Anti siphon loop vent failure

[Bristol30]

The anti siphon loop vent line on my Bristol 30 3gm30 is streaming water into the bilge. The vented loop is a 3/4" hose barb plastic device. I'd like to replace it but I am unsure as to the correct type of material. Is plastic/marelon acceptable for this application or should the anti siphon loop be bronze.
Any recommend brand would be appreciated.

Thanks in advance for the forums assistance.

Bristol 30
S/V Shifting Gears

[GordMay]

A "Forespar" (Marelon) Vented Loop/Siphon Break is satisfactory for an engine exhaust system.

FWIW: To clean the valve (duckbill,) soak it in white vinegar for a few hours to dissolve salt and calcium deposits. When reassembling, remember not to over-tighten the cap.
Replacement may be necessary if the vent cap/duckbill assembly is clogged, deformed or not functioning properly.

[DotDun]

Vetus makes several models also.

[DeepFrz]

Remember also that these are a maintenance item. Cleaning once a year is a worthwhile endeavor.

[barnakiel]

Yes, I have seen some from Vetus in plastic and Volvo makes bronze ones.

b.

[Nicholson58]

Bronze in the engine sea water out to the exhaust ell. All others can be plastic. I had a failed diaphragm in my main engine out GROCO and put 200 gallons of water in the bilge. temporary fix was vice grips. New diaphragms are available on line.

[delmarrey]

Originally Posted by Nicholson58

Bronze in the engine sea water out to the exhaust ell. All others can be plastic. I had a failed diaphragm in my main engine out GROCO and put 200 gallons of water in the bilge. temporary fix was vice grips. New diaphragms are available on line.

Another temporary fix could be; attaching a small hose and running it up above the waterline and then overboard, which could be back into the exhaust system.

[Nicholson58]

Originally Posted by delmarrey

Another temporary fix could be; attaching a small hose and running it up above the waterline and then overboard, which could be back into the exhaust system.

Could have but its a long way to the rail from the engine room and spare hoses were burried under a kayak and sails. Tool chest was right there. We took the diaphragm out and cleaned all parts with a tooth brush in fresh water, removed the crusty stuff but old dry rubber was no good. I'm amazed at the list of spares needed on board. I always buy at least two when I need one.

[delmarrey]

Originally Posted by Nicholson58

Could have but its a long way to the rail from the engine room and spare hoses were burried under a kayak and sails. Tool chest was right there. We took the diaphragm out and cleaned all parts with a tooth brush in fresh water, removed the crusty stuff but old dry rubber was no good. I'm amazed at the list of spares needed on board. I always buy at least two when I need one.

Sorry! This wasn't directed at you but just an FYI for all.

[Nicholson58]

No problem Delmarrey. I did use the smiley thingy. Just glad to keep the wet stuff on the outside.

[Dulcesuenos]

I am curious if the actual vented loop pipe is above the water line, would this still allow water in the bilge in the event of a vent failure?

Mine appear to have the hose clamped to the pipe roughly 6" above the water line, placing the actual vent much higher.

[daddle]

A vented loop below the waterline? Does that make sense? I am thinking that would defeat the entire purpose because no siphon is necessary below the waterline as there is positive pressure. Also a vented loop is basically a pipe with a poorly plugged hole in it, as you have discovered, so that rather disqualifies it for below the waterline installation, no? But maybe I'm confused...

[Dulcesuenos]

Most actual vents are just above waterline. Mine are way above it. Two people here who had their vent fail had lots of water ingress. Wondering if that happens if the vents are 10" above wl. Did i word it erong?

[daddle]

I wouldn't think a vent above the waterline could emit water. Sounds impossible without a pump of some kind in the system.

[DeepFrz]

If the vent fails to open, even if above the waterline, it can and will siphon water in. But what vent are you talking about?