Thermometers are tough, safe alternative to mercury

FLUKE 1551A Ex and 1552A Ex Stik Thermometers provide a highly precise and durable digital replacement for mercury-in-glass thermometers. Units are intrinsically safe (ATEX and IECEx compliant), so they can be used safely where potentially explosive gases may be present. More durable than mercury-in-glass thermometers, they can be used reliably outdoors or on the production floor.

http://www.fluke.com/stik