Quaternium-15 (Dowicil 100) Storage & Tank Compatibility

Storing Quaternium-15 (Dowicil 100)? Start Here

Quaternium-15 (CAS 4080-31-3; formula C₉H₁₆Cl₂N₄, molecular weight 251.15) is a cationic quaternary ammonium chloride salt built on a chloroallyl-substituted adamantane-type cage. Marketed under names such as Dowicil 100 and Dowicide Q, it works as a formaldehyde-releasing preservative and broad-spectrum biocide in cosmetics, paints, adhesives, latex emulsions, metalworking fluids, and industrial wash systems. Because the active is a water-soluble salt rather than an organic solvent, it carries no aggressive swelling chemistry toward polyolefins, which makes it an easy fit for polyethylene storage and dosing. The engineering challenge is the surrounding metal hardware and the formaldehyde it can release: choose HDPE or XLPE tanks with polypropylene or fluoropolymer fittings, keep carbon steel and aluminum out of the wetted path, and ventilate for formaldehyde rather than for the parent salt.

Polyethylene (HDPE / XLPE) Compatibility With Quaternium-15

Polyethylene is an excellent match for Quaternium-15. The product is a water-soluble quaternary ammonium chloride salt, and aqueous salt and quat solutions of this type do not chemically attack, dissolve, or measurably swell high-density (HDPE) or cross-linked (XLPE) polyethylene at ambient storage temperatures. Both the dry-powder makedown stage and the finished dilute preservative solution store and dose well in polyethylene tanks, totes, drums, and dip tubes.

Two practical notes apply. First, the hazard to manage in the headspace is released formaldehyde, not vapor of the salt, so vent and ventilate the storage and mixing area accordingly even though the polymer itself is unaffected. Second, where service runs hot or where a concentrate uses a co-solvent, confirm the rating against the supplier resistance chart for that specific formulation, since temperature and any carrier (not the quat) are the variables that matter. For routine aqueous Quaternium-15 service, HDPE and XLPE rate Suitable (S).

Material compatibility at a glance

Quaternium-15 is a water-soluble quaternary ammonium chloride salt used as a formaldehyde-releasing preservative and biocide, normally handled as a dry powder that is made down into aqueous solution. Polyethylene is the workhorse material of construction for storing and dosing those solutions: HDPE and XLPE rate Suitable (S), as do polypropylene, PVDF, PTFE, and EPDM seals. The cautions are metallic and procedural rather than polymeric: the corrosive, chloride-bearing solution makes carbon steel and aluminum unsuitable, even 316 stainless is conditional under hot or concentrated service, and ventilation must address released formaldehyde rather than any vapor of the parent salt.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

• Toxic by ingestion and skin contact (H301/H311) and harmful by those routes at lower exposure (H302/H312). Wear chemical-resistant gloves, goggles, and protective clothing; avoid all skin and mouth contact.
• A known formaldehyde releaser and strong skin sensitizer (H317): may cause an allergic skin reaction. Minimize repeated and prolonged contact and treat dust and mist as sensitizing.
• Causes skin and serious eye irritation (H315/H319). Use splash goggles and a face shield when handling powder or making down solutions.
• Suspected of damaging fertility or the unborn child (H361). Limit exposure for all workers and follow occupational reproductive-hazard controls.
• Handle the dry powder with local exhaust ventilation to control airborne dust and released formaldehyde; do not eat, drink, or smoke in the work area.
• Store cool, dry, and away from strong oxidizers and strong acids; the chloride salt is corrosive to metals, so keep it out of contact with carbon steel and aluminum and ship per the product Safety Data Sheet.

Common questions

Can I store Quaternium-15 solution in an HDPE or XLPE tank?

Yes. Quaternium-15 is a water-soluble quaternary ammonium chloride salt, and polyethylene resists aqueous salt and quat solutions without swelling or attack at ambient temperature. Both HDPE and XLPE rate Suitable (S) for the dry-powder makedown stage and the finished dilute preservative solution.

Why are carbon steel and aluminum unsuitable for Quaternium-15?

Quaternium-15 forms a corrosive, chloride-bearing solution. Chlorides promote pitting and general corrosion of carbon steel and aluminum, so those metals are not recommended in the wetted path. Use polyethylene, polypropylene, or fluoropolymer instead.

What gaskets and fittings work with Quaternium-15?

EPDM seals and polypropylene, PVDF, or PTFE fittings are good choices for aqueous Quaternium-15. Viton (FKM) is conditional and should be verified for hot service or co-solvent formulations, and 316 stainless is acceptable for short contact but conditional under hot, stagnant, or concentrated conditions.

Is Quaternium-15 flammable, and what is the main airborne hazard?

The aqueous solution is not readily flammable; the solid carries an NFPA flammability rating of 1. The practical airborne hazard is released formaldehyde plus sensitizing dust, not vapor of the parent salt, so ventilate the work area and control dust during makedown.