Agrico Plastics | Closed Top Vertical Plastic Tanks | Water, Storage and Chemical Applications

Closed vertical plastic tanks for water and liquid storage

Closed vertical plastic tanks, also known as vertical tanks, storage tanks or cylindrical tanks, are designed for above-ground stationary liquid storage in limited floor space. Their vertical shape makes efficient use of available height in a plant, agricultural building, sugar shack, greenhouse, business, cottage or municipal facility.

These high-density polyethylene tanks, also called PEHD or HDPE, can be used as a potable water tank, water reserve, maple sap tank, rainwater collection tank, buffer tank or supply tank for a water pumping, treatment or filtration system.

They can also be used for stationary storage of compatible food-grade liquids, urea, liquid fertilizers, pesticides and various compatible chemicals, after validating the exact product, its specific gravity, concentration, temperature and the components in contact with the liquid.

To compare this format with horizontal, rectangular, cone-bottom, double-wall or caged models, see the section on plastic tanks for liquid storage and transport. Our article How to choose the right plastic tank in Quebec also explains the main criteria to check before selecting a model.

Design of a closed vertical tank

The cylindrical tank has a self-supporting flat bottom and must be installed on a flat, rigid, stable base capable of evenly supporting the entire bottom of the tank, such as a concrete slab, firm and level ground, a plant floor or even grass if the ground is solid.
The closed dome-shaped or cross-ribbed top helps protect the contents from debris and outside contaminants and can accommodate bulkhead fittings to create a filling connection, for example.
All closed vertical tanks have an access lid on top with a diameter ranging from 5", 6", 8", 15", 16" to 22" to allow filling, inspection and, depending on the opening diameter, certain cleaning operations or even entry into the tank.
Depending on the tank model, it has an access lid with or without a vent. A vent can always be added if needed, either because there is none or because the existing vent is not sufficient for the pump.
A molded graduation may or may not be included. When there is none, the manufacturer offers the option of applying one at the factory.
Depending on the type of tank, an outlet is factory-installed for drainage, while other models do not include one. When the drain is not included, it can be added as needed by choosing the diameter, fitting and gasket materials, as well as the most strategic location for the project.
The tanks are made of polyethylene that meets FDA requirements and are NSF approved for the uses covered by their certification.
The resin contains a UV-stabilizing treatment to improve tank resistance when installed outdoors, which slows down the wear of the plastic that would otherwise crack and dry out quickly in the sun.
Actual service life depends on the liquid, temperature, exposure, installation and stresses applied to the tank and its fittings, but the average service life of a tank often reaches 10 to 15 years.
The closed vertical tank is designed for above-ground stationary storage. It must not be buried or moved when it contains liquid.

For potable water and food products, see the information on FDA-compliant and NSF-approved food-grade tanks. For agriculture, greenhouses, irrigation, fertilizers and maple sap, also see the liquid storage solutions for the agricultural sector.

Common applications

A vertical plastic tank can be integrated into many processes, including:

Creating a reserve of potable water, process water or emergency water.
Collecting and storing rainwater for watering, outdoor washing or any other use where rainwater is permitted.
Storing maple sap (filtrate) in a sugar shack or supplying maple production equipment.
Serving as a buffer tank in a water supply, pumping, dosing or filtration system.
Storing liquid fertilizers, urea, pesticides or compatible chemicals.
Holding a liquid ingredient or compatible food product in a processing plant.
Supplying water to campgrounds, water parks, hunting camps, cottages or homes with a problematic well.

The fact that a liquid appears among these applications does not automatically guarantee that every model is suitable for it. The right choice depends on the exact composition of the product, its concentration, temperature, specific gravity, required volume and operating conditions.

The plastic tank FAQ answers common questions about materials, potable water, specific gravity, installation, maintenance, warranty and transport.

VFN and VFA series features

VFN - Commercial and agricultural grade / Drain included / Molded graduation in US gallons included / Domed top / Access lid with included vent / Specific gravity 1.5 white or 1.9 blue. / Opaque black or green available as an option.
VFA - Industrial and commercial grade: for compatible chemicals or potable water / Drain not included / Optional graduated decal in Imperial gallons and litres, therefore not included / Drain not included / Cross-ribbed, domed or flat top depending on model / Access lid - No vent included / Specific gravity 1.9 white or 2.2 white by special order. / Other opaque colours available as an option.

How to choose between the VFN and VFA series?

The series should not be chosen based only on volume or price. You first need to know the specific gravity of the liquid. At the same volume, a denser product puts more load on the tank walls and bottom. The specific gravity rating of the selected model must therefore be equal to or greater than that of the liquid under actual operating conditions.

The commercial and agricultural grade VFN series is suitable for most water and compatible liquid storage applications because the 1.5 specific gravity is offered for all tanks and the 1.9 specific gravity is offered on tanks of 1000 US gallons and up. The 1.9 tank is identified by its blue colour. Since the drain, molded graduation and vent integrated into the lid are included, this series simplifies certain standard installations. Simple to select, and practical to install.
The industrial-grade VFA series is designed for more demanding, chemical or corrosive applications. The tank has a specific gravity of 1.9 and is suitable for higher-density liquids. All accessories such as the drain, vent and graduated decal must be added à la carte. You therefore need to think through your project in order to make the right selections. The advantage is being able to choose the diameter and location of the drain and vent, which are often determined by available space, piping configuration, equipment around the tank and the process itself. Choosing materials compatible with the stored liquid is one way to help ensure the success of the project.
A specific gravity of 1.9 or 2.2 does not automatically make a tank compatible with all chemicals. The chemical resistance of the polyethylene, gaskets, fittings and accessories must be validated separately.

The plastic tank information guide presents the main formats, materials and selection factors. You can also consult our specific gravity document before comparing models.

Fittings, outlets and custom modifications

Some tanks can be adapted to a specific need by adding threaded polypropylene or PVC connections, bolted stainless steel bulkhead fittings or custom welded flanges and fittings for specialized piping.
The diameter, location and material of each fitting must take into account the flow rate, pump, piping, accessibility and mechanical constraints.
The piping must be supported independently to avoid transferring its weight, vibration or lateral stress to the tank wall.
Lids, vents, valves, Camlock fittings, level gauges, filter baskets, male reducers, female reducers and other tank accessories can complete the installation.

Chemical compatibility and operating conditions

Before using a polyethylene storage tank for urea, liquid fertilizer, pesticide, sodium hypochlorite or another chemical product, it is essential to validate the chemical compatibility with polyethylene.

This verification must cover the exact chemical name, concentration, density, service temperature and storage duration. Gaskets, valves, fittings, hoses and other components in contact with the liquid must also be compatible.

The final choice must also consider capacity in litres or US gallons, diameter, height, access space, filling method, discharge flow rate, venting, possible secondary containment and the standards applicable to the project.

Before commissioning, review the recommendations regarding tank inspection, installation and use.

Which model should you consider based on the application?

Application	Series most often considered	Critical point to validate
Potable water	VFN or VFA depending on the project	Intended use, applicable certification, fittings and accessories
Maple sap	VFN often relevant	Volume, access, drainage, cleaning and installation
Rainwater	VFN often relevant	Overflow, filling, drainage, freezing, outdoor exposure and support base
Liquid fertilizer	VFN often used	Density, concentration, temperature and chemical compatibility
Urea	VFN or VFA	Concentration, specific gravity, filter vent, fill and drain hose, fittings
Pesticide	VFN often used	Exact product, density, concentration, safety, containment and compatible accessories
Compatible chemical product	VFN or VFA	HDPE compatibility, fittings, gaskets, valves, density, fumes, temperature, storage duration
Compatible food-grade liquid	VFN or VFA	Compatibility, certification, cleaning, temperature, accessories and operating conditions.

When should you choose another type of tank?

The closed vertical tank is appropriate when the installation is fixed, above ground and floor space needs to be optimized. In some cases, another format may be better suited.

Need	Format to consider
Liquid transport	Horizontal tank, totes (IBC), rectangular tanks or pick-up truck tank
Complete gravity drainage	Open-top or closed-top cone-bottom tank
Integrated secondary containment	Double-wall tank or containment basin
Full access from the top	Open-top vertical tank
Standard pallet format	Tote (IBC)
Height constraint	Horizontal or rectangular tank.

The right choice depends on the real flow: filling, storage, drainage, cleaning, movement, access, safety, connection and liquid compatibility.

Need help selecting your vertical tank?

Prepare the liquid name, concentration, specific gravity, temperature, required volume, maximum available dimensions, planned installation and required fittings. This information makes it easier to compare the VFN and VFA series and avoid an undersized tank, an incompatible material or a poorly positioned connection. You can also think about how you will fill and empty it, because we can install fittings to offer you a turnkey project.

Agrico Plastiques is a Quebec company specializing in plastics, including plastic tanks, and offers expert consulting services to assist you with the selection of your tank and accessories, sales and after-sales service to answer all your setup or usage questions, as well as plastic tank modification services for more specific projects in the agricultural, commercial, industrial, food-processing, municipal and institutional sectors across Canada.

Visit our plastic tank expertise section, request a consultation for your tank project or contact Agrico Plastiques.

Hesitating between two models?

Describe your liquid, volume, installation and desired fittings. Agrico Plastiques can help you choose a closed vertical tank suited to your application.

For questions about quotes, orders, availability, pickup and delivery in Canada, contact us or see the general FAQ.

FAQ — Closed vertical tanks

What is the difference between a VFN and VFA closed vertical tank?

The VFN series is geared toward commercial and agricultural use, with a domed top, a specific gravity of 1.5 or 1.9, and accessories included such as the drain, molded graduation and vent in the lid. The VFA series is geared more toward industrial and commercial use, and offers no inclusions, so no drain, graduation or vent. This series offers more flexibility to adapt fitting and vent diameters and materials according to the project. The VFA is often considered for more demanding liquids or compatible chemical applications.

Which closed vertical tank should I choose for potable water?

For potable water, you need to choose a tank whose material, intended use, fittings and accessories are suitable for the application. The volume, installation, cleaning, lid, drainage and added components must be validated before purchase. If the potable water is for human consumption, ANSI/61 certification must be added. Otherwise, all tanks can hold potable water for general use.

Which closed vertical tank should I choose for maple sap?

For maple sap, a closed vertical HDPE tank can be used when the application is stationary use for storing filtrate or water. You need to consider the required volume, maximum space dimensions, lid access, drainage and cleaning so the tank is well suited to the installation. The VFN series is often relevant for this type of application, but the final choice depends directly on the required capacity, available space, required fittings, therefore a diameter that allows fittings to be added if needed, and cleaning.

Which specific gravity should I choose: 1.5 or 1.9?

The specific gravity of the tank must be equal to or greater than that of the stored liquid; otherwise the tank walls will bulge under the pressure of the liquid and could split. A 1.5 specific gravity is suitable for many standard liquids such as water, which has a density of 1.0. A 1.9 specific gravity should be considered for heavier liquids or certain more demanding applications such as intense cold, heavy vibration, multiple openings or required welded flanges, an installation location that is difficult to access or in a remote area where replacement or repair would be difficult if needed. A thicker wall remains stronger. Specific gravity alone does not confirm chemical compatibility.

Can a closed vertical tank be used for chemicals?

Yes, several chemicals can be stored in a closed vertical HDPE tank, but only after validating chemical compatibility. You need to know the exact product, its concentration, temperature, specific gravity, storage duration and the accessories in contact with the liquid.

What fittings can be added to a closed vertical tank?

Depending on the model and application, threaded or bolted bulkhead fittings or welded flanges can be added. Vents, level gauges or any other connections needed for the project to operate properly can also be added. Several choices of valves or adapters can be connected to these fittings, such as Camlock adapters, hose barbs, tee or cross fittings, reducers and other accessories such as hoses. The choice must take into account the flow rate, piping, pump, accessibility and liquid compatibility.

Can a closed vertical tank be installed outdoors in Quebec?

Yes, a closed vertical tank can be installed outdoors when the operating conditions allow it. The critical point is often freezing of the liquid, which can create expansion and cause the walls to crack, and weaken the fittings and valve. For installation, the support base, expansion space, ground anchors to prevent the tank from moving, and fittings compatible with sun exposure and weather conditions must be planned accordingly.

Can an above-ground closed vertical tank be buried or pressurized?

No. An above-ground closed vertical tank is not designed to be buried or pressurized. For an underground or pressurized installation, equipment specifically designed for that use must be used. The walls will bulge under pressure and the lid may blow off, just as the walls can collapse inward if suction is too strong. Always use the tank at ambient atmospheric pressure.

For general questions about warranty, maximum temperature, installation, freezing, pressure, burial, connection or service life, also see our complete FAQ on plastic tanks.

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