AS 4566:2005 pdf – Flue cowls—Gas appliances.
(b) not materially reduce the capacity of the flue.
2.4 PERFORNIANCE
2.4.1 Flue pressure differential
A flue cowl for direct attachment to a hue terminal shall not produce a static pressure differential exceeding 8.5 Pa when the air velocity in the flue pipe is 3 rn/s. In the case of rectangular flue pipes equivalent diameter for the purpose of air velocity calculation shall be obtained from Table Al.
2.4.2 Flue pressure differential in wind
A flue cowl for direct attachment to a flue terminal shall not produce a static pressure differential exceeding 17 Pa positive when the air velocity in the flue pipe is 3 mIs and winds up to a maximum of 65 km/h are directed against it from an’ angle. In the case of rectangular flue pipes equivalent diameter for the purpose of air velocity calculation shall be obtained from Table Al.
2.4.3 Flue cowl static pressure
A flue cowl for direct attachment to a flue terminal shall produce a negative static pressure of no less than 8.5 Pa with no flow in the flue and winds ranging from 32-65 km/h directed against it from any angle.
2.4.4 Strength of flue cowl
A flue cowl shall resist, without damage or permanent distortion, a sind of 95 km/h from any direction.
2.4.5 Rain resistance of cowl
The quantity of rainwater entering the flue with the flue cowl in place shall not exceed 2% of that which would enter the flue if unprotected by a flue cowl.
2.5 INSTRUCTIONS
Installation instructions shall be provided by the manufacturer for all flue cowls.
These shall contain description of the parts required and the step-by-step process of installing the flue cowl, its methods of support if required and the manufacturer’s name and address.
The distances and clearances shall be as required by the authority but in any case shall be mi less than those given in AS 5601.
2.6 MARKINGS
Each individual flue cowl shall he permanently marked with the manufacturer’s identification and model number as well as the certificate of compliance number obtained from a certifying body.
2.7 TESTING
One sample of cacti site shall be submitted for testing. Full specifications shall accompany’ the application for test.
B2.3 APPARATUS
1 Source of low pressure air.
Flowrator or similar flow measuring device to an appropriate capacity.
Length of flue of a size appropriate to the cowl under test with a pressure tapping5 diameters from the outlet and at least 10 diameters from the inlet.
An accurate differential manometer calibrated in Pa.
Wind machine capable of supplying winds of up to 65 km/h over a wind front of atleast 1.0 m’. A suitable wind machine is shown in Figure A1.
B2.4PREPARATION OF APPARATUS
l Locate flue so that terminal will be situated at centre of rotation of the wind machine.
Connect the air supply to the length of flue through the flowrator.
2 Connect the manometer to the test point on the flue, the other side being open to
atmosphere.
B2.5 PROCEDURE
Turn on air supply and adjust flow to give a velocity of 3 m/s in the flue.Read pressure drop from test point on manometer.
3 Fit test cowl to the outlet of the flue and locate cowl at centre of rotation of the windmachine.
AS 4566:2005 pdf – Flue cowls—Gas appliances
