G-Cal permeation tubes offer a proven and repeatable means of generating a desired gas or vapor concentrations. The permeant gas escapes through the proprietary membrane system and mixes with a carrier gas (nitrogen is the most common) at a controlled flow rate to obtain a known mixture in ppm or ppb. Applications include calibration of gas monitoring systems and chromatographs, accuracy check of gas detectors, and generation of known test atmospheres for a specific application. G-Cal devices exhibit the lowest temperature sensitivity among available similar products. The permeation rate of the polymer used in G-Cal devices changes only 1-3% per degree C, eliminating the need for a temperature-controlled chamber. Most G-Cal devices are guaranteed for 12 months operating life. Over 100 different substances are available, including arsine, phosphine, and gas phase devices such as CO, NO, and methane. Available permeation rates range from less than 200 ng/min to 30,000 ng/min and over. Each G-Cal device is individually calibrated and verified to generate a given output (ng/min) vs. temperature. A graph which shows permeation rate vs. temperature from 0 to 50°C is included with each device.