250 Gallon Double Wall Containment Tank, 34" Dia x 83"H, 14" Threaded Manway

The 250 Gallon Double Wall Containment Tank (34" Dia × 83" H with 14" Threaded Manway) is a heavy-duty, point-of-use secondary containment chemical storage vessel engineered for large commercial aquatic centers, municipal water treatment facilities, waterparks, and multi-pool resort complexes.

Featuring a slim vertical aspect ratio with a 34-inch outer profile, it delivers bulk chemical storage while fitting through standard 36-inch equipment room doorways without structural modifications. Its integrated "tank-within-a-tank" secondary containment system fulfills EPA 40 CFR 264.175 and OSHA containment regulations without external concrete dikes, secondary catch basins, or floor berms. It serves as primary bulk storage for high-volume chemicals such as liquid sodium hypochlorite (12.5% to 15%), muriatic acid (31.45%), sulfuric acid, and liquid coagulants.

Mechanical & Structural Architecture

• Integrated Secondary Containment (115% to 120% Capacity): Sized to hold 115% to 120% of the primary inner vessel's fluid volume. In the event of primary vessel mechanical rupture, stress cracking, or bottom-seam fatigue, all chemical volume is contained within the outer interstitial envelope.

• Rotomolded Monolithic Construction: Rotationally molded in a seamless, single-piece configuration using virgin High-Density Linear Polyethylene (HDLPE) or High-Density Cross-Linked Polyethylene (XLPE). Eliminates welded joints, seams, and stress points susceptible to chemical embrittlement and cyclic hoop stress.

• Specific Gravity Rating (1.5 to 1.9 SG): Built with thick sidewall construction rated to handle high-density chemicals up to 1.9 Specific Gravity, safely holding heavy 12.5%–15% sodium hypochlorite (~1.20–1.22 SG) and 31.45% muriatic acid (~1.16 SG) without hydrostatic wall bulging.

• 14" Threaded Access Manway: Equipped with an oversized 14-inch threaded polypropylene access lid with an integrated pressure-relief vent. The wide diameter enables easy internal visual inspection, drop-tube installation, and manual hose filling, while the breathable labyrinth/membrane vent relieves oxygen gas released from decomposing sodium hypochlorite and prevents vacuum collapse during high-rate dosing.

• Reinforced Top Equipment Flats: Molded flat mounting landings on the top dome provide a stable foundation to anchor commercial electronic diaphragm metering pumps, peristaltic feeders, level-sensor transmitters, and rigid top-draw suction lances.

• Visual Fluid Inventory Tracking: Molded in natural translucent polymer with raised gallon and liter graduation marks down the exterior sidewall, allowing operators to visually check chemical inventory levels without opening the manway.

Technical Specifications

• Nominal Primary Volume: 250 US Gallons (approx. 946 Liters).

• Secondary Outer Volume: Approx. 290 to 300 US Gallons ($>115\%$ containment capacity).

• Overall Exterior Dimensions: 34" Outer Diameter × 83" Overall Height (approx. 86.4 cm Dia. × 210.8 cm H).

• Access Manway: 14" threaded polypropylene access lid with integrated pressure-relief breather.

• Specific Gravity Rating: Standard 1.5 SG (dilute acids/water) or Heavy-Duty 1.9 SG (concentrated bleach/acids).

• Operating Temperature Limits: -20°F to 120°F (-29°C to 49°C) continuous service.

• Fittings & Port Landings:

  • Top-dome flats accommodate up to three 2" NPT female bulkhead adapters (for top-draw suction lances, bulk delivery fill lines, and interstitial leak detection float switches).

  • Top-draw plumbing architecture standard to prevent gravity drainage or siphon leaks.

Chemical Compatibility Reference

• Sodium Hypochlorite (12.5% – 15%): Fully compatible. The 14" vented threaded cap allows continuous dissipation of decomposing oxygen gas.

• Muriatic Acid (Hydrochloric Acid, 28% – 31.45%): Fully compatible. Sealed top-draw piping isolates corrosive fumes from mechanical room equipment.

• Sulfuric Acid (up to 50% concentration): Fully compatible under ambient equipment room conditions.

• Liquid Coagulants & Polyaluminum Chloride (PAC): Fully compatible; smooth non-stick interior minimizes polymer film buildup.