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What is FRP tank?
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What is FRP tank?

Views: 105     Author: Site Editor     Publish Time: 2021-06-16      Origin: Site

What is FRP tank?

As the name implies, it means a tank made of FRP or Fiber Reinforced Plasticsis a composite material made of glass fiber and its products (glass cloth, tape, felt, yarn, etc.) as reinforcing material and synthetic resin as the matrix material.

In short, it is in the process of making FRP tank, the glass fiber is dipped in resin slurry and finally wound on the inner liner, therefore, some people will also call it FRP resin tank.

Classification of FRP tanks:

FRP tanks is the largest range of definitions, with categories such as FRP Water Pressure Tank and FRP storage tanks. Resin tanks and filter tanks fall under the category of water treatment tanks.

Resin tanks:

Many people refer to fiberglass resin tanks collectively as resin tanks, in fact, this statement is not accurate, most of the time what we call resin tanks is softening tanks, used to fill the tanks of softening resin, so often called resin tanks, also known as water softening tanks.

frp tank with manual head

The resin tank is part of the water softener and is used for water softening. The tank is equipped with a salt tank next to the tank to help regenerate the resin inside the tank. Water softeners mainly apply ion exchange technology to remove scale by exchanging functional ions on the resin with calcium and magnesium ions in the water, thus adsorbing these hardness ions in the water.

Filter Tank:

Filter tanks are a class of FRP tanks used in the filtration process of water treatment. Depending on the filter media filled inside, there are various types of filter tanks, such as quartz sand filter tank, activated carbon filter tank and multi-media filter tank.

fiberglass water tank

The filter tank is the main component of the filter, using the tank filled with different filter media to remove impurities, colloids, organic matter and active chlorine and other substances in the water, commonly used in the softening process before, to ensure that the water quality to meet the softening requirements, to protect the subsequent equipment.

In short, resin tanks and filter tanks are both FRP tanks, because the use is different, so the name is also different.

What is the principle of resin tank filtration?

Resin tank is an important accessory in activated carbon filter, made of FRP and filled with activated carbon inside. It can be used to filter free matter, microorganisms, and some heavy metal ions in water, and can effectively reduce the color of water.  

Its working principle is: a layer of balanced surface concentration is formed on the surface of the activated carbon particles, and then the organic material impurities are adsorbed into the activated carbon particles, and the adsorption effect is high at the initial stage of use. However, over time, the adsorption capacity of activated carbon will weaken to varying degrees and the adsorption effect will decline. If the water is turbid and the organic content is high, the activated carbon will soon lose its filtering function. Therefore, activated carbon should be cleaned or replaced regularly. 

What is the principle of resin tank filtration?

The size of the activated carbon particles also has an effect on the adsorption capacity. Generally speaking, the smaller the activated carbon particles are, the larger the filtration area is. Granular activated carbon is not easy to flow because of particle formation, and impurities such as organic matter in water are not easy to be blocked in the activated carbon filter layer, which has strong adsorption capacity and is easy to carry and replace.

The adsorption capacity of activated carbon is proportional to the contact time with water, the longer the contact time, the better the filtered water quality.

Note: The filtered water should flow out of the filter layer slowly. New activated carbon should be washed and cleaned before the first use, otherwise there will be ink-black water flowing out.

Activated carbon filter is one of the important equipment in the raw water pretreatment system to protect the water quality of the supply water, and can also be used for the filtration after secondary treatment.

Learn more about activated carbon cartridges!

What are the pressure levels of FRP resin tanks?

FRP resin tank can be used as a container for water treatment, filled with filter media or resin, with a certain pressure-bearing capacity.

The pressure levels of FRP resin tanks commonly available in the market are 100psi (7kg), 125psi (8.5kg), 150psi (10kg), the higher the pressure level, the stronger the pressure-bearing capacity.

Amanda FRP water treatment tanks are available in 125psi and 150psi pressure levels, and the tanks pass strict pressure tests :

Burst test.

Fill the tank with water, ramp up to 2550KPa within 5min, hold pressure for 15min after pressure stabilization, after ensuring no abnormalities in the tank, ramp up directly to do burst test, ramp up to 4200KPa within 70s, hold pressure for 15s after pressure stabilization.

FRP tank (9)

Fatigue test.

Fill the tank with water, set the system pressure to 1040KPa, ramp up to 1050KPa and then instantly ramp down, ramp down to a pressure <14KPa and then start ramping up again to enter the next test cycle, with a cycle period of no more than 7s and a number of 100,000 times.

In general, we will directly use the standard 8.5 kg or 10 kg to describe the tank pressure, rather than simply use the wall thickness of the tank to describe. The higher the tank pressure, the more raw materials used and the thicker the wall thickness.

How is the FRP tank wall layered?

The reasonable layering structure of FRP tanks is the basis for ensuring the strength and corrosion resistance of FRP tanks. FRP tank wall is composed of three layers: inner layer, structural layer, outer layer combination. The following is a detailed introduction to these three layers.

Inner layer: composed of resin-rich layer and intermediate layer. FRP hydrochloric acid tank rich resin layer by the lining resin plus organic fiber polyester felt reinforcement, resin content of more than 90%, its thickness is about 015mm, the layer is good airtight, very lubricious, mainly to provide corrosion resistance and anti-soaking ability of the product. The middle layer is composed of resin lining and alkali-free glass fiber radiating yarn, with resin content of 70%~80% and thickness of about 2mm. The main role of this layer is to maintain the resin-rich layer, improve the inner layer's ability to resist internal pressure failure and stop the spread of cracks.

Outer layer: also known as outer resin-rich layer, resin content is more than 90%, Baidu is about 115MM, using glass fiber exterior felt reinforcement, in other cases can also be reinforced with 011-012MM thin glass tape, and in the resin to participate in the ultraviolet absorber to avoid aging. As the layer is the outer layer is mainly in contact with the outside world, its main is to maintain the outer wall from some other damage and UV protection has a role.

Structural layer: also known as the reinforcement layer, which uses non-twisted glass fiber roving composition. Glass fabric reinforcement, accepting tensile stress, compressive stress and various external loads, maintaining the inner layer. FRP transport tank resin content of 30%-40%, its thickness is calculated according to the load conditions. A reasonable amount of filler is added to each resin to help strengthen the performance of the FRP tank (abrasion resistance).

What are the processing methods of FRP tanks?

In recent years, the use of FRP tanks has become more and more widespread, and has gradually replaced the market of stainless steel, carbon steel. Many people will be curious about how FRP tanks are made, the following is a summary of some of the production methods, I hope it will help you.

Glass fiber reinforced plastic tank from the production method is divided into wet contact molding and dry pressurized molding. From the process characteristics are divided into hand paste molding, lamination molding, RTM method, extrusion method, molding and winding molding.

At present, the most used molding methods in the world are the following four.

1. Hand paste method: The main countries used are Norway, Japan, UK, Denmark, etc.

2. Jet method: The main countries used are Sweden, the United States, Norway, etc.

3. Moulding method: Mainly used in Germany, etc.

4. FTM method: The main countries are Europe, America and Japan.

More than 90% of FRP products in China are produced by mechanical winding, and there are still many enterprises using hand gluing method in the world. The characteristics of hand gluing method are that it uses wet resin, simple equipment, less cost, and can gluing many whole products at one time. The disadvantages are low mechanization, long production cycle and unstable quality.

I believe that with the continuous progress of technology, development, FRP tank production methods will become more and more convenient and fast.

What are the process characteristics of FRP composites.

  • (1) light quality, high strength: the weight of the composite tank body is only 1.3 of the weight of the steel tank body; using FRP composite material process to repair the tank body can not only be connected to the metal tank body, with good stability, and the repair of the tank body strength is high, its strength can be multiplied on the basis of the strength of the original steel tank body.

  • (2) High temperature resistance, corrosion resistance, aging resistance, maintenance-free, long service life.

  • (3) construction cycle is short, safe and convenient: construction without stopping production, do not need to use mechanical equipment and fire operations, with safety, convenience and speed; the use of non-metallic materials on site to make the roof, not only to ensure its strength and rigidity, but also with the metal tank body can be firmly combined, with strong corrosion resistance.

  • (4) Good heat preservation performance, less heat loss, can meet the temperature requirements of oil-water separation.

  • (5) Less investment, significant economic benefits.

Factors affecting the service life of FRP tanks

The normal life of FRP tank should be between 9 and 16 years. FRP tank is a combination of tree fingers and glass fiber winding from a non-metallic composite tank FRP tank's service life has a lot to do with his installation base, standardized operation. Legitimate manufacturers have their set of technical guidance program from design to installation and use, all aspects of the details have strict implementation standards to ensure the long service life of FRP tanks.

As the FRP tank is wound as a whole, the strength of the positive pressure is relatively strong, relatively speaking, the ability to engage in negative pressure is somewhat weak. Especially those over 2000mm FRP tanks. Many steel tank quality accidents, mostly due to the steel tank in the process of pumping material, due to the exhaust hole or exhaust hole blockage, resulting in negative pressure inside the FRP tank, resulting in internal suction damage. Therefore, it is very important to keep the vent hole open or the internal pressure inside the steel tank to maintain the life of the FRP tank.

FRP tank in use for a period of time, it is not beneficial to move frequently Hu, which will cause axial stress damage to the structural layer of the glass fiber reinforced plastic tank. Make the strength of the tank decreases, affecting the service life of the FRP tank.