dogwood36322
Southeast USA
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Joined: 08/03/2009
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The same thing happened to the guy next to me a couple of months ago. It was primarily fresh water that dumped as he accidentally hooked his fresh water hoes to his black tank flush. It caused the tank to expnad and drop from the underbelly breaking lines as it did so. My unit also has the decal warning tio leave the drain valves open.
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millertime
Whittier, Ca.
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Joined: 09/13/2003
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I was told to fill the tank and then drain. Its kind of hard to fill with the drain valve open
Chuck and Cindy
2002 Dodge 2500/Cummins
Reese 15000#
CF28BH Cruiser picked up 12-22-03
hyd/disk brakes installed 12/07
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Duck
Miami Lakes, Fl
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I will close the drain valve when using the tank flush so that I can build up enough water to get the tank clean. I never walk away from the drain valves so I will not forget and let the tank over fill. That seems to be when people get into trouble. I do not let the tank flush run for more then five minutes with the valve closed. Worked for me the past six years.
Don
08-FORD F350 PSD
08-Hitchhiker II 34.5 UKSBG
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Kennedycamper
Algoa, Texas
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I close my valve and let the water from the black tank rinse buildup some in the tank everytime. I do time it, and never walk away though.
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laknox
Arizona
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Joined: 01/06/2008
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Jim&Peg wrote:Possibly they were backflushing the tank to rinse it. If you overfill the tank with a flusher it is possible to burst the tank. These large flat tanks will not withstand any pressure. The tank often bursts before the water rises to the top of the vent. There is at least one or two posts of that happening every year. Sometimes it even bulges and ruins the floor above the tank.
I'm still trying to get my head around a tank bursting with a 2" column of liquid less than 10' high providing pressure on it. A water-column barometer holds what, about 35' at 1 atmosphere pressure (i.e. 30" of mercury)? Is there a back-flow valve in the vent that prevents liquid from rising in the vent pipe but allows gas outflow? I just don't understand how this could "explode" from pressure in the tank unless it's a closed system and you're getting 40-60 psi from the hose. Makes much more sense if a seam weakened and let loose while the tank was near-full. 
Lyle
2002 GMC Sierra 2500 HD Duramax Crew Cab 4x4
Banks Bullet Tuner and Monster Exhaust
B&W Turnover Ball with 5th Wheel Companion
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1936 John Deere Model A
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B W M
Princeton IN.
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Joined: 08/23/2009
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If they can find some hot lime this is what they need. This is what we used in the old out house or the John.
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smsage999
Humble, Texas
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dblr wrote:On mine it as a decal that reads that the drainvalve must be open when useing the black tank flush.
Same with mine.
Steve , Michele , and Austin
07 Dodge 2500 Mega Cab 4X4 6.7 Cummins(6spd manual)
09 Cougar 320SRX
Mikey- Golden Retriever
Chuey- Dachsund
Raisin- Mini-Dachsund
Max- Cockerpoo
It's better to have it and not need it than to need it and not have it!
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rick83864
Sandpoint, ID
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Joined: 09/04/2009
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laknox wrote:Jim&Peg wrote:Possibly they were backflushing the tank to rinse it. If you overfill the tank with a flusher it is possible to burst the tank. These large flat tanks will not withstand any pressure. The tank often bursts before the water rises to the top of the vent. There is at least one or two posts of that happening every year. Sometimes it even bulges and ruins the floor above the tank.
I'm still trying to get my head around a tank bursting with a 2" column of liquid less than 10' high providing pressure on it. A water-column barometer holds what, about 35' at 1 atmosphere pressure (i.e. 30" of mercury)? Is there a back-flow valve in the vent that prevents liquid from rising in the vent pipe but allows gas outflow? I just don't understand how this could "explode" from pressure in the tank unless it's a closed system and you're getting 40-60 psi from the hose. Makes much more sense if a seam weakened and let loose while the tank was near-full.
Lyle
Now I think I'll just keep doing it the same way, with the valve closed. Lyle is right, if the vent is not clogged there would be no more pressure than what the sewage would put on the tank. I also think many turn it on and forget about it. I could see that causing a problem. Thus the warning label. They warn us about GVWR and 60% ignore it too.
06 Dodge 3500 Laramie 4x4 Dually
5.9 Cummins HO Automatic,Jacobs brake, Dodge Navigation
06 Grand Junction 34' Mor/ryde, 5500 Onan genny, Dual A/C, Fireplace
21500 GVW
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danr1707
Flower Mound, TX & Pagosa Springs, CO
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So the black tank has a vent? Maybe is was clogged with leaves? I've overflowed my gray tank and that just backed up into the shower. It didn't "explode".
Theresa & Dan
2008 Ford F-350 PS 4x4 CC SB SRW King Ranch
2010 Keystone Fuzion 302
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kakampers
Fulltimer
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Joined: 04/02/2004
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Duck wrote:I will close the drain valve when using the tank flush so that I can build up enough water to get the tank clean. I never walk away from the drain valves so I will not forget and let the tank over fill. That seems to be when people get into trouble. I do not let the tank flush run for more then five minutes with the valve closed. Worked for me the past six years.
Don
This is exactly what we do too! Have seen too many friends "forget" and they paid the price...what a mess!!!
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