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close this book Wind systems for pumping water: A training manual
View the document Acknowledgments
View the document Introduction to training
View the document Training guidelines
View the document Objectives for wind system construction training
View the document Session 1 Introduction and objectives
View the document Session 2 History of wind systems
View the document Session 3 Large projects and community analysis
View the document Session 4 Shop safety and tool care
View the document Session 5 Representative drawings for construction
View the document Session 6 Shafts and bearings
View the document Session 7 Strengths and testing
View the document Session 8 Joinery
View the document Session 9 Pumps and pump design
View the document Session 10 Siting considerations
View the document Session 11 Sizing wind water pumping systems
View the document Session 12 Design considerations for pumps and windmills
View the document Session 13 How to design
View the document Session 14 Presentation of designs
View the document Session 15 Construction of wind measuring poles
View the document Session 16 Exportation for wind sites
View the document Session 17 Tower raising
View the document Session 18 Plumbing the wind system
View the document Session 19 Testing installed wind system
View the document Session 20 Presentation of projects
View the document Session 21 Maintenance - preventive and routine
View the document Bibliography
View the document Construction materials list
View the document Tool list for 24 participants
View the document Technical vocabulary
View the document Report on the wind-powered in-service training
View the document Recommendations

Session 7 Strengths and testing

TOTAL TIME: 2 Hours

OBJECTIVES: Familiarize participants with the strengths and characteristics of the local materials.

Discover what is available in the way of local building materials.

MATERIALS: Small poles, pipe, bamboo, and whatever materials you wish to examine and test to use in wind system construction.

PROCEDURES:

Step 1: 30 minutes

Walk around the site looking at the types of materials available for use. Comment on and discuss the uses, qualities, strengths and weaknesses of the various types of materials represented.

Step 2: 15 minutes

Explain the method of destructive testing-pushing things to their limits.

Step 3: 15 minutes

Test some poles by supporting them at varying distances horizontally along their lengths and having someone stand on the middle of the poles.

Step 4: 5 minutes

Make some educated guesses at the stresses involved.

Step 5: 30 minutes

Discuss the forces on a mill and give some idea of the size of the forces-wind load and centrifugal load on the rotor and tower, as well as the pump loads.

Trainer Note

Approximate stresses on the windmill are given in the handout titled "Rules of Thumb for Wind Waterpumps"

Step 6: 25 minutes

Test more materials for strength and flexibility.

RESOURCES: Copies of Attachment 7-A

Attachment 7-A

Material Strengths & Testing

RULES OF THUMB FOR WIND WATERPUMPS

Centrifugal Force - (assuming a rotor tip speed ratio of approximately 1)

1 pound at one foot from the hub exerts with a force of 55 pounds in a 60 mph wind.

1 kilogram at 1 meter from the hub exerts with a force of 180 kilograms in a 100 km. per hour wind.

Maximum Windmill Drag Approximation - (in a 60+ mph (100+ km. per hour) wind)

10 pounds per square foot

45 kilograms per square meter

Power Calculation -

One horsepower is equal to lifting 400 gallons of water to a height of 10 feet in one minute.

One horsepower is equal to lifting 1500 liters of water to a height of 3 meters in one minute.

This formula is for theoretical horsepower and does not include the efficiency (or inefficiency) of the pump or the hydraulic friction losses in the pipe or the mechanical friction. For real life, use about one quarter of these figures for single acting pumps, and one half of these figures for double acting pumps.

Pumping Capacity

A 2" pump puts out a quart for every 18 inches of stroke

A 2" x 2" square pump puts out a quart in 14" of stroke

A 3" pump puts out a quart for every 8 inches of stroke

A 5 cm. pump puts out a liter for every 50 cm. of stroke

A 5 cm. x 5 cm. pump puts out a liter each 40 em. of stroke

A 8 cm. pump puts out a liter for every 20 cm. of stroke