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.

Physicochemical properties

1. Odorless, tasteless and non-toxic. It is one of the lightest resins commonly used;

2. Excellent mechanical properties, including tensile strength, compressive strength and hardness, outstanding rigidity and bending fatigue resistance, the movable hinge made of PP can withstand more than 7 × 10 to the power of 7 folds and bends without breaking, and the impact strength is poor at low temperatures. The tensile strength of PP is generally 21-39 MPa; The flexural strength is 42-56 MPa, the compressive strength is 39-56 MPa, the elongation at break is 200%~400%, the notched impact strength is 2.2-5 kJ/m2, and the low-temperature notched impact strength is 1-2 kJ/m2. Rockwell hardness R95~105;

3. Good heat resistance, continuous use temperature up to 110-120°C;

4. Good chemical stability, except for strong oxidants, it does not interact with most chemicals; The solvent cannot dissolve PP at room temperature, only some halogenated compounds, aromatic hydrocarbons and high boiling point aliphatic hydrocarbons can make it swell, and the water resistance is particularly good;

5. Excellent electrical properties, good resistance to high-frequency electrical insulation, and good electrical insulation in humid environments;

6. Since there are many tertiary carbon atoms with methyl groups on the backbone of PP, the hydrogen on the tertiary carbon atoms is susceptible to oxygen attack, so the weathering resistance of PP is poor, and antioxidants or ultraviolet absorbers must be added

7. Mice were gavaged 1~5 times at a dose of 8g/kg, and no obvious poisoning symptoms were caused. The decomposition products of polypropylene heated to 210~220 °C were inhaled 30 times for 2 hours each time, and the symptoms of ocular mucosa and upper respiratory tract irritation appeared. As with polyethylene, it is forbidden to use its recycled products for food.

Polypropylene modification

In view of the poor impact resistance, poor weather resistance, poor surface decoration of polypropylene at low temperatures, and the gap between the functionality and actual needs in electricity, magnetism, light, heat, combustion, etc., the polypropylene has been modified, which has become the most active and fruitful field in the current plastic processing development.

• PP chemical modification

Through copolymerization modification, cross-linking modification, grafting modification, adding nucleating agent, etc., the polypropylene polymer components and macromolecular structure or crystal configuration are changed to improve its mechanical properties, heat resistance, aging resistance and other properties, improve its comprehensive properties, and expand its application fields.

(1) Copolymerization modification

Copolymerization modification is the modification of propylene monomer synthesis stage by using catalysts such as metallocene. When the monomer is polymerized, the added olefin monomer is copolymerized with it, and the random copolymer, block copolymer and alternating copolymer are polymerized, and the mechanical properties, transparency and processing fluidity of homopolymer PP are improved. The complexes formed by metallocene catalysts are used as a single active center in a transition state with a certain restriction of irregular shape, so as to achieve precise control of the relative molecular weight and its distribution, comonomer content, distribution on the backbone and the crystal structure of the polymer.

(2) Grafting modification

The PP (polypropylene) resin molecule has a non-polar crystalline linear structure, low surface activity, and no polarity. Poor surface printability; Poor coating and adhesion; Difficult to blend with polar polymers; Disadvantage that it is difficult to be compatible with polar reinforcing fibers and fillers. Graft modification is to introduce polar groups to its macromolecular chain to improve the blendability, compatibility and adhesion of PP, and to overcome the shortcomings of difficult blending, incompatibility and bonding. When the active free radical encounters the unsaturated carboxylic acid monomer, it promotes the unstable bond of the unsaturated carboxylic acid monomer to open and react with the PP active free radical to form the free radical, which is then terminated by the molecular chain transfer reaction. The common grafting modification methods of PP are: melting method, solution method, solid phase method, suspension method, etc. The hydrogen atoms in the grafted modified PP molecular chain are replaced and show strong polarity, and these polar groups enhance the compatibility of PP, and the heat resistance and mechanical properties are greatly improved.

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

1.Material & Characteristics :

• PP ducts are usually made of polypropylene random copolymer (RPP) or homopolymer, which is non-toxic, hygienic, high-temperature resistant and recyclable. It has good corrosion resistance and can resist most chemicals, including high concentrations of acids and alkalis. The pressure resistance is moderate, but not as good as PPH pipe
• PPH air duct is made of polypropylene copolymer (PPH) as raw material, which is modified by β to make it have a uniform and delicate Beta crystal structure, with excellent chemical corrosion resistance, wear resistance, high temperature resistance, corrosion resistance, aging resistance and good insulation. It has an operating temperature range of 100°C and in some cases 110°C. PPH pipes also have high system safety, non-toxic, light weight, and easy transportation and installation

2.Application field :

• PP air ducts are often used in indoor hot and cold water supply systems, heating systems, and general water treatment, electroplating, printing and dyeing industries. It is also suitable for liquid transportation in municipal water supply and drainage systems, food, medicine and other industries
• PPH ducts are widely used in chemical, metallurgy, pharmaceutical, electronics, sewage treatment plants and other industries, especially in the occasions that need to withstand high temperature, high pressure and strong corrosiveness. It is suitable for high acid and alkali chemical product transportation system, pure water transportation system, drinking water transportation system, sewage and wastewater transportation system and environmental engineering

3.Air duct connection:

• PP air duct can be connected by welding, hot melt connection, electric fusion connection and other ways, making PP pipe more flexible and convenient in the installation process
• PPH air duct is mainly connected by hot melt welding, which has high connection strength and sealing

4.Special properties :

• PPH air duct has the characteristics of good heat setting, high temperature resistance, good chemical resistance, creep, high tension, good insulation, insoluble in organic solvents, no dry cracking, no toxicity and so on. These characteristics make PPH ducts suitable for chemical plants, electronic semiconductor factories, pharmaceutical factories, sewage treatment plants and other industries

5.Service life :

• PPH duct and PP duct are also different in terms of service life. Due to the material characteristics of PPH air duct, it can maintain good performance stability in some special environments, while PP air duct may have a decrease in performance after long-term use

6.Use efficiency:

• In the ventilation project, the resistance of the circular PP air duct is small, the air leakage is less, and the space occupied is small, and the efficiency of the circular PP air duct is the highest and the operating cost is low in the whole ventilation project, so the utilization rate of the circular PP air duct is getting higher and higher

In summary, PPH ducts are superior to PP ducts in terms of corrosion resistance, high temperature resistance, special properties and application fields, especially in industrial applications with high chemical resistance. PP air duct is widely used in building drainage systems and some occasions with low requirements for chemical resistance because of its low cost and certain corrosion resistance

Material characteristics

• Chemical resistance—– Of all polypropylene tubing, experiments have shown that (β)-PPH tubing has the strongest chemical resistance.
• Long life—– Beta-(β)-PPH duct has a longer service life and higher system safety.
• Impact Strength —– Compared with the traditional (α)-PPH tube, the (β)-PPH tube has significant low temperature impact strength.
• Temperature resistance—– (β)-PP-H pipes are suitable for temperature ranges from -20°C to 110°C according to the actual application.
• Pressure-resistant —– (β)-PPH pipe has the highest pressure resistance (MRS10) of all polypropylene materials used in piping systems.
• The high-performance —– (β)-PP-H pipe has excellent performance, flexible welding equipment and professional technical support team can not only ensure the welding and installation quality of (β)-PP-H pipe system, but also provide customers with customized processing of non-standard products according to their needs.

Areas of application of PPH

• Packaging industry: Because PPH material is non-toxic and tasteless, and has good thermal stability and moisture resistance, it is often used in the packaging of food, medicine and other products.
• Automotive industry: The impact and corrosion resistance of PPH makes it an ideal material for automotive interior and exterior trim parts, such as bumpers, instrument panels, etc.
• Home appliances: PPH materials are also often used in the shells and components of household appliances such as washing machines and refrigerators, because it can not only meet the strength requirements, but also have aesthetics.
• Medical industry: PPH is also used in the manufacture of medical devices and containers due to its biocompatibility and chemical stability.
• Piping system: PPH pipes are widely used in chemical industry, water supply, drainage and other fields because of their corrosion resistance, high strength and long life.

Storage methods and precautions

• Avoid direct sunlight: PPH pipes should be kept out of direct sunlight during storage to avoid material aging. Choose a cool and ventilated warehouse for storage, and ensure that the temperature in the warehouse is appropriate.
• Prevent moisture: PPH pipes should be avoided from moisture during storage to avoid deformation of the material due to moisture. Ensure that the humidity in the warehouse is moderate, and take moisture-proof measures, such as laying moisture-proof mats, etc.
• Classified storage: PPH pipes of different specifications and models should be stored separately to avoid confusion. During storage, the pipes should be avoided from crushing or colliding with each other to avoid damage to the pipes. For pipes below DN25, they can be bundled, and the length of each bundle should be consistent, and the weight should not exceed 50Kg; Pipe fittings should be packed separately according to different varieties and specifications.
• Stacking requirements: PPH pipes should be stacked horizontally on flat cushions, the width of the cushions should not be less than 75mm, the spacing should not be more than 1m, the overhang at both ends of the pipe should not exceed 0.5m, and the stacking height should not exceed 1.5m. The pipe fittings should be stacked layer by layer, and should not be stacked too high.
• Avoid contact with chemical substances: During storage, contact between the pipeline and chemical substances such as acids and alkalis should be avoided to avoid chemical reactions affecting the quality of the pipeline.
• Regular inspection: Regularly inspect the stored PPH pipes, including whether the appearance is intact, whether there is deformation, etc. If problems are found, they should be dealt with in time to ensure the quality of the pipes.
• Keep away from heat sources and fires: PPH pipes should be stored away from heat sources and fires to prevent fires. In summary, the correct storage method is essential to guarantee the quality and prolong the service life of PPH pipes. During the storage process, the above points should be strictly adhered to ensure the safe, stable and efficient operation of the pipeline system.