Reliance Water Controls 3.5 Bar 102 Series Pressure Relief Expansion Valve Features: Set At 3.5 Bar Max. operating Temperature: 140°C Test Pressure of Body: 25 bar WRAS Approved Made from hot pressed brass, the 102 series Pressure Relief valve is predominately used to protect closed circuit water heating systems from overpressure. It has a high grade fibre glass reinforced plastic cap. Available in ?" or ?" connections, it also has a set pressure relief range from 3.5 bar to 8.0 bar with the response pressure indicated on the cap cover.