Onion Type Airflow Ridgevent

Onion type Airflow Ridgevent is an economical, effective, and low maintenance method of exhausting heat, moisture, and air-borne contaminants from industrial and commercial buildings. By taking advantage of natural thermodynamic forces, ridge ventilators offer a sustainable solution to improving energy efficiency, without moving parts. Airflow Ridgevent™ is ideally suited to the extraction of low to medium heat loads, with virtually no running costs or maintenance. Best for solar panel roof in future.

FEATURES AND BENEFITS

» Natural ventilation – No running expenses
» Efficient airflow – cooler building
» Assemble unit – easy installation
» Knockdown form – cost-effective, damage resisting
» Extensive size range – suits most designs
» No moving parts – low maintenance
» Compound design – resists rainwater entry
» Self-draining – no additional plumbing
» Mesh guarding provides bird and vermin barrier
» Suitable – solar panel installation building
» Warranty 36 month
onion ridge vent
Onion Type Airflow Ridge Vent

Standard Range

Model

T

H

W

D

AirFlow Onion

300

404

800

860

AirFlow Onion

450

404

900

960

AirFlow Onion

600

516

1100

1150

AirFlow Onion

750

627

1200

1250

Dimensions (mm)

PLEASE NOTE: Units available in modules up to 3000 mm long. Larger throat openings are available on request.
As natural ventilators, the units will be weather tight under all normal positive pressure conditions.

Ridge vent image

Abridged Air Change Table

Situation

Air changes per hour *

Boiler Houses

20 - 30

Compressor Rooms

30 - 60

Engine Rooms

20 - 30

Factories ( workshops)

6 - 10

Furnace Shops

30 - 60

Garages

8 - 12

Kitchens (Commercial)

15 - 20

Laboratories

4 - 6

Machine Shops

6 - 10

Paint Shops

30 - 60

Poultry Houses

6 - 10

Warehouses

4 - 8

Table: 1

*The air changes up to eight an hour provides for removing contamination normally caused by human occupants. The higher rates of air changes provide for removing heat and steam in temperate zones. In hot climates, the air changes per hour should at least be doubled.

The most Suitable RidgeVent is depend on the number of air changes required per hour and the size of the building.

To calculate the suitable ridgevent size the usage of the building should firstly be determined and then the relevant number of air changes specified (see table 1). For example a building that is being used as a boiler room will require approximately 25-40 air changes per hour compared to 4-8 air changes per hour for a warehouse.

It is then appropriate to calculate the ventilation rate:

 

FORMULA:

Q = L x W x H x A                3600                      

Where,
Q = required volume flow rate in m3 per second.
L = Length of building in meters.
W = Width of building in meters.
H = average height of building in meters.
       [(Wall ht. + Ridge ht.)/2]
A = required air changes per hour.
3600 = Conversion constant.

For example to ventilate a building 60 meters long,30 meters wide and 6 meters high with a required air change rate of 5 air changes per hour(for building to be used for Warehouse)-

                                                                                             Q= 60 x 30 x 6 x 8
  3600
Q = 24 m3 per second

Assume effective stack height = 6m,          Then refer to (Table 2) for the exhaust velocity

Assume length of ridgevent as 55m,           Assuming a wind velocity of 2m/s.

Temperature difference between                Then use 1.32 m/s, for exhaust velocity
Outside & inside of ridgevent of 6°C,

FORMULA=24/55 x 1.32     ventilator size = 330 mm, Therefore use throat size 300 mm.

Table 2: EXHAUST VELOCITY (m/s)

Temp. Diff. Exhaust K (°C)

Effective Stack Height (m)

Wind Velocity m/s

0

1

2

3

3

3

0.31

0.66

1.01

1.37

6

0.43

0.79

1.14

1.50

9

0.53

0.88

1.24

1.59

12

0.61

0.96

1.32

1.67

15

0.68

1.04

1.39

1.75

6

3

0.43

0.79

1.14

1.50

6

0.61

0.96

1.32

1.67

9

0.75

1.10

1.46

1.81

12

0.86

1.22

1.57

1.93

15

0.97

1.32

1.68

2.03

Temp. Diff. Exhaust K (°C)

Effective Stack Height (m)

Wind Velocity m/s

0

1

2

3

9

3

0.53

0.88

1.24

1.59

6

0.75

1.10

1.46

1.81

9

0.91

1.27

1.62

1.98

12

1.06

1.41

1.77

2.12

15

1.18

1.54

1.89

2.25

12

3

0.61

0.96

1.32

1.67

6

0.86

1.22

1.57

1.93

9

1.06

1.41

1.77

2.12

12

1.22

1.57

1.93

2.28

15

1.36

1.72

2.07

2.43

The above velocities are indicative only and when used in the formula shown will determine approximate Ridge vent throat size

“Ventilation should never be an afterthought in constructing a factory building, Your building needs to breathe”

Z-Purlin
C-Purlin

Spacing/ Support

Onion type Airflow Ridgevent frames must be installed at the spacings given in dimension D of the table at left or less. Purlin must be positioned to allow attachment of the frame on the purlin flanges as defined by dimension E. Designers are reminded to allow for point loadings applied to the purlins for both dead and wind loadings.

AIRFLOW  RIDGEVENT™

Vent Size (Throat) T

Purlin  Spacing (I/I) A

Type

300

410

Onion Airflow Ridgevent

450

560

Onion Airflow Ridgevent

600

710

Onion Airflow Ridgevent

750

860

Onion Airflow Ridgevent

Foot Traffic

Standing or walking on Airflow Ridgevent™ is not recommended, as this could be unsafe and may cause superficial or visual damage to the vents.

Ventilation

Ventilation through the Airflow Ridgevent™ Ridge Vent is passive, therefore performance will vary and will be highly dependent on building geometry, internal building use, and weather conditions. The cooling benefits of passive venting are universally recognised and airflows under a variety of conditions.

Exhaust Performance

The performance of any ridge ventilator will depend on the throat size of the vent, the height of the structure to the top of the vent, the inlet height (assumed to be half the door or inlet- vent height above the floor), and the temperature difference between the outside and inside of the building.

Handling/Storage

Onion type Airflow Ridgevent™ components and assemblies should be handled with care at all times to preserve the product capabilities and quality of the finish. Packs should always be kept dry and stored above ground level while on site. If the materials become wet, they should be separated, wiped, and placed in the open to promote drying.

Installation

Uncrate vent and place upside down. Cut end cap to match building pitch if greater than 1:12.ridge vent angle details

  1. Apply sealants to end cap flashing. Secure end cap flashings (or multiple vents flashing where needed) with fasteners. Vents may be placed together to provide a continuous run.
  2. Drill pilot holes through vent skirt (both sides) a minimum of 300mm on center.
  3. Seal closures with 25mm wide mastic and silicon silent recommendations.
  4. Locate vent over closures and opening, drill pilot holes through Apron, closures, and roof panels. Secure fasteners along the sides.

“Airflow Ridgevent located precisely where they do the most good”