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What is blade pitch and why is it important?Blade pitch is the manufacturer's recommended degree angle of attack from the blade'shorizontal axis and is the optimum angle that will load the motor to provide the amount of air

required to perform the cooling specified.Note: This does not mean that the full load horsepower of the motor is being utilized).

How and where do you set the blade pitch on Hudson fans?Pitch angles on all Hudson fans are set approx. 1"-2" from the tip of the blade using aprotractor that rests on a flat bar that extends across the leading and trailing edges of theblade. The protractor must be of a type that reads angles in degrees from horizontal.

What is blade tracking and why is it important?Blade tracking requires lifting of the blade tip during installation to ensure that all bladesarein the same horizontal plane with the other blades in the assembly. Blade tracking isset atthe same time as pitch. Poor tracking is one of the major causes of fan vibration.

What is the seal disc and why is it important?The fiberglass seal disc is installed on top of the fan hub and helps prevent hot airrecirculation back through the middle of the fan system. The seal disc adds approx.5%-8%efficiency to the fan performance.

What is the inlet bell and why is it important?The inlet bell consists of several segments of formed fiberglass that are installed belowthefan to shape the air flow and reduce turning losses due to the abrupt corners in fanrings. Thisshaped air flow improves air distribution and fan efficiency.

How does excessive tip clearance affect fan performance?Excessive or irregular tip clearance causes uneven blade tip loading, reduced air draw,hot airrecirculation and repetitive vibration. Tip clearance between the blade tip and thefan ringshould be a min. of 3/8" to a max. of 3/4" per API-661. Articles are available on our website.

How can I reduce my excessive tip clearance problem?Refer to this website for Tip Seal retrofit materials or call Hudson at 1-800-634-9160.

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What type of oil should be used in Hudson's Auto-Variable fan hubs?

We recommend Aprovis 55 synthetic oil, available through Hudson. Contact Hudson forcomparable substitutes at 1-800-634-9160.

What are the proper torque values for the blade clamp bolts?It depends on the fan diameter and the fan hub being used. Refer to our installationmanualson this website or call Hudson at 1-800-634-9160.

Is there a quick check list that may assist in trouble shooting vibration problems?Yes. Most vibration problems can be traced to blade tracking, blade pitch settings, belt and

sprocket alignments, structural looseness and/or bearing wear. Refer to our installationmanuals on this website or call Hudson at 1-800-634-9160.

How often should we grease the fan and motor bearings?Every Customer and plant location will differ somewhat and there is no substitute for a wellexecuted Maintenance Program. Refer to our recommended Lubrication Schedules on thiswebsite or call Hudson at 1-800-634-9160.

My cooling tower fan blades have pits in the leading edges. What causes this?Cooling tower fill gets blocked by algae growth, etc., which leads to air flow restrictions indifferent quadrants under the fan. Areas that have more air flow allow water droplets tobecome entrained with the air flow. These droplets impact and erode the leading edge.y What are the rivets for on the Hudson Tuf-Lite II blades?They are only used to secure the blade while the epoxy cement is permanently bonding theblade to the hub section. They are not necessary for any strength requirements; however,they should not be intentionally removed as this would create a hole for moisture entrance in

addition to affecting the balance of the blade.What is the difference between a Tuf-Lite series "B" blade vs. the "BH" blade?

Prior to mid 1976, the Tuf-Lite "B" blades & "C" blades were just that B & C. After extensivefield testing, Hudson Products saw the need to strengthen certain blades with additional clothto the leading edge side of the blade; therefore, the letter "H" was added to the part numberindicating a slightly heavier blade.NOTE: This does not apply to the following blade sizes:T-6B, T-7B, T-8b, T-9B, T-10B, T-16B, T-18B, T-20B & T-22B

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"CH" should apply to all the "C" blades