adesso funziona con questa
$pcode = array($row[manufacturers_code]);
usort($pcode, "strnatcmp");
print_r($pcode);

Pero' mi da: e io no vorrei questa parte qui Array ( [0] => ) e' possibile?
Array ( [0] => E1 )
Array ( [0] => E1 )
Array ( [0] => E1 )
Array ( [0] => E1 )
Array ( [0] => E14 )
Array ( [0] => EC1 )
Array ( [0] => EC3 )
Array ( [0] => N1 )
Array ( [0] => N1 )
Array ( [0] => NW1 )
Array ( [0] => NW1 )
Array ( [0] => NW1 )
Array ( [0] => NW3 )
Array ( [0] => NW3 )
Array ( [0] => NW5 )
Array ( [0] => NW6 )
Array ( [0] => NW8 )
Array ( [0] => SE1 ) A
rray ( [0] => SE1 )
Array ( [0] => SE1 )