How RV Gas Detection Works

A short technical primer on what an RV gas detector actually senses, and what the readings mean.

Two gases, two reasons to care

Propane (LP / LPG)

Propane is the fuel for your RV stove, furnace, and water heater. It's heavier than air, so a leak settles in low spots — under cabinets, in floor wells, in the tongue compartment. A propane leak doesn't make you sick the way CO does — it just sits there until something ignites it. Detection thresholds are measured as a percentage of the Lower Explosive Limit (LEL) of propane, which is 2.1% concentration in air. UL 1484 sets the alarm threshold at 25% LEL — well below the explosive concentration, but enough warning to leave the rig and shut off the tank.

Carbon Monoxide (CO)

CO is produced by any combustion: your furnace, generator, water heater, an idling vehicle next to your campsite, even a charcoal grill near an open vent. It's odorless, colorless, slightly lighter than air. It binds to your hemoglobin 200× more readily than oxygen, so even small concentrations starve your tissues. Symptoms (headache, nausea, confusion) appear quickly but feel like flu — by the time you realize, you may already be too disoriented to act.

UL 2034 sets the standard alarm threshold at 150 ppm. SENSYX adds a pre-alarm at 75 ppm — enough warning to identify the source and ventilate before symptoms set in.

How sensors work

Propane sensor: catalytic bead or semiconductor

The SENSYX SRC2000 line uses a semiconductor-type sensor element. Gas molecules adsorb on the heated sensor surface, changing its electrical resistance. The change is calibrated to gas concentration in real time.

CO sensor: electrochemical

An electrochemical cell with two electrodes generates a small current proportional to CO concentration. The cell consumes a tiny amount of electrolyte over its lifespan, which is why all CO sensors have a hard 5-year service life printed on the unit.

Why digital LCD matters

An LED-only detector tells you "alarm" or "not alarm." An LCD shows you which gas and how concentrated. When the alarm wakes you at 3 a.m., that information determines your response: a 200 ppm CO reading means evacuate immediately; a 25% LEL propane reading means shut off the tank and ventilate. Different actions, same alarm.

Why 5-year replacement matters

Both gas sensor types degrade over time. Catalytic surfaces poison; electrochemical cells exhaust their electrolyte. After 5 years a sensor may still appear to function but no longer reach proper sensitivity at the alarm threshold — which is the worst possible failure mode for safety equipment. SENSYX prints the retail-sale start date on the housing so you know exactly when to replace, no guessing.

LED vs LCD: What's the Difference → · When to Replace Your Detector →