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Introduction
This article contains everything you will need to know about poly tanks and their use.
You will learn:
What is a Poly Tank?
Types of Poly Tanks
How Poly Tanks are Made
Uses for Poly Tanks
And much more …
Chapter 1: What is a Poly Tank?
A poly tank is a plastic storage tank used to store, transport, and collect water, other liquids, and granular or powder materials. They are made of polyethylene or polypropylene and are a cost effective, lightweight, and easy to handle storage unit that is versatile and capable of storing high volumes of material.
Storage tanks have been a part of industrial operations for many years. They have become a critical aspect of several industries due to their strength, durability, and ease of use. The introduction of poly tanks has been a revelation to the storage industry in that poly tanks are long lasting and reliable. Although there are metal tanks that are necessary for certain industries, poly tanks have become the standard by which storage tanks are measured.
Regardless of their stability, poly tanks still need a surface upon which to set. Foundation materials include crushed rocks, dust, wood chips, or other materials that are sufficiently durable to hold the tank in place. In the majority of cases, under normal use, poly tanks can last up to 20 years and have UV ray stabilizers to help the tank endure the effects of the sun. Poly tanks require less maintenance and can be set up with a tank self cleaning system that removes debris that may settle in the bottom of the tank.
Chapter 2: Types of Poly Tanks
The types of poly tanks are separated into various groups in accordance with their grade, use, type of polyethylene. Poly water tanks are divided by the type of water they store with potable poly tanks being used for the storage of water while non potable poly tanks being used for any other type of fluid or liquid.
Vertical Poly Tanks
The vertical placement of poly tanks is the most common positioning of a poly tank since it makes the tank more accessible. Water, chemicals, and farm fertilizers are stored in vertical poly tanks due to their ease of access and longevity. Vertical poly tanks are very versatile and are used for industrial storage, chemical storage, water storage, fertilizer storage, and storage of other bulk materials.
The process used to produce poly tanks includes molding the plastic material such that it forms a solid impenetrable surface that is resistant to tears, impacts, punctures, and extreme changes in environmental conditions. Food grade vertical poly tanks are manufactured to meet the Food and Drug Administrations (FDA) for containers that store raw ingredients for the production of food. Various accessories can be added to vertical poly tanks and include fittings, nozzles, flanges, couplings, insulation, ladder systems, and internal and external piping, to name a few.
The formational structure of vertical poly tanks allows them to be larger and more durable than horizontal poly tanks. Their strong and sturdy upright positioning makes them a viable storage device for agriculture and various industrial and manufacturing applications. They are able to store a wide range of fluids, liquids, and chemicals including various forms of acids.
Horizontal Poly Tanks
Horizontal poly tanks are smaller and more mobile than vertical poly tanks. They can be moved using a forklift, truck, tractor, or trailer. In certain instances, horizontal poly tanks are permanently placed on the bed of a truck or a trailer. They are easy to fill or load and have a low profile that prevents them from interfering with the center of gravity of a truck.
Unlike vertical tanks that sit on the ground, horizontal poly tanks have built-in legs that serve as their foundation, which makes it possible to easily maneuver and change their positioning. This added convenience enhances the versatility of horizontal tanks and broadens the number of applications where they can be used. Some of the features of horizontal poly tanks include being translucent to be able to see the level of the contents of the tank and calibration markings. The wide use of horizontal poly tanks is due to their low profile, which makes them convenient for locations with limited space.
As with vertical poly tanks, horizontal takes are easy to fill or load and normally have an access hatch on their top center. They are constructed such that their length is not greater than six times their diameter to ensure their structural integrity and is the reason for their sizes. A typical horizontal tank is equipped with pressure vacuum vents, gage hatches, and sample wells. Aside from the typical cylindrical version of horizontal poly tanks, there are horizontal poly tanks with a square or rectangular cross section.
Underground Poly Tanks
Underground poly tanks, which are referred to as cistern tanks when used to store and capture potable water, are very large and can have a storage capacity of up to 20,000 gallons of fluids. They are heavy duty tanks that are waterproof and resistant to the effects of soil. Underground poly tanks have risers for access to the tank that are added after their installation.
For a poly tank to be used for underground storage, it has to be molded, designed, and configured to fit the application. They are used to preserve land space or in areas where above ground poly tanks are not permitted. Additionally, the placement of a poly tank underground may be a choice to protect the tank from the effects of the sun’s rays. The risers for an underground poly tank are connected to a pump and pipe system to provide access to the contents of the tank.
The installation of an underground poly tank requires careful preparation to ensure the stability of the tank and proper placement. Aside from the obvious digging of the hole, the bed of the hole needs to be filled with granular material that will allow any moisture to pass through and not accumulate under the tank. It can take the form of pebbles, grain, or granular sand. The tank must be placed level regardless of any slope in the location.
Underground poly tanks can take several forms and include horizontal and vertical poly tanks with vertical, cylindrical tanks being the most popular. The size of the tank is determined by the material that is being stored, its location, and requirements of the application. Potable water underground poly tanks are required to follow a strict set of regulations and requirements for the safety of its users.
Silo Poly Tanks
Silo poly tanks are unlike vertical or horizontal poly tanks due to one end of the tank having a conical shape for the dispensing of the contents. There are specifications for silo poly tanks that may not apply to other forms of poly tanks due to the nature of their use, which includes the storage of animal feed, grain, and other agricultural products. The weight of the product stored in a silo poly tank requires a strong and sturdy framework to hold and support the tank.
Clearance below the tank is precision measured to ensure safe and easy access to the contents. Silo poly tanks are designed with a huge capacity of 10,000 L (22,000 lbs.) with fittings of the appropriate size to fit the properties of the contents. The form, shape, and design of silo poly tanks gives them a very small footprint since most of the mass is located in the frame above the ground. At the top of a poly silo tank is a large hatch like opening that makes it possible to fill and load the tank.
Chemical Poly Tank
Chemical storage is a critical part of several industries and requires close attention to safety for workers and the environment. One of the uses of chemical poly tanks is to contain and control hazardous waste. Poly chemical tanks have been gaining a great deal of popularity in recent years due to their durability, resistance to corrosion, and low cost. The volume of chemical waste determines the size of a chemical poly tank, all of which are made of highly resilient materials capable of withstanding the effects of chemicals and weather conditions.
A central factor in the use of poly chemical tanks is compliance with the many regulations that govern their use for chemical storage. The Environmental Protection Agency (EPA) regularly upgrades its standards to meet the growing need for safe storage of dangerous and hazardous chemicals. Chemical poly tank manufacturers closely adhere to EPA requirements and provide certification as to the compliance of their products.
Although the purchase of a chemical poly tank is a very intelligent and logical decision, the maintenance of the integrity of a chemical poly tank is a constant challenge since it requires close attention to the tank being discharged, cleaned, and regularly maintained. The most critical of the maintenance operations is discharge, which necessitates a special set of procedures for environmental safety. As with many poly tanks, chemical poly tanks have a flange outlet that is included in the molding process of the tank, which is a necessity for chemical poly tanks.
The majority of chemical poly tanks are vertical tanks due to vertical tanks having a higher capacity. Their one-piece construction, which is common for molded poly tanks, enhances their seal, content protection, and ability to prevent leaks, damage from impact, or environmental factors. A special feature of chemical poly tanks is their double wall design that increases their strength and durability.
Poly Septic Tanks
Poly septic tanks are underground tanks that are designed to be unaffected by chemicals in the soil and chemicals and gases in sewage. As with all poly tanks, poly septic tanks are tightly sealed due to their single unit construction. Poly septic tank manufacturers provide the tanks already plumbed and ready to be installed, which lowers the initial cost of a poly septic tank.
A major advantage of a poly septic tank over concrete septic tanks is their lightweight, which makes them easy to install since installation requires one piece of heavy-duty equipment, a factor that lowers the overall cost. Additionally, poly septic tanks are more versatile and adaptable than concrete septic tanks since they can be installed in a wide variety of locations that are not ideal for concrete septic tanks.
As may be assumed, poly septic tanks are far less expensive than concrete septic tanks but last just as long. This factor further lowers their price since the initial cost can be amortized over several years. When a poly septic tank is delivered, it is plumbed and ready to install. As with other underground tanks, poly septic tanks are placed underground in a solid bed of materials that prevent the accumulation of moisture around the tank. If the residence where the tank is located needs to expand or make additions, a poly septic tank, as with other horizontal tanks, can be easily repositioned without the need of major adjustments or construction.
Recreational Vehicle (RV) Poly Tanks
RV poly tanks is a generic term that refers to a widely used set of tanks that can be found on boats, ballast tanks, graywater tanks, and several freshwater tank applications. As with the majority of poly tanks, RV poly tanks have a seamless construction to prevent leaks or the possibility of contamination. RV tanks come in an endless variety of sizes due to the many applications in which they are used.
The standard shapes of RV poly tanks are rectangular in several shapes and sizes with some RV tanks having more than one rectangular shape joined and molded as a single unit. They are connected to pumps to supply freshwater to toilets, tubs, showers, and sinks. The system that includes a RV poly tank is very similar to the plumbing system found in a home with the basic difference being the water supply coming from a tank and not the city.
The specifications for RV poly water tanks have been established by the FDA using the same standards as those that are used for city water supplies. Poly water tanks are designed and manufactured to FDA and EPA requirements since they involve the storage of fluids for human consumption.
Rectangular Poly Tanks
Rectangular poly tanks are a unique set of tanks that take several different forms. Their unique construction makes them adaptable for a wide range of applications and locations. The uses of rectangular poly tanks are similar to cylindrical horizontal and vertical poly tanks. One of the main uses for rectangular poly tanks is water storage, which is due to their custom shapes and configurations.
The rectangular design of rectangular poly tanks that isn’t possible with other shapes of poly tanks are open topped poly tanks that come with or without a lid. They are used for recirculating systems, research, transporting materials, and the production of food and beverages. Unlike cylindrical poly tanks, rectangular poly tanks are stackable for applications that have limited space. The rectangular design gives them stability and the ability to be freestanding. The flat firm base of rectangular poly tanks enables users to place them in any location, while the highly durable poly materials ensures protection for the contents.
Poly Water Tanks
Poly water tanks, also known as polyethylene water tanks, water storage tanks, or plastic water tanks, have been used for many years by farmers, rural communities, and isolated locations as a means of water storage of well water and capturing and storing rainwater. They are molded water storage tanks that are available in a wide range of sizes, diameters, capacities, and heights. Poly water storage tanks can be horizontal or vertical with larger versions having capacities that range over 2000 gallons (11,356.24 L) and as large as 50,000 gal (189,270.59 L).
The practical use of poly water tanks is expressed in their available colors, which are green or black with some manufacturers offering dark brown or mocha colored poly water storage tanks. This limited selection of colors attests to the use of poly water storage tanks as a source of water for remote and difficult to access areas.
A major factor in the design of poly water tanks is their specific gravity rating, which is a measure of a poly tank's ability to hold water and is the gravity of water compared to its weight per unit volume. As the specific gravity of a poly water tank increases, its ability to endure hydrostatic stresses caused by water increases. Since the weight of a gallon of water is 8.334 lbs. (3.78 kg), its specific gravity is 1.0.
For poly water tanks, wall thicknesses and tank design are the determining factors of a poly water tank's specific gravity. Consumers who live in rural areas purchase poly water tanks with thick walls and designs that accommodate where the tank will be installed. The collapse or rupture of a water storage tank in a remote area can be disastrous and catastrophic and cause significant damage.
There are several reasons why poly water tanks are chosen for use by rural communities and farmers aside from their strength and durability. A common factor related to water storage tanks is the negative effects of radical changes in temperature. Poly water tanks are unaffected by such changes in temperature and can withstand temperatures that range from -40°F up to 100°F (-40°C up to 38°C). The addendum to this stipulation is when poly water storage tanks have to endure temperatures over 100°F for an extended period.
A major concern with water stored for long periods in rural areas is the growth of bacteria and algae, which is common with other forms of storage tanks and requires regular inspection and cleaning. Since poly water tanks do not decay or rust or have contact with the ground, there aren't any conditions that would allow the growth of mold or algae. As a preventative measure, an algicide can be used to remove the possibility of algae development.
Poly Water Tank Sizes
The choice of the size of a poly water tank is dependent on several factors. Large capacity poly water storage tanks of 10,000 gal up to 50,000 gal do not have to be filled as often, which can save on labor, time, and water transport costs. The disadvantage of larger tanks is their weight, which can make water transport difficult for trucks and trailers.
Larger Poly Water Tank Advantages
Better pricing because they can store more
Smaller footprint than having multiple tanks
Single pump
Smaller Poly Water Tank Advantages
Cost less
Less spillage
Easy to load on trucks and trailers
A common form of poly water tank is an underground water tank, which is used when a property owner does not have sufficient area above ground for a water tank. As with all forms of poly water tanks, underground poly water tanks are rotation molded for a complete tight seal of the tank. The installation of an underground poly water tank protects the tank from sunlight that can damage the tank and cause microbiological growths.
Underground poly tanks are approved for potable water and normally have pumps and piping systems for access to the contents of the tank. They are placed sufficiently deep to protect them against freezing. Although above ground water tanks can come in sizes that hold hundreds of gallons, underground water tanks can also have versions that hold hundreds of gallons and include ones that hold thousands of gallons buried at depths of four feet to ten feet (1.22 m to 3 m).
The poly tanks that have been described above are a small sampling of the many poly tanks that manufacturers have available and do not include the many custom forms of poly tanks that are specially produced for unique and unusual applications. Poly tank manufacturers work closely with their clients to provide tanks that precisely fit the needs of their clients and include proper fittings, connections, plumbing, and other accessories that meet a client’s requirements.
Chapter 3: How are Poly Tanks Made
A critical feature of poly tanks is their seamless and solid walls, which prevent leakage and are able to endure impacts. The manufacture of normal plastic products involves various types of molds that can be permanent or non-permanent where hot melted resin is poured into a die or mold. The sizes of poly tanks necessitate the use of manufacturing techniques capable of producing large containers with thicker and more durable walls.
Rotational molding and blow molding are the main manufacturing methods used to produce poly tanks since both processes use large molds. The two polymers that are used in the production of poly tanks are polyethylene and polypropylene, which have tough, strong, and durable compounds for the production of poly tanks.
Rotational Molding
Rotational molding, also known as roto molding, is used to produce large poly tanks of several gallons. It is a three-step process that involves rotating the mold as it is heated. The heating of the mold and its rotation are carefully monitored to ensure that the plastic resin is spread evenly over the surface of the mold. The resin for the rotational molding process is placed in the mold in a granular form to be melted during the heating of the mold.
Loading
At a workstation, that may be raised for easy access to the mold, a worker loads the mold with the appropriate amount of resin that has been measured to fit the exact proportions of the poly tank to be molded. The resin has a fine granular consistency, is homogenous, and is dry for proper flow to prevent the formation of bubbles in the walls of the poly tank. The amount and measurement of the resin determines the thickness of the walls of a poly tank and its strength.
In order to easily remove the completed molded poly tank, a release agent is sprayed on the interior of the mold. The cavity of the mold has the shape and form of the poly tank to be produced and is made of cast metal.
Heating
The resin filled mold is tightly sealed in preparation for its being rotated as it moves into the furnace that will heat the mold and resin. As the mold moves away from the workstation, it begins to slowly rotate on multiple axes to ensure the even distribution of the resin. The wall thickness is achieved by the proper rotation of the mold, which is the ratio of the number of rotations per minute (RPM) on the horizontal axis over the RPM on the vertical axis. The ratio is set in coordination with the type of poly tank to be formed since each poly tank requires a different rotational ratio and varies in accordance with the type of shape with spheres and cubes having a different ratio from that of other shapes.
As with the rotational ratio, the heating time for a poly tank varies according to the shape and type of tank being manufactured. As may be assumed, the heating time is critical to the quality of a poly tank and is carefully monitored since over heating or under heating can cause flaws in the final poly tank.
Cooling
The cooling stage of the process is where a poly tank takes form and achieves its desired shape. During the cooling stage, the melted and distributed resin hardens on the walls of the mold and solidifies. Cooling air is slowly applied to avoid cooling the mold too quickly. In some designs, water is sprayed onto the mold to reduce cooling time but has to be carefully monitored since it can affect the properties and dimensions of the poly tank.
As with the heating time, the cooling time is meticulously controlled with cooling being applied at the proper rate for the size and type of poly tank. Too fast or too slow cooling time can damage the structure of a poly tank leading to poor quality.
Demolding
After the poly tank has sufficiently cooled, it returns to the work station where a worker can remove it from the mold. The process of demolding is assisted by an air ejection system that helps lift and release the molded poly tank from the mold. The demolded poly tank is inspected for wall consistency, bubbles, deformations, or any other flaws. Since poly tanks are a single piece mold, they do not have to be divided or separate. Any secondary processing is in regard to trimming openings for flanges, fittings, connections, lids, or other special forms for the tank.
Blow Molding
Blow molding is the other process that is capable of producing several sizes of poly tanks and can produce tanks far larger than those produced by rotational molding. As with rotational molding, blow molding involves the use of a mold, which can be as small as a garbage can and as large as a several gallon underground poly tank. The blow molding process is widely used for the production of clear plastic bottles and containers that are mass produced by the process.
The production of large poly tanks takes more time but is capable of producing poly tanks with exceptional tolerances. As with rotational molding, there are three steps to the blow molding process but includes an additional step for melting and heating the resin before it is injected into the mold.
Heating and Feeding Resin
With the blow molding process, the resin is heated and melted prior to being injected or blown into the mold. This particular aspect of the process is similar to other molding processes and involves the use of a mechanism referred to as an extruder, which has a hopper, screw, heaters, barrel, and nozzle. The resin is slowly fed into the barrel from the hopper. As the screw turns, the resin is moved along the barrel toward the nozzle and is heated to soften and melt it.
Parison
The extrusion process produces a large flexible inflated preform that is referred to as the parison, which is the part of the blow molding process that will be formed into a poly tank. The parison is formed at the end of the extruder by the nozzle into a closed end tube and resembles a large cylindrical balloon. As the parison is forming, the wall thicknesses of the poly tank programmed into the parison are formed such that when the parison expands in the mold, the poly tank will have consistent and smooth walls.
The extrusion head is used to control the thickness of the poly tank using its conical shape. The inner surface of the final poly tank can be adjusted using the outer ring of the extrusion head, which has a conical shape. By changing the position of the mandrel and the outer ring, the thickness of the parison ring can be changed to a desired thickness.
Die Clamping
Once the parison is properly formed and prepared, it is placed into the die, which has two halves that are clamped and sealed together. For the proper formation of a poly tank, the die is tightly sealed to prevent the formation of voids and the even distribution of the parison across the walls of the die. It is essential that the parison be spread evenly to ensure the proper thickness of the walls of the poly tank.
The sizes of blow molding dies seem to be limitless and capable of producing poly tanks of a few gallons up to tanks of several thousand gallons. The smaller dies for blow molding are easily manageable while the larger dies tend to be like forging presses.
Pressurized Air
Pressurized air is blown into the parison, which causes it to rapidly expand against the walls of the mold. The application of the air into the mold has to be uniform such that the walls of the poly tank have an even thickness. As with the heating process in roto molding, the application of air in blow molding is closely controlled to avoid stretching the parison.
For poly tanks that are square or rectangular, the application of air can include several orifices to ensure even air flow since the angles and corners of such molds can be difficult to reach. The use of multiple air supplies forces the parison into the corners and angles of the poly tank.
Cooling
The final phase of the blow molding process is the cooling and solidification of the formed poly tank. Since the only part of the process that was heated was the parison, the cooling process for blow molding takes less time than that which is required for roto molding but is the longest part of the process. The cooling of a blow molded poly tank begins during the application of the air stream and continues during that process.
The heat of the parison is transferred from the parison to the interior surface of the mold. A concern during the cooling stage is heat that is trapped inside a poly tank. To overcome this difficulty, internal cooling is applied, which is a safe and productive method for efficient cooling.
Ejection
Like the molds for roto molding, the mold for blow molding has two halves that open when the poly tank has sufficiently cooled. During and after ejection, a poly tank is carefully examined for deformities or leaks. This is especially true for very large poly tanks of several hundred or thousand gallons.
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Chapter 4: Plastics Used to Make Poly Tanks
The polymers that are used to produce poly tanks are resins that are produced from petroleum. Although we may use the terms polymer, poly, or plastic, the scope of those terms covers a wide range of plastics of varying grades, types, strengths, composition, and chemical makeup. Each and every plastic has a set of characteristics and properties that makes it ideal for the production of different plastic products.
The manufacture of poly tanks requires the use of a specific set of popular polymers that are used worldwide for an endless number of applications. These two dynamic polymers are polyethylene and polypropylene, which are used for the manufacture of clothes hangers, soft drink bottles, and housings for heavy duty equipment.
Polyethylene
Polyethylene, known as PE, polythene, or polyethene, is made from the polymerization of ethylene, which is an organic hydrocarbon with the chemical formula of C2H4. Included in the polymerization of ethylene is titanium chloride and nonpolar saturated hydrocarbons that have high molecular weight, which gives polyethylene properties that are similar to those of paraffin. Since the molecules of polyethylene are not linked, polyethylene is considered a crystalline plastic, a factor that gives it greater density and chemical stability.
As with all forms of plastic, there are several types of polyethylene, which include low density (LDPE), linear low density (LLDPE), linear medium density (LMDPE) high density (HDPE), ultra high molecular weight (UHMWPE), and cross linked (PEX). Although all of the forms of polyethylene are used to produce plastic products, the specific plastics used to produce poly tanks are PEX, LMDPE, and HDPE, which have exceptional mechanical properties, strength, and resistance to environmental factors.
Polypropylene
Of the different materials used to produce poly tanks, polypropylene, known as propene, PP, and propylene, is the most versatile of the different plastics since it can be used as fabric, packaging, and poly tanks. It is made from the polymerization of the propene monomer using the Ziegler Natta method or the metallocene catalysis method. Polypropylene has a crystalline structure with flexibility, toughness, chemical tolerance, and resistance to temperature changes. It belongs to the olefin group of double bonded hydrocarbons. During polymerization, the propene molecular bonds are broken and reconnected to produce the polymer chain for polypropylene.
Polypropylene is known for its chemical resistance, tolerance to temperature changes, and purity. The strength and durability of polypropylene makes it ideal for the manufacture of containers, such as poly tanks.
Polyvinyl Chloride
The variations of polyvinyl chloride, PVC, include flexible and rigid varieties, which vary in accordance with their types of additives. PVC has exceptional mechanical properties that makes it ideal for hostile and harsh environments that demand a strong material. The strength of PVC makes it comparable to various metals and the reason that it is widely used for plumbing products. The primary ingredient of PVC is chlorine in the form of a salt with carbon and hydrogen added. It is produced from the vinyl chloride monomer, which is from the chlorination of ethylene and pyrolysis. The vinyl chloride monomer is polymerized to form PVC.
PVC has thermoplastic capabilities and softens when it is heated, which makes it capable of being formed into poly tanks. The rigid form of PVC is used for the manufacture of poly tanks. It is a very dense plastic that is resistant to impact and chemical solutions.
Chapter 5: Benefits of Poly Tanks
Poly tanks have been used for years as a means for storing water and transporting chemicals, such as pesticides and fertilizers. They have become very popular in agriculture due to their longevity, durability, mobility, and strength. The light weight of poly tanks makes it possible to arrange them and place them in several locations without concerns that they will crack or leak.
Cost
One of the main reasons that poly tanks are used over metal tanks is their cost, which is far less than any type of metal. Poly tanks cost less due to the low cost of the raw materials used to manufacture them, manufacturing time, and the processes used to produce them.
Weight
Lightweight poly tanks can be easily positioned and do not require any form of special support. Underground poly tanks are easier to install than concrete tanks. Their solid walls and sides prevent leaks, and the poly material is not susceptible to the effects of chemicals in the soil.
Positioning
An additional factor that is related to the lightweight of poly tanks is how easily they can be positioned or repositioned without the need of heavy equipment or special tools. In many cases, tanks have to be moved when a company expands or is adding new construction. Poly tanks can be emptied and lifted easily and repeatedly to meet changing needs.
Variety
Of the many products on the market for industrial use, poly tanks are available in an endless number of sizes, colors, shapes, configurations, and forms that are able to meet any type of space or application. In addition, manufacturers work with their customers to produce specialized poly tanks for unique and unusual circumstances.
Architectural
With the many forms and colors of poly tanks, it is easy to fit them into the architectural requirements of a structure. This particular feature cannot be said of any other form of storage tank. In many cases, architects plan their designs with poly tanks in mind.
Strength
Poly tanks have exceptional strength and are capable of withstanding the most demanding conditions. They are used in harsh environments for the storage of water and chemicals. Unlike certain types of metal, poly tanks do not rust and are unaffected by climatic conditions. They are known to be able to endure many years of use without the need of maintenance or any form of special type of cleaning.
Sanitary
Poly tanks have been approved by the FDA and EPA for the transport and storage of potable water. The plastics used to construct poly tanks are hygienic and extremely sanitary, which is the reason that poly tanks are so widely used in the food and pharmaceutical industries.
Chapter 6: Regulations for Poly Tanks
Due to the varieties of liquids and fluids that poly tanks store, it has been necessary for the FDA, EPA, National Sanitation Foundation (NSF), and American National Standards Institute (ANSI) to develop regulations and standards regarding the manufacture of poly tanks. Many of the requirements are in regard to the storage of potable water and food products. The focus of the requirements is in regard to any types of fluids or liquids that come in contact with humans.
Water Tank Regulations
Since poly tanks are so widely used for the storage and transport of potable water, there are several stipulations that have been outlined by the various regulatory agencies. The polyethylene material used to manufacture water tanks must be inert and unaffected by water, not leach chemicals into the water, and not react with the water. All poly tank manufacturers have certifications from Environmental Protection Agency (EPA), the Food and Drug Administration (FDA), the Code of Federal Regulations (CFR), the National Sanitation Foundation (NSF), and the American National Standards Institute (ANSI), which are displayed on their products.
Poly tanks must be manufactured such that they are capable of withstanding the pressure from the weight of the water. Included in this aspect of the requirements is the thickness of the walls of the tanks and their consistency, which is tested and measured during the manufacturing process. Although each manufacturer uses different types of resin, they each use resins that are chemically compliant with administrative and organizational regulations.
FDA/CFR Title 21
In title 21, the FDA and CFR specify the requirements for poly tanks used for food and beverage storage and preparation. Outlined in title 21 are the types of acceptable resins, additives, and the composition and design of the poly tanks. Poly tanks are favored over other types of tanks due to their single piece seamless construction, which makes them safer and more reliable.
CFR 1250.82 Title 21
CFT 1250.82 title 21 provides a detailed description of the specifications regarding poly tanks used for potable water. Included in the regulations are drainage requirements, overflow, venting, and methods for measuring the depth of the water. One of the concerns of the regulations is any backflow that could contaminate the stored potable water.
In addition, there are different regulations regarding the use of poly tanks in every sector of society with emphasis on poly tanks used for industrial purposes. In all cases, the main concern is safety since water can potentially become contaminated, and chemicals need to be tightly sealed and kept from leaking. In order to provide a complete set of restrictions, each organization has specifications for above ground use of poly tanks and below ground use with below ground requirements being stricter and more demanding.
Conclusion
A poly tank is a plastic storage tank used to store, transport, and collect water, other liquids, and granular or powder materials. They are made of polyethylene and are a cost effective, lightweight, and easy to handle storage unit that is versatile and capable of storing high volumes of materials.
In the majority of cases, under normal use, poly tanks can last up to 20 years and have UV ray stabilizers to help the tank endure the effects of the sun. Poly tanks require less maintenance and can be set up with a tank self-cleaning system that removes debris that may settle in the bottom of the tank.
There is an endless list of the types and kinds of poly tanks, which are separated into various groups in accordance with their grade, use, the type of polyethylene, and where they are located with some poly tanks being located below ground.
One of the outstanding features of poly tanks is their versatility, which has made them applicable to a wide variety of conditions and environments.
Polyethylene and polypropylene are the polymers that are used to produce poly tanks and how they get their name.
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