With the increased use of Natural Gas as a fuel, higher natural gas prices, and the new federal regulations, buyers and sellers of natural gas are seriously looking at ways to improve their natural gas measurement and reduce the unaccounted for natural gas. An error in measurement of only one tenth of one percent (0.1%) on 100 MMSCF/D Natural Gas selling at $5.50/MCF will cause an over or under billing of $200,750.00 in one year. This will more than pay for a proving system. If the company undercharges it has lost money and if it over charges it has the risk of lawsuits later for huge amounts of money. The Btu in one barrel of oil for example is equivalent to approximately 5,600 cubic feet of natural gas. At $6.50 per thousand cubic feet, the natural gas equivalent of one barrel of oil is $36.40 equal to, or more than the cost of a average barrel of oil. In the petroleum liquid industry no custody transfer liquid measurement system would be complete without a method to prove the meter, either as part of the equipment or there would be connections provided for a portable prover