PP square ducts have a modular design, a design concept that greatly simplifies the installation process. Each module is like an independent component, and at the construction site, the installer can quickly put the modules together like building blocks. This approach not only reduces the time and workload of on-site processing, but also reduces the probability of errors in the installation process.

PP square ducts offer a variety of choices in terms of connection methods. Heat fusion connection is one of the commonly used methods, through the special heat fusion machine to heat the air duct port, so that it melts and quickly butt and apply pressure, after cooling, the joint can be tightly combined to form a solid whole. The advantage of this connection method is that the strength of the connection is high, almost equal to the strength of the pipe body, and can effectively prevent leakage. In some places that require very high sealing, such as laboratories, pharmaceutical workshops, etc., PP square ducts with heat fusion connection can meet the needs very well.

Flange connection is also one of the common connection methods. First, the flange is welded to the duct port to ensure that the flange is horizontal and there is no gap, and then a bolt is placed in the middle of the flange to tighten the two flanges and align the ports, and finally a sealing gasket is used to seal the gap to ensure that there is no air leakage in the connection. This type of connection is relatively simple to operate, easy to disassemble and repair, and is suitable for some ventilation systems that require frequent maintenance and adjustment.

In the installation process, the sealing treatment is crucial. Regardless of the type of connection, it is important to ensure that the sealing material is used correctly. Commonly used sealing materials include rubber gaskets and sealants. When selecting the sealing material, it should be determined according to the environment in which the duct is used and the medium to be conveyed. When conveying corrosive gases, chemical-resistant sealing materials should be selected to ensure the durability of the sealing effect.

In addition, the installer needs to pay attention to the installation position and direction of the duct to ensure that it meets the design requirements. Plastic shims with a thickness of 3-5mm should be inserted between the duct and the bracket to minimize friction and vibration. The distance between the brackets is generally 1.5 – 3m, for the side length or diameter greater than 1250mm duct, lifting shall not exceed 2 sections; side length or diameter less than 1250mm duct, combined lifting shall not exceed 3 sections. When handling the duct, it should be carried gently and put down gently to avoid falling and touching to prevent cracks. When lifting vertically, control ropes should be tied to prevent the air duct from swinging and collision and rupture.

(ii) Maintenance

The routine maintenance of PP square duct is relatively simple, mainly including cleaning and inspection. Because of its smooth surface, dust and dirt are not easy to adhere to, so cleaning is very convenient. Regularly wipe the surface of the duct with a damp cloth to keep it clean. For the inside of the duct, you can use professional cleaning tools, such as duct cleaning brushes, vacuum cleaners, etc., to remove accumulated dust and debris to ensure smooth ventilation. In some dusty industrial places, quarterly internal cleaning can meet the requirements.

The inspection work is mainly to see whether the connection parts of the air duct are loose, whether there is any leakage phenomenon, and whether there is any damage to the air duct body. Regular inspections can detect potential problems in time and avoid malfunctions. It is generally recommended to conduct a comprehensive inspection every six months. When checking the connection parts, pay attention to see whether the bolts are tight, and whether the sealing gasket is aging or damaged. If problems are found, they should be repaired or replaced in time. For damage to the duct body, small cracks can be repaired with special repair materials, while larger damage requires replacement of the damaged section.

The stability of PP material makes PP square ducts have low maintenance cost. Compared to metal ducts, it does not require corrosion protection and there is no need to worry about rust. Under normal use, PP square ducts are only 30% – 50% less expensive to maintain than metal ducts. And, because of its long service life and low replacement frequency, long-term maintenance costs are further reduced. In commercial buildings, the use of PP square duct ventilation systems can save tens of thousands of dollars in annual maintenance costs.

The maintenance cycle varies according to different use environments and places. In commercial and public places, such as shopping malls, office buildings, etc., it is recommended to carry out a comprehensive maintenance once a year; in industrial places, due to the harsher environment, the maintenance can be carried out once every half a year; the ventilation system of the residential houses is used less frequently and the environment is relatively good, so it is enough to carry out a maintenance once every 2 – 3 years. Of course, if the ventilation system appears obvious odor, air volume decreases or energy consumption increases and other abnormalities, it should be promptly inspected and maintained.

PP flame retardant pipe and PVC pipe are both common pipe materials, and they each have unique advantages and application scenarios. PP flame retardant pipe is widely used in specific occasions due to its flame retardant performance and good durability, while PVC pipe is used in many fields due to its excellent corrosion resistance and low cost. When these two materials are connected, although they are connected in different ways (PP flame retardant pipes are usually connected by hot melt, while PVC pipes are connected by adhesive), they can be used together in practical use, especially in occasions where flame retardant properties are required, such as the protection of electrical circuits.

• Connection of PP flame retardant pipe: Since the PP flame retardant pipe adopts the hot melt connection method, this connection method ensures the firmness and tightness of the pipe connection, so as to ensure the safety and durability of the pipeline system. The hot melt connection melts the pipe end by heating it, and then quickly connects the two sections of pipe, which when cooled to form a strong connection.
• Connection of PVC pipes :PVC pipes are usually connected by adhesive, which is suitable for the connection of PVC pipes and fittings, which can provide a certain degree of tightness and durability. Adhesive connections require the use of specialized glue to apply glue to the ends of pipes and fittings, and then butt them to cure them under a certain pressure and time, thus forming a strong connection. Although PP flame retardant pipes and PVC pipes are connected differently, they can be used together in practical engineering applications, especially in occasions where flame retardant properties are required, such as the protection of electrical wiring. In addition, if you need to make a connection between PP flame retardant pipe and PVC pipe, you can consider using a special PP adhesive PVC plastic glue, which can effectively solve the bonding problem between these two materials, provide strong adhesion and firmness, and can maintain its performance and quality for a long time in different temperature environments

PP flame retardant air duct and PPH air duct

With its excellent corrosion resistance and mechanical properties, PPH pipes are widely used in chemical industry, environmental protection and other fields. Both materials can be joined by hot melt welding, including hot plate welding, hot air welding, and hot melt butt welding, which allows them to be flexibly combined in practical applications.

• The properties of PP flame retardant pipe make it ideal for fireproof occasions. It has good flame retardant properties, which can effectively stop the spread of flames and protect the safety of people and property.

• PPH pipes are known for their excellent corrosion resistance, wear resistance and high temperature resistance, and are suitable for chemical, electronics, pharmaceutical factories and other fields. The β modification of PPH tubing gives it a uniform and delicate Beta crystal structure, which improves its chemical resistance and mechanical strength.

Since both can be joined by the method of hot melt welding, this means that in engineering projects, PP flame retardant pipes and PPH pipes can be combined according to specific needs, and they can be joined together by welding technology to form a complete system. This combination not only increases the safety and reliability of the system, but also expands the range of applications for materials that meet the special needs of different engineering fields. In summary, PP flame retardant pipes and PPH pipes can be used together to achieve a seamless connection through hot melt welding technology, providing more options and possibilities for various engineering applications

• Profiles and processed profiles are the largest areas of PVC consumption in China, accounting for about 25% of the total consumption of PVC, mainly used to make doors and windows and energy-saving materials, and their application is still growing significantly in the country. In developed countries, the market share of plastic doors and windows is also the highest, such as 50% in Germany, 56% in France, and 45% in United States.

PVC pipes

• Among the many PVC products, PVC pipes are its second largest consumption area, accounting for about 20% of its consumption. In China, PVC pipes were developed earlier than PE pipes and PP pipes, with many varieties, excellent performance and wide range of use, and occupy an important position in the market.

PVC film

• The consumption of PVC in the field of PVC film ranks third, accounting for about 10%. After PVC is mixed with additives and plasticized, a three- or four-roll calender is used to form a transparent or colored film of a specified thickness, and the film is processed in this way to become a calendered film. It can also be cut and heat-sealed to process packaging bags, raincoats, tablecloths, curtains, inflatable toys, etc. Wide, transparent films can be used in greenhouses, plastic greenhouses and mulch films. Biaxially oriented film can be used for shrink wrapping due to heat shrinkage.

PVC hard materials and sheets

• Stabilizers, lubricants and fillers are added to PVC, and after mixing, the extruder can be used to extrude rigid pipes, special-shaped pipes and corrugated pipes of various calibers for use as sewer pipes, drinking water pipes, wire sleeves or stair handrails. The calendered sheets are superimposed and hot-pressed to make rigid sheets of various thicknesses. The sheets can be cut into the desired shape and then welded with hot air using PVC electrodes into a variety of chemically resistant tanks, air ducts and containers.

PVC soft products

• The extruder can be extruded into hoses, cables, wires, etc.; Using injection molding machines with various molds, it can be made into plastic sandals, shoe soles, slippers, toys, auto parts, etc.

PVC packaging material

• Polyvinyl chloride products are mainly used for packaging, mainly in various containers, films and rigid sheets. PVC containers are mainly used in the production of mineral water, beverages, cosmetic bottles, and also for packaging of refined oils. PVC film can be used to co-extrude with other polymers for low-cost laminates, as well as transparent products with good barrier properties. PVC film can also be used in stretch or heat shrink wrap for mattresses, fabrics, toys, and industrial goods.

PVC wainscoting and flooring

• PVC wainscoting is mainly used to replace aluminum wainscoting. In addition to a part of PVC resin, the rest of the components in PVC floor tiles are recycled materials, adhesives, fillers and other components, which are mainly used in the hard ground of airport terminals and other places.

Polyvinyl chloride consumer goods

• Luggage bags are a traditional product made from PVC, which is used to make a variety of imitation leather, used in luggage, sports products such as basketball, football and rugby. It can also be used to make belts for uniforms and special protective equipment. PVC fabrics for clothing are generally adsorbent fabrics (no coating required), such as ponchos, baby pants, faux leather jackets and various rain boots. Polyvinyl chloride is used in many sports and entertainment products, such as toys, records and sports goods, and PVC toys and sporting goods have grown significantly and have advantages due to their low production costs and ease of molding.

PVC coated products

• Artificial leather with a substrate is made by applying PVC paste to cloth or paper and then plasticizing it at temperatures above 100 °C. It can also be made by calendering PVC and additives into a film and then pressing it with a substrate. Artificial leather without substrate is directly rolled into a soft sheet of a certain thickness by a calender, and then pressed with a pattern. Artificial leather can be used to make suitcases, bags, book covers, sofas and car cushions, etc., as well as floor leather, which is used as a flooring material for buildings.

PVC foam products

• When soft PVC is mixed, an appropriate amount of foaming agent is added to make sheets, which are foamed into foam plastics, which can be used as foam slippers, sandals, insoles, and shockproof cushioning packaging materials. It can also be used as a basis for extruder into low-foaming hard PVC sheets and profiles, which can replace wood and is a new type of building material.

PVC transparent sheet

• PVC is mixed with impact modifier and organotin stabilizer to become a transparent sheet after mixing, plasticizing and calendering. It can be made into thin-walled transparent containers or used for vacuum blister packaging by thermoforming, which is an excellent packaging material and decorative material.

The biggest feature of polyvinyl chloride is that it is flame retardant, so it is widely used in fire protection applications. But PVC releases hydrogen chloride and other toxic gases, such as dioxins, during combustion.

The density of pure PVC is 1.4 g/cm3, and the density of PVC plastic parts with plasticizers and fillers is generally 1.15-2.00 g/cm3.

Rigid polyvinyl chloride has good tensile, bending, compressive and impact resistance, and can be used as a structural material alone. The softness, elongation at break, and cold resistance of flexible PVC will increase, but the brittleness, hardness, and tensile strength will decrease.

Polyvinyl chloride has good electrical insulation properties and can be used as low-frequency insulation materials, and its chemical stability is also good. Due to the poor thermal stability of polyvinyl chloride, long-term heating will lead to decomposition, release HCL gas, and discolor polyvinyl chloride, so its application range is narrow, and the use temperature is generally between -15~55 °C.

PVC used to be the world’s most produced general-purpose plastic and has a wide range of applications. PVC is available in both hard (sometimes abbreviated as RPVC) and soft. Rigid polyvinyl chloride is used in building pipes, doors and windows. It is also used in the manufacture of plastic bottles, packaging, bank cards, or loyalty cards. Adding plasticizers makes PVC softer and more elastic. It can be used in pipes, cable insulation, flooring, signage, gramophone records, inflatable products, and rubber substitutes.

PVC is a white powder with amorphous structure, the degree of branching is small, the glass transition temperature is 77~90 °C, and the decomposition begins at about 170 °C, the stability of light and heat is poor, above 100 °C or after long-term sun exposure, it will decompose and produce hydrogen chloride, and further automatic catalytic decomposition, causing discoloration, physical and mechanical properties also decline rapidly, stabilizers must be added in practical applications to improve the stability of heat and light.

The molecular weight of industrially produced PVC is generally in the range of 50,000~110,000, with large polydispersity, the molecular weight increases with the decrease of polymerization temperature, there is no fixed melting point, it begins to soften at 80~85 °C, becomes viscoelastic at 130 °C, and begins to transform into viscous flow state at 160~180 °C. It has good mechanical properties, tensile strength of about 60 MPa, impact strength of 5~10kJ/m2; It has excellent dielectric properties. PVC is insoluble in common solvents, but swells in monomers and some chlorinated hydrocarbon solvents.

PVC composition

• Polyvinyl chloride is a polymer material that uses one chlorine atom to replace one hydrogen atom in polyethylene, and is an amorphous polymer with a small amount of crystalline structure. The structure of this material is as follows: -(CH2-CHCl)n-. PVC is a linear polymer in which VCM monomers are mostly linked by a head-tail structure. The carbon atoms are arranged in a zigzag pattern, and all the atoms are connected by σ bonds. All carbon atoms are sp3 hybridized.

• There is a short inter-regular structure on the PVC molecular chain. With the decrease of the polymerization reaction temperature, the regularity of the interstructured structure increases. In the macromolecular structure of polyvinyl chloride, there are shortcomings such as head structure, branched chain, double bond, allyl chloride, tertiary chloride, etc., which make the heat deformation resistance and aging resistance poor. After cross-linking, such shortcomings can be eliminated.

Crosslinking is divided into radiation crosslinking and chemical crosslinking.

• Radiation cross-linking: the use of high-energy rays, generally the rays generated by the cobalt-60 radiation source or the electron rays generated by the acceleration of electrons, mainly using the latter. A cross-linking additive (a monomer with two or more carbon-carbon double bond structures) is then added for cross-linking. However, it is difficult to operate and has high requirements for equipment.
• Chemical cross-linking: Triazole dimercaptoamine salt (FSH) is used for cross-linking, and the cross-linking mechanism is that the amine and sulfhydryl group combine to attack the carbon-chlorine polar bond to carry out the substitution reaction. After cross-linking, the performance of the product will be comprehensively improved in terms of ultraviolet resistance, solvent resistance, temperature resistance, impact toughening, etc.