Valve closed for vapor but open for liquid.

[weeber]

I'm involved in a project that is pumping remediation wastewater to a storage tank. The main problem with the liquid is that it stinks to high-heaven (very high sulfur content).

The storage tank is going to have an odor control system connected to the tank vent. However, we are also going to have an overflow line that goes to secondary containment. We want to ensure that we don't have odors escaping from this overflow line.

Our initial thought was to install a U-pipe pipe filled with water and have a sight tube so someone can see if its filled. The problem is, this is just another maintenance issue that I would like to avoid and I'm concerned that unless it's a fairly large U-tube it may be possible to push the water out or suck it in from filling or emptying operations.

Are there other options out there, like a flap valve that will be vapor tight, but open with enough pressure head (like a foot or two of water sitting on top of it)?

Thanks.

 

[kenvlach]

Just put a float-ball or flapper check valve on a verticaal section of the overflow line, to open with upward flow of the liquid.

 

[25362]

How can you be sure that overflow water wouldn't be as stinky as the primary waste water ?

 

[bimr]

Drop pipes are usually installed to prevent the situation that you are describing.

Suggest that you put a drop pipe on the inlet so that the incoming fluid does not free fall into the tank, but rather enters under the liquid level. This will help to prevent the fluid from venting during the free fall.

On the overflow, you can also install a drop pipe to below liquid level so that the liquid will not allow the tank to vent. Be sure to put a small hole in the pipe so that the overflow will not siphon the tank.

 

[schnipp]

Very important to put the small hole in the overflow pipe. Previous plant I was at sucked in a large tank due to this.

 

[jeap]

weeber (Civil/Environme),

Install an overflow leg, which is an inverted "U" atacched to the bottom of your tank, and on the other side attached to the secoundary containment. It is a common solution to overflow problems like yours. The height of this leg should be calculated to evacuate stinky water only if the level of the tank is grater than the height of the leg. Add a siphon breaker in the top of the inverted "U" and connect it to the vapor section of your tank. That's simple.

On the other hand, be sure that your odor control system y correctly dimensioned an allows air entrance during emptying operation.


Regards