Thursday, August 26, 2010

Water tanks: fill pipes, vent lines, and manifolds



I have eight water tanks under the sole of the forward cabins. The total capacity of the tanks is about 380 gallons. I guess I'll find out for sure what the capacity is once I fill all of them and begin using water. But for right now, I'm sticking with the story of 380 gallons in eight stainless steel tanks.

Because I have 8 tanks I decided to connect all the tanks together via the supply line feeding the fresh water pump. I installed a gate valve at each tank giving me the ability to isolate any one of the eight tanks. I would hate to have a water leak in one tank, and have that leak drain all the tanks. If I do develop a tank problem, I want to be able to isolate it quickly then deal with it on my terms and time. In order to totally isolate the tanks on the suction side, I had to be able to isolate them on the vent and fill side too. Manifolds were the easiest way I could think to accomplish what I had to do.

My deck fill line is 1 1/2" that manifolds to 1" that will fill each tank. I used 1" PVC ball valves and pressure fittings to build the manifolds.

My vent lines are 1/2" leaving the tank, then bush up to 3/4" tube witch goes into 3/4 ball valves, then into a 1" manifold. 1" stainless steel welded into the deck with a goose neck completes the vent. Again, I used PVC ball valves and pressure fittings for all the fittings.

My suction line feeding my pump is 3/4" wire reinforced tube rated for food service. All the ball valves on the suction line are 3/4" brass.

For the vent lines I welded 1" stainless steel into the the hull, then welded a goose neck on the vent above the deck. I epoxied 1" PVC couplers on to the 1" stainless thru hull, then bushed down to my 1" PVC manifold, bushed down to 3/4" slip x thread ball valves, threaded in 3/4" x 1/2" barbs, then went to the each tank with 1/2" tube.

The deck fill is 1 1/2" stainless deck fill bolted the the deck going into a 1 1/2" flexible PVC tubing, that leads to the 1 1/2" sch. 40 manifold.

I had to position the fill manifold ball valves so they would be flush behind the hull liner. The valve handles are easy to operate even though one is turned facing the hull sheathing. I'll have an easy to get to access port in the hull liner behind a cabinet to operate the valves if the need happens.

In some of the pictures, you can see the 1 1/2" bilge pump discharge lines plumbed next to the fill manifold. I have two 1 1/2" bilge pump discharge lines on each side of the hull. More on that later.

All my "behind the wall" construction is done regarding my water tank fill and vent. For that matter all the work under the sole concerning the water tanks is also complete. I'm getting pretty close to start installing the finished hull liner material.

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