2 replies to this topic

[desh]

Hi there,
I have been tasked with designing a tank to replace an existing one on the plant. It was decided to include an overflow volume in the new tank instead of a second overflow tank. Can anyone give me some advice on this? Is there a design guideline where a certain percentage of actual tank volume is added to accomodate overflow? Or is it more complicated than this? References, if available, will be appreciated.

[ankur2061]

Hi there,
I have been tasked with designing a tank to replace an existing one on the plant. It was decided to include an overflow volume in the new tank instead of a second overflow tank. Can anyone give me some advice on this? Is there a design guideline where a certain percentage of actual tank volume is added to accomodate overflow? Or is it more complicated than this? References, if available, will be appreciated.

Desh,

When you say that you want to include an overflow volume does it mean that the overflow from the tank is a normal operation? If so, would you be kind enough to give some more details about the operational aspects of your tank. Most storage tanks, are provided with an overflow to prevent the undesirable phenomena of tank overfilling and the liquid coming out of the open vent. The tank roof for vertical vessels is generally not designed to be as strong as the cylindrical portion of the tank, & any overfilling upto the roof may lead to structural damage. Most of the overflow connections that I have seen on vertical storage tanks are a few inches (6-8) from the cylindrical top of the tank. The line connected to the overflow connection will not have any isolation valve and a siphon breaker would be provided on the line.

Any further details from you will help us understand better your requirement.

Regards,
Ankur.

[djack77494]

desh,
I've never heard of the situation you seem to be describing. Any space in a tank above the high high level I guess could be considered "overflow volume". I've always kept this to a minimum, determined by mechanical considerations. I don't know why you'd have a second overflow tank either. I've never used one in many years of design experience. I can only imagine that you must have some very challenging material that cannot be allowed to escape your system. And you mustn't have a suitable drain system to put it into. So what happens if you overflow the overflow volume?