Industries · water treatment
Water treatment: vented lids, Viton seals, and respect for hypochlorite
Dosing chemistry is unforgiving of small specification mistakes. Hypochlorite degasses, polymer is extremely slippery, coagulants stain everything, and all of it often lives outdoors behind a fence. Here is what to ask for.
Request dosing totes
Tell us the chemical, the concentration and whether the totes live outdoors.
Treatment chemicals in totes
| Chemical | SG | Gasket | Critical detail |
|---|---|---|---|
| Sodium hypochlorite 12.5% | 1.20 | Viton | Degasses; vented lid, shade, rotate stock |
| Ferric chloride 40% | 1.42 | Viton/EPDM | Stains permanently; corrosive to cage |
| Aluminium sulphate (alum) | 1.33 | EPDM | Can crystallise in cold weather |
| Polyaluminium chloride | 1.35 | EPDM | Viscous; ball valve preferred |
| Anionic polymer emulsion | 1.01 | EPDM | Extreme slip hazard; drip trays |
| Caustic soda 25% | 1.27 | EPDM | Can crystallise in cold; heat trace |
| Sulphuric acid 93% | 1.83 | Viton | Reduce fill for weight |
| Sodium bisulphite 38% | 1.32 | EPDM | Releases SO₂; vent and ventilate |
| Phosphoric acid 75% | 1.58 | EPDM | Common corrosion inhibitor |
| Fluorosilicic acid 23% | 1.20 | Viton/PTFE | Attacks glass and steel; strict PPE |
Hypochlorite decomposes, generating oxygen, and a sealed tote can bulge. Vent it, keep it out of the sun, and rotate stock — strength falls over time, faster in warm conditions. Confirm compatibility against your SDS.
Setting up a dosing station properly
- 01
Containment first
A spill pallet or bunded area sized to the rules that apply to your site — 110% of the largest container is a common benchmark. Plan it before the chemical arrives, and check current regulations.
- 02
Level, rated base
A full tote of hypochlorite weighs well over a ton on a 48 × 40 in footprint and needs a proper slab. Outdoors, a steel pallet keeps the bottle off wet ground.
- 03
Vent path
Vented lid on any degassing chemistry, and in an enclosed space a route for the gas that is not the operator’s face.
- 04
Compatible seals throughout
Gasket, pump internals, hose and fittings. A Viton tote gasket with an EPDM hose is still an EPDM failure.
- 05
Wash-down and eyewash
Expected for acids, caustics and hypochlorite, and genuinely useful for polymer.
- 06
Stock rotation and labels
Date every delivery. Hypochlorite and bisulphite both lose strength; dosing on the label value instead of the measured value causes problems.
Municipal buying, practically
Public purchasing usually runs on purchase orders, sealed quotes and lowest compliant bid. That works well only when the specification states the grade, gasket material and pallet type — otherwise price comparison rewards whoever cuts the most corners.
The single most useful clause is one sentence: documented prior content required; units with undocumented history not acceptable.
Questions people actually ask
Can sodium hypochlorite be stored in an IBC tote?
Yes, it is very common. Use a vented lid because hypochlorite decomposes and releases oxygen, fit a Viton gasket, keep it out of direct sun and rotate stock — strength falls over time in warm conditions.
Do I need secondary containment for dosing totes?
Often yes, under state, local or fire-code requirements; sizing to 110% of the largest container is a common benchmark. Check current regulations and plan for it as part of the purchase.
What pallet should outdoor dosing totes have?
Steel generally survives wet ground, UV and chemical splash better than composite or wood, at the cost of a little more tare weight.
Dosing system design notes by chemical
| Chemical | Ventilation | Pump type | Special note |
|---|---|---|---|
| Sodium hypochlorite 12.5% | Essential — degasses | Diaphragm, degassing head | Shade; rotate stock |
| Ferric chloride 40% | Recommended | Diaphragm, PVDF head | Stains everything permanently |
| Alum | Not critical | Diaphragm | Can crystallise in cold |
| Polyaluminium chloride | Not critical | Progressive cavity | Viscous; size the line up |
| Anionic polymer | Not critical | Progressive cavity | Extreme slip hazard — plan wash-down |
| Caustic soda 25% | Recommended | Diaphragm | Can crystallise in cold; heat trace |
| Sulphuric acid 93% | Essential | Diaphragm, PTFE | Reduce fill for weight |
| Sodium bisulphite 38% | Essential — SO₂ | Diaphragm | Degasses; vented lid |
| Fluorosilicic acid 23% | Essential | Diaphragm, PVDF | Attacks glass and concrete |
| Phosphate corrosion inhibitor | Not critical | Diaphragm | Common and benign |
Secondary containment is commonly required for dosing chemicals. Check the rules that apply to your site and confirm compatibility against your SDS.
Writing a tote specification for a municipal tender
A structure that produces comparable bids.
Many tote specifications describe a product rather than a requirement, which means the lowest compliant bid can win by cutting whatever the specification forgot to mention.
Specify these eight things
- Capacity and footprint, with any clearance constraint stated.
- Chemical service, naming the product and concentration.
- Gasket material, explicitly — the clause most often value-engineered away.
- Pallet type, with a wood exclusion if the totes live outdoors or in a wet area.
- Prior content requirement: "documented prior content required; undocumented units not acceptable".
- Leak or pressure test, with a record supplied per unit.
- Venting, for any degassing chemistry.
- UN marking status, and whether a current marking is genuinely required — many dosing installations do not transport anything.
Do not specify
- A brand name, unless there is a genuine interchangeability reason.
- "New" as a default. Ask instead for a stated grade and condition, and let reconditioned units compete.
- Cosmetic condition, unless the tote is publicly visible.
Ask for
A written grade, a content-history record, a wash record and a test result with every unit. A bidder who cannot supply those is not offering the same thing as one who can, and the bid comparison should say so.
Water treatment questions
How long does hypochlorite last in a tote?
Strength falls over time, faster in warm conditions and sunlight. Shade the tote, rotate stock, and dose against the measured strength rather than the label value.
Do we need a vented lid on every dosing tote?
On anything that degasses — hypochlorite, bisulphite, peroxide, peracetic acid — yes. On stable chemistry it still helps gravity discharge.
Can totes sit outdoors year-round?
With a steel pallet, UV protection and a freeze plan, generally yes. Freeze damage is a more common outdoor failure than chemical attack.
What about secondary containment sizing?
Follow the rules that apply to your site, and consider the largest credible release rather than just one container. In a multi-tote array, think about what a structural or handling failure could release at once.
Specifying totes for a municipal tender, clause by clause
Eight clauses that make bids comparable.
- 01
Capacity and dimensions
"275 US gallon (about 1,040 L) caged IBC, nominal footprint 48 × 40 in." State any height or clearance constraint.
- 02
Chemical service
"For storage and dispensing of sodium hypochlorite 12.5%." Naming the product makes every other clause checkable.
- 03
Gasket material
"Viton (FKM) gaskets throughout, valve and lid." The clause most often value-engineered away.
- 04
Venting
"Vented lid required." Essential for degassing chemistry.
- 05
Pallet type
"Steel or plastic base; wooden bases not acceptable." Outdoor dosing installations are hard on wood.
- 06
Prior content
"Documented prior content required; units with undocumented history not acceptable." Arguably the most important sentence in the document.
- 07
Testing
"Each unit to be leak tested prior to delivery, with a record supplied per unit."
- 08
UN marking status
"UN marking not required" — if the totes never leave the site and that is consistent with current regulations, say so.
More water treatment questions
Does NSF/ANSI 60 apply to IBC totes?
Certification applies to specific products, and NSF/ANSI 60 covers treatment chemicals rather than the storage container. For a tote, focus on material compatibility, documented history and integrity, and confirm any claims and documentation with the supplier.
How do we handle hypochlorite degradation?
Shade the tote, rotate stock, and dose against measured strength rather than label strength. Warm, sunlit storage speeds the loss.
Can totes be used for potable water storage at a plant?
For emergency or temporary potable supply, a rebottled unit with a new bottle, potable-rated gaskets and sealed lids is the usual starting point, plus appropriate treatment. Check current regulations and confirm documentation with the supplier.
Can totes be delivered to remote pump stations?
Often, with a liftgate and a firm place to set the units. Describe access — gravel tracks and gate widths are the usual issues — in your quote request.
Where people go from here
Reuse first, then recycle.