The Casavent SRD-75-50 is a 75mm diameter radial semi-rigid air duct supplied as a 50 metre coil, designed for MVHR (Mechanical Ventilation with Heat Recovery) and MEV radial ductwork installations in residential properties. Built with a dual-layer HDPE construction, the duct combines a corrugated outer layer for mechanical strength and flexibility with a smooth inner bore enriched with an antistatic and antimicrobial additive that reduces electrostatic tension and minimises dust accumulation along the duct walls.
Radial ductwork runs individual duct lengths from a central manifold or distribution box directly to each supply or extract point, rather than branching off a single trunk line. This simplifies installation, supports balanced airflow across a property, and allows the duct to be routed through ceiling voids, suspended ceilings, walls, or floors.
75mm
Outside Diameter
60mm
Internal Diameter
50m
Coil Length
290mm
Bending Radius
394N
Compression Strength
-25°C to +90°C
Service Temperature
System Component
This is a radial (semi-rigid) duct, not flexible insulated hose. It requires manifold/distribution boxes, plenums, flanges, lock rings and sealing rings (sold separately) to complete a working system.
Antimicrobial & Antistatic Inner Bore
The smooth inner layer is enriched with a highly effective antistatic and antimicrobial additive that significantly reduces surface electrostatic tension, minimising the attraction and build-up of dust particles along the duct walls over the system's lifetime.
Corrugated Outer Layer
The dual-layer HDPE construction gives the duct excellent mechanical strength and resistance to deformation, allowing it to withstand demanding operating conditions while remaining easy to handle and install.
290mm Bending Radius
A defined 290mm bending radius lets the duct form gradual bends through joists and service voids without kinking or restricting the internal bore, helping maintain consistent airflow through the run.
394N Compression Strength
Rated to 394N compression strength, the 75mm duct resists crushing and deformation during installation and once built into the fabric of the building.
Wide Service Temperature Range
Rated from -25°C to +90°C, the duct is suited to the temperature range typically encountered in loft voids, external walls, and ducted MVHR/MEV supply and extract runs.
Wide Mounting Flexibility
Unlike round flexible duct that is typically limited to ceiling or wall runs, this semi-rigid profile is suitable for ceiling, floor, or wall mounting, giving installers more routing options through a building's fabric.
Compatible System Accessories
This duct connects to manifold boxes, plenums, round flanges, lock rings and sealing rings to form a complete radial system. These components are sold separately — check compatible accessories before ordering.
Product Overview
Brand
Casavent
Product Code
SRD-75-50
Description
Radial Semi-Rigid Ducting, Anti-Microbial & Anti-Static, 75mm x 50m Coil
Pressure difference across the duct rises with airflow rate, as shown on the manufacturer's performance chart — at low-to-moderate flows the 75mm duct maintains a low pressure drop, which increases progressively as airflow approaches 50 m³/h. Refer to the full chart for intermediate values when sizing a system.
What is the internal diameter of the 75mm duct?
The outside diameter is 75mm, with an internal bore diameter of 60mm.
What is the bending radius for this duct?
The bending radius for the 75mm duct is 290mm. Bending tighter than this can restrict airflow and stress the duct wall.
What does the antimicrobial and antistatic lining do?
The inner bore is treated with an additive that reduces surface electrostatic tension, which in turn minimises the attraction and build-up of dust particles inside the duct over time — helping keep the system cleaner and airflow more consistent.
Can this duct be used for both supply and extract air?
Yes. This radial semi-rigid duct is suitable for both supply and exhaust/extract runs in residential MVHR and MEV systems.
What accessories do I need to complete a system with this duct?
A complete radial run typically needs a manifold or distribution box at the central end, a plenum or round flange with lock ring at the room end, and a sealing ring for an airtight connection. These are sold separately.
What temperature range is the duct rated for?
The duct has a service temperature range of -25°C to +90°C, suitable for typical loft void, wall, and ducted MVHR/MEV installation conditions.
