In a raised floor data center, cold air from a pressurized sub-floor plenum reaches the data center room space through perforated floor tiles. Presently, commercially available tool "Flow Hood" (also known as "Balometer") is used to measure the air flow rate through the tiles. In the present paper, we will discuss the operating principle and the shortcomings of the commercial tool and will investigate a simple tile air flow rate measurement tool having an array of thermal anemometers (here termed as "Anemometric Tool"). The performance of both the tools is compared for different types of tiles (passive and active) for a wide range of tile air flow rates. It is found that the Anemometric Tool results in lower flow rate measurement uncertainty and works more effectively for high porosity tiles, as compared to the commercial tool Flow Hood.