{"product_id":"vetus-asdv-anti-siphon-valve-fits-13-32mm-hose","title":"VETUS ASDV Anti-Siphon Valve | Fits 13-32mm Hose","description":"\u003cp class=\"nvn-hero\"\u003eThe VETUS ASDV is the little part that keeps a big problem off your boat. It's an anti-siphon valve with a duckbill that sits at the top of a vented loop and breaks the siphon before seawater can back up into your engine, head, or livewell. One fitting steps down to fit 13, 19, 25, and 32 millimeter hose, and the air bleed rotates a full 360 degrees so you can aim the vent wherever the install needs it.\u003c\/p\u003e\n\n\u003cdiv class=\"nvn-description\"\u003e\n\u003cp\u003eEvery boat with a through-hull below or near the waterline has a siphon risk. When a pump shuts off or an engine stops, water can start flowing backward through the hose and keep going, quietly filling a place it was never meant to reach. That's how engines get hydrolocked and how bilges fill overnight at the dock. An anti-siphon valve breaks that chain. Mounted at the high point of a vented loop, the VETUS ASDV lets air into the line the instant flow reverses, and air can't siphon. The column breaks and the backflow stops.\u003c\/p\u003e\n\u003cp\u003eThe heart of this one is a duckbill valve. Under normal flow, water pressure holds the duckbill shut and the system runs sealed, so you don't get a mess of drips or spray at the vent. The moment pressure drops and the line tries to pull a vacuum, the duckbill opens and admits air. Simple, mechanical, no electronics to fail. The air bleed connection rotates a full 360 degrees, so once the body is clamped to the hose you can spin the vent outlet to point exactly where you want it, away from wiring, away from a bulkhead, wherever keeps the install clean.\u003c\/p\u003e\n\u003cp\u003eThis is a genuinely versatile fitting. Boaters use it on raw-water engine cooling and exhaust injection loops, on marine head intake and discharge lines, on macerator and holding-tank plumbing, and on livewell and baitwell drains. Anywhere a hose runs from a fitting near the waterline up and over to somewhere it could siphon, this valve belongs at the top of that loop. The one hard rule is height. Mount the ASDV above the waterline at the peak of the loop, oriented vertically, so the vent is always the high point. On a livewell drain in particular, mounting it vertically above the waterline is what keeps a planing hull from pushing water backward when you're up on plane.\u003c\/p\u003e\n\u003cp\u003eFitment is flexible. The stepped barbed inlet accepts 13, 19, 25, and 32 millimeter hose, which covers most of the small and mid-size plumbing on a boat, from bilge and livewell lines up to larger discharge hose. Cut the barb back to the size you need, slide the hose on, and secure it. Use worm-gear hose clamps, and this matters, don't crank them down like a lug nut. The body is plastic and installers have cracked the base at the larger barb by overtightening. Snug and checked is the goal, not gorilla-tight.\u003c\/p\u003e\n\u003cp\u003eA word on upkeep, because a duckbill is a wear part. In raw-water service the valve sees salt, grit, and whatever the water's carrying, and over six to twelve months of hard use the duckbill can start to stick. If you run a powerboat hard in salt, plan on flushing the system with fresh water when you can and swapping the duckbill about once a season. On a macerator line, an inline strainer upstream keeps debris off the duckbill lip and cuts down on weepy leaks. It's a cheap habit that keeps the valve sealing the way it should.\u003c\/p\u003e\n\u003cp\u003eOne thing to check before you buy: clearance. The body stands 5.2 inches tall, 3.8 inches deep, and 2.7 inches wide. On a 25 to 32 foot boat with a tight cockpit sole, that height fits, but it doesn't leave much room for a generous service loop above it, so plan the hose routing before you commit to a spot. Measure the high point of your loop and make sure you've got the headroom before you drill or glass in a bracket. Get the location right and the ASDV is a quiet, do-its-job part you'll forget is even there, and that's exactly what you want from an anti-siphon valve. It's the kind of small fitting that saves a very expensive engine.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul class=\"nvn-features\"\u003e\n  \u003cli\u003eDuckbill valve stays sealed under flow and opens to admit air the instant the line tries to siphon, breaking the backflow mechanically with no electronics\u003c\/li\u003e\n  \u003cli\u003eStepped barbed inlet fits 13, 19, 25, and 32 millimeter hose, covering most small and mid-size boat plumbing\u003c\/li\u003e\n  \u003cli\u003eAir bleed connection rotates a full 360 degrees so you can aim the vent outlet exactly where the install needs it\u003c\/li\u003e\n  \u003cli\u003eCompact body at 2.7 in wide by 3.8 in deep by 5.2 in tall fits at the high point of a vented loop\u003c\/li\u003e\n  \u003cli\u003ePlastic construction holds up to raw-water, head, and livewell service\u003c\/li\u003e\n  \u003cli\u003eWorks on engine raw-water and exhaust injection loops, head intake and discharge, macerator lines, and livewell drains\u003c\/li\u003e\n  \u003cli\u003eReplaceable duckbill makes seasonal service simple on hard-run raw-water systems\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cdiv class=\"nvn-trust\"\u003e\n  \u003ch2\u003eWhy Buy from NVN Marine\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eAuthorized VETUS reseller, full manufacturer warranty\u003c\/li\u003e\n    \u003cli\u003eNMEA member and ABYC certified, advice from real boat techs\u003c\/li\u003e\n    \u003cli\u003eSame-day shipping before 3 PM ET on in-stock items\u003c\/li\u003e\n    \u003cli\u003eNY headquarters and Fort Lauderdale flagship retail store\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cdiv class=\"nvn-faq\"\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat does an anti-siphon valve actually do?\u003c\/summary\u003e\n    \u003cp\u003eIt stops water from siphoning backward through a hose after a pump or engine shuts off. Mounted at the top of a vented loop above the waterline, the ASDV admits air into the line the moment flow reverses. Air can't siphon, so the water column breaks and the backflow stops before it can flood your engine, bilge, or head.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhere should I install the ASDV?\u003c\/summary\u003e\n    \u003cp\u003eAt the highest point of the loop, above the waterline, mounted vertically so the vent stays up top. Any hose that runs from a fitting near the waterline up and over to a spot it could siphon into wants this valve at the peak of that loop. Get it too low and it can't do its job.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat hose sizes does it fit?\u003c\/summary\u003e\n    \u003cp\u003eThe stepped barbed inlet fits 13, 19, 25, and 32 millimeter internal-diameter hose. You cut the barb back to the size you need, so one part covers everything from small bilge and livewell lines up to larger discharge hose.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eCan I rotate the vent after it's clamped down?\u003c\/summary\u003e\n    \u003cp\u003eYes. The air bleed connection rotates a full 360 degrees. Once the body is secured to the hose, spin the vent outlet to point wherever keeps the install clean, away from wiring or a bulkhead.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat kind of hose clamp should I use?\u003c\/summary\u003e\n    \u003cp\u003eWorm-gear hose clamps. And go easy on them. The body is plastic and it's possible to crack the base at the larger barb by overtightening, so snug it up and check it rather than cranking it down hard.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow often should I replace the duckbill?\u003c\/summary\u003e\n    \u003cp\u003eThe duckbill is a wear part. In hard raw-water service it can start to stick after six to twelve months, so on a powerboat run hard in salt, plan to swap it about once a season. Flushing the system with fresh water when you can helps it last.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eCan I use it on a marine head or macerator line?\u003c\/summary\u003e\n    \u003cp\u003eYes, it's used on head intake and discharge, macerator plumbing, and holding-tank lines. On a macerator line especially, an inline strainer upstream keeps debris off the duckbill lip and cuts down on weepy leaks.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWill water spray out of the vent during normal running?\u003c\/summary\u003e\n    \u003cp\u003eNo. Under normal flow the water pressure holds the duckbill shut and the system runs sealed. The valve only opens to admit air when the line tries to pull a vacuum, so you won't get drips or spray at the vent in regular use.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat is the valve made of?\u003c\/summary\u003e\n    \u003cp\u003eThe body is plastic, chosen to stand up to salt water and the grit that comes with raw-water, head, and livewell service.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003ctable class=\"nvn-specs\"\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003cth\u003eTitle\u003c\/th\u003e\n\u003ctd\u003eVETUS ASDV Anti-Siphon Valve with Duckbill\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003ctd\u003eVETUS\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eManufacturer Part Number\u003c\/th\u003e\n\u003ctd\u003eASDV\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eUPC\u003c\/th\u003e\n\u003ctd\u003e8717372282133\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eProduct Type\u003c\/th\u003e\n\u003ctd\u003eAnti-Siphon Valve \/ Air Vent\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eValve Type\u003c\/th\u003e\n\u003ctd\u003eDuckbill valve\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eCompatible Hose Sizes\u003c\/th\u003e\n\u003ctd\u003e13, 19, 25, 32 mm internal diameter\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003ePlastic\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eAir Bleed Connection\u003c\/th\u003e\n\u003ctd\u003eRotates 360 degrees\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eWidth\u003c\/th\u003e\n\u003ctd\u003e2.7 in\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eDepth\u003c\/th\u003e\n\u003ctd\u003e3.8 in\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eHeight\u003c\/th\u003e\n\u003ctd\u003e5.2 in\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n    \"@context\": \"https:\/\/schema.org\",\n    \"@type\": \"FAQPage\",\n    \"mainEntity\": [\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What does an anti-siphon valve actually do?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"It stops water from siphoning backward through a hose after a pump or engine shuts off. Mounted at the top of a vented loop above the waterline, the ASDV admits air into the line the moment flow reverses. Air can't siphon, so the water column breaks and the backflow stops before it can flood your engine, bilge, or head.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Where should I install the ASDV?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"At the highest point of the loop, above the waterline, mounted vertically so the vent stays up top. Any hose that runs from a fitting near the waterline up and over to a spot it could siphon into wants this valve at the peak of that loop. Get it too low and it can't do its job.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What hose sizes does it fit?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"The stepped barbed inlet fits 13, 19, 25, and 32 millimeter internal-diameter hose. You cut the barb back to the size you need, so one part covers everything from small bilge and livewell lines up to larger discharge hose.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Can I rotate the vent after it's clamped down?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Yes. The air bleed connection rotates a full 360 degrees. Once the body is secured to the hose, spin the vent outlet to point wherever keeps the install clean, away from wiring or a bulkhead.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What kind of hose clamp should I use?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Worm-gear hose clamps. And go easy on them. The body is plastic and it's possible to crack the base at the larger barb by overtightening, so snug it up and check it rather than cranking it down hard.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"How often should I replace the duckbill?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"The duckbill is a wear part. In hard raw-water service it can start to stick after six to twelve months, so on a powerboat run hard in salt, plan to swap it about once a season. Flushing the system with fresh water when you can helps it last.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Can I use it on a marine head or macerator line?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Yes, it's used on head intake and discharge, macerator plumbing, and holding-tank lines. On a macerator line especially, an inline strainer upstream keeps debris off the duckbill lip and cuts down on weepy leaks.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Will water spray out of the vent during normal running?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"No. Under normal flow the water pressure holds the duckbill shut and the system runs sealed. The valve only opens to admit air when the line tries to pull a vacuum, so you won't get drips or spray at the vent in regular use.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What is the valve made of?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"The body is plastic, chosen to stand up to salt water and the grit that comes with raw-water, head, and livewell service.\"\n            }\n        }\n    ]\n}\n\u003c\/script\u003e\n","brand":"VETUS","offers":[{"title":"Default Title","offer_id":45061793448029,"sku":"2008595","price":93.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0299\/7266\/0317\/files\/ImageServerAPI_e1d55623-f094-4680-bee2-3e5dd61e2dfd.jpg?v=1789558180","url":"https:\/\/nvnmarine.com\/products\/vetus-asdv-anti-siphon-valve-fits-13-32mm-hose","provider":"NVN Marine","version":"1.0","type":"link"}