Explosion Proof Fans and Spark Resistant Construction
Knape Associates supplies explosion proof fans for Class I and Class II areas in AMCA Type A, B and C spark resistant construction, with motors rated for the classification.
We carry several manufacturer lines rather than one, so the selection is made against your airstream, your service conditions and your delivery date instead of against a single catalog.
Have questions? Need a fan quote?
AMCA Type A, B and C Spark Resistant Construction: What Each Type Requires
| Type | Construction | Specified when |
|---|---|---|
| A | Every part in contact with the airstream is non-ferrous: housing, wheel, inlet cone and fasteners. The steel shaft is sheathed or replaced with monel. | The airstream itself carries the flammable gas, vapor or dust |
| B | Non-ferrous wheel, plus a non-ferrous rub ring where the shaft passes through the housing. | The wheel is the contact risk. The common industrial specification |
| C | Non-ferrous inlet cone and rub ring. The inlet takes any contact first. | Contact is incidental and limited to the inlet |
The AMCA type is not assigned by the area classification. NEC Articles 500 through 505 set the motor by class, division and group. AMCA 99-0401 sets the fan construction, and that decision follows the airstream and the authority having jurisdiction.
A submittal that derives the construction type from the division alone is the one that gets questioned.
The motor carries the rating, so a substitute motor can void it. If a fan is being re-motored or rebuilt, send us the existing nameplate before the order.
Explosion Proof Axial, Centrifugal, Inline and Wall Mounted Fan Types
Spark resistant construction is available across the fan types below. The airflow, the static pressure and the mounting decide which one fits. Where the motor cannot sit in the gas stream, a bifurcated housing or a belt drive moves it out.
| Fan type | Hazardous service it suits |
|---|---|
| Tube axial fans | In-duct exhaust at moderate static pressure |
| Vane axial fans | Higher static pressure in the same duct diameter |
| Bifurcated fans | Motor held outside the airstream for hot or contaminated gas |
| Propeller and wall fans | Through-wall ventilation at low static pressure |
| Panel and box fans | Wall mounted general area ventilation |
| Centrifugal fans | Ducted exhaust where static pressure is the constraint |
| Utility sets | Roof or grade mounted exhaust with the motor out of the airstream |
| Pressure blowers | High pressure duties such as purge and combustion air |
| Plenum fans | Unhoused service inside a cabinet or plenum |
| Mixed flow fans | Axial footprint with centrifugal pressure |
| Man coolers | Spot cooling for personnel in a classified area |
| FRP fans | Corrosive exhaust where coated steel will not last |
On a retrofit, the existing opening and duct connection usually narrow this list before anything else does. Send the dimensions with the classification and we will work inside them.
Explosion Proof Fan Lines Knape Represents
Knape is a distributor, not a factory. We hold lines from several manufacturers that build spark resistant construction, so the fan is selected against your conditions rather than against one factory’s range.
Industrial Air Technology builds a spark resistant fan and blower line in Type A, B and C construction. Hartzell Air Movement offers spark resistant and leak resistant construction, explosion-proof motors, and non-sparking construction to USCG standard for marine and offshore work. Loren Cook publishes a spark resistant product guide covering its centrifugal and axial range.
When one line cannot hold the delivery date, the selection moves to one that can. On a turnaround, that is usually the constraint that decides the order.
Related Hazardous Location Ventilation and Heating Equipment
Ventilation is one part of a classified area. We supply the rest of it.
| Equipment | Where it fits |
|---|---|
| Explosion proof actuator | Damper control in a classified area |
| Explosion-proof heating | Space heating inside the classified envelope |
| Explosion proof duct heaters | Heating the supply air into a classified space |
| Explosion proof immersion heater | Process and tank heating in hazardous service |
| Industrial Air Technology | The spark resistant fan and blower line |
| HVAC oil and gas | Process area ventilation and control room pressurization |
| Offshore HVAC | Platforms and rigs |
| Corrosive air movement equipment | Where the airstream attacks the fan as well as ignites |