flexible underground ducting. Urethane Flex Medium duty duct hoses are another example of 12” duct that has become increasingly popular in several fields. flexible underground ducting

 
 Urethane Flex Medium duty duct hoses are another example of 12” duct that has become increasingly popular in several fieldsflexible underground ducting  Model No: Insduct102

OPW-FCS’s supply piping is totally bonded multi-layer composite construction. 7mm in Diameter) with a pre-installed Fiber Cable Ideal for MDU and FTTX Installations The Fiber Cable is pre-installed in the Micro Duct for One-Step installation of Micro Duct and Fiber Cable Dura-Line. 9. For example, a three foot offset in a 10-foot run of duct can add an estimated 120 lb F of tension to a pull1. Find My Store. 4" x 25' Flexible nsulated Duct - Black Jacket R6. Min Order: 1000 meters. ANSI, the American National Standards Institute, has accredited SMACNA as a standards-setting organization. Hydrostatic pressure and water surface tension drive water into small conduit openings, seeking the. Size 110mm. For duct wrap, the installed thickness shall be assumed to be 75 percent (25 percent compression) of nominal thickness. Also known as Ridgicoils or Ridgiduct, utility ducting is a strong yet flexible ducting for underground utilities. Flexible High-Temperature Ducting Hoses (Hot Air Hose), for temperatures up to 1100°C, are manufactured and supplied by Masterflex Technical Hoses Ltd in Oldham, UK. 12 products. The exterior surface of the board is covered with foil, acting as an air and moisture barrier; the interior surface of the fiberboard — in contact with air flow — is not as smooth as metal. DETAILS. Galvanized steel shall conform to ASTM A653. Some exhaust system ducts are addressed in Chapter 5, such as kitchen exhaust ducts and clothes dryer exhaust ducts. Can be joined using our Smooth-Cor Flex Adapter or Coupler Kits. Designed with a unique interlocking joint, the EPR Kits’ two half shell, bell by bell pieces simply close around the installed wire and cable. Rectangular flexible ducting - This is a pvc flexible ducting which is often used in ventilation systems where space is restricted and circular ducting cannot be used. Flexible Conduit Ducting: Navigate intricate installations with ease using flexible conduit ducting. For short runs of ducting, 6-metre lengths of rigid PVC or twinwall HDPE (for extra strength) ducting may be your best option as these are much easier to lay than coiled flexible ducting. Underground Electric Cable Ducting Coil 137/160mm x 25m Black. Delivery. Length: 50 metres. Class 3 power ducting is for general applications (450kN compression performance at operating temperatures of 23°c). 00 incl VAT. Vat) UK mainland only. 500+ bought in past month. This 100mm flexible ducting hose from Verplas provides a channel for your air conditioning or extractor fan, to stop build-ups of condensation and fumes in your home. Model # L5329565. Orders over £750: £15 + VAT. JDP's comprehensive range of duct pipe systems caters for all aspects of building works and enables total identification, protection and access to cables and service pipes. D. Underground Ducting. These pipes facilitate the efficient transfer of air, gases, and particles from one location to another. Bundle wiring and protect from abrasion and heat. 00 incl VAT. For the most reliable underground ventilation system possible, make Plascorp your next choice. Finding the Right Pipe Supplier No. Flexible metal conduit allows for bends and twists without the use of extra hardware. 3. The duct has R6 insulation which contains 33% more insulation than the standard R4. You might also like36, Jalan Industri PBP 8, Taman Perindustrian Pusat Bandar Puchong, 47100, Puchong, Selangor. Lightweight - easier installation, 40% lighter than PVC. Conduit and Conduit Fittings. Monoxivent UnderDuct 824 Low Smoke has been approved for underground applications. Some common uses include: Flexible Underground Ducting Innovation, quality and reliability are the core values of our company. Solid wall (PVC-U) green ducting is often used in cable TV operations, such as Virgin Media. Share View product details Pack size:. Ordering from Grain needs to be 40 min. Print options available. Joints and seams for duct systems shall comply with SMACNA HVAC Duct Construction Standards-Metal and Flexible. Manufactured from polyethylene. £19. £ 36. In these circumstances the IPEX EPR repair kit allows the contractor or electrician to quickly and easily repair the damaged conduit or duct quickly and reliably. The maximum duct temperature for plastic ducts shall not be greater than 150°F (66°C). Size 121-136mm to 100-115mm. Competitive Prices and Free Samples for Various Ductings and Fittings of Ductwork. 25. 4. galvanized steel housing, aluminum prop fan ;Drainage Flexible Coupling/ Adaptor Stepped 121-136mm to 100-115mm. 00 incl VAT. For. Twinwall HDPE, solid wall Polyethylene and solid wall uPVC systems are available to suit the various applications depending on the specification and project. MEGAenclosures corrugated duct is a flexible double walled corrugated pipe manufactured with continuous co-extrusion of both walls. FREE delivery Sun, 29 Oct on your first eligible order to UK. Extraction Hose. In stock and ready to ship. These measurements refer to the outside diameters (O. Harga OOKAS Ducting Exhaust Fan Plafon 12 Inch Kipas Blower Exhaust Plafon. Underground Drainage Damp Proof Membrane/Radon Barrier Flexible Couplings Channel Drainage Land Drainage Ducting - Perforated Gas Ducting - Access Boxes - Cable Duct 6m Lengths. Attach a paint stick to. 85% Reference Fuel C – 15% MTBE 70% Reference Fuel C – 30% Ethanol 85% Reference Fuel C – 15% Methanol. PVC Domestic Flexible. Complete your ducting project for less. Engineered with the utmost care and. Our black flexible duct is used for ducting all kinds of electrical installations with a voltage rating up to 500 volts. Products in the conduit suite include Comm-Line™ for casing power and telecommunications lines, Hard-Line™ for high-pressure, high-corrosive and heavy wall applications, MicroPath™ for power and telecommunications microcabling, Power-Line™. Underground duct systems shall be constructed of approved concrete, clay, metal or plastic. Our extensive range of 400mm sewer pipe and fittings are UK manufactured in the UK by Brett Martin, certified & approved, surpassing all necessary regulations for uPVC underground sewer systems. Others, such as stainless steel hose can withstand temperatures of. Supaflex flexible ducts provides economical means for handling misalignment between system components and ducting around obstacles where fabricated and fitted ducts are difficult and costly to install. Ducts should not be placed where water infiltration may occur. Flexible Ducts: These ducts are made of flexible materials such as aluminum foil or plastic, allowing for easy bending and maneuverability. £16. For those difficult cable runs, our range of ducting offers the perfect solution to protect those cable running underground. 5. Click & Collect. £165. 3. Free 30-day returns to. Metal ducts shall be protected from corrosion in an approved manner or shall be completely encased in concrete not less than 2 inches (51 mm) thick. Perry Fiberglass FRP duct is filament wound with glass and resins formulated for your specific application. 0086-152-6787-7895; beyond@bi-yang. This makes it ideal for use in environments which include tight bends or requires wiring to be secured at specific angles. Flexible PVC Ducting: Applied hard-wearing, flexible vinyl woven polyester with carbon wire spring and adhesive tape, smooth inside wall. These ducts provide a protective conduit for wiring related to lighting and signals, ensuring consistent performance and minimising disruptions. Add to basket. 50 incl VAT. Company. Surface Water Drainage. However, with acoustic aluminium flexible ducting the inner core is perforated to allow for sound attenuation. Flexible Underground Cable Ducting (60 products available) 35mm wide slot plastic Electric Flexible Underground cable ducting $0. 49. some argue that it turns a previously flexible duct into a long unreinforced concrete beam of little strength, prone to fracture with ground. asbestos cement, plastic, tile, concrete, reinforced fiberglass, and other materials have been used. 0 Flexible Pipe Fabrication 14. Suitable for commercial and domestic use. I'd like to get this joined into the new. The flexibility eliminates the need for special bends and the smooth bore has a low co-efficient of friction for ease of cable installation. CABLE FLEXIBLE / RIGID - ELCOR PIPES – instaling instructions 20 24. Cable Ducting Twin Wall Black 50mm. Orders over £1,000: Free of charge. Gulf-O-Flex® Flexible Insulated Duct is made of a triple lamination of aluminum foil. Underground Electric Cable Ducting Coil 137/160mm x 25m Black. Spiral Manufacturing Co. PVC hoses are used for many commercial applications because they are affordable, durable, offer good chemicals resistance, and are available in a variety of grades. 00. Twinwall Utility Duct Bend - 90 Degree x 125mm For All Colours. Brand Mission Rubber. This Underground Electric Cable Ducting Coil is a part of Naylor's premium MetroDuct Twinwall Ducting System. Electrical Underground Ducting (392 products available) 35mm wide slot plastic Electric Flexible Underground cable ducting $0. It is available in a range of coil diameters from 40mm up to 110mm. Our ultra-tough twin wall underground ducting has an HDPE crush resistant corrugated outer wall and a smooth inner wall for easy cable installation. To its credit, PVC hose is perhaps one of the most versatile types of ducting on the market. COD application services include Construction of underground ducts for High Speed Internet Superhighway networks Cable Television CCTV on the e[press highway, high & low voltage power cables, Video Phone. ADD. The first question leads to what is called “deeply buried ducts. Seal the joint: Apply a 1/8-inch thick layer of duct mastic to the mesh with a paintbrush. for pricing and availability. Naylor Underground Traffic Cable Ducting Coil 94/110mm x 50m Orange. ( 26) $26. All coils of the UGC-Series are supplied complete with a draw-cord pre-installed throughout and one conduit coupler per coil. 82 Per M. 0-m along the duct line to position the ducts. SUNCOURT. Ronbar 50mm Black Ducting (50M Reel) Part Code: NR050BL. OPW-FCS’s supply piping is totally bonded multi-layer composite construction. Buy Flexible Ducting 3m Lengths In Sizes 50/63mm & 94/110mm Here! The flexible underground ducting 3m lengths are the perfect solution for small scale domestic jobs as well as large scale industrial projects and are supplied with a coupler as standard!. Brand PBSL Group. For that reason, our mine ducting includes hose with temperature ranges from a low of -50 to a high of 285 degrees Fahrenheit which. 5 4. 2 Underground duct systems. This chapter covers duct materials, duct construction, duct installation, duct insulation properties, duct sealing, above-ground and underground ducts, return air intake locations and air plenums. underground cable ducting and protection system for . RELATED: The Body's Defenses Against Breathing Dusty Air. Flexible Conduit Ducting: Navigate intricate installations with ease using flexible conduit ducting. Naylor MetroDuct T Box 105mm x 105mm. 82 Inc VAT. Communication Downtown / Business quarters infrastructure Undersea’s infrastructure. Depth The top of the duct can. Our blue flexible ducting is used for ducting water supply services, usually blue MDPE pipes. All contact surfaces between main corrugated duct and built-in sub-ducts are fused together during extrusion process to prevent movement or twisting of subducts inside the main COD duct. Careers Locations Catalogs. A 6 Inch flexible aluminum duct's a simple way to vent a gas or electric dryer without having to install elbows to go around corners. Its flexibility and mechanical resistance allows installation. Suitable for commercial and domestic use. Naylor General Purpose Black Cable Duct 45º Bend. Made from HDPE, its flexible & lightweight which is great for transportation. Most conduit is rigid, but flexible conduit is used for some purposes. Quantity Discount. 50 + VAT. The Pipe Equipment Flexible Tracer Rod has been designed to easily locate underground plastic pipes ducts and hoses. 2. XP Flexible Pipework. £. Add to basket. ), all dimensions can be found in the table alongside the product image. High density polyethylene or HDPE pipe is a strong, light weight and flexible product that can be used as conduit (duct) or innerduct. £1195 (£1. Rigid conduit offers solid protection. APT® XP pipework provides a highly flexible pipework solution that makes installation simple and easy in any weather condition or site configuration. Shop our great collection of flexible ductwork at everyday low prices. It’s easy to install by trenching, jetting, pulling, and HDD (horizontal directional drilling) methods, as well as being used as innerduct. 0 Tank Sump Plumbing Trees 12. Material: PVC. Find My Store. Underground duct and fittings should always be round and have a minimum thickness as listed in. Flexible ducting is available in various options such as standard, thermal, and acoustic. User notes: About this chapter: Chapter 16 addresses duct construction for HVAC and most exhaust systems. Duct for Electrical Branch Circuits: Type EPC-40-PVC RNC, direct-buried unless otherwise indicated. Our black flexible duct is used for ducting all kinds of electrical installations with a voltage rating up to 500 volts. D. Evenly distribute air from fans and blowers throughout large spaces. Our black flexible duct is used for ducting all kinds of electrical installations with a voltage rating up to 500 volts. Min Order: 100. Easy to use and transport. Bryan spends some time discussing duct types and tips at the Kalos morning meeting. The high-density polyethylene is highly chemical and water resistant and has a compression resistance of higher than 450N. Buy 100 mm Ducting at Screwfix. Conduit Box Connectors. , and 12 in. Whether it coal, iron, or silver, temperature extremes are not uncommon to mines of all types. as well as indirect burial within flexible ducting for future replacement capabilities. When your ducting system is built by Sulong. Duct VelocityFlexible Underground Cable Ducting (60 products available) flexible ducting polyester insulated air conditioning aluminum flexible insulation duct $0. Colour: Black. Our lightweight, flexible HDPE pipe (also called poly-pipe, conduit, duct, or innerduct) is made from strong, durable high density polyethylene. Safely route and protect cables with CEF's underground ducting solutions. 7-10 days. 00. Show: 75mm Cable Ducting are ideal for protecting electrical cables through walls or underground, sourced from a top brand. £2. HDPE, high density polyethylene, high chemical and. Eagle’s ventilation ducting is designed for positive pressure ventilation and negative pressure applications. is available in five sizes. • 1000*1000 550gsm. Nominal Outer Diameter: 178mm. £208. Connexs 32mm Black PVC Flexible Conduit (5m Reel) Part Code: V32/5M. Model # 01-225-6. The high-density polyethylene is highly chemical and water. In June 2017, Furukawa Electric Co. Cable Ducting Twin Wall Black 75mm. The acoustic flexible ducting sizes range from 80mm to 400mm in diameter. The Walkerduct system provides wire management for open space environments while maintaining aesthetics of the space with duct that is buried in the floor and activations that can be placed on top of the runs for easy access to power and data. The Master Flow 4 in. Size 125mm. Ducting Systems. • 1000*1000 550gsm. vat. Duct for Electrical Feeders 600 V and Less: Type EPC-80-PVC RNC, direct-buried unless otherwise indicated. Underground duct systems shall be constructed of approved concrete, clay, metal or plastic. Code D110G. Delivery 7 days a week Free. Applications of a ducting pipe. A leader among U. Length: 50 metres. Cables must be protected during and after installation making the use of cable ducts essential. 99Inc Vat. waste water evacuation. Used to deliver cables, heat and/or cold, as well as gaseous substances, ducting pipes thus play a key role in a number of fields and productive sectors. Our ultra-tough twin wall underground ducting has an HDPE crush resistant corrugated outer wall and a smooth inner wall for easy cable installation. Orders over £750: £15 + VAT. 16 18. pipes 160mm diam and. Twinwall flexible underground ducting 63mm, 50mm inner diameter (~£140) The only thing I don't like is that I guess it means the router will have to go in the remote barn, not the main network cabinet. The ribbed external wall ensures that the duct can withstand high compressive forces whilst the smooth inner bore resists any snagging. Some exhaust system ducts are addressed in Chapter 5, such as kitchen exhaust ducts and clothes dryer exhaust ducts. Flexible Underground Piping Manual . EFLEX Square Duct underground cable-protecting pipe. PU Clear Flexible ducting Hose, 50mm Dia. com Step 1 - Choose the correct colour. Naylor Underground Traffic Cable Ducting Coil 94/110mm x 50m Orange. Available in a variety of options to suit any need, it is. It helps protects electrical cables in burial and concrete applications. x 25 ft. You asked and we delivered! The new pipe is more flexible, lighter and has reduced memory. Add to basket. Inductor 16-in dia Galvanized Steel Axial Duct Fan Inline Duct Fan. Some exhaust system ducts are addressed in Chapter 5, such as kitchen exhaust ducts and clothes dryer exhaust ducts. Nominal Size (OD/ID): 63mm/50mm. 999. The ducting/tubing also conforms to CAN/CSA-M427-M91. Lightweight - easier installation, 40% lighter than PVC. Designed with a unique interlocking joint, the EPR Kits’ two half shell, bell by bell pieces simply close around the installed wire and cable. Product Type. Low-velocity ductwork design is very important for energy efficiency in air distribution systems. 50mm o. INDEX 1. x 25 ft. Nonmetallic underground conduit (PVC) – Also known as Schedule 40 (heavy wall) or schedule 20 – EB – these raceways are typically used underground within concrete. 0 Flexible Pipe Fabrication 14. About this chapter: Chapter 6 addresses duct systems used in HVAC systems and some exhaust systems. Naylor MetroDuct Twinwall Electric Cable Duct 100/120mm x 6m. Brand PBSL Group. Our progress depends about the advanced products ,fantastic talents and continuously strengthened technology forces for Flexible Ducting Underground, Pvc Air Duct, Underground Ventilation Pipe, Mine Tunnel Ventilation,Underground Ventilation Sleeve. In February 2018, we added two large-diameter sizes for a total of five sizes. air flow. Our black flexible duct is used for ducting all kinds of electrical installations with a voltage rating up to 500 volts. Explore the full range of cable ducting and accessories from. Urethane Flex Light Duty Flexible Polyurethane Hose. PVS duct suppliers, you can count on Spiral Mfg. Biyang, a leading Supplier for Rectangular Flexible Duct in China. Because of its inherent compact, flexible constitution, 4 inch duct is capable of being used in. Our mine ducting products work well with mine ventilation heat systems because they feature a wide temperature range. In stock and ready to ship. We are quality-focused, while keeping a close eye on time and budget. Standards: Class 3, Kitemarked, BS EN 61386-24. D. 110mm OD Twinwall Duct x50m; Traffic Signal ORANGE. IP44. Multilayered PVC and aluminum body ensures worry-free use. Attach conduit to a knockout in electrical boxes. 8-in dia Galvanized Steel Axial Duct Fan Inline Duct Fan. HomeAire. As flexible ducting is easier to work with during installation, it’s also easy to handle it during maintenance. See full list on etechcomponents. Shop everything from aluminum, flexible, insulated ducts & more at the Home Depot. As low as £2. Fast Online Delivery Available from our 18 Branches Nationwide. Help & Advice > Product Guides > Underground Ducting. Duct Sizing - the Equal Friction Method The equal friction method for sizing air ducts is easy and straightforward to use. This additional insulation provides greater thermal efficiency to save energy. This lightweight product has an internal steel helix and. 11. Fiberboard ductwork is often used for heating. Our locally-manufactured products include flexible ducting, diffusers, grills, duct lock range, volume control dampers, accessories like washers, access panels, and nuts and bolts, insulation, and a variety of tapes and adhesives. Flexible Conduit Ducting: Navigate intricate installations with ease using flexible conduit ducting. Fiberboard ductwork is often used for heating. ). For duct wrap, the installed thickness shall be assumed to be 75 percent (25 percent compression) of nominal thickness. Live Chat. MPN: FXKVR50. Cable Duct 150mm (ID), 178mm (OD) Ridgiduct cable duct is suitable for underground cable ducting of low and high voltage power cables, this includes 400/1000 volt, 11kV, 33kV and triplex cables. Model # DB414E. £. 6 in. Our ducting piping options include standard coiled flexi duct for use in the installation of various buried services, BT duct for telecoms, smooth bore electrical Polyduct, twin wall ducting and rigid PVC duct. The method of construction shall ensure that the standard spacing is maintained and that all space between the ducts and a minimum of 75-mm surrounding the ducts is filled with concrete. Whether it’s for HVAC systems, exhaust systems, or any other air circulation application, ducting pipes. Code UDB12590. Rubber-Cal. £110. Can be joined using our Smooth-Cor Flex Adapter or Coupler Kits. 23 £7. Code D63G. 0 meters. 32/37mm x 50m Polyduct Power Black £ 84. Ask a Free Sample Now. cable installs. These measurements refer to the outside diameters (O. £35. Conduit Ducting; Back to Plastic Push Fit Conduit Ducting 15mm x 50m Product Code: 92502 92502. As low as £5. Brand Mission Rubber. To minimize the effect of bends and offsets, begin such pullsThis ducting is crafted to be lightweight and flexible, making for seamless installation and easy handling that minimises excess time and energy. Underground duct systems shall be constructed of approved concrete, clay, metal or plastic. 15 - $5. pipes 125mm diam and acc. Ridgiduct is a twin wall cable duct system specified by most of the UK DNO's and regional electricity companies. Flexible and Convenient: Thanks to the built-in steel wire, the length and shape of this ducting is flexible to change for fitting exhaust fan blower or inline fan; Being portable and lightweight, it can be installed at any place; Comes with 2 duct clamps in the same duct opening size for easy setup and securer connection ;External  Diameter: 50mmInternal Diameter: 40mmLength: 50mThis double-walled underground burial conduit has a corrugated exterior and a smooth core. Model No: Insduct102. Flexible ducting is easier to hide behind walls, underground, behind columns, and above or within the ceiling. Urethane Flex Medium duty duct hoses are another example of 12” duct that has become increasingly popular in several fields. Self extinguishing, low toxicity and smoke density. It is available in a range of coil diameters from 40mm up to 110mm. 00 incl VAT. ): 6. 15. Blue twinwall ducting for underground water utility services, and accessories such as couplers and drawcord, available in sizes from 50/63mm to 300/354mm. This lightweight product has an internal steel helix and. Underground ducting is made of PVC, polyethylene, uPVC or twinwall HDPE plastic and is either flexible or rigid. Protect wiring from impact and the environment in runs indoors, outdoors, and underground. The ventilation duct/tubing is certified by Natural Resources Canada under Certification # 1181. For use in all civils, utility and telecommunications sectors. Product Description. These versatile ducts allow for adaptable routing of various utilities, ensuring optimal. Rectangular flexible ducting - This is a pvc flexible ducting which is often used in ventilation systems where space is restricted and circular ducting cannot be used. Flexible Heating Duct, Nylon Duct, Underground Ventilation Duct and so on. Daftar Harga Exhaust Ducting Terbaru; November 2023; Harga Promo! 220V Duct Booster Vent Fan Metal Inline Ducting Fan Exhaust. 2 Underground duct systems. Full range of fittings and accessories available. In stock and ready to ship. Get free shipping on qualified Flexible Ductwork products or Buy Online Pick Up in Store today in the Heating, Venting & Cooling Department. for pricing and availability. Flexible Land Drainage Pipes - Perforated/Unperforated Coils. The BlueDuct is the only proven, direct-burial underground duct system made from ultra-durable, advanced HDPE (high-density polyethylene). Type: Electric Cables. This cable ducting has a ribbed outer section and smooth inside wall making it ideal for protecting electrical cables when installing through walls or underground. 0 bids. 22. This chapter addresses air plenums such as above-ceiling and below-floor plenums. Urethane Flex Heavy Duty Flexible Heavy-Duty Hose. 90. SWEDFAN works according to the quality system ISO 9001 and all strength values are continuously tested in the production. Available in a variety of options to suit any need, it is. Also which type of cable can I use buried in conduit underground? T&E? - but if the conduit did let water in at some point T&E isn't suitable. Type: Electric Cables. £34. 100mm gravity grille in white with gravity flaps to prevent backdraught. d - 40mm i. View options. Cable Ducting – pipes-underground. Walkerduct Flexible In-Floor Duct System. Available in a range of sizes, this ducting coil is designed for underground electric cable applications. Both smooth and corrugated HDPE varieties are available. Duct Material: High Density Polyethylene (HDPE) This 50mm ID / 63mm OD twinwall ducting comes in a 50mtr coil with a factory fitted drawstring, complete with one coupler to connect multiple coils together. 42 Ex VAT. TwinDuct Oval chambered ducting for positive pressure ventilation. ON BACK ORDER - Please contact us for availability and alternatives. Polypropylene Flexible Conduit 20mm x 100m Coil Black ★★★★★ ★★★★★ £69. Easily installed in metal or flex ducting ; Suitable for air temperatures up to 150deg ; Permanently lubricated shaded pole ; 24-g. Protects cables and reduces risk of damage. length and inner diameter measurements of 4 in. Had three guys from Open Reach install an underground Fibre cable across 80 metres of my garden. These measurements refer to the outside diameters (O. We carry a wide array of PVC pipe including: Multi-Gard, Bore-Gard, Split Duct, Schedule 40 & 80 Conduit, P& C Duct, and Telephone Duct. Installation must be made safely above the water table. We also provide above ground solutions such as Cable Guards and Hockey. 5 out of 5 stars 138. For any projects requiring fans, blowers or confined spaces, turn to Eagle’s flexible ducting. A comprehensive duct layout indicating sizes, design airflows, pressure class, and routing of the duct system.