Anti Siphon Loop -- Bilge Pump

[zstine]

Originally Posted by Cheechako

Yes, you are correct of course if the exit fitting stays submerged, most often they dip in and out. details, details! Aint boating fun?

'dip in and out' you are a fortunate one. My discharge is about 3 ft below the waterline when I'm on starboard tack and worse, my loop is not that high. so I actually get down hill flow into my bilge.

[Sailor Doug]

A loop is no anti syphon valve, big big difference. Below wl drain can sink a boat with 10 vent loops. You need a anti syphon even valve.


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[Schooner Chandlery]

Originally Posted by Sailor Doug

A loop is no anti syphon valve, big big difference. Below wl drain can sink a boat with 10 vent loops. You need a anti syphon even valve.


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??


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[Sailor Doug]

Originally Posted by Schooner Chandlery

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Loop will not break vacuum!!😎


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[Terra Nova]

A vented loop will break the siphon.

[Cheechako]

Originally Posted by zstine

'dip in and out' you are a fortunate one. My discharge is about 3 ft below the waterline when I'm on starboard tack and worse, my loop is not that high. so I actually get down hill flow into my bilge.

Not sure why anyone would put that below the water line, especially hat far, you ought to change it!

[Sailor Doug]

Originally Posted by Terra Nova

A vented loop will break the siphon.

If your pump fills the loop while your drain line is underwater you can siphon water into your boat. A anti syphon valve will vent in air to break syphon. A loop has marginal anti syphon even safe guard. You most likely have a anti syphon valve on your head water supply.


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[Terra Nova]

You don't need a valve--just a vented loop.

[Sailor Doug]

Originally Posted by Terra Nova

You don't need a valve--just a vented loop.

A loop would require to have a hole in it to vent.😊😊


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[Terra Nova]

Originally Posted by Sailor Doug

A loop would require to have a hole in it to vent...

They do; that's how they vent, which is what breaks the siphon. Elementary.

[Snowpetrel]

Originally Posted by Terra Nova

They do; that's how they vent, which is what breaks the siphon. Elementary.

Until the tiny flap of rubber and the little hole blocks up...

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[Schooner Chandlery]

Originally Posted by Snowpetrel

Until the tiny flap of rubber and the little hole blocks up...

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Unless you have an old fashioned vented loop that just has a little hose or pipe that screws into that high loop on the pipe being vented and goes up, up, up through deck or to cabin top etc. No little rubber bit in those. They're open to the atmosphere at all times.


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[Snowpetrel]

Originally Posted by Schooner Chandlery

Unless you have an old fashioned vented loop that just has a little hose or pipe that screws into that high loop on the pipe being vented and goes up, up, up through deck or to cabin top etc. No little rubber bit in those. They're open to the atmosphere at all times.


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Ha, yes they work well.. until someone leaves the outlet shut, or the outlet blocks, then you end up with a firehose blasting out the vent line, so I guess it needs to go outside someplace. This is what I do with my engine vent line, and at revs I get a little trickle telling me it isnt blocked.

[Schooner Chandlery]

Originally Posted by Snowpetrel

Ha, yes they work well.. until someone leaves the outlet shut, or the outlet blocks, then you end up with a firehose blasting out the vent line, so I guess it needs to go outside someplace. This is what I do with my engine vent line, and at revs I get a little trickle telling me it isnt blocked.

Outside of course! That's what I meant by through the deck or to the cabin top (certainly different thing than the overhead...). 😚


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[barnakiel]

The vented ones are only used for below water outlets like toilets or raw water inlets on engines.

Bilge pumps normally have outlets above water plane. Hence the loop, NON vented one.

And as the trap (aka non-return) is in line just behind the pump, and hence a strainer ahead of the pump, there is hardly ever any question about having one. Otherwise the whole raise will return to the bilge every time you pump. When the raise is big diameter and long, you will flood the bilge and the pump may in some situations circulate like this forever.

People who claim non returns are stupid clearly never seen diaphragm bilge pumps on ships? Open one, look inside, there will be two non returns in the design, at times more. Very stupid design used commonly on maxi yachts.

If you happen to not own a maxi yacht, just open your toilet pump and look inside. Once is enough. Can you NOT see the non return valves? And yet thick brown matter will pass and not clog it. How odd.

Not sure why solutions that are common place on serious boats are a matter of so much discussion here.

The loop is not vented and the non return feature is fine.

b.