The invention includes a central vacuum system for use in a dwelling. The device spreads the finally output quantization coefficients into bit-planes from the MSB to LSB, generates coding passes in each bit-plane, performs arithmetic coding in the coding passes, controls the code quantity to a target code quantity from the generated arithmetic codes, and generates a packet of the image data by attaching a header to the arithmetic codes. Knowing the compressibility factor of the gas, the temperature, and the diameter of the pipe, the wall thickness of the pipe may be calculated for the pressure range of the gas at the selected temperature.