The Snyder Industries 35 Gallon Doublewall Tank is the heavier-density (1.9 specific gravity) build in the 35-gallon Captor doublewall line: an inner tank set inside an integral outer wall, so a leak from the inner tank is captured by the outer wall rather than released. It stands 36" tall on a 22" x 22" square footprint and is molded in white High Density Linear Polyethylene (HDLPE). This is the unit people search for as a 35 gallon double wall tank when they need primary and secondary containment in a single integrated design and need to carry a denser fluid than a standard lower-SG unit would support.
Will it work for your application?
The inner tank holds 35 gallons. At plain water that is about 292 lb full; the tank is rated to carry up to 555 lb of contents, which is what gives it headroom for a denser fluid. That 555 lb ceiling over 35 gallons works out to roughly a 1.9 specific-gravity limit (555 ÷ 35 ÷ 8.34 lb per gallon of water), so confirm your intended contents sit at or below about 1.9 SG before ordering. Note that 1.9 SG is a structural weight rating — the maximum fluid density the wall is engineered to support, not a chemical-compatibility rating. Plumbing is straightforward out of the box, with a 6" threaded/vented port and a cap with a 4-1/2" access opening for fill and inspection. For any off-gassing fluid the vent on that port is functional, not optional, so keep it clear and unobstructed in service. See the technical drawing on this page for fitting placement and the double-wall section. If you are sizing for the actual usable volume rather than nominal capacity, the Tank Sizing Calculator and Tank Sizing Guide will walk you through freeboard and fill levels.
Chemical compatibility
We do not list verified chemical-compatibility data for this tank, so we will not make a compatibility claim for any specific chemical or concentration here. Polyethylene resin chemistry varies by grade (for example HDLPE versus XLPE), and compatibility shifts with both concentration and operating temperature. Gaskets and seals are a common compatibility miss even when the poly wall itself is fine, so when connecting to the 6" threaded port, confirm your gasket, seal, and any vent-line material are compatible with the intended fluid. Before placing this tank in any chemical service, verify suitability against the manufacturer's chemical-resistance chart for your exact chemical, concentration, and operating temperature, or call our team to confirm before you order.
What to get right before you order
The most common mistake on a tank like this is treating specific gravity as a formality. The 1.9 SG figure is the maximum fluid density the wall is rated to carry, so confirm the density of your intended contents falls within that limit and do not down-spec to a lighter-rated unit to carry a heavier load. This is a tall, narrow profile — 36" of height on a 22" x 22" base — so set it on a flat, fully supported pad sized to that footprint and plan for lateral and wind load where it matters. Plan your connections around the existing 6" threaded/vented port and 4-1/2" access cap rather than cutting new penetrations into the wall. For containment design and code context on double-wall poly tanks, the guides on SPCC 40 CFR 112 compliance, freeboard sizing per ASTM D1998, and concrete pad sizing are worth reading first.
This tank ships LTL freight from the Snyder plant in Marked Tree, Arkansas, with freight quoted live to your ZIP. Run your address through the Freight Cost Estimator for a freight figure, or call 866-418-1777 and we will quote it for you and confirm fitting and SG details before you order.
