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Re: Floor Flatness Numbers

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Is is unreasonable to specify the numbers you listed below for flatness, and let the contractor/sub determine which method can meet your specification? Since there is no one-for-one correlation between the cryptic F numbers and the performance requirement you need, I think you are asking for unnecessary liability in trying to do the conversion yourself.

At 07:39 PM 11/8/2004 -0600, you wrote:
I asked a similar question back in September and received some very helpful comments. I have an additional one I haven't been able to find an answer to.

I was given the floor tolerances of a fork truck (Jungheinrich) for a warehouse system. The tolerances by the manufacturer are based on lengths and tolerance. Let me give a few examples;

0.04" in 4" interval
0.08" in 40" interval
0.12" in 80" interval
0.16" in 120" interval
0.20" in 160" interval

I am looking at equating this to the floor ASTM 1155 "Standard Test Method for Determining Ff Floor Flatness and Fl Levelness Numbers" The 0.16" in 120" interval appears to be an Ff of 50. I have tried to find out how to equate these numbers to the Fl value and have not found anything to help me. I read through the ASTM and there are equations for calculating the Fl values based on the readings of the tests, but I don't see anything to help define what is the appropriate number to specify prior to construction. I know the Ff is the flatness value and the Fl is the level value. I know we can't equate these values directly to the old 1/8" in 10 feet for a straight edge (which is what I appear to be trying to do), but how does one take a manufacturer's recommendation like these and turn them into specification criteria? How is the Fl established?

I called the manufacturer and they weren't any help. They said they don't deal with the "American" system.

Thanks for any help.


Jordan Truesdell, PE

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