Natural gas compressors are able to compress natural gas (methane) up to 200 bar. America, Canada, Italy and Argentina are the main owners of technology to manufacture these compressors. Major consumer countries of this technology are Iran, Russia, Italy, Argentina and parts of Eastern Europe. Currently, there are about 17 million personal cars in Iran, and about 20% of them use natural gas that the major problem for the owners of such vehicles is accessing to CNG fuel. According to the fuel quota in Iran, Iran’s international sanctions about charging fuels, and lack of subsidies on gasoline, a great need for natural gas refueling stations have created. According to the National Iranian Gas Company, at this time there isn’t enough fuel stations around the country due to increasing demand of clean and low price fuel for the national transportation industry. The strategic importance of national producing of this product is because of the following reasons:

• Good Alternative for gasoline
• Complete cessation of imports from foreign countries like Italy and Argentina
• Long-term natural gas resources for use in the transportation industry (at least 170 years)
• Make the fuel sanctinos ineffective
• The use of natural gas as a clean fuel alternative to gasoline and diesel fuel
• The use of natural gas as a low cost fuel in comparison with gasoline  

Large stations are classified as L class of compressors that compresses the natural gas from the relative pressure of 17 barg to 200 bar in 4 to 6 stages. The technology used in these compressors is hydraulic drive and the seals process is static. Also the compressors compress the natural gas in a isothermal thermodynamic process, so that the efficiency is increased. The nominal capacity of these compressors is started from 250 normal cubic meter per hour but the most used capacities are 500, 750, 1000, 1250, 1500, 2000 normal cubic meter per hour.