What are the repeatability and reproducibility of the MS-200?
Each MS-200 is required to pass a factory acceptance test specifying repeatability of better than 10% for 3 consecutive measurements of 1 ppm benzene in a nitrogen standard, with a background check between measurements. Typical achieved performance is better than 5%. Also, a linearity of response of better than 10% is required from mixtures of benzene in nitrogen over the range 200 to 1000ppb of benzene. The MS-200 is designed to operate in ambient temperatures up to 35°C. To maintain constant permeation properties of the membrane, the inlet is operated at approx 45°C to minimize the effects of ambient temperature fluctuations over the range 15-30°C. The temperature is controlled to within 0.1 degrees around the set value. At ambient temperatures of ~35°C the membrane temperature has to be set higher. The maximum temperature set point of the membrane in the present system is 90°C.
