Base to Equipment weight ratio 1

[johnp]

In designing bases for equipment - where does the base to equipment weight ratio come from? Some recommend a factor of 2, 2.5 or 3.

When designing screen support girders the mass of the screen does not come into the picture. It only appears in the primary mode of vibration where the screen is bouncing on its own springs. At the second mode it becomes the exciting force generator, with the beams vibrating at the natural frequency.

So how does taking the rotating weight (excluding non moving parts) multiplied by 2 reflect in a meaningful stability ratio?

 

[BigInch]

It does not, but is a typical inadequate vendor's rule of thumb for foundation recommendations for many types of very lightly loaded and relatively smooth relatively high frequency vibration producing equipment falling into the small inexpensive, non-critical and insensitive, fire and forget catagory, like tiny centrifugal pumps less than 25 HP, that many try to apply to the design of highly loaded, low frequency vibration producing equipment of the same natural frequency as the foundation itself.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[johnp]

Thanks Biginch,
I've just been quoted that piece of wisdom by an Internaltional Vendor as technical guidance for the design of a 200 tph 800 kW Ball Mill - use a factor of 2.5 to 3.

Makes you think, doesn't it.

 

[BigInch]

Its prerecorded. You will also see in the fine print of their exclusions to your proposed equipment supply contract that you are totally responsible for the geotechnical investigation and foundation design. They will exclude any and all responsibility and void their warranty if the foundation vibrates unacceptably or otherwise goes wrong.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com