Aerovent: Fan Design with Safety & Maintenance in Mind

Aerovent: Fan Design with Safety & Maintenance in Mind

When DuPont™ was looking to replace an aging supply fan in one of their plants, they knew that employee safety, reduced fan maintenance and fan longevity were high priorities. DuPont had many unique design ideas to incorporate into their replacement fan; they needed a fan company able to work with their ideas and create a fan design that would meet their objectives. DuPont wisely chose Aerovent.

Since the fan was a replacement, much of the overall design criteria were already established. The fan had to be an SWSI, downblast discharge centrifugal supply fan to deliver 60,000 CFM at 4 inches of static pressure. This was accomplished with Aerovent Model CB-SW, Size 730, Class II, Arrangement 1 with a unitary base and 80% narrow width wheel. The housing material is mild steel with a DuPont™ Corlar epoxy prime coat and DuPont™ Imron finish coat.

Several special features were incorporated into the fan design. These features were designed with employee safety, fan longevity and low maintenance in mind. Special features include the following:

• Two Piece Flanged/Bolted Belt Guard
For safety reasons, the belt guard was designed in two pieces, the lower half permanently mounted to the bearing pedestal with the upper half bolted to it. This made it impossible to completely remove the guard and forget to replace it when maintenance was required. The guard was also designed with motor and fan shaft tachometer holes for measurement purposes. These tach holes were covered with pivot point swing doors for safety.

• Fan Lifting Lugs
The lifting lugs were required because of the extraordinary installation. In order to install the fan, part of the building’s roof had to be removed. The fan was then lowered into position with a crane. For this reason, the lifting lugs were designed to support 150% of the total unit weight.

• Stainless Steel and Teflon Coated Hardware
The hardware used for the motor slide base and bearings was Teflon coated for corrosion resistance. The remaining hardware on the fan was stainless steel and required anti-seize lubricant to prevent thread galling, or seizing of the nut and bolt, during tightening.

• Thru-Bolt Raised Access Door
For safety reasons, the operation of the raised access door could not be affected by gravity. Therefore, the door was designed to swing in the horizontal plane with a two-point hinge. The access door hardware was required to be thru-bolt to prevent hardware from being broken off during removal or tightening which can occur with standard weld studs. EDPM full-face gasket was used around the door to minimize air leakage.

• Special Drain
The drain was required to be tangential to the housing, eliminating elbows in the drain piping below the fan. This design reduced the possibility of a plugged drain which could have resulted in a build-up of water in the fan.

• Seal Welding on the Entire Unit including the Unitary Base
The continuous welding (no stitch welding allowed) of all support members on the housing and unitary
base eliminated the possibility of crevasse corrosion or rust build-up beneath these members. Caulking was unacceptable because it was not considered a permanent moisture barrier.

• Insulation Pins
1/4” diameter, 2-1/2” long threaded insulation pins were fully welded to the exterior of the fan housing on 18” centers. Two inch square retaining washers and nuts were shipped loose with the fan to hold the customer installed insulation in place.

• SST Bearing Shims
1” thick stainless steel bearing shim plates were sized to fit directly underneath the fan bearings. These shims will make replacement of the fan bearings much easier due to the 1” space created between the bearings and bearing pedestal after the shims are removed.

DuPont was extremely happy with Aerovent’s design and the final product! The installation went well and Aerovent looks forward to a long relationship with DuPont.

For all your fan needs, contact Fluid Engineering today.

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