Snyder Industries 4500 Gallon HDLPE Vertical Double Wall Liquid Chemical Storage Tank (1.9 SG)

The heavy wall with the berm inside

A 1.9 specific gravity wall is sized for a liquid nearly twice as dense as water, and at 4,500 gallons that is 3,800 pounds of resin in the primary and the outer shell together. A single wall tank of that chemical needs a berm sized to its volume, a concrete basin with a sump and a drain valve that must stay closed; a double wall tank carries its containment inside the outer shell, so the 102 inch footprint is the whole footprint, and the SPCC 40 CFR 112 compliance walkthrough covers where that satisfies a spill plan on its own. The list below is the resin's rated chemistry; check the liquid at its concentration in the chemical compatibility database, because weight rating and chemical resistance are separate properties, and work out the usable volume once thermal expansion and the interstice are accounted for with the Captor double wall freeboard sizing guide. The tank sizing calculator sizes the volume to feed rate and delivery interval, and the tank sizing guide covers the reserve.

Grades on the 102 x 197 inch double wall, and the sizes beside it

The N52 is another 1.9 grade in this shell at the same weight, and the N30 is the sulfuric acid grade. The N43 is the 1.5 wall, 800 pounds lighter, for coagulants and brines that never approach this density, and the N40 is cross-linked polyethylene for oxidizers at that weight. The 5610000N45 is the 4,000 gallon double wall in this same grade, 19 inches shorter on the same base, and the 5630000N40 is the 5,000 gallon step up at 216 inches.

Still deciding between these? Freight to your ZIP often settles it; the wider tanks ship differently. Or call 866-418-1777 and we will walk the table with you.

Openings and the alarm layers

• Access: 18 inch threaded, vented manway on the primary, 197 inches up; fill down a dip tube, run the vent outside on acid and caustic, and size it for the unload rate.
• Outlet: both walls together at one flanged penetration, expansion joint after it, valve supported from the slab; name the chemical when ordering so the fitting matches it.
• Service limit: 120 F / 48 C.

Two levels need watching: the primary, with a sender chosen for the chemical per the level gauge selection guide, and the interstitial space, which is the leak alarm and gets a float or conductivity switch, a look into the port each shift, and a logged check each week. Liquid in the space means the primary has failed, and the tank is emptied that day. Tanker fills are where overfills happen; the tank spillover redundancy guide explains the alarm and cutoff stack that keeps an overfill from reaching the interstice at all. Nothing leans on the outer shell, nothing penetrates it, and the interstice is never a storage space.

The slab and the platform

Full, the tank loads a 102 inch circle to 71,307 pounds at the rating, and a rotationally molded floor bears on the whole pad, so the pad is what matters: an engineered slab in full contact under the entire floor, screeded flat, with no pipe trench or drain crossing under it. Strap it before it is filled, because 197 inches of empty polyethylene is a sail, and the straps go slack once the tank is full and its own weight anchors it. The manway is reached from a fixed platform on its own footings, not hung from the tank, with a rail, and the interstitial port is where the operator can see it from the ground.

Fill day

The truck's pump outruns the manway vent, so size the vent for the unload rate or give the fill its own top bulkhead and vent line. The fill pipe runs to the floor so caustic or coagulant does not free-fall and foam. Dense liquids heat up when diluted, so a tank topped off with water for a batch is filled water first, chemical second, never the other way. Somebody stands at the tank for the whole of the first delivery, checking the slab edge, the outlet fitting and the interstitial port as the level rises, and every delivery after that goes in the log with a date and a strength.

Inspecting the primary

The headspace, not the liquid line, is where a polyethylene wall ages, so once a year the manway comes open and a light goes over the top third for crazing and chalking of the primary. The interstitial port is the daily check, and a dry port is the whole point of the second wall. The outlet penetration and the flanged transition are checked at every delivery, because that is where a tank this heavy moves as the level changes, and the expansion joint is what takes that movement instead of the fitting.

Put to use

Ferric, acid and caustic bulk storage at water systems that cannot build a berm, dense process chemicals inside tall process buildings, and any regulated liquid at plant scale at a site an inspector visits. One chemical per tank; label it once for both inspectors; keep the manway shut so nothing escapes as vapor.

Chemicals this resin is rated for, with the fitting and gasket to order

These are the chemicals listed for this tank at the concentrations shown. Each links to the full compatibility page; confirm your exact concentration and temperature there or in the chemical compatibility database before ordering.

• Aluminum Sulfate
• Calcium Chloride
• DEF
• Ethylene Glycol
• Ferric Chloride
• Ferric Sulfate
• Ferrous Sulfate
• Hydrochloric Acid
• Hydrofluoric Acid
• Hydrofluosilicic Acid
• Hydrogen Peroxide
• Magnesium Chloride
• Peracetic Acid
• Phosphoric Acid
• Polyaluminum Chloride
• Potassium Carbonate
• Potassium Hydroxide
• Propylene Glycol
• Sodium Bisulfate
• Sodium Bisulfite
• Sodium Carbonate
• Sodium Hypochlorite
• Sodium Thiosulfate
• Sulfuric Acid
• Urea Solution
• Zinc Orthophosphate

How it ships

At 102 inches across and 197 inches long on the deck the 5620000N45 is oversize freight (NMFC 156600) on a flatbed at a lane rate; the freight cost estimator prices the move to your ZIP, and the price on this page is before freight. A crane sets 3,800 pounds upright on the slab; a forklift can take it off the deck, not raise it. Hold a water test on the primary with the interstitial port watched, then drain and dry ahead of the first chemical. A strap that is checked once a season is a strap that holds; put it on the same calendar as the gutters.