Can You Store Sodium Hypochlorite in a Poly Tank?
Yes, with the right resin and fittings.
By James Riggins, Lead Engineer, Liberty Chemical & Equipment Supply, Inc.
Yes. Polyethylene is a common material for sodium hypochlorite storage, but a generic HDPE tank is the wrong spec. Manufacturers split on resin: Poly Processing and Assmann favor cross-linked XLPE, while Snyder's published test data favors linear HDLPE. Fitting design, sunlight and temperature matter as much as the resin.
Sodium hypochlorite: tank spec points
| Point | What the manufacturer documents | Source |
|---|---|---|
| Resin | XLPE (Poly Processing, Assmann) or HDLPE (Snyder offers a dedicated hypochlorite resin, #880059). A standard linear HDPE tank can crack at stress points in oxidizer service. | HDPE vs XLPE for sodium hypochlorite |
| Fittings | Fitting choice gets as much attention as resin in Snyder's bulletin: a titanium fitting sized for full drainage, flushed on a six-month schedule to clear the salt and heavy-metal buildup that oxidizes polyethylene. | HDPE vs XLPE for sodium hypochlorite |
| Sun and temperature | Olin's handling guidance lists chemical strength, temperature, sunlight exposure and fitting design as variables alongside resin choice. | HDPE vs XLPE for sodium hypochlorite |
| Leak paths | Poly Processing groups sodium hypochlorite with lye as chemicals that find leak paths, so avoid drilled sidewall fittings where an alternative exists. | Rule: leak-seeking chemicals |
Where manufacturers disagree
Poly Processing and Assmann argue that cross-linked structure resists the oxidative stress cracking hypochlorite promotes at fittings and molded transitions. Snyder's own bulletin recommends HDLPE: in accelerated-aging tests run with the University of Nebraska, HDLPE kept 400 ft-lb of Izod impact strength after six months in 16.5% sodium hypochlorite at -40°F, against 160 ft-lb for XLPE. Weigh both data sets rather than assuming one resin is right for every site.
Frequently Asked Questions
Is XLPE or HDPE better for sodium hypochlorite storage?
It depends on whose data you weight. Poly Processing and Assmann recommend cross-linked XLPE; Snyder recommends linear HDLPE and publishes accelerated-aging results. A standard commercial HDPE tank is the choice to avoid.
What else causes a sodium hypochlorite tank to fail?
Fittings, sunlight and temperature. Salt buildup and heavy-metal contamination oxidize polyethylene, so fitting design and flushing matter as much as the resin.
Can I use a drilled sidewall fitting on a hypochlorite tank?
Avoid it where you can. Hypochlorite finds leak paths, and a molded outlet flange or a purpose-built fitting is a safer design than a drilled sidewall hole.
Related
Other chemicals
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Reviewed by James Riggins, 30+ years specifying water and chemical process equipment · Updated