Ferric Chloride & Ferric Sulfate Equipment Selection Guide

If a quote for a ferric chloride or ferric sulfate system comes back with an FRP storage tank, that's a spec error — Poly Processing's own literature states plainly that FRP is not suitable for ferric chloride because it acts as an etching medium on the resin. Getting a ferric coagulant system right means three separate equipment decisions across three vendors, each with a different depth of published data: the storage tank (XLPE only, with hard concentration limits), the metering/dosing pump (rated at saturated concentration), and the bulk transfer/recirculation pump (mag-drive sealless, material scaling with flow and pressure, but no published hard concentration ceiling).

Why Ferric Coagulants Are Harder to Store Than They Look

Ferric chloride and ferric sulfate aren't just corrosive — they're also prone to separation and settling, and that tendency gets worse with temperature swings. These chemicals are frequently delivered at elevated temperature, which puts real thermal cycling stress on the tank as it expands and contracts. That's a direct reason XLPE (crosslinked polyethylene) is specified over standard HDPE: the crosslinked structure tolerates that expansion/contraction without losing structural integrity, where a standard resin is more likely to fatigue over repeated cycles.

There's also a vegetation hazard that doesn't come up with most stored chemicals: ferric fumes can defoliate surrounding vegetation if the tank vents outdoors without a scrubber. Poly Processing's recommended system for ferrics pairs four things: an IMFO® true-bottom-drain outlet (handles settled sludge and eases cleaning), heat pads/insulation (reduces separation/settling risk from temperature swings), a mixing system (prevents separation in the first place), and a scrubber if the tank vents outdoors.

XLPE Only — FRP Is Explicitly Not Suitable

This is the single most important spec call on a ferric coagulant system. Poly Processing's own literature is explicit that FRP is NOT suitable for ferric chloride — it acts as an etching medium on the fiberglass resin. That's a real differentiator against generic FRP marketing that treats fiberglass as a universal corrosion-resistant material for aggressive chemicals; ferric coagulants are a chemistry where that generic assumption fails.

Source: Poly Processing chemical-storage guidance and Tank_Specs.pdf — the fitting/gasket/bolt spec is identical for both Ferric Chloride and Ferric Sulfate.

Hayward Flow Control Z Series — Real Material Ratings, One Honest Gap

For precision metering — injecting a controlled feed rate of coagulant into a process stream — Hayward Flow Control's own 20-chemical resistance table rates the wetted materials on its Z Series solenoid diaphragm metering pump against ferric chloride and ferric sulfate. The PTFE diaphragm and EPDM seal option both rate A (Excellent) for both chemistries; the FPM/Viton seal option rates B (Good, minor effect) for both. Hayward's table does not carry a PVDF rating for either ferric chemistry specifically — a real, stated gap, not an assumption of compatibility — so confirm the pump-head material rating with LibertyCES before ordering at your actual concentration.

The Z Series Digital model adds closed-loop pH/Redox Control dosing on top of Constant, Timed, and Proportional Dosage modes — useful for automated, feedback-driven coagulant dosing. Liberty previously specified Grundfos SMART Digital/DDA pumps here, which published a saturated-concentration rating and a high-viscosity "Slow Mode" specifically for coagulants; Grundfos left Liberty's manufacturer lineup as of September 2026, and Hayward's own literature doesn't document an equivalent saturated-concentration figure or high-viscosity mode for this line. On a high-viscosity or high-concentration ferric application, confirm actual dosing performance with LibertyCES before ordering rather than assuming parity with the prior spec.

Mag-Drive Sealless — March Pump's 13-Model Ferric Chloride Lineup

Bulk transfer between tanks, tank-to-process feed, and in-tank recirculation are a distinct equipment category from metering — different flow rates, different duty cycle, different vendor. March Pump names 13 specific mag-drive sealless centrifugal models for ferric chloride transfer and recirculation duty. Mag-drive means no mechanical shaft seal, which March's own application copy calls out as eliminating the #1 leak-failure point on a corrosive chemical like ferric chloride. Wetted material scales up with flow and pressure across three real tiers:

Viton (FKM) O-rings/gaskets and ceramic shafts/thrust washers are constant across every model regardless of size — only the bulk housing and impeller resin change as flow and discharge pressure rise. The pattern is the same materials-of-construction escalation logic already documented on the tank side (XLPE over standard resin): as mechanical demand goes up, the vendor moves off its cheapest compatible material toward something built for more pressure and wear.

A Real Design Basis, If You Handed Me a Ferric Coagulant System

If you handed me a ferric chloride or ferric sulfate feed and storage system to spec, here's where I'd start:

• Storage tank: XLPE construction, specific gravity 1.65 rating, PVC/CPVC fittings, EPDM gaskets, titanium bolts — never FRP. Confirm concentration is within 50% (Ferric Chloride) or 60% (Ferric Sulfate).
• Tank system add-ons: IMFO true-bottom drain for sludge control, heat pads/insulation for delivery-temperature swings, a mixing system to prevent separation, and a scrubber if the tank vents outdoors.
• Metering/dosing pump: Hayward Flow Control Z Series (or equivalent) with PTFE diaphragm and EPDM/FPM seals — both rate well against ferric chloride/sulfate per Hayward's own resistance table; confirm the PVDF pump-head material rating and the pump's actual saturated-concentration performance directly with LibertyCES before ordering, since neither figure is published for this line the way it was for the prior Grundfos spec.
• Transfer/recirculation pump: a mag-drive sealless centrifugal pump sized to your real flow and head — March Pump's 13-model lineup as a reference point, material tier (PP / Ryton / Kynar) matched to your flow and pressure.
• Before ordering a transfer pump at high concentration or high specific gravity: confirm directly with the pump manufacturer or LibertyCES — this is the one spot in the system where published data stops short of a hard number.

Ferric Chloride & Sulfate Equipment FAQ