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Aqueous Ammonia Tank

Aqueous Ammonia Tank

Aqueous Ammonia Tank

We recently purchased an ammonia storage tank with an overflow pipe that is being vented at ground level with no cap or valve. Is this normal? I have never seen an ammonia storage tank with an overflow pipe. They usually just come with a liquid drain and a SRV that vents above the tank.

RE: Aqueous Ammonia Tank

Definitely seems unusual... maybe the overflow pipe is supposed to dip in to a water seal of some kind?

RE: Aqueous Ammonia Tank

Is there a vacuum breaker in addition to the SRV on that tank?

If yes, that tank design might be meant for unloading tankers equipped with a compressor. In that case, the line you are referring to is meant to feed into a scrubber tank with water. See the 1st diagram "Compressor Method" on page 9: Aqua Ammonia

Andrew H.

RE: Aqueous Ammonia Tank

Is this for aqueous ammonia or anhydrous ammonia?

If aqueous ammonia, why did you delete your/this question from the Relief forum? What conc. of aqueous ammonia? What is the tank's MAWP? Is the overfill scenario credible or is there enough control system mitigation (weigh cells, level instrumentation, etc.) to prevent the scenario? Who designed the tank with overflow? Ask them. Look at the project P&IDs. Surely someone did a P&ID and calcs before they bought a tank. How else would they specify the tank, unless it was copy cat engineering of an existing installation?

DuffBeer - I see you are new here. Your lack of detail makes it impossible to answer. Notice, vt2012, SuperSalad, and I are having to pull information out of you before we can help. So, please, read Tips on how to write a "good" question and other posting guidelines and take them to heart. If you keep wasting people's time with inadequate detail in your questions you will get a bad reputation and no one will help you.

Good Luck,

RE: Aqueous Ammonia Tank

I would call the tank supplier and ask hat person the question as ammonia is nothing to fool with.

RE: Aqueous Ammonia Tank

One design I saw was that the tank have the liquid P-trap with water seal in the overflow line, and have a Nitrogen gas blanket purge on top of tank for the odor control.

RE: Aqueous Ammonia Tank

Here is the updated Tanner Industries link to the question I answered in the post above ....


Here is one from AirGas with properties....



Bottom line:

- Aqueous Ammonia is typically stored at atmospheric (or very low pressure) tanks, typically rated at 30-50 psig deign pressure. Carbon or Stainless is commonly used. An overflow device or conservation vent device would typically be found on these tanks

- Anhydrous Ammonia is far more dangerous and subject to State. Federal and local regulations. It is commonly stored in ASME carbon steel pressure vessels designed to a MAWP of 250psig. Special ammonia duty pressure relief valves protect the vessels and are designed to the rules of ASME. There are no overflows on anhydrous ammonia tanks

OSHA has rules on Anhydrous Ammonia:


Sr. Process Engineer

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