Natural gas as a city energy supply is well established in the developed countries while in the developing countries the usage of natural gas in city utility industry has significantly increased in recent years. The “town gas” or the “water-coal gas” generated from the process manufacturing of coal is vastly being replaced by natural gas. According to the worldwide energy consumption outlook released in 2011 by US Energy Information Administration, the worldwide annual natural gas consumption is at an average growth rate of 1.6% and will reach to 186.7 trillion cubic feet in 2035. The amount is almost doubled compared to that in 2003. This is not only from the requirements of environmental pollution control but for a better life style as natural gas is normally directly delivered to the residence providing much cleaner energy with higher efficiency. Metering the usage of natural gas is therefore a basic requirement for gas companies so that tariff can be fairly applied to customers and in return the revenue can further support gas company operation. This is particularly important today as current energy costs have skyrocketed. Some governments of Eastern European countries that were used to subsidizing or even providing free natural gas for residents are now starting to install gas meters under their new tariff system.