PVC Flexible Duct Connector

Product Model	Transparent corrugated soft connector series
Category	PP Molded Products
Reference Price	Price on request

Hot Customizable for Working Conditions 11 Technical Parameters

Product Overview

PVC soft joint is a corrugated flexible pipe connector made of transparent or semi-transparent PVC, connecting both ends to air ducts or equipment interfaces. The soft Connector utilizes the Retractable and bending capabilities of its corrugated segments to absorb vibrations generated by fan operation and installation deviations in pipelines, blocking vibration transmission along rigid air ducts. It can also serve as a variable diameter connection for fan inlet and outlet, making it a commonly used flexible connector in ventilation systems.

Transparency is a standout feature of PVC soft joint. Through the soft joint wall, operators can directly observe internal gas flow, water mist carryover, and liquid accumulation, enabling judgment of fan and upstream equipment operating conditions—advantages not possessed by opaque canvas or metal soft joints. The soft Connector also offers certain acid and alkali resistance, suitable for ventilation systems with low corrosivity. It is lightweight, easy to install, and cost-effective.

PVC soft joints supplied by Xicheng Environmental Protection are available in straight-tubular corrugated and variable-diameter corrugated forms, fixed to air ducts via clamps, flanges, or bands. The product is primarily used for vibration reduction at fan inlet and outlet, flexible transition between equipment and pipelines, and pipe sections requiring internal observation. For highly corrosive environments, PP or corrosion-resistant soft joints should be selected, while high-temperature applications require temperature-resistant soft joints.

Working Principle

The vibration isolation principle of the soft Connector is flexible isolation. When a fan operates, its impeller and motor generate vibrations. If the fan is rigidly connected to the air duct, vibrations will transmit along the duct and supports, causing pipeline resonance, noise, and interface loosening. The low stiffness of the corrugated flexible segment of the soft Connector allows deformation in axial extension, radial misalignment, and angular deviation, absorbing vibration displacement and attenuating vibration energy—effectively creating an isolation break between the fan and the air duct.

The variable diameter and compensation principles of the soft Connector stem from the deformability of its corrugated segment. When equipment inlet/outlet diameters differ from air duct sizes, variable-diameter soft joints provide smooth transitions via conical corrugated segments. For minor installation misalignments or thermal expansion/contraction in pipelines, the soft joint compensates for deviations through extension and deflection, reducing installation stress. The transparent PVC wall does not obstruct visibility, allowing light to penetrate the pipe, enabling observation of internal water mist, dust accumulation, and liquid buildup from the exterior.

Structural Composition

PVC soft joints consist of a flexible corrugated segment and two end connection/fixation parts. The corrugated segment has its wall pressed into a circular wave pattern, which grants the component Retractable and bending capabilities while maintaining a circular cross-section to prevent collapse under fan suction. The two ends are either smooth or thickened, designed to fit over air ducts and be secured with clamps or bands, or to be pressed against flanges for fixation.

Variable-diameter soft joints have one end with a larger diameter and the other with a smaller one, transitioning via conical corrugated segments, used for connecting fans to air ducts of different diameters. Straight-tubular soft joints have identical diameters at both ends and primarily serve vibration isolation and compensation functions. The length of the soft joint is selected based on required compensation and vibration reduction needs. The end clamps are typically metal components, and in highly corrosive environments, they can be treated for corrosion resistance or replaced with plastic clamps.

Specification Model Table

The table below lists soft joint forms and their primary functions, with pipe diameters matching fan and air duct interfaces.

Form	Primary Function	Typical Location
Straight-tubular soft joint	Vibration isolation and compensation	Fan inlet/outlet with same diameter
Variable-diameter soft joint	Vibration isolation with variable diameter	Fan inlet/outlet with different diameters
Transparent soft joint	Vibration isolation with observation	Pipe sections requiring internal observation

Product Features

PVC soft joints integrate vibration isolation, variable diameter, compensation, and observation functions, making them a common accessory for fan connections. Key features include:

Corrugated flexible segment extends and deflects to effectively isolate fan vibrations
Blocks vibration transmission, reducing pipeline resonance and noise
Transparent wall allows observation of internal gas flow, water mist, and liquid accumulation
Variable-diameter form serves as a transition for fan inlet/outlet with different diameters
Compensates for installation deviations and thermal expansion/contraction, reducing stress
Lightweight, with quick and easy installation via clamps or bands for replacement
Offers certain acid and alkali resistance, with cost-effective pricing

Material	PVC 聚氯乙烯
Tube wall features	Transparent corrugated flexible section
Form	Straight tube / Tapered tube
Connection Method	Clamp / Strainer / Flange
Function	Shock Absorber Diameter Adjustment Compensation Observation
Corrosion resistance performance	Resistance to general acids and alkalis
Formability	Axial extension Radial deflection
Installation Location	Between the fan and the ductwork
Color	Transparent / Off-White
Temperature Range	Room Temperature Exhaust
Fasteners	Clamp Band

Application Industries

Shock absorption soft joints between corrosion-resistant fan inlets and ducts
Conical joints for connecting fan outlets to main ducts with different diameters
Flexible vibration isolation for fan sections in spray towers and washing towers
Soft joints between laboratory exhaust fans and plastic ducts
Exhaust stacks requiring observation of internal water mist accumulation
Vibration isolation joints between equipment and pipelines with significant vibration
Flexible compensation segments for pipeline installation with misalignment deviations

Typical Installation Locations

The most typical locations for soft joints are the inlets and outlets of fans. Fan inlet soft joints connect intake ducts or equipment outlets, while fan outlet soft joints connect exhaust main ducts. These two soft joints isolate the fan body from rigid ducts to prevent vibration transmission to the pipeline network. Soft joints should be installed near the fan body, securely fastened with clamps at both ends, and maintained in a natural state without being stretched to the limit or compressed into deformation.

In sections requiring observation, transparent soft joints are installed at spray tower outlets, after demisters, or at fan inlets. Operators can inspect the water and dust accumulation through the pipe wall to assess demisting effectiveness. Soft joints cannot replace fixed pipeline load-bearing capacity; independent support brackets should be installed on both ends of the pipelines and equipment. Soft joints remain in a free Retractable state. During maintenance, clamps can be loosened to replace the soft joint. Before installation, verify the fan and duct diameters, straight or conical forms, ensure alignment of both ends of the pipelines with misalignment deviations within the soft joint compensation range, evenly tighten clamps or flanges, and retain the natural relaxed arc of the soft joint segment without forced stretching or twisting. Soft joints do not bear pipeline and equipment weight; independent support brackets should be installed on both ends of the pipelines. During operation, inspect the corrugated sections for collapse, bulging, and aging cracking. Replace immediately if hardening or tearing is detected.

When the fan is operating, the motor and impeller generate vibration. If the fan is directly connected to a rigid duct, the vibration will be transmitted along the duct, causing duct resonance, bracket loosening, flange leakage, and noise amplification. In the long term, it may lead to fatigue cracking of welds and joints. A flexible vibration isolation break is formed between the fan and the duct by the soft joint, absorbing vibration displacement and compensating for thermal expansion and contraction of the duct and installation deviations. This is a common practice to reduce noise and protect the pipeline network. One soft joint is installed at both the fan inlet and outlet for more reliable vibration isolation. The soft joint should be installed as close to the fan body as possible, with independent brackets for both ends of the duct and equipment, keeping the soft joint in a free, non-load-bearing state. In addition to vibration isolation, the soft joint also facilitates fan disassembly and reassembly and correction of minor misalignments. If soft joints are not installed at the fan inlet and outlet, vibration and noise issues will significantly increase, and later modifications will also be more troublesome.

Soft joints collapse under suction, typically due to insufficient stiffness in the corrugated section or excessively thin pipe walls, which cannot withstand the negative pressure at the fan inlet. During high airflow concentration, the pipe walls inwardly collapse, resulting in increased resistance and noise at a mild level, or blockage of the airflow path and insufficient airflow at a severe level. It is recommended to select soft joints with reinforced corrugations matched to the fan's negative pressure, avoiding excessively thin or long products. For large-diameter and high-negative-pressure fan inlets, it is particularly important to verify the pressure-bearing capacity of the soft joint. If necessary, support rings should be installed inside the soft joint or its length should be shortened. During installation, the soft joint should not be stretched to its limit, nor twisted or eccentric, maintaining a naturally slightly loose state. Collapse may also be caused by excessive airflow at the fan inlet, incorrect valve closure, or filter blockage leading to elevated negative pressure. The system conditions should be simultaneously checked. If collapse is detected, replace the soft joint with sufficient pressure-bearing capacity and eliminate abnormal negative pressure to prevent repeated damage.

PVC flexible connectors will gradually age under long-term exposure to vibration, ultraviolet light, temperature fluctuations, and corrosive gases,Manifested as tubing wall hardening and yellowing, loss of elasticity, crack formation, whitening at wave patterns, and even cracking or air leakage. Replace the connector promptly if it becomes hard, damaged, or if the clamp area tears, or if vibration isolation performance declines or abnormal shaking occurs. Flexible connectors have a longer service life in indoor moderate-temperature corrosive environments, but their lifespan is significantly reduced under outdoor exposure to sunlight, near high-temperature pipelines, or in highly corrosive environments. Consider adding shading measures or selecting weather-resistant and temperature-resistant materials for flexible connectors. During routine inspections, check for signs of collapse, bulging, cracking, or loose clamps on the connector, and replace aging components regularly during fan maintenance. As flexible connectors are wear parts, it is recommended to keep a small stock based on pipe diameter, allowing for immediate replacement upon issue to prevent vibration damage to ductwork and equipment after vibration isolation failure.

The length of the flexible joint must meet the requirements for vibration isolation and compensation, but it is not necessarily the longer, the better. If the length is too short, it cannot fully absorb vibration and installation deviations, resulting in poor vibration isolation performance. If it is too long, it tends to collapse under negative pressure and oscillate or bulge under positive pressure, which Conversely increases resistance and wear. Generally, standard lengths are selected based on the fan's diameter, vibration amplitude, and installation spacing, ensuring that the flexible joint maintains a natural, slightly slack state after installation without being stretched or compressed. For tapered flexible joints, it is essential to ensure that the large and small ends match the fan and duct, respectively, with a smooth transition. Specific dimensions can be selected by referring to the product specifications based on the diameters of the two ends and the required axial and transverse compensation amounts. If unsure, provide the fan model and interface dimensions, and the supplier will provide matching components. When installation space is limited, prioritize ensuring the required length for vibration isolation; do not forcefully insert excessively long flexible joints into confined spaces.

Through transparent soft connections, you can observe whether there is obvious water mist entrainment, liquid droplet flow, dust accumulation, and liquid accumulation inside the pipe, thereby determining whether the upstream demister is carrying water, whether the pipeline is blocked, and whether the fan inlet conditions are normal. Transparent soft connections are installed at the outlet of the spray tower, after the demister, and at the fan inlet. During inspections, no holes need to be drilled or the machine needs to be shut down to monitor the internal status, which helps to promptly identify water carryover, dust accumulation, and liquid accumulation issues. Transparent soft connections expose the operational status visually, which is helpful for judging demister effectiveness and pipeline flushing timing. However, transparent soft connections can only serve as an intuitive operational observation window and cannot replace professional detection instruments such as differential pressure and flow meters. Accurate judgment still relies on instrument data. When the transparent material yellows due to aging, the observation effect decreases. It should be cleaned or replaced promptly to maintain a clear view.

After inserting the flexible connector into the duct or equipment interface, secure the end with a flange or clamp that matches the diameter. Position the flange on the straight edge of the connector's light port, adding a sealing pad or applying sealing adhesive if necessary. Tighten the bolts evenly. The two ends of the pipes must be aligned and coaxial to avoid long-term eccentric stress on the flexible connector. The number and width of the flanges should match the diameter. On the negative pressure side, if the flexible connector is not securely fastened, it may draw in air, affecting airflow. On the positive pressure side, it may leak corrosive gases. Therefore, after installation, check for air leaks, collapse, and abnormal vibration at the connection points during fan operation. Re-tighten if loose. Each end of the flexible connector and the equipment should have independent supports to avoid placing weight on the connector. Re-tighten the flanges after a period of operation. Replace aging, torn flexible connectors and failed flanges promptly to ensure long-term sealing of the connection.

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