Quote:
Originally Posted by Montana Man
A properly mounted rotomolded tank won't rupture be merely filling it via the tank rinser. Water will find the next path(s) of resistance and flow there.
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It appears a further explanation is in order to my quoted statement. I have no knowledge any tank roto molded or 2 piece, having survived rupturing, being subjected to NON STOP filling via the on board flush system with the dump valve closed. I would also like to know if someone out there has had an overfilled black tank to the point that effluent exited the roof without a tank failure. What I do know is the physics involved for that to happen. Montana Man seems to think that the vent pipe in the top of the black tank will prevent any pressure buildup. This is provably false as there are many stories that describe a tank rupturing after accidentally leaving the flush line running and the dump drain valve closed. The amount of pressure to be present in a black tank such that liquid can be pushed upwards to the top of the vent opening, is relatively small. A scant 4.34 psi is all that is required to do the job. So how can 4.34 psi cause a tank to fail??? Here's where physics comes in. Let's discuss the terms pressure and force. One of Boyle's Laws states that force is equal to pressure times area or F=P x A. A 35 gallon tank for example having a top dimension of 20"x40"= 800 Sq. inches. Using Boyle's law we see that 4.34 psi X 800 sq in = 3,472 of force pushing upward on the tank's top. The tank's bottom also will also be subjected the same force plus the weight of water it supports. So even if you've got the Home Improvement Binford 9000 roto molded tank and it is able to push liquid out the roof vent, I can guarantee that the Binford 9000 roto molded tank, will not be shaped like a suitcase anymore but rather more like a beach ball. As for the Superman support struts and the bullet proof floor above the black tank, something is going end up bad. If you are using a wand inserted into the toilet to flush your tank, the above warning does not apply. I'll leave it to the reader to figure out what happens when a wand type flusher is left unattended in the toilet.
