Failsafe gas leak detection and mitigation system and method

A hydrocarbon gas (HCG) leak mitigation (HLM) system comprising:

• (a) hydrocarbon gas sensor (HGS);
• (b) sensor signal conditioner (SSC);
• (c) digital control processor (DCP);
• (d) alarm status indicator (ASI);
• and
• (e) HCG relay controls (HRC);
• wherein:
• said HGS detects ambient hydrocarbon gas (AHG);
• said HGS indicates said AHG detection as a hydrocarbon sensor voltage (HSV);
• said HSV is electrically coupled to said SSC;
• said SSC is electrically coupled to said DCP;
• said SSC and said DCP form a closed control loop (CCL);
• said CCL operates such that said DCP dynamically adjusts electrical characteristics of said SSC based on the value of said HSV;
• said CCL comprises a WARMUP STATE in which said HGS is heated until it stabilizes to a nominal fresh air resistance (FAR) value;
• said CCL comprises a MONITOR STATE in which said SSC is adjusted such that said HSV is maintained within a lower threshold voltage (LTV) and an upper threshold voltage (UTV);
• said CCL comprises a GAS DETECTION STATE in which a STEP COUNTER (SCT) is decremented if said HSV falls below said LTV and incremented if said HSV exceeds said UTV;
• said GAS DETECTION STATE is iteratively executed with a variable sample time between readings of said HSV from said HGS;
• said CCL comprises an ALARM STATE that triggers a hydrocarbon gas (HCG) leak alarm (HLA) if said SCT exceeds a selected threshold detection count (TDC);
• said DCP is configured to log alarms to said ASI if said HLA is triggered by said ALARM STATE;
• said HRC is electrically coupled to said DCP;
• and
• said DCP is configured to individually activate and/or deactivate the state of said HRC when said HLA is triggered by said ALARM STATE.

A hydrocarbon gas (HCG) leak detection (HLD) method comprising:

• (1) with a digital control processor (DCP) and a sensor signal conditioner (SSC), calibrating a hydrocarbon gas sensor (HGS) (0902);
• (2) with said DCP and said SSC, initializing a sensor threshold voltage (STV) for said HGS (0903);
• (3) with said DCP, initializing a LEVEL COUNTER to 0 (0904);
• (4) with said DCP and said SSC, monitoring a hydrocarbon sensor voltage (HSV) from said HGS (0905);
• (5) with said DCP and said SSC, determining if said HSV from said HGS is less than said STV, and if so, proceeding to step (1) (0906);
• (6) with said DCP and said SSC, determining if said HSV from said HGS is greater than said STV, and if not, proceeding to step (1) (0907);
• (7) with said DCP and said SSC, increasing said STV (1008);
• (8) with said DCP, increasing said LEVEL COUNTER (1009);
• (9) with said DCP, determining if said LEVEL COUNTER is greater than an ALARM TRIP value, and if so, proceeding to step (14) (1010);
• (10) with said DCP and said SSC, determining if said HSV from said HGS is less than said STV, and if not, proceeding to step (7) (1011);
• (11) with said DCP and said SSC, reducing said STV (1012);
• (12) with said DCP, decrementing said LEVEL COUNTER (1013);
• (13) with said DCP, determining if said LEVEL COUNTER is 0, and if not, proceeding to step (11), otherwise proceeding to step (1) (1014);
• (14) with said DCP, activating audible and/or visual alarms and proceeding to step (14) (1016).

A hydrocarbon gas (HCG) leak mitigation (HLM) method comprising:

• (1) with a digital control processor (DCP), enabling HCG flow and/or compressor and/or fan operation in a HVAC system (0901);
• (2) with said DCP and a sensor signal conditioner (SSC), calibrating a hydrocarbon gas sensor (HGS) (0902);
• (3) with said DCP and said SSC, initializing a sensor threshold voltage (STV) for said HGS (0903);
• (4) with said DCP, initializing a LEVEL COUNTER to 0 (0904);
• (5) with said DCP and said SSC, monitoring a hydrocarbon sensor voltage (HSV) from said HGS (0905);
• (6) with said DCP and said SSC, determining if said HSV from said HGS is less than said STV, and if so, proceeding to step (2) (0906);
• (7) with said DCP and said SSC, determining if said HSV from said HGS is greater than said STV, and if not, proceeding to step (2) (0907);
• (8) with said DCP and said SSC, increasing said STV (1008);
• (9) with said DCP, increasing said LEVEL COUNTER (1009);
• (10) with said DCP, determining if said LEVEL COUNTER is greater than an ALARM TRIP value, and if so, proceeding to step (15) (1010);
• (11) with said DCP and said SSC, determining if said HSV from said HGS is less than said STV, and if not, proceeding to step (8) (1011);
• (12) with said DCP and said SSC, reducing said STV (1012);
• (13) with said DCP, decrementing said LEVEL COUNTER (1013);
• (14) with said DCP, determining if said LEVEL COUNTER is 0, and if not, proceeding to step (11), otherwise proceeding to step (1) (1014);
• (15) with said DCP, disabling HCG flow and/or compressor and/or fan operation in said HVAC system (1015);
• (16) with said DCP, activating audible and/or visual alarms and proceeding to step (15) (1016).