BLOWERSBUYING GUIDE

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BLOWERS A ThomasNet Buying Guide

Blowers are mechanical or electro-mechanical devices used

to induce gas flow through ducting electronics chassis

process stacks etc--wherever flow is needed for

exhausting aspirating cooling ventilating conveying and

so on See also Fans Key specifications include intended

application blower type port design as well as the

parameters of flow capacity electrical ratings and

dimensions Blowers cool electronic enclosures induce drafts in boilers increase airflow on engines and

are configured in a variety of designs such as centrifugal flow or rotary lobe styles Motors usually drive

blowers though they can be powered by other means such as engines Often used interchangeably with

ldquoFansrdquo blowers are defined by the ASME as having a ratio of discharge pressure over suction pressure

between 111 and 12 while fans are defined as anything below this ratio and compressors are defined

as anything above it Some makers of portable fans refer to their units as blowers even if they do not

necessarily conform to the ASME distinction which applies to permanently installed industrial process

equipment Another kind of blower is the mobile or hand held device used for moving fallen leaves

Types of Blowers

Centrifugal Blowers Centrifugal blowers use high speed impellers or blades to impart velocity to air or other gases They can

be single or multi-stage units Like fans centrifugal blowers offer a number of blade orientations

including backward curved forward curved and radial Blowers can be multi- or variable speed units

They are usually driven by electric motors

often through a belt and sheave

arrangement but some centrifugal blowers

are directly coupled to drive motors Fan

speed can be changed to vary flow rates by

resizing sheaves using variable speed drives

etc but dampers are even more common as

a means of adjusting flow Fan affinity laws

dictate that a percent reduction in speed will

produce a like reduction in flow

Positive Displacement Blowers Positive Displacement blowers are similar in principle

to positive displacement pumps in that they use

mechanical means to squeeze fluid and thereby

increase pressure andor velocity Centrifugal designs

on the other hand impart velocity and pressure to

media by flinging them outward with impellers

Among positive displacement blowers the Roots or

rotary lobe type is common which uses two counter-

rotating lobed rotors to move fluid through the

blower much the way a gear pump moves oil

or other viscous liquids A cutaway blower

(below) shows one of the two rotors Positive

displacement lowers are often driven by direct-

coupled electric motors but they can be driven

by gas engines hydraulic motors etc in

unusual circumstances

Applications and Industries Centrifugal blowers are routinely used for combustion air supplies on cooling and drying systems for

fluid bed aerators with air conveyor systems for dust control etc Positive displacement blowers are

also used in pneumatic conveying and for sewage aeration filter flushing and gas boosting as well as

for moving gases of all kinds in the petrochemical industries

Centrifugal blowers are often built as close-coupled units meaning that the impeller wheel is not

supported by independent bearings but is cantilevered on an extension of the motor shaft and relies on

the motor bearings for support Close coupled mounting dispenses with the need for shaft couplings

Other arrangements cantilever the wheel off pillow block bearings such as designs that use belt drives

Blowers are sometimes stepped up from motor speed but are just as often stepped down or 11 ratios

The centrifugal blower outlet is usually arranged tangentially to impeller rotation and can be specified

usually in one of eight angular orientations with respect to the direction of the blower wheel rotation

making for sixteen possible arrangements of rotation and discharge orientation in 45 degree

increments Industry practice specifies impeller rotation either as CW or CCW as viewed from the drive

endmdashusually the motor endmdashof the unit

On smaller centrifugal blowers the housings can often be rotated through a full circle to permit any

angle of discharge

Rotary lobe blowers usually orient the input and output ports in line due to the design of the blower

Considerations Blowers are specified on the basis of pressure and flow rate As mentioned the ratio of system inlet

pressure and outlet pressure determines whether a fan or blower should be picked according to strict

definition although the terms are sometimes used synonymously Where higher pressures are needed

a designer may have to select a positive displacement machine over a centrifugal type Manufacturers

often publish fan performance curves or similar charts which help the designer to narrow his choice to

one or several models that

match requirements The

chart at right is fairly

common among blower

makers

System designers decide

the flow rate and pressure

needed and add additional

capacity to overcome

frictional losses in the

systems due to ducting

piping etc They can select

materials or coatings that

combat the effects of

corrosive media

Most blower capacity charts are based on standard temperature and pressure ie 70 degree F air at sea

level Where design conditions are different designers can apply correction factors which size the

blowers based on actual conditions

Important Attributes

Blower Type Checking centrifugal or positive displacement will separate search results into the two main blower

types Another few boxes can further refine the blower type that is picking rotary lobe rotary vane

Roots etc will narrow the results to positive displacement machines of these specific types There are

some non-industrial blowers which can be selected here as well leafblowers for instance

Blades Backward inclined and forward curved refer to centrifugal blowers and relate to the orientation of the

blades Forward curving blades move larger quantities of air than backward inclined blades do albeit at

lower pressures Backward inclined blades tend toward higher efficiencies Radial blades also relate to

centrifugal units representing simple paddle type construction with no backward or forward

inclinations They can be self-cleaning an important consideration for blowers handling dirty media

Airfoil blades also apply to centrifugal blowers

Flow Capacity This attribute is important when selecting a blower Blower capacity is generally rated in cubic feet per

minute

Maximum Operating Pressure Along with flow capacity this is another important attribute in blower selection Manufactures generally

rate this item in inches of water column

Port Design The choices of duct flange round and rectangular apply to both inlet and outlet ports as these are

where the blowers attach to ductwork or piping and in the case of replacement blowers need to match

existing plumbing

Features Here the blower specifier can select important blower options such as diffusers louvers dampers etc

which can be used to adjust blower flow Other options could include variable speed motors to

accomplish the same thing

Related Product Categories Fans are mechanical or electro-mechanical devices used to create air flow

AirGas Compressors are mechanical assemblies that pressurize air or gas usually through

mechanical means like pistons

Air Flow Dampers are mechanical valve-like devices within closed air flow systems such as

ductwork used for controlling or regulating the current of air

Vibration Dampening Mounts are mechanical devices used to isolate vibrating machinery from

their supporting foundations

Resources

General Centrifugal Fan Design httppowertechindustrialcomauPDFsPlant-Engineers-Fan-Design-Referencepdf Fans and Blowers httpwwwsaylororgsitewp-contentuploads201109Chapter-35-Fans-Blowerspdf Fan Balancing httpwwwahrinetorgApp_ContentahrifilesGuidelinesAHRI20Guideline20G2028I-P29-2011pdf Trade Associations httpswwwamcaorg httpwwwahrinetorg

BLOWERS A ThomasNet Buying Guide

Blowers are mechanical or electro-mechanical devices used

to induce gas flow through ducting electronics chassis

process stacks etc--wherever flow is needed for

exhausting aspirating cooling ventilating conveying and

so on See also Fans Key specifications include intended

application blower type port design as well as the

parameters of flow capacity electrical ratings and

dimensions Blowers cool electronic enclosures induce drafts in boilers increase airflow on engines and

are configured in a variety of designs such as centrifugal flow or rotary lobe styles Motors usually drive

blowers though they can be powered by other means such as engines Often used interchangeably with

ldquoFansrdquo blowers are defined by the ASME as having a ratio of discharge pressure over suction pressure

between 111 and 12 while fans are defined as anything below this ratio and compressors are defined

as anything above it Some makers of portable fans refer to their units as blowers even if they do not

necessarily conform to the ASME distinction which applies to permanently installed industrial process

equipment Another kind of blower is the mobile or hand held device used for moving fallen leaves

Types of Blowers

Centrifugal Blowers Centrifugal blowers use high speed impellers or blades to impart velocity to air or other gases They can

be single or multi-stage units Like fans centrifugal blowers offer a number of blade orientations

including backward curved forward curved and radial Blowers can be multi- or variable speed units

They are usually driven by electric motors

often through a belt and sheave

arrangement but some centrifugal blowers

are directly coupled to drive motors Fan

speed can be changed to vary flow rates by

resizing sheaves using variable speed drives

etc but dampers are even more common as

a means of adjusting flow Fan affinity laws

dictate that a percent reduction in speed will

produce a like reduction in flow

Positive Displacement Blowers Positive Displacement blowers are similar in principle

to positive displacement pumps in that they use

mechanical means to squeeze fluid and thereby

increase pressure andor velocity Centrifugal designs

on the other hand impart velocity and pressure to

media by flinging them outward with impellers

Among positive displacement blowers the Roots or

rotary lobe type is common which uses two counter-

rotating lobed rotors to move fluid through the

blower much the way a gear pump moves oil

or other viscous liquids A cutaway blower

(below) shows one of the two rotors Positive

displacement lowers are often driven by direct-

coupled electric motors but they can be driven

by gas engines hydraulic motors etc in

unusual circumstances

Applications and Industries Centrifugal blowers are routinely used for combustion air supplies on cooling and drying systems for

fluid bed aerators with air conveyor systems for dust control etc Positive displacement blowers are

also used in pneumatic conveying and for sewage aeration filter flushing and gas boosting as well as

for moving gases of all kinds in the petrochemical industries

Centrifugal blowers are often built as close-coupled units meaning that the impeller wheel is not

supported by independent bearings but is cantilevered on an extension of the motor shaft and relies on

the motor bearings for support Close coupled mounting dispenses with the need for shaft couplings

Other arrangements cantilever the wheel off pillow block bearings such as designs that use belt drives

Blowers are sometimes stepped up from motor speed but are just as often stepped down or 11 ratios

The centrifugal blower outlet is usually arranged tangentially to impeller rotation and can be specified

usually in one of eight angular orientations with respect to the direction of the blower wheel rotation

making for sixteen possible arrangements of rotation and discharge orientation in 45 degree

increments Industry practice specifies impeller rotation either as CW or CCW as viewed from the drive

endmdashusually the motor endmdashof the unit

On smaller centrifugal blowers the housings can often be rotated through a full circle to permit any

angle of discharge

Rotary lobe blowers usually orient the input and output ports in line due to the design of the blower

Considerations Blowers are specified on the basis of pressure and flow rate As mentioned the ratio of system inlet

pressure and outlet pressure determines whether a fan or blower should be picked according to strict

definition although the terms are sometimes used synonymously Where higher pressures are needed

a designer may have to select a positive displacement machine over a centrifugal type Manufacturers

often publish fan performance curves or similar charts which help the designer to narrow his choice to

one or several models that

match requirements The

chart at right is fairly

common among blower

makers

System designers decide

the flow rate and pressure

needed and add additional

capacity to overcome

frictional losses in the

systems due to ducting

piping etc They can select

materials or coatings that

combat the effects of

corrosive media

Most blower capacity charts are based on standard temperature and pressure ie 70 degree F air at sea

level Where design conditions are different designers can apply correction factors which size the

blowers based on actual conditions

Important Attributes

Blower Type Checking centrifugal or positive displacement will separate search results into the two main blower

types Another few boxes can further refine the blower type that is picking rotary lobe rotary vane

Roots etc will narrow the results to positive displacement machines of these specific types There are

some non-industrial blowers which can be selected here as well leafblowers for instance

Blades Backward inclined and forward curved refer to centrifugal blowers and relate to the orientation of the

blades Forward curving blades move larger quantities of air than backward inclined blades do albeit at

lower pressures Backward inclined blades tend toward higher efficiencies Radial blades also relate to

centrifugal units representing simple paddle type construction with no backward or forward

inclinations They can be self-cleaning an important consideration for blowers handling dirty media

Airfoil blades also apply to centrifugal blowers

Flow Capacity This attribute is important when selecting a blower Blower capacity is generally rated in cubic feet per

minute

Maximum Operating Pressure Along with flow capacity this is another important attribute in blower selection Manufactures generally

rate this item in inches of water column

Port Design The choices of duct flange round and rectangular apply to both inlet and outlet ports as these are

where the blowers attach to ductwork or piping and in the case of replacement blowers need to match

existing plumbing

Features Here the blower specifier can select important blower options such as diffusers louvers dampers etc

which can be used to adjust blower flow Other options could include variable speed motors to

accomplish the same thing

Related Product Categories Fans are mechanical or electro-mechanical devices used to create air flow

AirGas Compressors are mechanical assemblies that pressurize air or gas usually through

mechanical means like pistons

Air Flow Dampers are mechanical valve-like devices within closed air flow systems such as

ductwork used for controlling or regulating the current of air

Vibration Dampening Mounts are mechanical devices used to isolate vibrating machinery from

their supporting foundations

Resources

General Centrifugal Fan Design httppowertechindustrialcomauPDFsPlant-Engineers-Fan-Design-Referencepdf Fans and Blowers httpwwwsaylororgsitewp-contentuploads201109Chapter-35-Fans-Blowerspdf Fan Balancing httpwwwahrinetorgApp_ContentahrifilesGuidelinesAHRI20Guideline20G2028I-P29-2011pdf Trade Associations httpswwwamcaorg httpwwwahrinetorg

Positive Displacement Blowers Positive Displacement blowers are similar in principle

to positive displacement pumps in that they use

mechanical means to squeeze fluid and thereby

increase pressure andor velocity Centrifugal designs

on the other hand impart velocity and pressure to

media by flinging them outward with impellers

Among positive displacement blowers the Roots or

rotary lobe type is common which uses two counter-

rotating lobed rotors to move fluid through the

blower much the way a gear pump moves oil

or other viscous liquids A cutaway blower

(below) shows one of the two rotors Positive

displacement lowers are often driven by direct-

coupled electric motors but they can be driven

by gas engines hydraulic motors etc in

unusual circumstances

Applications and Industries Centrifugal blowers are routinely used for combustion air supplies on cooling and drying systems for

fluid bed aerators with air conveyor systems for dust control etc Positive displacement blowers are

also used in pneumatic conveying and for sewage aeration filter flushing and gas boosting as well as

for moving gases of all kinds in the petrochemical industries

Centrifugal blowers are often built as close-coupled units meaning that the impeller wheel is not

supported by independent bearings but is cantilevered on an extension of the motor shaft and relies on

the motor bearings for support Close coupled mounting dispenses with the need for shaft couplings

Other arrangements cantilever the wheel off pillow block bearings such as designs that use belt drives

Blowers are sometimes stepped up from motor speed but are just as often stepped down or 11 ratios

The centrifugal blower outlet is usually arranged tangentially to impeller rotation and can be specified

usually in one of eight angular orientations with respect to the direction of the blower wheel rotation

making for sixteen possible arrangements of rotation and discharge orientation in 45 degree

increments Industry practice specifies impeller rotation either as CW or CCW as viewed from the drive

endmdashusually the motor endmdashof the unit

On smaller centrifugal blowers the housings can often be rotated through a full circle to permit any

angle of discharge

Rotary lobe blowers usually orient the input and output ports in line due to the design of the blower

Considerations Blowers are specified on the basis of pressure and flow rate As mentioned the ratio of system inlet

pressure and outlet pressure determines whether a fan or blower should be picked according to strict

definition although the terms are sometimes used synonymously Where higher pressures are needed

a designer may have to select a positive displacement machine over a centrifugal type Manufacturers

often publish fan performance curves or similar charts which help the designer to narrow his choice to

one or several models that

match requirements The

chart at right is fairly

common among blower

makers

System designers decide

the flow rate and pressure

needed and add additional

capacity to overcome

frictional losses in the

systems due to ducting

piping etc They can select

materials or coatings that

combat the effects of

corrosive media

Most blower capacity charts are based on standard temperature and pressure ie 70 degree F air at sea

level Where design conditions are different designers can apply correction factors which size the

blowers based on actual conditions

Important Attributes

Blower Type Checking centrifugal or positive displacement will separate search results into the two main blower

types Another few boxes can further refine the blower type that is picking rotary lobe rotary vane

Roots etc will narrow the results to positive displacement machines of these specific types There are

some non-industrial blowers which can be selected here as well leafblowers for instance

Blades Backward inclined and forward curved refer to centrifugal blowers and relate to the orientation of the

blades Forward curving blades move larger quantities of air than backward inclined blades do albeit at

lower pressures Backward inclined blades tend toward higher efficiencies Radial blades also relate to

centrifugal units representing simple paddle type construction with no backward or forward

inclinations They can be self-cleaning an important consideration for blowers handling dirty media

Airfoil blades also apply to centrifugal blowers

Flow Capacity This attribute is important when selecting a blower Blower capacity is generally rated in cubic feet per

minute

Maximum Operating Pressure Along with flow capacity this is another important attribute in blower selection Manufactures generally

rate this item in inches of water column

Port Design The choices of duct flange round and rectangular apply to both inlet and outlet ports as these are

where the blowers attach to ductwork or piping and in the case of replacement blowers need to match

existing plumbing

Features Here the blower specifier can select important blower options such as diffusers louvers dampers etc

which can be used to adjust blower flow Other options could include variable speed motors to

accomplish the same thing

Related Product Categories Fans are mechanical or electro-mechanical devices used to create air flow

AirGas Compressors are mechanical assemblies that pressurize air or gas usually through

mechanical means like pistons

Air Flow Dampers are mechanical valve-like devices within closed air flow systems such as

ductwork used for controlling or regulating the current of air

Vibration Dampening Mounts are mechanical devices used to isolate vibrating machinery from

their supporting foundations

Resources

General Centrifugal Fan Design httppowertechindustrialcomauPDFsPlant-Engineers-Fan-Design-Referencepdf Fans and Blowers httpwwwsaylororgsitewp-contentuploads201109Chapter-35-Fans-Blowerspdf Fan Balancing httpwwwahrinetorgApp_ContentahrifilesGuidelinesAHRI20Guideline20G2028I-P29-2011pdf Trade Associations httpswwwamcaorg httpwwwahrinetorg

Considerations Blowers are specified on the basis of pressure and flow rate As mentioned the ratio of system inlet

pressure and outlet pressure determines whether a fan or blower should be picked according to strict

definition although the terms are sometimes used synonymously Where higher pressures are needed

a designer may have to select a positive displacement machine over a centrifugal type Manufacturers

often publish fan performance curves or similar charts which help the designer to narrow his choice to

one or several models that

match requirements The

chart at right is fairly

common among blower

makers

System designers decide

the flow rate and pressure

needed and add additional

capacity to overcome

frictional losses in the

systems due to ducting

piping etc They can select

materials or coatings that

combat the effects of

corrosive media

Most blower capacity charts are based on standard temperature and pressure ie 70 degree F air at sea

level Where design conditions are different designers can apply correction factors which size the

blowers based on actual conditions

Important Attributes

Blower Type Checking centrifugal or positive displacement will separate search results into the two main blower

types Another few boxes can further refine the blower type that is picking rotary lobe rotary vane

Roots etc will narrow the results to positive displacement machines of these specific types There are

some non-industrial blowers which can be selected here as well leafblowers for instance

Blades Backward inclined and forward curved refer to centrifugal blowers and relate to the orientation of the

blades Forward curving blades move larger quantities of air than backward inclined blades do albeit at

lower pressures Backward inclined blades tend toward higher efficiencies Radial blades also relate to

centrifugal units representing simple paddle type construction with no backward or forward

inclinations They can be self-cleaning an important consideration for blowers handling dirty media

Airfoil blades also apply to centrifugal blowers

Flow Capacity This attribute is important when selecting a blower Blower capacity is generally rated in cubic feet per

minute

Maximum Operating Pressure Along with flow capacity this is another important attribute in blower selection Manufactures generally

rate this item in inches of water column

Port Design The choices of duct flange round and rectangular apply to both inlet and outlet ports as these are

where the blowers attach to ductwork or piping and in the case of replacement blowers need to match

existing plumbing

Features Here the blower specifier can select important blower options such as diffusers louvers dampers etc

which can be used to adjust blower flow Other options could include variable speed motors to

accomplish the same thing

Related Product Categories Fans are mechanical or electro-mechanical devices used to create air flow

AirGas Compressors are mechanical assemblies that pressurize air or gas usually through

mechanical means like pistons

Air Flow Dampers are mechanical valve-like devices within closed air flow systems such as

ductwork used for controlling or regulating the current of air

Vibration Dampening Mounts are mechanical devices used to isolate vibrating machinery from

their supporting foundations

Resources

General Centrifugal Fan Design httppowertechindustrialcomauPDFsPlant-Engineers-Fan-Design-Referencepdf Fans and Blowers httpwwwsaylororgsitewp-contentuploads201109Chapter-35-Fans-Blowerspdf Fan Balancing httpwwwahrinetorgApp_ContentahrifilesGuidelinesAHRI20Guideline20G2028I-P29-2011pdf Trade Associations httpswwwamcaorg httpwwwahrinetorg

inclinations They can be self-cleaning an important consideration for blowers handling dirty media

Airfoil blades also apply to centrifugal blowers

Flow Capacity This attribute is important when selecting a blower Blower capacity is generally rated in cubic feet per

minute

Maximum Operating Pressure Along with flow capacity this is another important attribute in blower selection Manufactures generally

rate this item in inches of water column

Port Design The choices of duct flange round and rectangular apply to both inlet and outlet ports as these are

where the blowers attach to ductwork or piping and in the case of replacement blowers need to match

existing plumbing

Features Here the blower specifier can select important blower options such as diffusers louvers dampers etc

which can be used to adjust blower flow Other options could include variable speed motors to

accomplish the same thing

Related Product Categories Fans are mechanical or electro-mechanical devices used to create air flow

AirGas Compressors are mechanical assemblies that pressurize air or gas usually through

mechanical means like pistons

Air Flow Dampers are mechanical valve-like devices within closed air flow systems such as

ductwork used for controlling or regulating the current of air

Vibration Dampening Mounts are mechanical devices used to isolate vibrating machinery from

their supporting foundations

Resources

General Centrifugal Fan Design httppowertechindustrialcomauPDFsPlant-Engineers-Fan-Design-Referencepdf Fans and Blowers httpwwwsaylororgsitewp-contentuploads201109Chapter-35-Fans-Blowerspdf Fan Balancing httpwwwahrinetorgApp_ContentahrifilesGuidelinesAHRI20Guideline20G2028I-P29-2011pdf Trade Associations httpswwwamcaorg httpwwwahrinetorg

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