Hazardous Location Alarms


For applications where a spark can cause a fire or explosion, Mallory’s SCH Series of audible alarms is qualified by UL and CUL for Class I Div II Groups A, B, C, & D hazardous location applications. These alarms mount in a 30mm hole, and are equipped with a neoprene gasket, ensuring NEMA 4X waterproof protection. Electrical connection to the alarm is made to the two backside screw terminals which are sealed completely into the alarm with epoxy.

Hazardous location models are available with:

  • Voltages ranging from 1 Vdc to 250 Vac
  • 1900 Hz. 2900 Hz, & 4500 Hz sound frequencies
  • Sound levels varying from soft to extra-loud
  • Various sound types including the popular continuous tone as well as pulsing tones, chimes, & sirens

With 55 available models, selecting the right one for your application has been made easy. You can utilize Mallory’s website’s parametric search table, submit your questions directly to Mallory, or call for technical assistance at 317-612-1000. Popular models include:

Model No. Rated Voltage Sound Type Sound Level Sound Feq.
SCH110NR 120 V ac Continuous Extra-Loud 2900 Hz
SCH110R 120 V ac Continuous Medium 2900 Hz
SCH250R 250 V ac Continuous Medium 2900 Hz
SCH628ANPR 28 V ac/dc Fast Pulse Extra-Loud 2900 Hz
SCH628DR 28 V dc Continuous Soft 1900 Hz
SCH628NR 28 V dc Continuous Loud 2900 Hz
SCH628R 28 V dc Continuous Medium 2900 Hz


Petroleum refining facilities

Solvent extraction plants

Oil well equipment

Hydrogen operations

Dip tanks

Petroleum dispensing areas

Dry cleaning plants

Utility gas plants and operations

Spray finishing areas

American Flag - Made in the USAMallory’s SCH Hazardous Location series is made-in-the-USA. These models are UL & CUL approved for Class I DIV II Groups A, B, C, & D applications. Additional approvals include NEMA 3R, 4X, & 12. Lead-times are 1 week or less.

Mallory Sonalert Products | 4411 South Highschool Rd | Indianapolis, IN 46241 | 317-612-1000