Engineer-specified sodium hypochlorite (NaOCl) tanks for water treatment, mining and industrial dosing.
Industrial Plastics fabricates custom sodium hypochlorite (NaOCl) storage and dosing tanks in PVC (uPVC), the recognised material for sustained NaOCl service, with UV-stabilised high-density polyethylene (HDPE / PE100) available only for mild-concentration, lower-temperature, shorter-duty applications. Material selection is engineered to your duty: concentration, temperature, residence time, venting and design life. Each tank is designed for the specific concentration (12.5%, 15% trade-strength), temperature, residence time and venting requirements of your application.
Brisbane workshop, since 1971. ISO 9001:2015 certified by SGS. Tanks designed to DVS 2205 (tank-design standard) and welded to DVS 2207, the German plastics welding standard, significantly more stringent than minimum AS/NZS requirements.
Why PVC is the recommended material for sodium hypochlorite
Sodium hypochlorite (NaOCl) is a strong oxidiser that degrades fibreglass (glass-reinforced plastic / fibre-reinforced plastic, GRP / FRP) and stainless steel over time. PVC (uPVC) is our recommended material because it carries excellent resistance to sodium hypochlorite and is the long-recognised material for sustained hypochlorite storage; sodium hypochlorite oxidises and degrades polypropylene, so PP-H is not used for this service. UV-stabilised high-density polyethylene (HDPE / PE100) is a fit only for mild-concentration, lower-temperature, shorter-duty applications, with PVDF available as a premium option for higher-concentration or elevated-temperature service, selected case by case, not by default. We don’t fabricate FRP or steel tanks for hypo, if a tank fails in service, our engineering responsibility is on us.
Matching material to concentration, temperature and duty
Sodium hypochlorite is most often supplied at 12.5 percent available chlorine, the usual trade strength, with 10 to 15 percent in use across water treatment and industrial dosing. It is not a stable product. It loses strength over time, and decomposition speeds up with higher temperature, higher concentration, sunlight and trace metals. As it breaks down it gives off oxygen, so the tank design has to manage both chemical attack and gas release.
For sustained service our standard recommendation is PVC (uPVC), which has well-documented resistance to sodium hypochlorite. UV-stabilised HDPE (PE100) suits milder concentrations, lower temperatures and shorter duty, where its impact resistance and cost are an advantage. For elevated temperature or the most aggressive duty, PVDF is the premium option. We match the material to your concentration, temperature, residence time and design life.
Standard configurations
- Bulk storage, 2,000 L to 50,000+ L. Tank-truck top-fill manway. Bottom drain. PVC or UV-stabilised PE100 with grade-stamped material certification.
- Day tanks & dosing, 200 to 5,000 L. Calibrated, level-indicated, pump-mount platforms. Compatible with diaphragm and peristaltic dosing pumps.
- Bunded & secondary containment, 110% bund volumes. Integrated or stand-alone. Roof-covered options for outdoor installs.
- Vented & scrubbed, Atmospheric vents with carbon scrubbers for chlorine off-gas. Internal baffles for stratification control.
Sizing: bulk storage, day tanks and dosing tanks
Most sodium hypochlorite installations use one of three tank duties, and many sites combine them. Bulk storage holds tanker or IBC deliveries and buffers several days of supply. A day tank decants a working volume, often a day of dosing, which limits how long any single batch sits and loses strength. A dosing tank feeds the metering pumps directly. Because the product weakens as it ages, sizing the day and dosing tanks to your actual consumption matters as much as total capacity. Oversizing simply stores weaker chlorine.
We size each tank to your dosing rate, delivery schedule and turnover, and design the vessel to DVS 2205 with welds to DVS 2207. Because decomposition gives off oxygen, we use vented or degassing designs and size the vent generously, commonly at least twice the inlet diameter, so the tank cannot build pressure. Sodium hypochlorite is a Class 8 corrosive (UN 1791), so we detail secondary containment to AS 3780 to suit the duty. Capacities run from small dosing day tanks to bulk vessels of 110,000 litres and above.
Standards we build to
Compliance
- DVS 2205, thermoplastic tank design (German engineering standard)
- AS/NZS 4766, polyethylene storage tanks for water and chemicals
- AS/NZS 4129/4130/4131, polyethylene pipe and fittings for connections
- DVS 2207, weld procedures for HDPE and PP
- AS 1940 compatibility, bunding, ventilation and signage where flammable adjacency applies
- HSNO/SDS-driven material selection on each project
Sectors we serve
We fabricate for mining, water treatment, food processing, energy and galvanising and powder coating. Each industry page sets out the scope we deliver, the standards that apply and named project examples. For the full list, see Industries we serve.
Frequently asked questions
For sustained service we recommend PVC (uPVC). UV-stabilised HDPE suits milder, lower-temperature and shorter-duty applications, and PVDF is the premium choice for elevated temperature or aggressive duty. We match the material to your concentration, temperature and design life.
As the product decomposes it gives off oxygen. A vented or degassing design lets that gas escape so the tank does not build pressure. A sealed tank can pressurise and, in the worst case, rupture.
Sodium hypochlorite is a Class 8 corrosive (UN 1791), so it is stored with secondary containment. We detail the bund to AS 3780 to suit your site and the largest vessel.
It loses strength continuously, faster when warm or more concentrated. Store it cool and out of direct sunlight, ideally below about 20°C, and size day and dosing tanks to your turnover so you dose fresher product.
It depends on your dosing rate and delivery interval. Tell us both and we will size the bulk, day and dosing tanks together, from small day tanks to bulk vessels over 110,000 litres.
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Considering a rotomoulded alternative? Read why fabricated HDPE outlasts rotomoulded for hypochlorite service, our full engineer-grade comparison.