MBR Sheet Metal, Specialising in sheet metal supplies we are located in Perth Western Australia.

MBR Sheet Metal
P:+61 8 9309 5000
mail@mbrwa.com.au

Ridge Ventilators

Ridge Ventilators Small

Ridge Ventilators Large

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AIR MOVEMENT REQUIREMENTS FOR BUILDINGS

The effectiveness of the MBR Ventridge is not dependent on wind power, however wind will further increase the extraction rate.
The most suitable ventridge is dependent on the number of air changes required per hour and the size of the building.

To calculate the suitable ventridge 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.

FRESH AIR INLET

To enable natural ventilators to function at their rated capacity, fresh air inlets should be provided as close to the floor level as possible.
MBR manufacture a full range of fresh air inlet louvres for this purpose. MBR require that the total free area of inlet represents 1.5 times the throat area of the ventilator and that it be so positioned so as to ensure uniform distribution.

SUGGESTED AIR CHANGE RATES FOR TYPICAL BUILDINGS EXHAUST CAPACITIES
Types of Buildings	Air Changes per hour
Public Halls
Assembly Halls	15-20
Auditoriums	10-15
Bowling Alley	10-20
Churches	10-15
Classrooms	15-20
Restaurants	20-30
Theatres and Cinemas	15-20
Toilet Rooms	12-15
Poultry Sheds
Brooder Houses	(factor of bird numbers)
Hen Houses	(factor of bird numbers)
Incubator Rooms	8-10
Kitchens and Food Processing
Bakeries	25-40
Breweries	20-30
Commercial Kitchens	20-30
Packing Houses	15-20
Power Plant and Associated Buildings
Boiler Rooms	25-30
Power Houses	(factor of power steam loss)
Pump Houses	12-15
Sub-Stations	(factor of power loss)
Transformer bays	(factor of power loss)
Clothing Industries
Dry Cleaning	30-40
Dye Houses	40
Laundries - ironing	30-40
- washing	20-30
Heavy Manufacturing Industries
Engine and Motor Rooms	15-20
Forge Shops - cold	16
- hot	25-40
Foundries - moulding	40-50
Pouring and Core Room	60-70
Furnace Rooms	(factor of heat loss)
Galvanising Shops	12-20
Heat Treatments	30-40
Machine Shops	6-10
Rolling Mills	30-40
General Industries
Motor Garages	10-12
Light Manufacturing	10-12
Warehouses	4-8

T diff Exhaust k (C)	Effective Stack Height	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	1.5
	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	1.5
	6	0.61	0.96	1.32	1.67
	9	0.75	1.1	1.46	1.81
	12	0.86	1.22	1.57	1.93
	15	0.97	1.32	1.68	2.03
9	3	0.53	0.88	1.24	1.59
	6	0.75	1.1	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 ventridge throat sizes.