Ultimate Airflow Efficiency

FRP is created through a process of combining wound filament and phenolic resin to maximize strength. In order to guarantee low flow resistance and increase power savings, each FRP section features a smooth, low friction surface for airflow, and are built to withstand high positive and negative pressures. Sections can also be fabricated with either flanged connections or bell and spigot connections which feature internal rubber gaskets to prevent leakage.

Phenolic Resin & Filament

Smooth, Low Friction Interior Surface

Our improved joint seal eliminates leakage.

Round or Oval Ducts available


Norvent Ventilation Ltd. is dedicated to providing quality products to the mining and tunnelling industries. Through continued research and development we have introduced innovative improvements to the manufacturing process for our filament wound rigid pipe. We take pride in announcing the precedent setting K Factor and Air Loss results as the best in our industry.


  • Filament wound rigid ducting.
  • Smooth inner surface – low friction loss.
  • Joints are manufactured with internal rubber gaskets to prevent leakage
  • Airtight joints.
  • Easy installation – guaranteed fit.
  • Strong nylon straps with D Rings for interlocking of sections
  • Suspension straps are available for added strength and safety.

Advantages & Features


  • Upholds its integrity in a fire longer than metals; will operate up to 200°C while maintaining stability.
  • Fire resistant according to ASTM E-162 with flame spread index of less than 25.
  • Will not promote or sustain combustion. Thermal conductivity is much lower than metals 0.20 – 0.24 w/m/k.3. Antistatic properties 10³ ohms @ 1% wt. surface resistivity.
  • Bell/Spigot ensures a safer installation – eliminating pinch points (flanged joints are available).
  • Joints – Bell and Spigot can move 7 degrees right to left and up or down for direction.
  • Available with a flanged end. Flanges are installed prior to filament winding. Flanged minimizes leakage and provides stabilization from high shock waves during the blasting cycle. V-lock couplings speed up installation.
  • Less than half the weight of steel. For example a Rigid Oval (36×62) x 20’ = 400 lbs approximately, whereas the identical sized steel vent would be approximately 1,000 lbs.
  • Low installation cost due to lightweight pipe.
  • Joints are manufactured complete with internal rubber gaskets to prevent leakage and reduce resistance at the joints.
  • When subject to loading or impact, springs back to shape (memory), while metal will dent and leak and may start to recoil.
  • Smooth interior to guarantee low flow resistance and therefore an increase in power savings.
  • EMR/CSA and MSHA approved for underground.
  • Can withstand high positive and negative pressures.
  • Acid mine water resistant and rot proof.
  • Long service life.

FRP Rigid Ventilation Ducting


Phenolic Resin: The Manufacturing Difference That Results in a Better Product

Rigid Ventilation Ducting is manufactured for use in mining and tunnelling applications.  We combine a filament winding process and phenolic resin for maximum rigid duct strength. One of the advantages of phenolic resin is its excellent acid resistance which is a result of the acid cure process. Because phenolic resin is water based and polyester is oil based, phenolic resin is inherently flame resistant, and no fire inhibitors are added. These inhibitors detract from the strength of polyester resins making them more brittle.


Destruction Test

  • Data was collected using a Gardner Variable Height Tester.
  • Flex strength ASTM D-790.
  • Flex Modulus ASTM D-790.reater stiffness allows higher negative pressure capability at equal weights.
Property Phenolic Duct Polyester Duct Interpretation
Impact Test
88 72 Ability to resist a point impact
Flex Strength (PSI)
58,619 66,6676 Load bearing strength
Flex Modulus
2325 1534 Stiffness

FRP Ducting – Fire Resistant Phenolic Resin

FRP ducting is manufactured using phenolic resins. One of the main attractions of phenolic materials is its fire performance. The table below shows some typical fire test results for phenolic/glass composites and compares these to polyurethane and polyester.


Fire Properties of Phenolic/Glass Composites Compared with Polyurethane and Polyester

Property Phenolic Polyester Rigid Polyurethane
ASTM D229 – Oxygen Index 45-55* 40 20-25
ASTM D229 – Rate of burning Does not ignite
BS 476 PT.7 – Spread of Flame Class 1 (Zero Spread) Class 1 Class 1 – Class 4
Toxicity of combustion products Very low Toxic Toxic
Smoke Virtually NIL Very high Very high
* Catalyst Dependent      


When phenolic resin ducting is exposed to fire they char on the surface which further protects the underlying layers from the heat source. In extreme conditions when fire does destroy the product only gasses of Carbon, Hydrogen and Oxygen are produced. This in essence means that the phenolic can only break down to form Carbon Dioxide, Water and Carbon Monoxide. These gasses will result from any form of combustion. A most significant factor is also the very low levels of visible smoke produced. See test results.


Phenolam Laminate Test Results


Test – Flammability ASTM Test Results
NBS Smoke Chamber E-622  
D16   >5 min.
Dmax   42
Radiant Panel Test E-162 6.7
Tunnel Test E-84  
FS1   19
Smoke   12
Limiting Oxygen Index D2863 67
Heat Deflection @ 264 psi D-648 >570°F
Linear Thermal Expansion   2.93 x 10.5 m/in. °F
Specific Heat @ 50°C   0.3 cal/ g°F


The physical properties of phenolic fiber reinforced composites are retained to at least 200°C at which temperature other matrix resins have generally degraded substantially. The inherent fire properties of phenolic resins composites are excellent having the highest fire rating in all test methods, extremely low smoke emission and virtually no toxic combustion products. E.M.R. Flame Certificate Number 395.


Round FRP Ducting

Round filament wound ducting is manufactured in a technically advanced process of bonding phenolic resin and fiberglass strands. Exceptionally smooth inner surface guarantees the lowest friction factor and highest volume of air. Due to its round shape and the outstanding strength Norvent Rigid Round Ducting withstands high positive and negative pressure and resists impacts caused by moving equipment, flying rocks and rough handling. Standard sizes range from 8” to 72” diameter. Standard lengths are 10’ and 20’ (homogeneous, no splice).

Oval FRP Ducting

Oval filament wound ducting is the most efficient way to handle today’s high air requirements in mine ventilation under low space conditions. The special shape and exceptionally smooth inner surface guarantees the lowest friction and highest volume of air. Oval FRP Ducting can be used for both negative and positive pressure ventilation systems. Standard sizes available from 20” equivalent (11 x 30) to 48” equivalent (36 x 62). Standard lengths are 10’ and 20’ (homogeneous, no splice). Fan adapters and fittings are also available.

Tapered FRP Ducting

FRP Tapered Pipe is tapered in shape, allowing sections of ventilation duct to be “stacked” for transportation increasing the number of units per load and reducing shipping costs by a considerable amount.  The design improvement has no impact on aerodynamic performance thereby maintaining the best K factor for rigid ventilation duct on the market.  Available in limited sizes.

FRP  Fittings & Accessories


Special sizes, lengths and wall thickness available on request.
Fittings for all applications are fabricated from flame retardant, corrosion resistant material.
  • Elbows
  • Tees.
  • Wyes – Lateral, Symmetrical and Pant Style.
  • All Wyes are available with 1 or 2 dampers.
  • Reducers and transition pieces.
  • Fan Adapters.
  • Bell & Spigot Connections.
  • Flanges also available


Suspension Hangers (straps) are an inexpensive way to eliminate costly chain or rope and damage to ducting. They are strong and durable and can be suspended from one common hook or from 2 to limit swaying. The Suspension Hangers (straps) can be manufactured to fit any size of round or oval ducting.