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jonesy01 (Mechanical) (OP)
18 May 11 15:39
Any help or ref much appreciated. I did a search for existing threads but not much was there. I am looking for any info, references, or suggestions when designing baffles that go inside a reservoir oil tank that can be used to help prevent trapped air from entering the supply line.

The situation is a reservoir tank with a supply line at the bottom and return line at the top. This is a non pressurized tank. The pump is sucking oil from the supply line to an engine then loops thru a cooler, filter and then makes its way back to the tank. It is a square tank that will hold an oil volume of 40 gallons.

Thanks.
CH5OH (Petroleum)
18 May 11 16:03
i dont think entrapped air will be removed by using baffle plates
reason to use baffle plates in an oil tank can be:
-structural integrity of the tank
-prevent oil from slushing back and forth (ships)
-allow solids to settle out

construction details:
-scallops in corner of tank, connecting the compartments
-suction on 1st compartment, return on last compartment
ornerynorsk (Industrial)
18 May 11 16:40
You may want to think about having your return below fluid level for the very reason of air entrapment.  Pumps are expensive to fix.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

jonesy01 (Mechanical) (OP)
18 May 11 18:38
CH5OH, you are correct. I want to use baffles to prevent sloshing and to allow oil to settle before it reaches the suction line. Maybe someone with past experience with reservoir designs or suggestions/lessons learned from previous designs can assist.

 
CRG (Mechanical)
19 May 11 0:29
Have you looked at the mathematics of the problem?  Keep the flow in the tank laminar such that air bubbles can rise and use Stokes Law to calculate the time necessary for an air bubble to rise to the surface.  Design the tank such that there is sufficient time for air to migrate to the surface.  I am clueless as to what size to estimate for the entrained air bubbles.        
Bobfromoh (Mechanical)
19 May 11 7:20
You may be thinking of a vortex breaker plate. It's one or two plates welded on the nozzle pipe at the tank enterence. It's difficult to explain. Maybe search the web for details.  
ornerynorsk (Industrial)
19 May 11 9:20
Also, do you know if your tank is sized correctly?  3X pump volume is a rough rule of thumb, for starters.  This is important for heat and air entrainment issues, as well.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

sreid (Electrical)
19 May 11 13:10
In Race Cars the scavange pump picks up a lot of air.  It pumps to the reservoir called a Swirl Can.  The oil is pumped in tangentially to the round can and the centrifugal force forces the entrapped air to the surface.  The bottom of the Swirl can is conical rather than flat and this helps the main oil pump to pick up only air free oil.
tbuelna (Aerospace)
19 May 11 23:44
jonesy01,

Aeration of the reservoir oil can be mostly eliminated by use of de-aeration devices such as swirl tanks or centrifuges.  However, these devices normally require a scavenge pump, since they are located in the return flow.  Here's an example of a swirl tank:

http://www.tedecoindustrial.com/how.gif

If your system has no scavenge pump, your best option is to make sure that the oil volume turnover rate is as low as possible.  Sometimes a screen mesh divider placed mid-level across the tank will help to discourage air bubbles migrating downward.

hope that helps
terry

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