ASD Series air vents – Vacuum breaking
anti-siphon air vents

If the point where the cooling water is injected into the exhaust is less than 15cm above the waterline, then when the engine is stopped, there is a risk that cooling water will siphon into the exhaust system and subsequently into the engine itself. Such siphoning may be prevented by fitting a VETUS ASD at least 40cm above the waterline.

Type ASDV is fitted with a reliable silicone pressure valve and therefore minimum maintenance is required.
Type ASDH has a hose connection to the outside of the hull. There is a constant bleed off of cooling water through this hose whilst the engine is running. No valve is used and therefore no maintenance needed.
Type ASDH comes complete with a skin fitting, hose clamps and 4m of hose. Both types have the advantage that the air bleed connection rotates through 360°.

Suitable for hoses with internal diameters of Ø 13, 19, 25 and 32mm (½”, ¾”, 1” and 1¼”). Version ASD38 connects to hose with internal diameter of Ø 38mm (1½”).


  • Suitable for Ø 13, 19, 25, 32 and 38mm hose
  • Corrosion free: Fully made of synthetic material, the valve is made from silicone
  • 360° rotating bleed connection
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