PCP compressors are available in 12v, 220v and battery powered, the cooling systems can be either air cooled, water cooled or radiator cooled. Air Cooled compressors are for small applications such as filling a cylinder of 500cc or less with a machine runtime of up to 8min and up to 300bar. Water cooled compressors typically have a fill rate double that of a air cooled machine. Water cooled compressors typically use a external water reservoir of say 5l as a water cooled machines fill faster and generates more heat requiring a lot of cooling. Battery powered compressors have a fill rate similar to a 12v compressor and is also air cooled. Radiator cooled compressors are self contained meaning they do not use a external reservoir like in water-cooled machines but rather a smaller reservoir of up to 1.2l to circulate through the radiator similar to those used in gaming pc's. Air-cooled machines use up to 500w whilst radiator cooled compressors use less then 1000w and finally water cooled machines use a minimum of 2.2kw or 2200w but can use up to 50% more at startup for the initial 10 seconds. Typical fill rates of air-cooled compressor are 6-8 liters per minute followed by radiator cooled and water cooled compressors at 14-18 liters per minute. Pcp compressors are usually rated for 200bar, 250bar and 300bar. The 200 and 250bar models are for those with 1 rifle or more but have small cylinders of up to 300cc, the 300bar models are slightly more expensive then their counterparts but are for those with 1 more rifles and cylinder capacities larger then 300cc. The idea is not to run the compressors longer then 10minutes at a time as to reduce wear and tear and extend the machines lifespan. Choose the correct compressor for your application the first time!