If the point where the cooling water is injected into the exhaust is less than 6" 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 air vent at least 16" above the waterline.
Two different models are available: type ASD and type AIRVENT. Model ASD is interchangeable with type AIRVENT and has the same fixing hole centres. It has the advantage that the air bleed connection rotates through 360°. In addition, the valve can be maintained without removing the vent from the wall and no tools are required to do this. For replacement, a set with 5 valves is available as a spare part.
• Acts as a siphon break when the injection point of exhaust cooling water is close to the waterline
• Model V has a reliable antisiphon pressure valve and is selfcontained but requires periodic maintenance to prevent clogging with salt crystals.
• Model H is maintenance-free providing a connection to the outside of the hull; cooling water bleeds through this opening while the engine is running. This can provide an instant visual check of whether your cooling water pump is functioning. Comes complete with 12' of hose, thru-hull, and hose clamps
• Designed to work with any of these hose sizes: 1/2" (13 mm), 3/4" (19 mm), 1" (25 mm), 1-1/4" (32 mm)
• Plastic housing