The Sierra Monitor Model 5100-05-IT Gas Sensor Module utilizes electrochemical Technology to accurately detect hazardous levels of Hydrogen Sulfide. Similar products are available to monitor for CO, O2, Cl2, HCN, NH3, HF and more. The gas detector can provide output in 4-20 mA analog, Modbus RTU digital, SentryBus, Relay Contacts and even HART making it very adaptable for a variety of locations and applications. It is FM and ATEX approved to provide the reliability you demand. It is available in either a Stainless Steel or Aluminum explosion-proof enclosure.