Inlet position and other water tank design parameters 2

[dsg1985]

I'm looking for advice on tank design parameters - basically I've been given a tank and been left with the task of sizing the inlet, outlet, baffle plates, and overflow pipe, and positioning them.

Pipe sizing, baffle plates, the need for a vortex reducer (and its design) - could anyone point me in the right direction standards wise? I've been told 'standards exist' but my search on our Australian standards online library came up short. Any textbook links / papers would be greatly appreciated.

The tank is 4.5m (diam) x 3m, roughly 50kL in size, and the maximum inflow and outflow rates are 30L/second and 20L/second respectively.

 

[JohnGP]

The tank itself you could probably use API-650, but for the rest of it there are guides around. Google is your friend, but for vortex breakers there is some info in these forums (fora), i.e. thread124-156148.

Companies will have their own specifications for line sizing - on my present project for example, maximum velocity for pump suction (on water) was set at 1.5m/s, and 3.5m/s for pump discharge, with target velocities of 1.2m/s and 2.5m/s.

Also, baffle plate size and configuration was provided by the agitator vendor for all our tanks, including loading data for the tank supplier to design supports.

Overflow pipes are typically a size or two larger than the inflow pipe size, and placed low enough that there is a driving head to handle the maximum flow into the overflow.

Just a couple of thoughts,
Cheers,
John

 

[JohnGP]

I meant to also point out that API-650 specifies the minimum distance that nozzles can be placed near the bottom of the tank - i.e. minimum distance for the centreline of a DN150 nozzle from the bottom is 200mm. It depends on what code the tank is built to - AS 1692 doesn't specify such requirements for a 50kL tank, but API-650 has set this requirement based on minimum distances between welds, so can be used as a guide.

 

[dsg1985]

Thanks John,

The tank is not metal, but I'll try to track down a copy of API-650 to see if it's applicable.

I've found some guidelines for vortex plate dimensions and minimum distances to avoid vortex generation in AS 2419.1—2005 (Fire hydrant installations standard). I think abiding by these guidelines will be enough to avoid vortex generation (and comparing with Gould website recommendations), however I'm concerned that the fluid flow into the tank will generate a 'whirlpool'. An engineer was going to provide me with American standards which addressed this phenomenon (and how to deal with it - baffle plates) today but he's now away on leave.

I'll update the thread if I find anything.