while (my $line = <$data>) {

  chomp $line;

  my @fields = split ",", $line, -1;
  my $sum = $fields[3];
     

  $fields[3] = 'volemd'  if ($fields[3] >  310 ) ;
  $fields[3] = 'volemd1' if ($fields[3] == 70  ) ;

 print join( ',', @fields ) . "\n" ;

}