What is the Recommended Way to Store Sodium Hypochlorite?
Before discussing the proper way to store sodium hypochlorite, it is important to
first understand how the quality of the sodium hypochlorite affects its storage
life. For more information about sodium hypochlorite quality and how it affects
the rate of decomposition, see
Sodium Hypochlorite Decomposition.
Light, heat, organic matter, and certain heavy metals (such as copper, nickel, and
cobalt) accelerate the rate of decomposition of sodium hypochlorite. The presence
of transition metal ions (copper and nickel) is known to catalyze the decomposition
of liquid sodium hypochlorite, contributing to the loss of sodium hypochlorite strength
and the formation of oxygen. Loss of sodium hypochlorite strength means more product
will be needed when the sodium hypochlorite is used as a disinfectant.
Oxygen build-up can pose problems when storing sodium hypochlorite in storage containers
or sodium hypochlorite transport piping due to pressure build-up. By removing suspended
solids to nearly undetectable levels from the sodium hypochlorite solution, the
rate of decomposition is significantly reduced. In addition, the formation of oxygen
is nearly eliminated.
All sodium hypochlorite decomposition is dependant on temperature. For any given
temperature, the higher the strength, the faster it decomposes. In summary, for
every 10°C increase in storage temperature, the sodium hypochlorite will decompose
at an increased rate factor of approximately 3.5.
Storage of sodium hypochlorite at approximately 60°F (15°C) will greatly
reduce the decomposition of the sodium hypochlorite. Therefore, if sodium hypochlorite
decomposition is a problem in storage and shipping, in many cases the problem can
be solved by cooling the stored sodium hypochlorite before shipping, and if necessary
cooling it upon receipt at the distribution center.
At the production facility it is relatively easy to chill the sodium hypochlorite
with a chilled water system and plate and frame heat exchangers. However, at the
customer’s site or distribution location, it is usually easier to install the storage
tanks, transport tote tanks, drums and bottles in a well insulated room or building
and install air conditioning to cool the room.
If the time from production to receipt at the final site is kept to a minimum, it
is common to not chill the sodium hypochlorite during the storage at the production
site and during shipping, but to keep the sodium hypochlorite in an air conditioned
room after receipt. In order to determine your best option, each application has
to be reviewed based on sodium hypochlorite strength, storage temperature, and storage
Many different types of materials are used for construction of storage tanks for
sodium hypochlorite. Two main types of the materials used are linear and cross linked
polyethylene and fiberglass reinforced plastic (FRP). Other choices include chlorobutyl
rubber lined steel and titanium. In some countries where these materials are not
readily available or the manufacturing quality is suspect, cubical concrete tanks
lined with flexible plastic liners such as PVC have been successfully used. The
choice of materials depends on available capital, tank location, and required service
life. Some tanks may only last 3-5 years. If properly specified and maintained,
the tanks could last 10-15 years. The only material noted for over 30 years service
life is titanium.
For more information, see the
Powell Sodium Hypochlorite General Information Handbook.
For more information about Determining the Strength of Sodium Hypochlorite, see
to Determine the Strength of Sodium Hypochlorite. "
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