Building Ventilation by Reversible Ventilators

By: Oleg Tetchel

The concept of venting smoke and heat was first outlined by Industrial Risk Insurers (IRI). Use of powered ventilation could eliminate the problems experienced with gravity vents. Specially designed roof mounted exhaust fans would mechanically vent heat and smoke under emergency fire conditions.

Buffalo Fan Co. engineers various models of Heat and Smoke Removal Power Roof Ventilators. These PRVs are especially designed, built and proven by independent test to meet the need of venting hot gases and smoke in the event of fire in commercial and industrial buildings, such as factories, warehouses, parking garages, shopping malls and department stores.

Type HS PRVs reliably extract large volumes of hot gases and smoke regardless of building configuration, location and weather conditions. They withstand high temperatures for long periods of time.

A reliable ventilation system that can operate during a fire is both vital and essential. It prevents smoke logging, allows people to escape quickly, minimizes damages to property and contents and enables firemen to attack the fire without hindrance. These power roof ventilators have the added advantage of providing normal day to day ventilation and in many cases can also be fitted with duct work for use in multi storey buildings.

In addition to the reliability and effectiveness of this powered ventilation concept, the use of HS PRVs to vent heat and smokes has these specific advantages:

* It is not dependent on air temperature differential or wind direction and velocity to create air movement.
* It does not rely on heat itself to activate the system. Smoke detectros and water-flow devices also may be utilized.
* It provides for normal ventilation needs of the building as well as for emergency use as a vital component of the fire protection system.
* There is ususally a substantial cost saving in the purchase and installation of the dual purpose system.
* Maintenance cost for building and equipment is frequently reduced.
* The system can be effectively used in multi storied and below grade building areas.
* Reliability of operations is assured because powered ventilators are in daily use and receive regular inspection and maintenance.

The unique Type HS power roof ventilators provide a solution for emergency heat and smoke venting that is dependable under the most extreme circumstances.

All critical components of HS PTV that exposed to the airstream are ferrous construction to withstand high temperature conditions. These heavy gauge materials prevent warping of fan parts and malfunction at high temperatures. This also insures years of trouble-free service in normal daily operation of the PRV.

The wind shroud is made of galvanized steel; an exterior finish coat of epoxy can be specified. Painted parts are coated with epoxy to provide a protective coating rated excellent for hardness, impact resistance, adhesion and chemical resistance.

Belt and bearings are protected from the air stream by enclosing them in a ventilated tube. Design of HS fan incorporates a heat slinger/impeller. It isolates the fan bearings from damaging heat and draws cooler outside air through the motor compartment and over the belt and bearings. A spring loade, fusible link activated device automatically opens dampers when temperature at the fan reaches 165 F. Thei enables the fan to function as a gravity ventilator prior to powered operation.

A safety disconnect switch is mounted to the PRV housing. This feature protects maintenance personnel from an accidental fan start when the unit is being serviced.

Type HC Power Roof Ventilators have been tested to operate:

- conituously at 650 F;
- 3 Hours at 800 F;
- 1.5 Hours at 1000 F;
- 1/2 Hour at 1,200 F.

Additional information can be found at the Buffalo Fan company web site

Oleg Tchetchel
Industrial Plants Air System Engineer
Buffalo Fan Co.

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Oleg Tchetchel Industrial Plants Air System Engineer Buffalo Fan Co.

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