Commercial Air Curtain Blower Wheel for Wide Spans

Managing Sag in Wide Equipment

Engineers often struggle to find an air curtain blower wheel for an

air curtain blower wheel that will not sag. The customer needed three wide impellers for a commercial air handler. First, they wanted a 121 mm wheel spanning 873 mm. Next, they asked for a 107 mm wheel at 705 mm long. Finally, they needed a 110 mm metal unit that was exactly 681 mm long.

This equipment sits above wide commercial entryways. Therefore, it requires a very long horizontal shaft. Long plastic wheels naturally bend under their own weight. Also, they warp when they spin fast. The system had to move a reference airflow of 1000 to 1500 CFM. Therefore, we had to balance the wheels perfectly. The final units run in quiet commercial spaces. Bad vibrations would ruin the external motor bearings quickly. So, we kept residual unbalance strictly under 0.3 grams at 1200 RPM for the plastic wheels. Meanwhile, radial runout had to stay under 0.7 mm. By contrast, the metal wheel ran at 1500 RPM. We kept its unbalance below 300 milligrams. Any design that failed these checks would also fail AMCA 210-16 air tests. In short, passing these tests ensures a long working life.

Engineering the Air Curtain Blower Wheel

Choosing the right material was vital to the project. First, we looked at normal ABS plastic for the blades. However, standard ABS is simply too soft. It cannot span 873 mm safely without bending. Instead, we chose AS+GF30%. This is a strong plastic mixed with 30% glass fiber. It makes the parts very stiff. Thus, it stops the center of the air curtain blower wheel from dropping into the metal housing. It also handles stress much better than pure plastic.

Even so, adding glass fiber creates major production hurdles. The joints had to survive a 1200 RPM test speed. So, we used sound waves to weld the plastic blades. This process melts the plastic together deeply. It adds no heavy glue to the rotor. Consequently, we stopped all air leaks and weak spots. The joints stay strong for years.

Balancing the Long Wheels

Next, we fixed the dynamic balance of the rotors. The 873 mm

air curtain blower wheel needed exact weight control. However, adding too many metal clips hurts the airflow. Extra clips also create loud air noise. Therefore, we allowed only 3 balancing clips per wheel. This strict rule forced us to mold the parts with great care. We had to reject any blade that was slightly too heavy.

Metal Wheel and Costs

By contrast, the 681 mm wheel used full metal construction. Metal parts handle heat better but weigh a lot more. Furthermore, they need physical rivets instead of modern welds. The final metal wheel has 45 separate blades. We kept the blade edge gaps strictly below 0.5 mm.

Finally, these careful choices cost real money. Molds for glass-filled plastic wear out very fast. We have to replace them often. Furthermore, the strict 3-clip limit caused more parts to fail our factory tests. In short, the customer paid for tighter rules to protect their motors in the field.

Technical Specifications

The table below shows the exact rules from the final engineering drawings. We extracted these numbers directly from the approved files.

Keeping the shaft runout under 0.2 mm ensures the whole unit spins smoothly. This protects the external motor bearings over time. Moreover, the tight radial runout limits prevent the air curtain blower wheel from scraping against the metal housing. This guarantees safe operation near the 1500 CFM reference target.

Reference: ISO 21940 covers the test method behind these figures.

Technical Documentation

The approved documents confirm all our material choices and balancing limits.

The first file,

longwell-wi-6948623418-technical-doc-01.pdf, covers the 110×681 mm metal unit and its 45 blades.
Next, longwell-wi-6948623418-technical-doc-02.pdf shows the blue plastic wheel and the strict 3-clip balancing limit.
Finally, longwell-wi-6948623418-technical-doc-03.pdf displays the 121×873 mm black impeller designed for counter-clockwise rotation.

This visual layout displays the three unmotorized impellers and their unique shaft ends.

Specifying Long Impellers

If you need a wide air curtain blower wheel for your system, check these details first:

• First, define your radial runout limit carefully. Long parts bend easily over time. Use glass-filled plastic for anything over 700 mm long. Pure plastic will simply fail.
• Next, strictly limit the number of metal balancing clips. Too many clips will block the air and make unwanted noise. They also add uneven weight to the rotor.
• Finally, give your supplier the exact motor shaft size immediately. A loose shaft fit will cause severe vibrations at high speeds. We always ask for this number before we start cutting metal.

Related: Cross Flow Fans.

Technical Questions

Browse our blowers range, the exhaust blowers section, or centrifugal blowers.