YQ series gas-pressure water supply device is a multifunctional common water supply device integrated with the functions of pressure boosting, regulating, water storing and supplying, etc. It can continuously supply water to a system, and work similarly with a water tower or a water tank. Product features (1) It can be used for a long term after pressurized with gas, and no other pressurizing unit is required; (2) The cylinder is a sealed unit in which gas is separated from water, and thus the water is protected from any external contaminant; (3) It occupies a small land area and can be installed quickly, the cost is low, the operation and maintenance are convenient; (4) It can replace the high-level water tank and water tower for fire fighting, heat supplying and gas conditioning, and is in favor of the building appearance and structural anti-seismic effect, and can additionally reduce the cost of building; (5) The water hammer and noise in the pipeline can be automatically eliminated; (6) It can work as the expansion tank for automatic water compensation in a hot-water heating and gas-conditioning system; (7) It can be controlled automatically, operated conveniently and function reliably. (8) The constant pressure cylinder can be widely applied in hotels, high-rise buildings, office buildings, large emporiums, entertainment places, catering industry, chemical industry, food industry, textile industry, paper making industry and so on for non-tower water supplying, replacing the expansion water tank in the heat supplying system, connected to a frequency converting water supply network, or used as a reliable constant pressure unit in a heat supply system.