The International Standard of Measurements uses the pascal unit (Pa). This device guarantees the external discharging of the steam that could form within the system after exceeding of the preset thermostatic values. The valve closes at 80% of the preset value. It opens overcoming the force applied to the shutter by a spring.Īt preset pressure, the security valve starts to open, and at the nominal discharging pressure (usually more than 10% of the calibration) it is completely open. The valve shutter is activated by the steam under pressure.

tank with an absolute precharge pressure of 2 bar (constant pV ratio: 200).ġ00 lts. See the table below for an example of constant pV ratio in a 100 lts. Introducing water in the tank, the air volume decreases, increasing pressure. Considering the air compression isotherm, the pV product is constant. The value of the air pressure in the tank balances the water pressure. The pf pressure is the value reached at minimum temperature, about 4 ☌ (in case of lower temperature, please check for possible modifications to the equation). The pi pressure is equal to the maximum system pressure, that is the maximum temperature reached by the system, preventively calculated 50 ☌. The water circuit on a conditioning system provides cold water from a refrigeration group and returns it after heating. Water temperature with the system operatingĭilation coefficient measured by temperature difference, see table aboveĭimensioning of an expansion vessel for conditioning systems Water temperature with the system switched off For a correct dimensioning, choose the smallest expansion vessel V, is the result, measured in liters, of the calculation. Given these parameters, the formula is as follows: P fa Absolute test pressure of the safety valve, sum of the relative precharge value of the valve and the air pressure: P ia Absolute precharge pressure of the expansion vessel, sum of the relative precharge value of the vessel (determined by the system) and the air pressure: (1.163 kW) of the heating power of the boiler.Į Water dilation coefficient: the maximum difference between the calibration temperature of the boiler thermostat and the water temperature with the system switched off. Pressurization / pumping with very aggressive conditionsĮxpanding water with glycol > 20% (99 ° C)įor a correct dimensioning of the vessel, these parameters should be known:Ĭ water volume inside the system including boiler, pipes and heating bodies considering a 15-20% safe weighting.īy and large, C is between 10 and 20 l each 1000 Ikcal/h Pressurization / pumping with aggressive conditions

Pressurization / pumping with submersible pumps Non potable hot water expansion with heat pumps

Chilled water expansion tank pressure