Timely, diligent field testing and calibration of gas volume recording and correcting instruments ensure that measurement information fairly represents actual volumes. The instruments save a company capitol and operating costs because they can record or integrate volumes at pressures and temperature above the normal pressurebase conditions specified in contracts for volume calculation. This allows the company to use smaller and fewer meters. Recording and correcting instruments normally are connected to positive displacement, rotary and turbine meters in lieu of a direct reading/compensating index. The compensating instruments include: