Safety valve 8115 6 bar 3/4 inch, solar 8115.20.153

Protection of Solar Installations Against Overpressure

Diaphragm safety valves from the 8115 series are a key component protecting pressurized heating systems from exceeding the allowable operating pressure. In the event of a sudden temperature rise in solar collectors, e.g., during stagnation, the heat transfer fluid may rapidly increase in volume. This element automatically opens upon reaching the set pressure, discharging excess fluid and preventing damage to the installation. Thanks to the use of a diaphragm, the valve ensures tightness in the closed state and precise response to parameter changes, which is particularly important in solar systems where duty cycles are intensive.

Application and Sizing Based on Installation Capacity

The device is dedicated to systems filled with liquid or inert gas, including water-glycol mixtures (up to a maximum concentration of 50%). The maximum operating temperature is 160°C, covering most emergency scenarios in modern solar installations. When selecting a specific model, not only the connection diameter but also the thermal power of the collectors must be considered. For a 3/4 inch (DN20) connection with a set pressure of 6 bar, the approximate protected collector area is up to 100 m², corresponding to a thermal power of approximately 192 kW.

For comparison, smaller valves with a 1/2 inch diameter at the same set pressure of 6 bar serve installations with a capacity of about 171 kW (approx. 85 m² area), while at lower set pressures (e.g., 2.5 bar), their capacity drops to approx. 72 kW for 1/2" and 101 kW for 3/4" diameters, respectively. These valves are available in several set pressures: 2.5, 3, 4, and 6 bar, allowing precise adaptation of the device to the expansion vessel parameters and the specifics of the given installation.

Construction and Operating Conditions

The valve features a simple diaphragm construction that eliminates the risk of mechanism seizure at high temperatures. It is designed for installation in locations exposed to hot heating fluid. For the model with catalog number ending in .20.153, the factory setting is 6 bar, making it suitable for systems with higher operating pressure or greater thermal power of the heat source.

Technical parameters of this model include a nominal diameter DN20 (threaded connection G 3/4") and a maximum operating temperature up to +160°C. The permitted heat transfer fluids are water, inert gases, and water-glycol solutions (up to a maximum concentration of 50%). The operation is based on the principle of direct diaphragm action without additional actuators or external springs that would adjust the opening force depending on ambient temperature.