Propane (LP Gas) Leak Detector Alarm for a Food Truck

For most food trucks, the right propane detector is a dedicated 12V unit that conforms to UL 1484 for RVs, mounted low per its manual near the cooking appliances, like MTI’s Safe-T-Alert 20-441-P, or the 35-741 if you want propane and CO in one box; plug-in kitchen alarms are a supplement, not the primary.

Confirm that your fire marshal accepts the exact model for your truck before buying. RV conformance and residential alarm specifications do not by themselves establish approval for a commercial mobile kitchen. A fixed alarm detects gas at its sensor; it cannot guarantee detection before ignition or replace required system testing.

Who this is for

These options suit different tasks around an LP cooking system: continuous detection with an accepted installed alarm, supplemental detection on shore power, and routine fitting checks after the system is safe to work on. A hood fire-suppression system does not replace ambient propane detection; confirm both requirements with your local fire marshal.

Where do you actually mount a propane detector?

Propane is heavier than air, so propane alarm instructions place the sensor low. Follow the exact model’s manual rather than applying one height to every gas or alarm.

Model	Propane mounting instruction	Placement limits
MTI 20-441-P	4–20 in. above floor	Interior kitchen area near potential appliance leak sources; follow manual exclusions
MTI 35-741	4–20 in. above floor	Interior kitchen area; separate areas can need separate alarms per the manual
Kidde KN-COEG-3	Near the floor	Residential scope; confirm acceptance for supplemental truck use
First Alert GCO1CN	Close to the floor	Residential scope; confirm acceptance for supplemental truck use

MTI excludes installation within 12 inches of doors, windows or vents; behind drapes or other airflow obstructions; on outside walls; in closets; or on GFCI or switch-controlled supplies. Its interior kitchen instructions do not establish a universal tank-locker installation requirement. Have the installer apply the manual to your actual layout.

A combo LP/CO alarm does not automatically belong at ceiling height. Kidde explains that CO is almost the same density as air; follow the combination alarm’s own instructions. Natural-gas placement differs from propane placement, so do not assume one mounting position covers either fuel equally.

Is your code requirement NFPA 58, NFPA 1, or NFPA 96?

Washington County, Maryland’s Mobile Food Unit Checklist uses these specific requirements: A16 calls for a propane detector “UL 1484 listed for vehicle use (50.8.8.2.1)”; A17 calls for monthly testing under 50.8.8.2.2. Those are the county’s requirements, not proof of nationwide adoption or approval of any particular detector.

NFPA’s October 2024 Food Truck Safety fact sheet separates three tasks:

• Gas detection testing: P8 says that where a gas detection system is installed, it must be tested monthly, referencing NFPA 96:17.8.2.2.
• System leak-test documentation: P6 calls for documenting system leak testing and keeping that documentation in the mobile facility, referencing NFPA 58:16.11.3 and 16.11.3.1. This is separate from the monthly alarm test.
• Piping and cylinder checks: P4 addresses pressure testing new or modified piping; P5 calls for noncorrosive leak-detecting fluid when replacing cylinders, referencing NFPA 58:16.11.5. A bubble check is not a piping pressure test.

NFPA 96’s 2024 edition places mobile and temporary cooking requirements in Chapter 17. The 2017 mobile-cooking annex moved into the standard in the 2021 edition, as described in NFPA’s December 2020 Standards Council material. Ask your local jurisdiction which editions and requirements apply to your truck.

UL 1484 covers fuel-gas alarms for residential occupancies and recreational vehicles. Its scope excludes gas detectors for hazardous locations. A maker’s statement of conformance to UL 1484 RV is not itself proof of a UL-issued listing; bring the exact model’s documentation to your fire marshal.

The picks

Detector	Type	Gases	Standard (per maker)	Mount	Replacement (per maker)	Best for
MTI Safe-T-Alert 20-441-P	Fixed 12V DC hardwire	Propane (alarm point also lists methane)	Conforms to UL 1484 RV (tested by ETL-Intertek)	4–20 in. above floor	5 years from retail purchase	Primary LP alarm
MTI Safe-T-Alert 35-741	Fixed 12V DC hardwire, 108 mA	Propane + CO	Conforms to UL 2034 RV / UL 1484 RV	4–20 in. above floor	5-year service life from installation	LP + CO in one box
Kidde KN-COEG-3 (900-0113)	Plug-in 120V AC, 9V backup	CO + natural gas or propane	Listed to UL 2034	Near the floor for propane	7-year life	Supplement on shore power
Forensics Detectors FD-91-RED	Handheld sniffer, 3 x AAA	Combustibles incl. propane (methane-calibrated)	None stated	Handheld, 10 in. probe	>5-year sensor life	Pinpointing a leak at a fitting
First Alert GCO1CN (maker note)	Plug-in 120V AC, 9V backup	Propane, methane, CO	Conforms to UL 1484 and UL 2034	Close to the floor for propane	5 years from installation	Supplement on shore power
RectorSeal Better Bubble 65273	Leak-detection solution	Natural gas, LPG, refrigerant	n/a	Applied at fittings	n/a	Fitting checks

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Primary dedicated LP alarm on an energized 12V circuit

MTI Industries Safe-T-Alert 20-441-P 12V Propane Gas Detector

Power

12V DC hardwire; manual: 100 mA; product page: 75 mA; 1 A inline fuse recommended

Mounting

4–20 in. above floor per 20-series manual

Alarm

85 dB at 10 ft; alarms below 25% of propane's lower explosive limit (LEL)

Standard

Conforms to UL 1484 RV; tested by ETL-Intertek

Replacement

5 years from retail purchase

A dedicated LP alarm for a powered 12V installation without dependence on shore power. It does not detect CO; the maker's alarm-point specification also lists methane. This link is the white 20-441-P-WT listing; MTI offers black and white. The manual and product page give different current figures, so confirm electrical requirements with MTI for your unit.

Specs: MTI Safe-T-Alert 20-series manual and product page

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LP and CO detection in one box

Safe-T-Alert 35-741 Dual LP/CO 12V Alarm (White, 35-741-WT)

Power

12V DC hardwire, 108 mA @ 12 VDC; surface mount

Gases

Propane and carbon monoxide

Mounting

4–20 in. above floor per 35-series manual

Standards

Conforms to UL STD 2034 RV / UL STD 1484 RV

Replacement

5-year service life from installation; if unknown, no later than 5 years from production

Combines LP and CO detection while retaining the manual's low mounting position. Both functions share one housing and one power feed, which matters when planning power and replacement. The linked version is white; the black version is 35-741-BL. Confirm acceptance for your truck with your fire marshal.

Specs: MTI 35-series manual and product page

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Supplement on shore power, subject to local acceptance

Kidde KN-COEG-3 (900-0113) Plug-In CO and Explosive Gas Alarm

Power

120VAC plug-in, 9V backup, 6 ft cord

Backup limitation

After 4 minutes on backup, explosive-gas sampling occurs once every 8 minutes

Gases and display

CO + natural gas or propane; CO ppm display with peak memory and GAS alert

Standard

Listed to UL 2034; UL 1484 not stated in the maker sheet or guide

Alarm and placement

85 dB at 10 ft; near the floor for propane

Warranty and life

5-year limited warranty; 7-year life

Kidde's guide limits intended use to ordinary indoor locations of family living units. Use it only as a supplement and confirm acceptance with your fire marshal. Battery backup operates, but its intermittent gas sampling is not equivalent to normal AC-powered operation.

Specs: Kidde product data sheet and user guide

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Diagnostic sniffer for locating a leak at a fitting after the area is safe

Forensics Detectors FD-91-RED Combustible Gas Leak Detector

Sensor

Semiconducting metal oxide; methane-calibrated; responds to propane and other combustibles

Power and probe

3 x AAA batteries; 10 in. flexible probe

Durability

Maker claims the ABS housing withstands a 10 ft drop

Warranty and life

1-year limited warranty; specification says >5-year sensor life (feature text says 5 years)

Protection limits

Maker: NOT A PERSONAL PROTECTION DEVICE; no installed-alarm standard stated

A diagnostic tool for fitting checks, not a replacement for an installed alarm. Its methane-calibrated readings are not propane concentrations. If you suspect an active leak, evacuate and call for help first; do not use this tool to search inside the truck before it has been made safe.

Specs: Forensics Detectors product page and FD91 manual

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For the fitting check a fixed alarm can't do

RectorSeal Better Bubble 65273 Leak Detector (1 Gallon)

Maker's stated use

Pinpoints the smallest natural gas, LPG & A/C refrigerant leaks

Application

Pipe, tubing and valves

Size and SKU

1 gallon; SKU 65273

For routine connection checks, PERC says to apply leak detector solution or thick soapy water to the valve area and connection and watch for bubbles. NFPA's food truck fact sheet calls for noncorrosive leak-detecting fluid when replacing cylinders (NFPA 58:16.11.5). A bubble check is not a pressure test of new or modified piping. If you smell gas, leave the truck and call for help first.

Specs: RectorSeal product page; PERC safety guide; NFPA food truck fact sheet

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Newer budget hardwired 12V options exist; verify the maker’s UL 1484 conformance documentation before buying.

What a propane detector does not do

A fixed alarm senses gas at its location. It does not repair a leaking fitting, find every leak elsewhere in the truck, or replace pressure testing of new or modified piping. The MTI 20-series is not a smoke, fire or CO alarm. Use the equipment and system checks required for each hazard.

For routine cylinder connection checks after the system is safe to work on, PERC describes applying leak detector solution or thick soapy water to the valve area and connection, then watching for bubbles. NFPA specifies noncorrosive leak-detecting fluid for food-truck cylinder replacement checks. Have a propane professional address a leak; do not attempt a gas-line repair yourself. If you smell gas or suspect an active leak, evacuate and call for help before any check.

Testing also has limits. MTI’s FAQ distinguishes the test button from its separate propane-or-butane sensor test. Follow your exact model’s procedure and schedule; the 20-series manual calls for testing weekly in use, before trips and after storage. Do not improvise a gas test or assume another manufacturer’s alarm uses the same method. Replace units on their model-specific schedule and when an end-of-life signal requires it.

Matching the detector to your rig

Start with an accepted alarm and a power supply that stays energized when detection is needed. A 12V hardwired model can operate without shore power only while its DC circuit remains powered. Treat residential plug-in alarms as supplements subject to your fire marshal’s acceptance, and account for their battery-backup limitations.

Use the selected model’s placement instructions: 4–20 inches above the floor for MTI 20/35, near the floor for Kidde, and close to the floor for First Alert when detecting propane. Have your installer determine the number and locations from the truck layout and applicable requirements. Confirm testing intervals, replacement dates and required system leak-test documentation before service.

For the rest of your safety setup, choose a fire extinguisher bracket that fits the extinguisher and mounting location. For cold-weather fuel-supply planning, see the propane tank warmer guide; a warmer does not replace leak detection or system testing.

Use the food truck equipment checklist for the broader build, the carbon monoxide detector guide for separate CO considerations, and the surge protector guide for electrical protection. The cafe equipment hub brings the equipment guides together.