Span Gas for all types of gas detectors and analyzer. To help comply with standards, various types of calibration gas cylinders are available for your usage. The most important accessory to any gas detector is a calibration kit, which provides the means to determine if the instrument is working properly. When using gas detection equipment, it is necessary to calibrate the equipment on a regular basis to guarantee accurate results. According to some regulations and standards, one must test the gas detector prior to each use with a suitable test gas. 4 Gas Mixtures: Very reactive gas mixture only available in 34, 58, 100 ltr cylinders