The NRTL listing means that the device fully complies with the US Mine Safety and Health Administration’s 30 CFR 75.351. It is the only post-accident, performance-tested and NRTL-listed CO sensor currently on the market.

MSHA dictates that new CO sensors undergo performance testing, including rigorous tests to prove accurate performance and resistance to radio frequency interference. CO units, the agency noted, can experience problems with RFI when used near two-way radios.

“Unlike other sensors, the S1000 was specifically designed for resistance to RFI, even in close proximity to two-way radios,” Matrix president Aric Pryor said.

“The S1000's resistance to RFI was confirmed by performance testing, which established that the sensor is fully compliant with 30 CFR 75.351 and APOL 2207, with no MSHA blasting clearance requirement.”

The sensor had already received MSHA approval for intrinsic safety (No. 18-A090002-0), allowing it to remain in continuous operation post-accident or during fan outages. More than 1000 of the units are already in use at US coal operations.

Warrior Coal general manager Eric Anderson said that his mine had about 110 Matrix S1000 wireless sensors underground.

"Installing, calibrating and relocating these new wireless CO sensors has saved our men significant time,” he said.

“We are excited to have a compliant CO sensor that can accurately monitor air conditions underground after the fan is shut off or during other mine emergencies that require the power to be turned off."

The Matrix S1000 CO sensor is part of the company’s Wireless Atmospheric Monitoring System. WAMS integrates with Matrix's Miner and Equipment Tracking System to create a single underground infrastructure for atmospheric monitoring, communication and tracking.

Both Matrix Design and Warrior Coal are subsidiaries of producer Alliance Resource Partners.