effects. The main role of the system is provided in the expansion tank (1) expansion, the system in fresh water after the expansion of the heated room. (2) pay the amount of water due to evaporation and replenishment system leakage losses and to ensure there is enough fresh water pump suction head. (3) Exhaust emissions air from the system. (4) administration, investment and chemicals in order to carry out chemical treatment of cooling water. (5) is heated, if the heating means disposed therein, the cooling water can be heated to warm cylinder. Features: 1, the first long-term use two inflatable, air and water does not touch the water quality from pollution 3, covering small easy to install, easy to operate 4, can be replaced by high water tank, beautiful architecture in favor of reducing the construction cost Scope: 1, industrial and 2 civil construction production and living water, hot water, heating and air conditioning 3, according to the actual situation, special manufacturing volume calculation 2: 95-70 ° C when the heating system V = 0.031Vc 110-70 ° C when the heating system V = 0.038Vc