Conical Tanks

A cone bottom tank is a one piece, rotationally molded polyethylene tank with a sloped conical bottom that improves full content discharge through a single center outlet. The cone shape is designed to empty the tank completely and leave limited to no residual heel depending on the storage contents and discharge outlet. Conical tanks are used for batching, mixing, granular solids, slurries, and any process where it is undesirable, costly, or potentially damaging to leave product behind. Choosing a cone tank depends on the fluid and its properties, which sets cone angle, resin, and specific gravity rating, and the tank’s support structure. Cone bottom tanks have no flat base and must sit on a stand rated for the total fill weight. The rest is tank-to-application configuration: top style, fittings, and accessories.

Tell us the fluid, concentration, temperature, and volume, and we'll help match the cone angle, resin, SG, and stand — and quote freight to your site.

How to Choose a Cone Bottom Tank

1. Cone Angle (Slope) & Fluid Viscosity

This is the primary variable that defines a cone bottom tank. Shallower cones have 15° to 30° slopes ideal for draining thin, water based liquids and keeping total tank height down. Steeper cones have 45° to 60° slopes ideal for viscous fluids, sludges, and solids or slurry that need the slope to overcome the material’s angle of repose and clear the cone. Specify cone angle to the heaviest, thickest cargo the tank will handle, not the average. Protank carries 15° to 60° conical tanks, with 10° available on select large diameter models.

Tank cone angles are horizontally measured: 15° is shallow and 60° is steep. Some manufacturers publish cone angles measured from vertical, which reverses the numbers. If you are cross-referencing competitor models or an existing tank on site, confirm which convention is used.

2. Resin Selection: HDPE vs XLPE

Cone bottom tanks are available in linear high density polyethylene (HDLPE) and crosslinked polyethylene (XLPE). HDLPE is weldable, easily customizable with additional fittings, and the lower cost, value option for water and compatible cargo. XLPE trades weldability for higher environmental stress crack resistance (ESCR) and impact tolerance that is suitable for demanding, material-compatible chemical duty. Neither is universally better. The right choice depends on the chemical, concentration, and working temperature. We verify resin selection against your fluid on the quote.

3. Specific Gravity (SG) Ratings, Fluid Density, Weight & Site

Conical tank specific gravity ratings include 1.5, 1.7, 1.9, and 2.0 SG, and depend on model. The tank’s specific gravity rating must be matched to the density of the fluid, at minimum. A fluid’s SG multiplies total weight-fill quickly: a 3,000 gallon tank rated at 1.7 SG carries roughly 42,000 lb of fluid at capacity (≈14.2 lb/gal) against about 25,000 lb for water. This load is what the stand, anchors, and tank foundation have to be engineered to carry.

4. Selecting the Right Cone Tank Support Stand

A cone bottom tank does not have a flat base and cannot stand on its own. Every install needs a stand or engineered support to carry the tank and provide outlet clearance for the drain valve and piping. Stands must be rated for the full filled weight at your SG. Stock stand types include poly or steel and are properly matched. Model availability varies. Outdoor and seismic zone installations need anchored stands and often need sign-off by a professional engineer.

5. Outlet, Valve & Discharge Clearance

Outlet size and valve type are determined by the material and tank capacity. Small outlets are typically sufficient for thin liquids in smaller tanks. Larger tanks and thicker or solid bearing liquids often need larger outlets — 3″, 4″, 6″, and up — to accommodate the slowest moving material and required discharge rates. Full port ball valves suit clean liquids. Knife and slide gate valves handle solids, sludge, and dry material that can foul ball seats. Butterfly valves fit applications where clearance is tight between the outlet and receiving vessel.

Stand height is important for what the tank discharges into. Gravity fill work into a drum, tote, or IBC tank needs clearance for the container, valve, and piping. Pump feeding adds whatever suction head the pump requires. Confirm discharge targets match height and clearance before selecting a tank size, angle, and stand. Total conical tank installation height, including the stand, can exceed 20 feet on high capacity models. Always confirm ceiling, doorway, and fill access clearance before ordering.

Cone Bottom Tank Specifications & Configuration Options

Cone Bottom Tank Standards, Temperature Limits & Compliance

Every Protank cone bottom tank is one piece, seamless, rotationally molded polyethylene, available in linear HDPE or crosslinked XLPE.

ASTM D1998

Cone bottom tanks are not manufactured to ASTM D1998 as the standard covers flat bottom, upright, cylindrical tanks only. Conical tanks fall outside the standard scope by definition of design. If your project specifications or project regulations require a D1998 tank, see our Engineered ASTM D1998 Upright Storage Tanks.

Service temperature

HDPE handles continuous service temperatures up to ~120°F. XLPE can handle temperatures up to ~140°F. Chemical compatibility and the poly tank structural rating derate as service temperature rises. Tank usable limit drops for aggressive, less than ideal-compatible fluids. Always confirm suitability at an application’s actual service temperature, not at the base 73°F rating alone.

Potable and food contact

Tanks are molded from FDA compliant resin. NSF/ANSI 61 certified cone tanks are available on select models. Confirm certification per product SKU, or request ANSI/NSF certification in your quote.

Cone Bottom Tank Features → Applications

Shaped for complete evacuation

Cone tanks discharge through a single low point so material moves to the outlet rather than pooling across a flat floor. How completely these tanks empty depends on the outlet location. An outlet placed at the cone’s true apex provides the most complete evacuation. A bulkhead fitting mounted on the cone wall above the apex will always leave a heel below the fitting. Some models are built specifically for full drain service. On others, the outlet location can be customized. If leftover material is problematic for the job due to cross contamination concerns between batches, bacterial growth, or operating loss from expensive product, specify full drain outlet placement on your quote rather than assuming the conical shape alone is sufficient.

Ideal for: Batching and mixing with frequent product changeovers, food and beverage production with limited heel tolerance, high purity chemical jobs where residual carryover is a concern for compliance, quality, or safety, and any high value or hazardous fluid where leftover heel means real product loss or disposal problems.

Cone angle as a process tool

Beyond drainage, the tank slope can do real work. Steeper cone angles support dry and granular material flow, solid settling, and solid-liquid separation. For separation work, tanks often have a decant fitting installed to draw off clarified liquid and the drain port is used to evacuate remaining solid through a flanged outlet or slide gate.

Ideal for: Solids settling and clarification, sludge or slurry dewatering, wastewater and process water treatment, dry bulk and granular material discharged through a slide or knife gate, and decant-and-drain workflows where tanks have to actively separate liquid from solids.

The support system

Cone bottom tanks are specified as a tank-plus-stand system, making the stand, outlet, and plumbing part of the buying decision. Models are available in tank only and tank plus stand options. Products may or may not come with a pre-installed bulkhead outlet fitting. Confirm outlet configuration on your quote.

If building or providing your own support, a cone bottom tank has to be cradled across the full cone, not only ring supported at the top flange or under the sidewall. Partial support transfers weight load to the cone-to-sidewall knuckle, concentrating stress at the weakest transition. Fabricated stands should match the cone angle and bear against the cone surface across its area, with the tank seated evenly and without point loads from weld seams or bolt heads under the cone. If you are integrating into an existing structure and unsure, a structural engineer should be consulted regarding the load rating.

Ideal for: Tank with stand models for new, standalone, or outdoor installs, and for buyers without structural engineering support. Tank only models are ideal for existing structure integration such as when a custom stand is already built into the factory floor, a custom designed mezzanine or platform exists, tank only replacements, or a multi-tank installation where one fabricated rack holds several tanks.

Inductor systems (15–150 gal)

The smaller inductor tanks are built for agricultural chemical mixing and induction. They feature an offset fill well, built-in graduated gallon indicators, a self vented slosh proof lid, tie down slots, and 2″ or 3″ manifold plumbing.

Ideal for: Batching herbicides, fertilizers, and spray mixes on application rigs.

Applications by Process

The above is representative, not an endorsement of product compatibility for use. Tank resin, specific gravity rating, and fitting types are specific to the contents, concentration, and temperature. If you are unsure or require assistance, send us your fluid and use case details and we can help match you to the right tank.

Freight & Delivery Logistics

Cone bottom tanks with stand ship as a unit. Larger capacity, fully assembled units are oversized freight as some are up to 12 feet wide. We move them LTL and freight with FOB points across the country. Origin point may be model specific. We’ll flag offload requirements when valid. Liftgate isn’t suitable on big units, and a forklift or a dock will be needed. Lead times vary depending on size, resin, FOB point, and whether the quote is off-the-shelf stock or customized. We quote honestly, and note that all lead times are approximate and vary by demand, back-log, logistics, and external conditions.

Frequently Asked Questions About Cone Bottom Tanks

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