Tank Inlets From Bottom

One reason is to minimize splashing and entrainment of air bubbles into the fluid. Also a (minor) saving in pumping costs, at least while the tank level is low.

Tornado & furio good answers. But sometimes for a certain fluid and as a hydraulically demand, the inlet from the top can avail a constant load at the pump.

Dear furio,

I do not understand how static charge builds up for top delivery to tank. Pl. explain how static charge is built up for top delivery to tank.

Thanks,

RAJESWARI

GA. old salt for detailed answer. congrats for 40th GA.

We have 1000 cu.m liquid nitrogen tanks with bottom inlet but identical liquid oxygen tanks with top inlet by the same supplier at the same time. Is the explanation given by you also relevant here?

It all depends on the material being contained in the tank and its properties. Even then it also depends upon what you want to do with the material contained and how you want to do it. There is no universal answer.

Perhaps better mixing of the incoming fluid with the store fluid.....

does providing dip pipe inlet serves the same purpose?

No.

All dip pipes should have an anti-syphoning hole or holes near the top, so as to prevent, in the absence of a non-return valve in the supply pipework, the tank from syphoning-out to the supply point.

Correct! This is also why bottom fills are not used in many situations. A backflow through a bottom inlet is a mechanical problem (if check valves, pumps, seals, etc. fail) that has to be engineered out. If engineering is not all inclusive it has the potential to be a conflagration, environmental disaster, or worse yet the origin of a massive loss of life. If your design engineering uses gravity to your favor, such as the top fill with anti-siphon holes, instead of having to compete with gravity it is almost always a safer situation.

Railroad cars are sometimes an exception to the rule. Compatibility of the material hauled and offloading can sometimes dictate that dip pipes from the dome to the inside bottom of the tank are used to fill and/or unload. A hose from the dip pipe is connected to the storage tank or to a pump which goes to the storage tank. The rail-car is slightly pressurized in order to prime the pump or in the case of direct connection to the storage tank pressure is increased enough to facilitate direct offloading. In either case, check valves are necessary to avoid refilling the rail car from the storage tank in case of transfer pressure loss. Rail cars are an unique breed and have their own set of regulations. There are more exceptions to the rules than there are rules.

Good Luck, Old Salt

Another reason for bottom fill 'anti-sedimentation' if the material is prone to settling or stratifying.

2¢ added to all above good inputs.