The flatness classification that Face Consultants recommend is that contained within table 3.2 of the Concrete Society’s Technical Report No.34 (4th Edition), in which section 3 discusses flatness requirements for very narrow aisle (VNA) warehouse floors, how to achieve them, the allowable values of the properties of flatness and how to measure them.
Table 3.2: Permissible limits on Properties dZ, dX, d2Z and d2X in defined-movement areas.
|Floor Classification||Racking top beam height||Property ZSLOPE||Property dZ||Property d2Z||Property dX||Property d2X|
|Calculation||–||mm per m||Z x ZSLOPE||dZ x 0.75||Fixed values 2 x ZSLOPE x 1.1||Fixed values|
|DM1||Over 13m||1.3||Z x 1.3||Z x 1.0||2.9||1.5|
|DM2||8 – 13m||2.0||Z x 2.0||Z x 1.5||4.4||2.0|
|DM3||Up to 8m||2.5||Z x 2.5||Z x 1.9||5.5||2.5|
Table 3.2 details the allowable values of the properties of flatness for differing categories.
N.B The values shown for dX and d²X are based on a longitudinal dimension of 2000mm (this is a fixed dimension)
It is not possible to specify and impose these limits for defined movement unless the exact design of the VNA installation is known before construction. The choice of classification to specify is dependent upon the height of the top beam of the racking.
However, the recommendations of the VNA fork lift truck manufacturer should also be sought, as each model is designed to cater for different requirements and is therefore affected differently by surface regularity.
Checking for compliance to Table 3.2 with the Face Profileograph.
A range of Profileograph set ups are available for us to check a range of defined movement specifications from across the world.
The Concrete Society’s TR34 (4th Ed) Chapter 3
The Concrete Society’s TR34 Free Movement (3rd Ed) Chapter 4
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