Vent pressure relief for bags???

[Fman]

Just realized something, my bags on my system have a fill and and a drain. Should there be a vented exit for air getting trapped in the bag while filling? I see they have a capped off port that could be used for this. I was just thinking how my front bag always tends to fill with air, this must be the reason.

Anyone have any ideas to utilize the extra hole on top of the bag to relieve pressure when filling? I thought about running another line off of it and using a one way check valve to allow air to escape but water would not be able to enter the line when draining the bag.

Just looking for some ideas, I think I am going to do this as my last ballast modification. My front ski locker pops open when filling the center bag and I bet its not even half full because of the air.

[atarpill]

I was going to look into installing a vent line off the front of that bag just to release the air pressure that builds up when it fills up. I have the same issue when I fill the bag in the ski locker it pops the top open and I think the bag is only like 1/2 to 2/3 full and the rest is air. I will let you know if I have any success.

[Sluggo]

In my 2005 SSV with stock bags, if I fill them and use the front cap to "Burb" them, I don't seem to have a problem from then on or until I let air back in to the system. I assume the way this works is that they fill from the upper hose and drain from the lower which means the lower hose or pump would have to have some sort of pressure valve so that when the bags are full (of water or water and air) that water comes out the drain system. Is it possible that the pressure valve is not strong enough or weakening over time?

[Fman]

In my 2005 SSV with stock bags, if I fill them and use the front cap to "Burb" them, I don't seem to have a problem from then on or until I let air back in to the system. I assume the way this works is that they fill from the upper hose and drain from the lower which means the lower hose or pump would have to have some sort of pressure valve so that when the bags are full (of water or water and air) that water comes out the drain system. Is it possible that the pressure valve is not strong enough or weakening over time?


I was looking at the bag today, I might move the fill line to the front of the bag where it is currently capped off and use the top rear upper quick disconnect for a vent line and Y or T it to the drain line. I saw wakemakers sells a one way valve which might be perfect for this application to allow air to escape but water would not enter back into the bag when draining. This could also easily be done for the rear bags as well.

I have a call into wakemakers to find out if they have any other methods of letting air escape from the bags while filling.

Ok, hmmmm.... another reason to get rid of this bag system and go with hard tanks! Anyone from Skiers Choice listening or watching this site???? :)

[87SunSportMikeyD]

Well if you use a reversable pump that will suck all the air out every time you don't NEED a vent line, but it is recommended for any sac so you don't overfill your sac and damage something. A reversable pump has more pressure too so it's even more important.

Basically it is a vent/overflow line that should be a dedicated line that goes out the top of the sac, through a one-way-check valve, and then out through the hull. It needs to be tested first before you drill. If it is too high it will require too much presure to get to that height and it is useless. Typically these check valves are the swing-type, not the spring-type.

[Fman]

Well if you use a reversable pump that will suck all the air out every time you don't NEED a vent line, but it is recommended for any sac so you don't overfill your sac and damage something. A reversable pump has more pressure too so it's even more important.

Basically it is a vent/overflow line that should be a dedicated line that goes out the top of the sac, through a one-way-check valve, and then out through the hull. It needs to be tested first before you drill. If it is too high it will require too much presure to get to that height and it is useless. Typically these check valves are the swing-type, not the spring-type.

Why did Supra not install these from the factory? I only have a fill/drain line on my Fly Hi Sacs. Could you tie a 3/4" vent line into the 3/4" drain line near the end of the line close to exit hole? and use the check valve so it would not go back into the bag when draining but would allow air to escape when filling? My drain pumps on each bag are aerator style, so I am assuming they dont suck out much air. I was reading on the Moomba site people are saying they get air in there front sac while trailering the boat, it comes through the drain hole in the front side of the boat???? I thought that was a little strange, but I guess it is possible. One guys said he puts a cork in the hole to not allow air to come in it. If I have to start putting a cork in my boat I am going to flip a lid.... thats just not acceptable if thats the case!!!!

Do you have any pictures of a check valve? I saw one on wakemakers, was wondering if it was the same fitting? I wonder how MC, and Malibu vent there hard tanks?

[Fman]

Just got off the phone with Jason at wakemakers. The fix for the air in the bag is running an additional line out the top of the bag with a "Y" and checkvalve tieing into the drain line right before it exits the boat. Not to difficult of a task, another $125 worth of parts. I am going to do this on all 3 bags, and get the air eliminated while filling.

I will post some pictures when I am finished.