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Running coefficient of friction between rubber and metal for water submerged elements
Q. My name is Suresh Patel and am a retired yet freelance working civil engineer. I was referred to a failure of sluice gate screw hoist at critical time of its operation during water flooding in a major water pump house in our city. My first observation was grossly under sizing of screw hoist because of lower friction values considered by a manufacturer that did not operate the gates. I would like to rework some calculations and submit my opinion for larger public interest.
I, therefore, would like to know the static and running coefficient of friction between rubber and metallic surfaces, say steel, for water submerged elements like sluice gates in water dams or water pumping stations. Can these water submerged elements be termed as lubricated elements?
Product Designer - Indore, Madhya Pradesh, INDIA
June 20, 2009
I like your question very much, Suresh. I just don't have any answers myself.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. I think that the pressure of the water against the steel to rubber portion of the gate is going to be a function of the size of the gate and how deep it is in the water. If I remember correctly, at 1 foot it is going to have 64 pounds of pressure pushing against the gate and at 10 feet it would have 640 pounds of pressure. That is a very major item of trying to move the gate.
How much the shaft will raise is going to be a function of the diameter, threads per inch, depth of the thread and strength of the rod material
Rather than rubber for a seal, think about using polypropylene sheet. Far less compressible, so far less friction as well as it is a lot smoother to start with.
- Navarre, Florida
June 24, 2009
A. THE FRICTION CO-EFFICIENT FOR NORMAL RUBBER IS 1.5 IF IT IS PTFE CLAD IT IS 0.5 THE MAJOR FRICTION IS SLIDING FRICTION THAT IS 50% OF TOTAL THRUST ON GATE . THAT MANUFACTURER MIGHT HAVE NOT CALCULATED PROPERLY
A.M.NAGABHUSHANA- Hospet, India
July 17, 2011
A. Sluice gates and slide gates in water control do not use rubber on sealing seats. Usually there are bronze seats on sluice gates. There may be a rubber seat on bottom seal but due to pull out forces you would not want to use a rubber type system. Unseating heads require more than seating heads for obvious reasons. Pull out forces require the material used in sealing to remain a constant. Rubber will not work!
Doug SayreWater and wastewater - Cincinnati Ohio USA
June 12, 2012
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