Flexi diesel tanks

Does any body know the theory behind flexi (Nauta) diesel tanks?Do they need to breath?Do they condensate?When they are filled with diesel,air will find its way into the tank,how does one prevent that air to go through the system?When the tank (bladder) gets empty,is there a risk that the sides could could get sucked to form a "seal" and prevent fuel to get pumped to the engine?

uys

 

When filling the cap removal lets any air out as you install the diesel.

No they simply flatten out , with no extra air needed to drain the fuel.

I have used them on boats that DID NOT return fuel to the tank underway, and do not know how they would like hot return fuel.

There usually tied in place , on an old piece of rug , and in the lazerette mnever did look to see if they had condensation on the surface. Since there sealed there is NO condensation inside.

They are very good a holding fuel . We installed both FW and diesel tanks in a well on our boat , and found no cross contamination of taste.

We use 200G of FW for cruising , but prefer the 200G for diesel when wintering in. 6 35 gal FW tanks and 6 35G diesel.

FF

 

Thanx for the reply!