Unox Pneumatic and Manual Bottom Blow-Off Valve
A pneumatic bottom blow-off valve is a valve used to discharge sediment and sludge that accumulate at the bottom of a steam boiler. Generally, it is used with a pneumatic (air-operated) actuator to open and close the valve. The valve can also be operated manually using a hand crank or lever, or automated using a pneumatic control system.
Bottom Blow-Off Valve
The purpose of the bottom blow-off valve is to periodically remove sediment and sludge from the boiler’s bottom to enhance efficiency and safety. Allowing sediment and sludge to accumulate can reduce the boiler’s heat transfer efficiency and increase the risk of corrosion and damage. By regularly operating the bottom blow-off valve, sediment and sludge can be removed, helping to maintain the boiler’s efficiency and safety.
It is important to note that the bottom blow-off valve should only be opened when the boiler is not in operation and the water level is low. Opening the valve while the boiler is operating can cause damage and create safety hazards.
General Specifications
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Body: GGG-40 Sphero Cast Iron
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Pressure Class: PN16 – PN25
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Function: Normally Closed
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Sealing: CLASS VI (PTFE Soft Seal)
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Characteristic: On-Off
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Stem Sealing: PTFE – Graphite Seal
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Max. Operating Temperature: 220 ºC (350 ºC)
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Flange Connection: DIN 1092-2 (PN16 – PN25)
Operating Principle in Normally Closed Position
Initially, the valve is in the closed position, preventing fluid flow. The spring force continuously applied to the movable piston keeps the orifice hole sealed with the plug, blocking the fluid passage. To open the valve, pressurized air is supplied to the actuator inlet. When the air in the actuator reaches a certain pressure, it overcomes the spring force, moves the piston forward, and opens the orifice hole, allowing fluid to pass.