Sodium Hypochlorite Storage Tanks

Extend the life and quality of Sodium Hypochlorite with an Assmann storage tank

“In the past few years, we have been purchasing more and more tanks from Assmann because they are much higher quality.” 

-Oddyssey Manufacturing Co 

Sodium Hypochlorite

What is Sodium Hypochlorite?

Sodium Hypochlorite is a chemical compound with the formula NaCIO. When dissolved in water, it is often known as bleach. Generally, Sodium Hypochlorite is a bleaching agent, often used in the textile, detergent, and paper and pulp industries. Large quantities are often used as disinfectant in water, wastewater treatment, and quality equipment.

Why does Sodium Hypochlorite break down?

Sodium Hypochlorite is an organic chemical, and all organic chemicals break down eventually. Because of its highly reactive nature, only few materials will withstand storing Sodium Hypochlorite over time. Improper selection of those materials may result in damage to both the handling system, and contamination to the product.  Proper storage for Sodium Hypochlorite is essential for the storage tank, the operators, and the sanctity of the product.

Assmann tanks have uniform wall thickness which slows down UV penetration into the tank, which is effective for storing and maintaining Sodium Hypochlorite.

Types of storage for Sodium Hypochlorite

Polyethylene – Polyethylene is the best method for storing bleach. It’s both cost effective and is readily available. Assmann polyethylene tanks are constructed of crosslinked or linear polyethylene, depending on the application.

Fiberglass Reinforced Plastic (FRP) – FRP is a second choice to Polyethylene because FRP tanks require inspection and re-lining every few years to avoid serious problems.

Specific Gravity

Storage tanks should always be rated for a minimum of 1.9 Specific Gravity. When practical, Sodium Hypochlorite should not exceed 100 degrees Fahrenheit at delivery or during storage, keeping a tank from direct sunlight can help regulate temperature.


Specific Gravity

Fitting Material

Gasket Material


Sodium Hypochlorite Spec Sheet

Download our Sodium Hypochlorite Spec Sheet to learn more

The Assmann Way

The Assmann difference is in the process. Assmann keeps quality first and failure far out of mind.

Uniform Wall Thickness

Uniform wall thickness provides better structural integrity compared to other tanks on the market. As well, uniform wall thickness allows for a more solid dome which will reduce UV penetration into the tank, providing a longer lifespan for Sodium Hypochlorite.

Air Cooling

Air cooling eliminates a process related stress in rotomolding, where water cooling shocks the plastic and causes an abrupt stop to the curing process. Assmann is the only manufacturer who uses non-shielded molds with low temperature heat and gradual air cooling to ensure reliability that lasts.

Avoiding Cross-Sectional Exposure

When storing Sodium Hypochlorite, avoiding cross-sectional exposure is critical as it eliminates an area for the bleach to start its chemical attack. All metallic titanium fittings are the best solution to eliminate cross-sectional exposure. Assmann offers custom and titanium fittings to prevent cross-sectional exposure.

Specific Gravity

Using a 1.9 rated tank gives additional wall thickness to help extend the lifespan of the storage tank. Assmann offers 1.9 rated storage tanks in either crosslink or linear polyethylene.


Under-venting is one of the most common causes for tank failure. When filling and draining tanks, it’s important to keep the tank from vacuum and pressure exposure. A vent two times the size of your largest inlet is required to avoid pressurization. Sometimes a larger vent is necessary when tanks are pneumatically filled. Assmann offers a variety of venting options in multiple sizes and configurations.

Pneumatic Tank Filling

Though it’s common to have Sodium Hypochlorite delivered by tanker trucks, when offloading into a chemical storage tank, do not allow your delivery drivers to purge their delivery lines into your tank. The sudden surge of air can cause rapid expansion of the tank. Sometimes this will cause immediate failure, other times a day to two later a tank will develop a crack. Do not allow your storage tank to be pressurized.

How to Avoid Tank Problems

Keep tanks from direct sunlight whenever possible, oversize your vent connections, monitor chemical deliveries, eliminate cross section exposure, only install required nozzles (no need for spares and unnecessary ports), and insulate bleach tanks for additional life.

Sodium Hypochlorite Guide

Download our Sodium Hypochlorite Guide to learn more

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