The Snyder Industries 3500 Gallon ASTM Black Captor Double Wall Tank (SKU 5600000N49) is a tank-within-a-tank for sites that cannot tolerate a release. The primary tank holds 3,500 gallons inside a secondary containment shell, both molded from high density linear polyethylene and rated to 1.5 specific gravity. At a full water charge the tank carries roughly 29,190 lb of liquid, and the structure is rated to a maximum contents weight of 43,785 lb - that 43,785 lb figure on the 102 x 102 in footprint is the number to design your pad and footing against, not the water-only weight.
Will it work for your site?
This double wall tank stands 158 in tall on a 102 x 102 in footprint, so confirm that height clears your doorway, roof line, or canopy before you order - this is a tall unit. The 1.5 specific gravity rating means it is built to hold contents up to 1.5 times the density of water. On plain water service (SG 1.0) that is genuine overbuild, and it is headroom you already own: the same tank covers a future switch to a heavier liquid such as brine or many ag and industrial solutions without re-buying. Plumbing comes off a FLANGE outlet, an 18" PE threaded/vented fitting, and a manway with 15" access for entry and inspection of the primary tank. See the technical drawing on this page for fitting elevations and the containment geometry before you set your piping. Confirm thread type off the drawing and bring matching bulkhead fittings and gaskets - plus a flange gasket for the FLANGE connection - to the install, since those aren't included. If you are still confirming gallons against your draw and refill cycle, run the numbers through our Tank Sizing Calculator and the Tank Sizing Guide.
Double wall and freeboard - the mistake to avoid
The most common error on a black double wall tank like this one is treating the 3,500 gallon rating as usable working volume and ignoring freeboard. The secondary shell is sized to contain the primary in a failure, and accounting for thermal expansion and contents density determines how much liquid you can actually run day to day. Our walkthrough on Captor double-wall freeboard sizing covers the real volume you can use, and the companion piece on HDPE wall thickness at the vapor-saturated headspace explains why failures start above the liquid line where inspections often miss them.
Containment and related guides
The integrated secondary containment is built into the Captor double wall design. For the regulatory and design context around double-wall containment and fire-water reservoir applications, see our SPCC 40 CFR 112 compliance walkthrough and the NFPA 22 fire-water reservoir design guide before you finalize the install.
This Captor double wall tank ships LTL freight, quoted live to your ZIP - and depending on stock and your region it may dispatch from the Snyder plant in Lincoln, NE or from the West Virginia plant, so confirm transit time when you get your number from the Freight Cost Estimator or by calling 866-418-1777. Before you order, run the offload check: vertical clearance for a 158 in unit, a slab sized for the 102 x 102 in footprint and poured to the 43,785 lb max-rated weight, and rigging - forklift or crane - rated for the loaded tank. Questions on fittings, containment, or sizing this Captor double wall tank to your application? Our team is ready at 866-418-1777.
