Spirax Sarco VS204

Air Vent

Spirax Sarco VS204 and VS206 air vents are intended for automatic discharge of air and non-condensable gases from steam installations, helping maintain efficient heat transfer during both start-up and continuous operation. 

The valves feature a robust stainless steel capsule that senses the temperature difference between steam and air. The device opens in the presence of air (which is cooler than steam) and closes tightly when saturated steam temperature is reached, preventing steam loss. This is critical for rapid equipment warm-up, uniform heat distribution, and system protection against corrosion.

Key features:

• All stainless steel (model VS206) or with a brass body and stainless steel internals (VS204).
• Requires no adjustment; adapts to changes in system pressure.
• The capsule is resistant to water hammer and overheating.
• Minimizes steam loss due to precise closing timing.

The air valve should be installed at the highest point in the steam space or at the end of steam lines where air accumulates. Vertical installation is recommended to ensure free drainage of condensate. A mesh filter should be installed upstream of the valve to prevent seat clogging.

VS204 Datasheet:

• Body Material: Brass (BS 2874 CZ 121)
• Internal Parts: Stainless Steel
• Sizes (NPT/BSP): 1/2", 3/4"
• Max. Working Pressure (PMO): 200 psig (14 bar)
• Max. Working Temperature (TMO): 200°C (392°F)
• Max. Allowable Pressure (PMA): 232 psig (16 bar)
• Max. Temperature Limiting Action (TMA): 250°C (482°F)
• Connection: Threaded (NPT)