This compact pressure accumulator tank is used in small constant pressure water systems with Seaflo or other brand pressure pumps. It smooths fluctuations in pressure due to pump cycling or other fixtures being opened or closed. When installed correctly, it will reduce the frequency of pump cycling. The accumulator tank comes pre-pressurized at 10 PSI but for optimum performance should be adjusted to 3-5psi less than the switch on pressure of your pressure pump. The pressure must be set while the system is off and all water pressure must be released before setting the pressure.