Outdoor Blower Casing

Technical Field:

The inventions described herein are in the field of outdoor blower casings. Background Art:

Vapor intrusion is a process by which chemicals (e.g., volatile organic compounds (VOCs), radon, etc.) in soil and/or groundwater migrate to or seep into building spaces. These vapors can be released from contaminated soil and/or groundwater underneath buildings. The vapors may enter basements, crawl spaces, rooms and/or other areas of a building or structure. As a result of vapor intrusion, the air within buildings may become contaminated thereby exposing individuals within the buildings to contamination.

Generally, VOCs are man-made chemical compounds that have a high vapor pressure and low water solubility. VOCs can be used and produced in the manufacture of fuels, paints, pharmaceuticals, and refrigerants. They are typically included in industrial solvents, paint thinners, dry cleaning fluids (e.g. tetrachloroethylene), fuel oxygenates (e.g. MTBE), and by-products produced by chlorination in water treatment. VOC contaminants can travel with, or on top of, groundwater. They can easily become gaseous and migrate through soil. As a result of negative pressures that are induced by various building designs and heating, ventilating and air conditioning (HVAC) operations, VOCs can be drawn from the soil and/or groundwater and into occupied spaces of buildings where human exposure can occur.

Radon is a Class A carcinogen that, according to scientific studies, can cause harmful effects on human lung tissue. Like VOCs, radon can be drawn into buildings from underlying soil and/or groundwater by the negative pressures that are associated with the structure and HVAC operations of buildings. Negative pressures can be caused by factors such as temperature differentials, where warm air exits an upper portion of a building (induces a stack effect). Negative pressures can also be caused by wind and exhaust appliances (e.g. kitchen vents). These forces can draw in VOC and/or radon gases through cracks, conduit openings and other pathways in slabs, sub-slabs or other flooring or foundation features of buildings.

There are many buildings constructed over contaminated soils. The soil and or ground water may be contaminated with one or more man-made chemical compounds or naturally occurring radon, methane or sulfur. Hence there is a need to effectively prevent the hazardous vapors and naturally occurring gases from entering into said buildings.

An effective way to prevent soil vapors from entering into a building is to induce a low pressure below the building and exhaust the soil gas contaminants from underneath the building using a blower. This is particularly effective when the building is built on a slab. The blower induces a negative pressure underneath the slab relative to the air pressure inside the building. The reduced pressure underneath the slab prevents the gaseous contaminants in the soil or groundwater from entering the building. The soil vapors are removed by the blower and conveyed by a duct to above the building where they can be safely exhausted to the outdoor environment. The blower used to do the exhausting, therefore, may be mounted outdoors on the rooftop or side of the building and hence be exposed to the elements (e.g. rain, snow etc.). The soil vapors exhausted by the blower may be flammable. Hence the blower must be suitable for handling potentially explosive air/vapor mixtures.

Figure 5 is right view of a vertical longitudinal cross section of a prior art blower system 500 for sub-slab ventilation. The system is suitable for potentially explosive vapors. It is also suitable for outdoor use. The prior art system is based in part on figure 3 of US2013/0101404, "Enclosure and Manifold for Adapting Nonconforming fans for Use in Harsh or Wet Environments" (Barr). Figure 5 is also based in part on Obar Systems Inc. model GBR 76UD with a Nautilair™ variable speed blower. The prior art system comprises an electric motor 504 with integral cooling fan 546, a centrifugal impeller 532 mounted inside an impeller casing 534, a vertical outlet duct 516, a vertical inlet duct 512, a weather tight enclosure 506, and a junction box 582 adapted to feed electric power from a conduit 584 into the enclosure and to the motor. The impeller casing may comprise an impeller cover 535 defining an impeller cavity 536 adapted to house said impeller. The electric motor comprises an armature 558 driving an arbor 556. The arbor is connected to the centrifugal impeller through an arbor hole 557 in the impeller casing. A centrifugal cooling fan 546 is attached to the rear of the armature. A shell 542 surrounds the armature and cooling fan. A plurality of inlet vents 543 are provided on the front face of the shell. A plurality of outlet vents 544 are provided around the rear circumference of the shell. The electric motor is mounted to the impeller casing by one or more motor mounts 548. The motor mounts each comprise a standoff so that there is a gap 505 between the front of the shell and the rear of the impeller casing. In operation, the motor drives the centrifugal impeller. Contaminated air 524 is drawn up from beneath a building sub slab. It is directed into the center of the centrifugal impeller by a box manifold 564. It is then pressurized by the centrifugal impeller and flows out 526 of the vertical outlet duct and into the outdoor environment some distance above the enclosure. The contaminated air may have a high dew point since it is exhausted from the ground below the building. This may cause condensation in the impeller casing or the outlet duct, especially in cold weather. Thus, an outlet condensate bypass 522 is provided to allow water dripping down the outlet duct to flow from the bottom of the outlet duct to the top of the inlet duct where it may then continue to flow back down to the sub slab region. A similar condensate bypass 544 may be provided in the bottom of the impeller casing.

While the electric motor is running, the cooling fan draws cooling air 552 into the armature through the gap between the front of the shell and the back of the impeller casing. The cooling air flows over the armature and other motor components and is warmed. Then it flows through the cooling fan and out 554 through the vents in the motor shell. The enclosure, however, is sealed against the outdoor environment to protect against the elements 562. Thus, the cooling air is trapped within the enclosure. The temperature in the enclosure rises until there is enough temperature gradient across the enclosure to conduct the heat of the motor to the outdoor ambient air. The temperature in the enclosure, therefore, can get quite high, especially in warm weather. The resultant increased temperature within the enclosure can cause premature motor failure. Thus, there is a need for a blower casing that is weather resistant and will have adequate cooling of the electric motor in an outdoor environment.

Disclosure of Invention:

The disclosure of the invention is a guide to understanding the invention. It does not necessarily describe the most generic embodiment.

Figure 1 is a lower left front view of a blower casing 100. The orientations front 101, rear 103, top 111, and bottom 113 are indicated. Figure 3 is a right view of a vertical longitudinal cross section of the blower casing 100. Reference will be made to items in both figure 1 and figure 3. Three-digit item numbers beginning with a "1" are initially presented in figure 1. Three-digit item numbers beginning with a "3" are initially presented in figure 3.

The blower casing is adapted to house, in an outdoor environment 105, an impeller, an electric motor adapted to drive said impeller, and a cooling fan adapted to cool said electric motor. The impeller, electric motor and cooling fan may be similar in design to the ones illustrated in figure 5. The blower casing comprises: a) an impeller casing 102, said impeller casing comprising: i) a blower inlet 104 adapted to feed contaminated air into said

impeller; ii) an impeller cover 108 defining an impeller cavity 302 adapted to

house said impeller; and iii) a blower outlet 106 adapted to exhaust said contaminated air to said outdoor environment; b) an electric motor casing 122, said electric motor casing comprising: i) a motor cover 128 defining a motor cavity 304 adapted to house said electric motor; and ii) a downward facing cooling air inlet 124 adapted to convey cooling air from said outdoor environment into said motor cavity; c) a blower baffle 344 between said motor cavity and said impeller cavity forming a barrier between said motor cavity and said impeller cavity, said blower baffle comprising an arbor hole 346 adapted to admit an arbor of said electric motor from said motor cavity into said impeller cavity wherein said arbor connects said electric motor to said impeller; d) a cooling fan casing 142, said cooling fan casing comprising: i) a cooling fan cover 144 defining a cooling fan cavity 306 adapted to house said cooling fan; and ii) a downward facing cooling air outlet 146 adapted to convey warmed cooling air from said cooling fan cavity to said outdoor environment; and e) a fan baffle between said motor cavity and said cooling fan cavity, said fan baffle 308 comprising a motor shell aperture 312 adapted to form a seal with a shell of said electric motor such that said cooling air will pass from said motor cavity, through said motor, and into said cooling fan cavity wherein:

f) said cooling fan casing, said electric motor casing and said impeller casing are joined together to form a weather tight seal.

The blower casing is designed to provide a weather resistant housing for an electric motor with integral cooling fan and centrifugal impeller similar to those shown in figure 5. The impeller casing, electric motor casing and cooling fan casing are designed to be made by casting a light weight, weather resistant material, such as an aluminum or other nonferrous alloy. The impeller casing, electric motor casing, fan baffle and cooling fan casing may be joined together by weather tight seals using one or more longitudinal mounting bolts 148 that pass therethrough. The blower casing may be coated with a coating that is resistant to or reflective of heat absorption and/or corrosion. A reflective while polymer or anodized coating may be suitable. The impeller casing 102 comprises a blower inlet 104, an impeller cover 108 and a blower outlet 106. The blower inlet may be horizontal. The blower outlet may be vertical and upwardly directed. The inside diameter of the blower inlet may be tapered 358 at an angle of about 10 degrees. It was found by experiment that this reduced blower power by about 20% relative to the prior art box manifold 564 (figure 5).

The impeller cover 108 may form a volute impeller cavity 302. The volute impeller cavity helps direct the air leaving the centrifugal impeller to a single vertical outlet direction.

An outlet condensate tap 112 may be provided in the bottom 113 of the blower outlet. This can connect to an upper drain tube 602 (figure 6) for returning condensed water to the top of the blower inlet. The water may then flow down an inlet duct (not shown) that coveys contaminated air from below the sub slab of a building to the blower inlet.

An impeller condensate tap 116 may be provided in the bottom 115 of the impeller cover so that a lower drain tube 624 (figure 6) may be provided to return condensed water to the blower inlet. This water will then also flow down the inlet duct.

The electric motor casing 122 comprises a motor cover 128 forming a motor cavity 304 for containing the electric motor. The electric motor casing may also comprise the blower baffle 344 on the front side of the motor cover forming a barrier between said motor cover and said impeller casing. Thus, the blower baffle and the motor casing may be a unitary piece.

The electric motor casing may comprise one or more longitudinal mounting bolt stanchions 348, a downward facing cooling air inlet 124, and a junction box 126 for connecting to an electrical conduit and housing control circuitry for the electric motor.

The blower baffle may comprise an arbor hole 346 to allow for an arbor (not shown) of the electric motor to pass there through and drive a centrifugal impeller (not shown) in the impeller housing.

The blower baffle may comprise one or more motor mounts 322 for mounting the electric motor thereupon. The motor mounts may each comprise a standoff 323 to provide a gap between the front of the electric motor and the back of the blower baffle. This will allow cooling air that is drawn in through the downward facing cooling air inlet to flow into the internal portions of the armature of the electric motor.

A conduit knockout 134 may be provided to connect to an electrical conduit (not shown) providing power to the motor. A downward facing entrance 132 may be provided in the cooling air inlet to provide a mount for an air filter (not shown).

A fan baffle 308 may be provided at the rear of the electric motor casing. The fan baffle may comprise a motor shell aperture 312 for forming a seal with a shell of the electric motor. The fan baffle forces cooling air to flow through the armature of the electric motor and not around the shell of the motor. The diameter 314 of the motor casing aperture is selected to match the outer diameter of the motor shell. Other shapes for the aperture may be provided to correspond to different motor shell designs. This allows different motors to be used in the same blower casing or the dimensions of the casing may be adapted to function with other motors with similar properties. The cooling fan casing 142 comprises a fan cover 144 which may form a volute fan cavity 306 for containing the fan. The cooling fan casing may also comprise one or more downward facing cooling air outlets 146. The volute in the cooling fan cavity helps keep a radially uniform flow going through the fan while providing one or more cooling air outlets pointing in a downward direction. The cooling air inlets and cooling air outlets face down so that the entrance of rain water or other precipitation is minimized. An air filter and/or mist separator comprising a baffle or hydrophobic material in the cooling air inlet reduces dust and/or rain splash accumulation in the electric motor. A filter and/or mist separator may also be provided in the cooling air outlet. When assembled, the longitudinal mounting bolts pass from the rear of the cooling fan casing, through the fan baffle, through the mounting bolt stanchions of the electric motor casing and into the impeller casing. Threads may be provided in the impeller casing for the mounting bolts to engage. When the mounting bolts are tightened, a weather tight seal is made between the components of the blower casing. Additional sealant, such as an elastomeric gasket, may be provided between the components. Alternative attachment means may be provided between the components, such as hand operated quick

disconnects.

Brief Description of Drawings: Figure 1 is a lower left front view of a blower casing.

Figure 2 is an upper right front view of the blower casing of figure 1.

Figure 3 is a right view of a vertical longitudinal cross section of the blower casing of figure 1.

Figure 4 is a rear view of a vertical latitudinal cross section of the blower casing of figure 1. Figure 5 is a right view of a vertical longitudinal cross section of a prior art sub slab blower system.

Figure 6 is a lower left front view of an alternative blower casing.

Figure 7 is an upper left front view of an alternative blower casing.

Figure 8 is an upper right front view of the blower casing of figure 7. Figure 9 is a right view of a vertical longitudinal cross section of the blower casing of figure 7.

Figure 10 is a rear view of a vertical latitudinal cross section of the blower casing of figure 7.

Figure 11 is a right view of a vertical longitudinal cross section of an enclosed motor cooling system.

Mode(s) for Carrying Out the Invention:

Non-limiting exemplary embodiments are described herein. Any individual features may be combined with other features as required by different applications for at least the benefits described herein. As used herein, the term "about" means plus or minus 10% of a given value unless specifically indicated otherwise.

As used herein, the term "shaped" means that an item has the overall appearance of a given shape even if there are minor variations from the pure form of said given shape.

As used herein, the term "generally" when referring to a shape means that an ordinary observer will perceive that an object has said shape even if there are minor variations from said shape.

As used herein, relative orientation terms, such as "top", "bottom", "front", "rear", "left", "right", "vertical", "horizontal", "distal" and "proximal" are defined with respect to an initial presentation of an object and will continue to refer to the same portion of an object even if the object is subsequently presented with an alternative orientation, unless otherwise noted.

Blower casing

Figure 2 is an upper right front view of the blower casing 100 of figure 1. The impeller casing 102, electric motor casing 122 and cooling fan casing 142 can be seen. The junction box 126 can also be seen. A cover plate 202 may be provided on the right side of the junction box to protect the control systems and electrical connections therein. The control systems may comprise one or more of a 0-lOV electronic controller for remote control, a potentiometer for manual control, or a mechanical controller that would be set by a user in the junction box. The cover plate may comprise control items, such as switches, and display means, such as a touch screen. Electrical connections may be provided such as for an internet connection. Wireless communication means, such as a wireless LAN, may be provided.

Figure 3 is a right view of a vertical longitudinal cross section of the blower casing 100 of figure 1. The cross section is through about the midpoint of the arbor hole 346. Most of the items of figure 3 have been described above. In addition, the general flow of the cooling air 315, 316 is illustrated.

An exemplary blower inlet 104 is illustrated in figure 3. The blower inlet internal diameter 352 is about 76 mm. The blower inlet length 356 is about 72 mm. The diameter 354 of the impeller inlet 355 is about 50 mm. This provides an inlet taper 358 of about 10 degrees. The inlet taper may be suitable for larger and smaller blower casings. As described above, the inlet taper improves the efficiency of the blower.

Figure 4 is a rear view of a vertical latitudinal cross section of the blower casing 100 of figure 1. The cross section is through about the midpoint of the electric motor casing 122. The impeller casing 102 can be seen. The left 401 and right 403 sides are labeled. The blower baffle 344, arbor hole 346, mounting bolt stanchions (e.g. item 348), and motor mounts (e.g. item 322) can be seen. The mounting bolt stanchions are shown before longitudinal holes have been drilled into them to accommodate the mounting bolts that will pass therethrough.

The cooling air inlet 124 comprises the downward facing entrance 132 and a smaller motor cavity inlet 404 above it. The width 405 of the motor cavity inlet is smaller than the width 402 of the downward facing entrance. This keeps the pressure drop across a filter (not shown) mounted in the downward facing entrance small. The width of the downward facing entrance may be about 61.5 mm. The cooling air inlet height 406 may be about 13 mm. The width of the motor cavity inlet may be about 20 mm. The walls 403 of the cooling air inlet may be smoothly curved so that the pressure drop of the cooling air passing therethrough is kept small.

The cross section of the junction box 126 shows the conduit knockout 134 after it has been knocked out. A junction box passage 408 can be seen. The junction box passage allows an electrical connection between the junction box and the electrical motor in the motor cavity 304. Cooling air may also pass therethrough.

Alternative embodiments

Figure 6 is a lower front left view of an alternative blower casing 600. The blower casing is similar in design to the embodiment illustrated in figure 1 except where noted. Any combination of additional elements illustrated in figure 6 may be incorporated into the embodiment of figure 1.

The alternative blower casing 600 may comprise an upper drain tube 602 that connects the bottom 604 of the blower outlet 606 to the impeller inlet 608. Thus, condensate that is collected in the bottom of the blower outlet will be directed to the inlet of the blower. The drain tube can be incorporated into the casting of the impeller casing 668. The blower casing 600 may additionally comprise a 90° inlet elbow 612. The inlet elbow has a downward facing blower inlet 614. The outlet 672 of the elbow may be connected to the impeller inlet 608.

A debris screen 618 may be provided near the blower inlet to prevent dirt, insects, vermin and other debris in the contaminated air 616 from going into the impeller. The dirt, insects, vermin and other debris may come from the soil below the building.

The 90° inlet elbow may have a tapered internal diameter. The internal diameter may be reduced from that of a standard duct size (e.g. 76 mm) at the blower inlet to a smaller diameter (e.g. 50 mm) at the elbow outlet. As discussed above, the converging internal diameter improves the impeller efficiency.

A hinged cover 622 may be provided in the elbow to allow access to the inlet of the impeller in the impeller casing 668. This allows the impeller to be inspected or otherwise serviced without removing the elbow.

A lower drain tube 624 may be provided connecting the bottom 626 of the face of the impeller cover to the blower inlet. This allows condensate in the impeller cavity to drain back into the duct bringing contaminated air up from below the building (not shown).

A low voltage junction box 632 and a high voltage junction box 636 may be provided in the electric motor casing 638. The low voltage junction box may house control circuitry. The high voltage junction box may house power connections to the motor. As used herein, low voltage is a voltage of 12 V or less. High voltage is a voltage of more than 12 V.

An air filter 642 may be provided in the downward facing cooling air inlet 646 to filter cooling air 644 going into the electric motor casing.

An insect screen 654 may be provided in the downward facing cooling air outlet 666. The insect screen may be held in by a retainer (not shown). The screen prevents insects or other creatures from entering the cooling fan casing 664.

A vertical cooling air exhaust extension 652 may be provided to lower the downward facing cooling air outlet below the downward facing cooling air inlet. This reduces the recirculation of the heated cooling air exhaust 656 back into the cooling air going in 644. A lateral offset 658 may be provided in the vertical cooling air exhaust extension to further reduce the recirculation of the cooling air. One or more cooling fins 662 may be provided in the cooling fan casing 664. Said cooling fins help dissipate the heat generated by the electric motor. Cooling fins may also be provided in the electric motor casing 638 and/or impeller casing 668.

To further assist cooling, the exterior of the blower casing may be treated with a coating that is resistant to or reflective to heat adsorption.

The measurements referenced herein for the blower casings 100 and 600 are suitable for the electric motor and impeller of the Nautilair™ blower described above. The measurements may change or be altered for different motor models or configurations.

A plurality of anchor attachment points (not shown) may be integrated into the exterior of the electric motor casing 122 (figure 1) for the purpose of attaching offset motor feet. To further dampen motor vibration and heat dissipation, some motor feet

embodiments may be made of corrugated stainless spring steel. Other motor feet may be made of other shock adsorbent weather resistant materials. Rubberized grommets may be used at the attachments points to further reduce vibration. An internal heat sink that is designed to stabilize the temperature of the circuit board components of the low voltage control system in the low voltage junction box 632, may be connected by thermally conductive material to a high surface area heat conductive grid that is adjacent to said downward facing cooling air inlet such that said grid is cooled by the incoming cooling air stream 644. Blower casing with integral elbow

Figure 7 shows an upper left front view of an alternative blower casing 700. Figure 9 shows a right view of a vertical longitudinal cross section of the blower casing 700.

Reference will be made to both figures 7 and 9.

The blower casing comprises an impeller casing 702, an electric motor casing 704, a cooling fan casing 706, a blower baffle 708 and a fan baffle 902.

The impeller casing comprises a downward facing blower inlet 714, a 90° inlet elbow 712, an upward facing blower outlet 720, an impeller cover 912 defining an impeller cavity 914, an outlet condensate tap 722 at the bottom of the blower outlet, an optional eyelet 724 proximate to the outlet condensate tap, a vertical web 718 proceeding down from the bottom of the horizontal portion 713 of the 90° inlet elbow, and a lower drain tube 716 proceeding from the bottom of the impeller cavity to the vertical portion 710 of the 90° inlet elbow. The lower drain tube comprises a central bore 912 to allow water collecting in the bottom of the impeller cavity to drain into the vertical portion of the 90° inlet elbow. An upper drain tube (not shown) may connect the outlet condensate tap to an opening (not shown) in the 90° inlet elbow. The eyelet may provide support for the upper drain tube.

The 90° inlet elbow serves to direct the flow of contaminated air from a vertical orientation to a horizontal orientation and into the impeller inlet 922.

The impeller casing may be a unitary piece cast from a weather resistant material, such as an aluminum alloy. Plastic materials can also be used. The upper and or lower drain tube may be provided in the initial mold and cast into place.

The electric motor casing 704 may comprise a motor cover 916 defining a motor cavity 918, a low voltage junction box 732 with a conduit knockout 736 on its bottom, a high voltage junction box 734 with a conduit knockout 738 on its side, a motor cavity inlet 802 (figures 8 and 10) and one or more stanchions 908. A cover plate 740 may be provided to seal the bottom of the high voltage junction box. A power feed aperture 928 may connect the junction box to the motor cavity. The power feed aperture provides a means of connecting wires from the power supply in the high voltage junction box to the motor in the motor cavity. The stanchions provide a means for connecting the fan casing, fan baffle and electric motor casing together with a weather tight seal. Similar means (not shown) may be provided for connecting the impeller casing, blower baffle and electric motor casing together with a weather tight seal.

The electric motor casing may be a unitary piece cast from a weather resistant material, such as an aluminum alloy. Plastic materials can also be used. One or more miscellaneous cavities 910 may be provided in any one of the casings to remove unneeded material and minimize the material needed for fabrication. The fan baffle 902 may comprise a motor shell aperture 904. The blower baffle 708 may comprise an arbor hole 906.

The cooling fan casing 706 may comprise a fan cover 924 defining a fan cavity 926, and one or more downward facing cooling air outlets 742.

The cooling fan casing may be a unitary piece cast from a weather resistant material, such as an aluminum alloy. Plastic materials can also be used.

Figure 8 is an upper right front view of the alternative blower 700. Figure 10 is a right rear view of a vertical latitudinal cross section of the alternative blower 700.

Reference will be made to figures 8 and 10. In figure 10, the blower baffle is rendered invisible so that the impeller inlet 922 and bore 912 of lower drain tube 716 can be seen.

A cooling air cover 804 may be provided to cover the motor cavity inlet 802. The cooling air cover defines a filter chamber 1002 and a downward facing cooling air inlet 806. The filter chamber is adapted to house a filter for filtering the cooling air going into the motor cavity.

Enclosed Blower Casing

Figure 11 is a right view of a vertical longitudinal cross section of an alternative blower casing 1100 where the impeller casing 534 is contained within the motor cavity 1156. The electric motor 504 and fan baffle 1126 are shown in a front view, not a cross section. The blower casing is a modification of the enclosure 506 of figure 5. The blower casing is adapted to house, in an outdoor environment 105, an impeller 532, an electric motor 504 adapted to drive said impeller, and a cooling fan 546 adapted to cool said electric motor. The cooling fan is shown as a broken line rectangle within the shell 542 of the electric motor. The blower casing comprising: a) an impeller casing 534, said impeller casing comprising: i) a blower inlet 1146 adapted to feed contaminated air 524 into said impeller; ii) an impeller cover 535 defining an impeller cavity 536 adapted to

house said impeller; and iii) a blower outlet 1144 adapted to exhaust 526 said contaminated air to said outdoor environment; b) an electric motor casing 1148, said electric motor casing comprising: iv) a motor cover 1149 defining a motor cavity 1156 adapted to house said electric motor; and v) a downward facing cooling air inlet 1166 adapted to convey cooling air 1120 from said outdoor environment into said motor cavity; c) a blower baffle 1152 between said motor cavity and said impeller cavity forming a barrier between said motor cavity and said impeller cavity, said blower baffle comprising an arbor hole 557 adapted to admit an arbor 556 of said electric motor from said motor cavity into said impeller cavity wherein said arbor connects said electric motor to said impeller; d) a cooling fan casing 1142, said cooling fan casing comprising: vi) a cooling fan cover 1143 defining a cooling fan cavity 1164 adapted to house said cooling fan; and vii) a downward facing cooling air outlet 1132 adapted to convey warmed cooling air from said cooling fan cavity 1134 to said outdoor environment; and e) a fan baffle 1126 between said motor cavity and said cooling fan cavity, said fan baffle comprising a motor shell aperture 1158 adapted to form a seal with a shell 542 of said electric motor such that said cooling air will pass 552 from said motor cavity, through said motor, and into 554 said cooling fan cavity wherein:

f) said cooling fan casing, said electric motor casing and said impeller casing are joined together to form a weather tight seal (e.g. the enclosure 1103 with the impeller casing contained therein).

The electric motor shell may comprise one or more inlet vents 543 adapted to allow cooling air to pass into the motor. The electric motor shell may comprise one or more outlet vents 544 adapted to allow warmed cooling air to pass out of the motor.

A dividing line 1162 is defined at a face of the fan baffle. The electric motor casing is defined as the portion of the enclosure on the electric motor inlet vent side of said dividing line. The cooling fan casing is defined as the portion of the enclosure that is on the electric motor outlet vent side of said dividing line. Thus, the baffle prevents warmed cooling air from being recycled into the inlet vents of the electric motor. The cooling fan casing and the electric motor casing form a unitary piece. The blower casing, by definition, may further comprise the impeller 532, electric motor 504 and cooling fan 546. Any style of impeller may be used including centrifugal or axial impellers. Positive displacement blowers may be used, such as roots blowers. Any blower system that provides the required pressure drop (e.g. 0 to 45 mbar) at the required flow rates (e.g. 0 to 340 m ³ /hr) of contaminated air may be used. The blower should be compatible with potentially explosive gas mixtures since methane or hydrocarbon vapors may be in the contaminated air. Blowers designed for providing premixed combustion gases to burners, such as the Nautilair™ 193 mm variable speed blower, may be suitable.

The blower inlet may comprise a 90° elbow 1172 adapted to convey the inlet contaminated air 524 from a vertical flow direction to a horizontal flow direction. This will improve the performance of the blower when the impeller is a vertically oriented centrifugal impeller.

An impeller casing condensate bypass 1176 and/or an outlet condensate bypass 1174 may be provided. The bypasses may be joined and fed into the blower inlet. An evaporative cooling ring 1122 may be provided to assist in the evaporation of the

condensate and hence cool of the contaminated air intake 524. The evaporative cooling ring may be made of sintered porous metal or other filter material.

One or more insect screens 1128 or other screen or filter may be provided in the cooling air inlet or outlet.

An alternative cooling air inlet 1110 may be provided in a vertical side of the enclosure. The alternative inlet should be downward facing or otherwise shielded from precipitation, such as by a canopy. The inlet may comprise an insect shield 1114 held on by a cover 1116. The inlet may comprise a 90° elbow 1112 to direct the cooling air 1118 from an initial vertical flow direction to a horizontal flow direction. A filter 1108 held on by a retainer 1106 may be provided at the outlet of the 90° elbow.

One or more heat sinks 1104 thermally connected 1102 to the impeller casing 534 may be provided. The heat sink may be in the path of the cooling air coming in through a cooling air inlet. The heat sink serves to reduce the temperature of the compressed contaminated air that emerges from the centrifugal blower. The heat sink may be radiator fins. The thermal connection may be a thermally conductive paste or thermally conductive metal piece between the heat sink and the impeller cover.

Any type of motor may be used to drive the impeller, such as an electric motor or pneumatic motor. Any type of transmission may be used to drive the arbor, such as a flexible cable or a geared transmission. Any type of cooling fan may be used. The cooling fan may have a separate motor. Conclusion

While the disclosure has been described with reference to one or more different exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt to a particular situation without departing from the essential scope or teachings herein. Therefore, it is intended that the disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention.