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Pressure relief valve for distribution transformers

Spring-inside-the-tank pressure relief valves
Operating pressure from 15kPa up to 70kPa
Shutter diameter 1", 2" and 50mm
Hole on the cover tank 45 mm, 2" and 65mm
Wire seal lip facility (R1, PR2"M and PR2"F)
Air drain screw (on demand for R1, PR2"M and PR2"F)
Wiring diagrams availability No contacts (R1, PR2"M and PR2"F
from 1 up to 2 contacts (RT50 model)
Body material brass (R1, PR2"M and PR2"F)
Aluminum alloy casting (RT50)
Shutter in stainless steel
Waterproof (IP65 protection degree) for RT50 model
Environmental conditions from -60°C up to +70°C
Vent screw available on demand (R1, PR2"M and PR2"F)
Finishing for exreme/high corrosive environments (RT50 model)
Download PDF
Full catalogue pdf



“R” series is a spring-inside-the-tank safety overpressure valve: this pressure relief valve is a protection device for distribution transformers. It opens when the pressure inside the tank rises above the set operating value and reduces the pressure inside the tank by releasing oil. 
The “R” series overpressure valve is used for applications on distribution oil-immersed transformers. As a safety valve, it is set at a certain overpressure value in order to prevent excessive mechanical stress for the walls; RT50 model can feature one or more switches, while R1 and R2 series have no contacts.
Overpressure can be caused by a short circuit due to a heavy insulation failure: this generates a fast rise in pressure, leading to potentially serious troubles at the transformer walls with the risk of permanent deformations or even the failure of tank walls and consequent spilling of hot oil. For this reason, “R” series valves are designed to relieve excess pressure almost immediately.
When the overpressure is detected by the shutter, R series valve works by quickly lifting the shutter upwards to allow oil to flow out, limiting the risk of tank explosion.
The RT50 flange is made of pressure die-casted aluminum alloy, the shutter of stainless steel, the cover of mild steel and the springs of special hardened spring steel. 
“R” series can also be used in extremely harsh environmental conditions (very low temperature, very corrosive air grade, etc.)



R series (models) Shutter diameter Hole on cover tank Connection type Wiring diagram Operating pressure [kPa] Catalogue
R1" 1" 45 mm Threaded 1"M and welded on the tank No contacts3 from 20kPa up to 70kPa (higher pressure rating available on demand) pdf
PR2" M 2" 2"F Threaded 2"M pdf
PR2" F 2"M Threaded 2"F
RT50 50 mm 65 mm Flange round shaped with 4 holes from 1 up to 2 contacts pdf

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