Dear Shri A K Bhatnagar,

As I understand, there is a no need to add in power and tensions due to 90degree curve. The pipe conveyor friction conveying coefficient is expected to take care of various vertical and horizontal curvatures encountered in the layout. Theoretically, your apprehension is right, but possibly, this does not have signification implication.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyor.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 5882916 ■

Dear Mr. A K Bhatnagar,

As I understand, there is a no need to add in power and tensions due to 90 degree curve. The pipe conveyor friction conveying coefficient is expected to take care of various vertical and horizontal curvatures encountered in the layout. Theoretically, your apprehension is right, but possibly, this does not have signification implication.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyor.

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 5882916 ■

Ash,

What do you mean by sharp?

Power and tension differential is synonomous. Any bend in the pipe increases the tension or power to pull the pipe around the bend. Smaller radii imply greater pressure. The degree of the radius will non-linearly alter the power to pull it through the arc (ie. smaller (sharp??) radii will cause a disproportionate increase in power).

Power/tension differential vary with belt construction. Fabric belts generally consume more power due to the greater working of the polymers.

As the pressure becomes large, the pipe will begin to buckle or deform into a non round shape. Larger losses will occur. The pipe transverse diameter will shrink and may collapse. The pipe will tend to rotate. All consuming more power. Also, the same radius place at the low or high tension area may consume very different power levels.

There is an accurate method to get reasonably close the the answer. I think you are aware of the 3.5 km Birla Copper pipe conveyor that Phil Staples has written about in BSH. Are you aware of the twisting that occurred with improper loading? We designed the conveyor system with Babcock RSA and Naveen of India.

There is no rule-of-thumb method based on the afore mentioned complexity.

We have built both a FEM model and an alternative method, to FEM, that took two years to develop.

There is more you need to know than I have eluded to. I am sure you have seen this from the CDI website and the treatment we describe for power analysis: www.conveyor-dynamics.com

You question is very non-specific. You therefore get a non-specific answer. If you don't want to hire the expertise, then suck-it-and-see as they say in OZ! We look forward to your gambling result.

Lawrence Nordell

President

Conveyor Dynamics, Inc. ■

Ash,

I just typed a comprehensive reply that got lost in the ether. I will now abreviate it.

1. Sharp (what ever your definition is of sharp) will cause a geater tension drop than a larger radii.

2. A 90 degree bend will produce a greater tension drop than a 45 degree tension drop contrary to Mr. Mulani. The theorectical power equation, for the pipe ad non-pipe, does not account for vertical and horizontal bends. For pipe, the losses are more acute.

2. Any radius will tend to increase power/tension to a greater degree than the increased pressure induced at the beginning of the curve. As the belt is bent, in a curve, the increased drag compounds the tension loss exponentially.

3. Belt construction alters the degree of tension change. Fabric belt will consume more power than steel cord belt.

4. The tension drop is greater nearer the discharge end than the loading end for the same radius.

5. There is no simple Rule-of-Thumb. It took CDI 2 man years of a Ph D's theorectical development to manage the 3-D physics of pipe conveyors. This was done for Bridgestone. We solved the problem by two methods. We compared the model with many (>10) field measurements.

6. You may be aware of CDI engineering of the 3.2km Birla Copper pipe conveyor with Babcock South Africa. Are you aware of the twisting problems when the belt is not properly loaded?

Lawrence Nordell

Conveyor Dynamics, Inc.

www.conveyor-dynamics.com ■

Ash,

I just typed a comprehensive reply that got lost in the ether. I will now abreviate it.

1. Sharp (what ever your definition is of sharp) will cause a geater tension drop than a larger radii.

2. A 90 degree bend will produce a greater tension drop than a 45 degree bend contrary to Mr. Mulani. The theorectical power equation, for the pipe and non-pipe, does not account for vertical and horizontal bends. For pipe, the losses are more acute.

3. Any radius will tend to increase power/tension. The increased pressure induced at the beginning of the curve will cause a greater losses along the curve. As the belt is bent, in a curve, the increased drag due to the transverse pressure compounds the tension loss exponentially.

4. See our website: www.conveyor-dynamics.com for a better undestanding of the principles.

5. Fabric belt will consume more power than steel cord belt.

6. The tension drop within a curve is greater nearer the discharge end than the loading end for the same radius due to the larger tension within the curve.

7. There is no simple Rule-of-Thumb. It took CDI 2 man years, of a Ph D's theorectical development, to manage the 3-D physics of pipe conveyors. This was done for Bridgestone. We solved the problem by two methods. We compared the model with many (>10) field measurements. This was done in 1993-1994.

8. You may be aware of CDI engineering of the 3.2km Birla Copper pipe conveyor with Babcock South Africa. Are you aware of the twisting problems when the belt is not properly loaded?

Lawrence Nordell

Conveyor Dynamics, Inc.

www.conveyor-dynamics.com ■

THIS POST HAS A TECHNICAL PROBLEM.

DR. WOHLBIER IS THE ONLY POSTER. MESSAGES CANNOT GET POSTED DIRECTLY.

LK NORDELL ■

Dear MR. Bhatnagar,

Bridge stone company, Japan has develop a formula for calculating the tension due to curvature. You may refer to them. But the magniture is very small & can be ignored.

Regards.

A.Banerjee ■

Dear Mr. Bhatnagar,

Curved path resistance can be calculated by using the following.

Fr = (Tc+ Tr)X pai/180 XA X Rf

Where, Tc=Carrying side belt tension in curved path,Kg

Tr= Retern side tension in curved path.,Kg

A= Bend angle, deg

Rf= Resistance factor

Regards.

A.Banerjee ■