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Ammonium Hydroxide drums bulge / expand / contract

Ammonia drum greyWhy do poly drums of Ammonium Hydroxide bulge or contract?

Bulging or contraction of ammonium hydroxide (aqua ammonia) drums is normal and no cause for alarm. Aqua ammonia solutions, at 28 – 29% concentration, boil around 85°F at atmospheric pressure. Strong aqua ammonia solutions have very large coefficients of expansion which are temperature dependent. The vapor pressure in the container is directly proportional to the temperature change. Puritan Products fills ammonium hydroxide at 70°F. If the container is filled at 70°F and the temperature rises to 90°F, the container will bulge. Likewise, if the same container is subjected to 50°F, the container will contract. If bringing the drum back to the fill temperature of 70°F does not return the drum shape to normal, follow the steps below to correct the physical condition of the container:

  1. Put on the appropriate PPE (rubber apron, chemical splash goggles, gloves, etc.)
  2. Place the container opening within close proximity to a point exhaust source
  3. Carefully open one of the 2” bungs to equalize the pressure.

Would vented bungs prevent bulging and contracting of ammonium hydroxide drums?

Vented bungs or plugs are not permitted for use on corrosive materials, such as ammonium hydroxide, where the vapors may be harmful. The drums used for packaging ammonium hydroxide are specially rated to handle the pressure (350 kPa rated) of bulging and contracting repeatedly.