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Tank Piping Sizing

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Frank D

Mechanical
Joined
Apr 20, 2018
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US
To ensure over pressurizing of a tank does not occur, what is the typical ratio of inlet to outlet pipe sizing?
 
too many variables to have a typical ratio.

Or do you mean vents?

Typically I would expect for a liquid tank that an open vent would be at least as big in square area as the sum of the pipes coming into the tank.

A bit more than one line of text might get you a better answer....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 

Frank D (Mechanical) said:
To ensure over pressurizing of a tank does not occur, what is the typical ratio of inlet to outlet pipe sizing?

There is no typical answer to this question. You need a full understandings of what fluid properties are involved (gas, liquid, etc.), the tank construction (code or tank standard), and the operational requirements (hazardous, etc.).
 
We typically provide a jacketed hopper for circulating hot water (>170 F). The single inlet is usually sized at 1" NPT and the return or outlet is sized at 1-1/2" NPT. we instruct the end user to provide an open loop circulation system and to be on the safe side we provide a 1" NPT relief valve pre-set at 7 psi. the water jacket is not intended to be a pressure vessel and we are providing precautions to minimize or eliminate the risk of over pressurizing.

Question...Is this a safe system? What would be the recommended configuration of the inlet vs outlet?
 
In the marine industry, Class rules dictate that a non-pressurized tanks have vents with total effective area of 125% of the filling line with a minimum of 2" diameter for water or 2.5" diameter for oils or a minimum of 1.5" for tanks of capacity less than 36ft^3.

Additional consideration should be given to vent height such that if the fluid were to enter the vent and approach the outlet, the additional head in the vent pipe would not cause pressures toward the bottom of the tank wall to exceed their rated capacities.

EDIT:
Considering your more recent reply involving the 7 psi relief valve, your tank construction must be able to withstand the 7 psig + head losses in the vent pipe at the source pumping rate + the head height of the tank.

I would be interested to know the intent of the relief valve vs. leaving it open to atmosphere.
 
Thank you to all that responded.
 
An assumption is that the hopper is open. Jacketed hoppers have a full range of options, including half pipe jackets, dimpled jackets or conventional jackets. If the water pressure is too high in the jacket, the jacket may rupture.

Since it appears that the contents of the hopper are not adding any additional heat, you would have to be concerned only about the heat from the hot water and excess water pressure in the recirculating loop.

High water pressure may occur if the recirculating loop is blocked by a closed valve. To overcome this you can install a pressure relief valve. The capacity of the pressure relief valve should be the capacity of the recirculating pump. The relief valve does not have to be installed on the jacket, but may be located in the recirculating loop.

The heat source should also have a relief valve for thermal relief. Relief valves are commonly installed on boilers, water heaters, etc. for this purpose.

 
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