Safety shutdown systems and methods for LNG, crude oil refineries, petrochemical plants, and other facilities

A method comprising:

• (a) sensing concentration of one or more flammable gases or vapors inside and/or outside the habitat;
• (b) sensing pressure inside and/or outside the habitat;
• (c) transmitting the sensed concentrations and pressure to a logic device;
• (d) maintaining the pressure, temperature, and/or humidity in the habitat by controlling one or more HVAC units and one or more air extraction units (AEUs) fluidly connected to the habitat and controlled by the logic device, the one or more AEUs extracting more air from the habitat than the one or more HVAC units supply to the habitat;
• (e) extracting blasting grit and dusts from the habitat employing one or more dust collection units (DCUs) fluidly connected to the one or more AEUs and controlled by the logic device;
• (f) extracting the flammable gases or vapors from the habitat employing an emergency gas extraction sub-system (EGES), an intake of the EGES fluidly connected to the habitat, the EGES controlled by the logic device, upon concentration of one or more of the flammable gases or vapors exceeding one or more maximum set point concentrations;
• and
• (g) transmitting one or more signals from the logic device shutting down one, more than one, or all operational equipment inside and/or outside the habitat upon the logic device receiving a signal indicating a pressure rise in the sensed pressure above a maximum set point pressure, the maximum set point pressure being less than atmospheric pressure.

A system comprising:

• (a) one or more explosive gas or vapor sensors for sensing concentration of one or more explosive gases or vapors inside and/or outside the habitat;
• (b) one or more pressure sensors inside and/or outside the habitat;
• (c) one or more logic devices in communication with the one or more explosive, gas or vapor sensors, and the one or more pressure sensors;
• (d);
• one or more HVAC units fluidly connected to the habitat and in communication with the one or more logic devices;
• (e) one or more air extraction units (AEUs) fluidly connected to the habitat and in communication with the one or more logic devices;
• (f) an emergency gas extraction sub-system (EGES) having an intake fluidly connected to the habitat, the EGES in communication with the one or more logic devices;
• (h) the one or more logic devices configured to:
• i) maintain the pressure in the habitat by controlling the one or more HVAC units and the one or more AEUs, the one or more AEUs configured to extract more air from the habitat than the one or more HVAC units supply to the habitat;
• ii) transmit one or more signals to shut down one, more than one, or all operational equipment inside and/or outside the habitat upon receiving a signal indicating a pressure rise in the sensed pressure above a maximum set point pressure, the maximum set point pressure being less than atmospheric pressure;
• and
• iii) transmit one or more signals to initiate operation of the EGES upon receiving one or more signals indicating concentration of one or more of the explosive, gases or vapors exceeds one or more maximum set point concentrations inside the habitat.