GENERAL CHARACTERISTICS
 
DAVINCI PRESSURE RELIEF / SUSTAINING VALVES are hydraulically operated diaphragm valves designed to control and protect the upstream pressure of a water system. Depending on their installation, they can operate either as a pressure relief valve or as a pressure sustaining valve, providing a versatile solution for network protection and pressure management.
When installed as a pressure relief valve, the valve opens automatically whenever the upstream pressure exceeds a preset safe value. The excess pressure is discharged through a bypass, return line, reservoir, or suitable outlet, preventing potentially damaging overpressure conditions. Once the system pressure returns below the established setting, the valve closes gradually and restores normal operation.
 
When installed in-line as a pressure sustaining valve, the valve modulates to maintain a minimum predetermined pressure upstream. If the inlet pressure begins to fall below the selected value, the valve progressively closes to preserve the required pressure in the supply network. This function is particularly valuable where priority areas, pumps, or upstream equipment must remain adequately pressurized.
 
Its main advantage is therefore the ability to provide automatic overpressure relief or upstream pressure maintenance without external electrical power. The hydraulic pilot system responds directly to pressure variations, helping stabilize the network, protect equipment, and reduce the risk of pipeline failures or interruptions in critical supply zones.
 
Available in sizes from DN50 to DN800 mm, the valve features a high-strength ductile iron body engineered to withstand demanding hydraulic conditions. All iron components are protected with a fusion-bonded epoxy coating, providing long-lasting resistance against corrosion and deterioration in water-service environments.
 
The internal operating assembly incorporates a top- and seat-ring-guided stem and diaphragm mechanism, ensuring accurate alignment, smooth modulation, and dependable performance. Its nylon-reinforced diaphragm is designed for repeated operating cycles, while the stainless steel seat and disc-retainer ring provide excellent corrosion resistance and long-term sealing integrity.
The globe-pattern body offers superior regulating characteristics and stable control across changing pressure and flow conditions. The valve provides drip-tight shut-off when fully closed, while its pilot-controlled operation allows a gradual response that helps limit sudden hydraulic changes and unnecessary system stress.
Service operations can be performed conveniently from the top of the valve. Inspection, adjustment, and internal maintenance do not require removal of the valve body from the main pipeline, helping minimize downtime, labour requirements, and operating costs.
 
DAVINCI PRESSURE RELIEF / SUSTAINING VALVES are widely used in municipal water distribution networks, pumping stations, irrigation systems, water treatment plants, industrial facilities, mining installations, reservoir supply lines, HVAC and cooling systems, high-rise buildings, and fire protection networks. Typical applications include pump discharge protection, bypass pressure relief, preservation of upstream supply zones, prevention of excessive network pressure, and maintenance of minimum pressure for critical services.
 
Manufacture and performance comply with EN 1074-5, with design and testing carried out in accordance with BS EN 1074-5, ISO 5208, BS EN 12266-1, and BS EN 558-1. Flanged connections are available in PN10, PN16, PN25, and ANSI Class 150, while face-to-face dimensions conform to EN 558-1, Series 1. Designed for water applications, the valve is available with pressure ratings of 1.0 MPa, 1.6 MPa, and 2.5 MPa, and is suitable for working temperatures from −10 °C to 80 °C. Pressure testing is conducted according to EN 12266-1, Leakage Rate A, including a body test pressure of 1.5 × PN and a seat test pressure of 1.1 × PN.
 
The applicable provisions of the EU Pressure Equipment Directive 2014/68/EU are observed. Products up to DN300 are excluded under Article 1, §2(b), while sizes from DN350 to DN600 are classified under Risk Category I, Module A.
 
A complete selection of pressure pilots, filters, pressure gauges, isolation valves, sensing lines, needle valves, and hydraulic control accessories is available for different system configurations. Optional V-Port trim can improve stability and accuracy under low-flow conditions, while a double-chamber design may be supplied for specialized operating requirements. Please consult the factory for customized pressure settings, discharge arrangements, alternative media, or special applications.