equalizing two storage tanks

[Custom2014]

Hi,

I have a 135' dia steel water tank that is inside a concrete basin. If something happened and somebody let the sludge lines open in the 135' tank, and that tank started to drain, I need to be able to take water from the outside tank to the inside tank. I need to be able to keep the two tank equalized. My inner tank will withstand up the 3.81" of water column. Does anybody have any ideas on how to make this possible.


thanks

danny

 

[rb1957]

i read your question as this ...

you have a tank within an outer containment wall (the outer tank?)
initally you have the inner tank full and the outer tank empty.
then you start to empty the inner tank into the outer one.
then, whilst this transfer is happening, you want to transfer from the outer to the inner? (to restore the inital condition?)

but then you say "I need to be able to keep the two tank equalized." ?? if the two tanks were equalised then there'd be no flow between them, no?

Quando Omni Flunkus Moritati

 

[Custom2014]

both tank have water at all times, the inner tank either gets its water from the ground or from a pipe above, it flows into the outer tank. if the operator left the sludge lines open, the inner tank would begin to drain. it can structurally hold 3.81" of water col (inner to outer) we need a way to hold at the most 3.81" of wc, we need to do this by water going into the inner tank from the outer tank. This will equalize the tanks, what is the best way to do or figure this.


thanks

danny

 

[rb1957]

you meant like a float valve ?

Quando Omni Flunkus Moritati

 

[Custom2014]

will a float valve allow water to flow from the outer tank to the inner tank

 

[chicopee]

I guess you want to maintain the original water levels within the inner and outer tanks at all times, assuming that the inner tank water level is always higher than that of the outer tank. Unless you have a pump with the proper controls for the inside and outer tank, I don't know how you could maintain both water levels in the event that the inner tank sludge line was opened. The pump flow rate should be equal to or greater than the expected maximum flow rate thru the open piping.

 

[ameyerrenke]

I assume that it is not acceptable for the fluid in the inner tank to mix with the fluid in the outer tank?

Just brainstorming as I have no experience relating to this... create an expanding diaphragm inside of the inner tank connected to the outer tank, such that, if pressure is higher on the outside tank, fluid would flow into the diaphragm equalizing the pressure.

I would think making it impossible to evacuate one tank without evacuating the other would be the best option. What mechanisms would allow the tanks to drain? Just valves? Can you put pressure sensors in place in each of the tanks and implement an electronic controller which would open or close the required valves if the critical pressure differences were approached?

 

[Custom2014]

we have looked at several valves, but nobody can tell us the flow rate, we want to use one of those flap valves but the manufacture will not give us the information.

 

[ameyerrenke]

Is it acceptable for the water from the outer tank to enter the inner sludge tank?

 

[Custom2014]

yes

 

[ameyerrenke]

Why not just use check valves (one way flow) with adequate flow? They would automatically close unless the pressure in the sludge tank was less than the pressure in the water tank.

 

[rb1957]

the flow between the tanks is governed by the pressure you supply .. and by the Cd of the valve, sure. if they won't give you flow rates (odd that, no?) then assume something for design purposes and test it.

but i'm confused about the problem. if the two tanks are equalised and someone opens a valve between them, there won't be any flow, no? if theyn't equalised then they'll flow towards an equalised state, no?? or is the outer tank draining to the outside world, so you have inequality between the inner and outer tanks.

i can see the question arising when you're filling the tanks, ie filling one of them.

Quando Omni Flunkus Moritati

 

[Custom2014]

we tried this I went to tideflex and purchased a 24" valve but it will only get us are 5-7" w.c. Every manufacture we call says an engineer has to verify flow, we need 2800gpm, but our structural engineers cannot figure this one out..

 

[Custom2014]

rb1957 (Aerospace)

the inner tank is filled either from the ground or from a pipe above, when the process is done it flows the basin or outer tank. The outer tank then flow out into the "world" If someone left the sludge line on the inner tank on the tank will then unfill, after 3.81" of wc difference my inner tank would collapse. What we are wanting is like a emergency method to get water back into the inner tank to hold 3.81"-. This way we know the inner tank will not fall down. A valve, pipe configuration, or something to keep this from happening


thanks

danny

 

[ameyerrenke]

not sure what "it will only get us are" was supposed to mean?

what type of 24" valve did you try? check valve?

 

[dhengr]

Custom2014:
Wouldn’t a couple 6-8" dia. steel pipes (you determine how many and pipe dia.), in a “U” shape with two vert. legs, with a 180̊ elbow at the top, and 4' vert. legs on one, and 6' vert. leg on the other (several different depths in the tanks) act as siphons once they were filled. You hang these siphons over the wall btwn. the two tanks, have some means of filling them, and some means (a sight glass or some such) to check that they are staying full. Alternatively, a small pump from the cleaner tank would keep them full, once they were filled. Any way the siphon can be broken is the issue here, air leakage, etc.

 

[Custom2014]

24" checkmate valve,

they said it cannot hold the 3.81" of w.c. that is could fall in the range of 4-7"

thanks

 

[rb1957]

"our structural engineers cannot figure this one out" ... i think maybe you need better engineers ... smile!

i think the point the manufacturers have is that pipe losses depend on things outside their control.

i'd design a piping that has twice the capacity of the accidentally opened outflows, so i'd ne reasonably confident that i'd have the flow. Next i'd need a control system to sense the difference in level between the tanks and react.

Quando Omni Flunkus Moritati

 

[cvg]

you can't vent the tank to prevent collapse?

 

[Custom2014]

what do mean by venting??????????????