Summary
In response to challenges in sourcing ohm meters and the risks associated with using improper equipment, this bulletin is intended to raise awareness of best practices and potential hazards when using blaster’s ohm meters and multimeters.
Blasters ohm meters and multimeters are intrinsically safe, specialized devices that measure resistance in blasting circuits and safeguard against detonation.
Standard blasters ohm meters are galvanometers. It measures resistance through connections between a coil of wire and the leads of a blasting circuit, which creates a magnetic field, but are current-limited.
Blasters multimeters are manufactured to include current-limiting circuits as a safeguard to ensure they do not accidentally cause detonation. When testing a blasting circuit, current-limiting ohm meters should be used to ensure safety. Conventional or off-the-shelf multimeters should never be used on blasting circuits.
Unlike blasters meters, off-the-shelf multimeters can exceed the no-fire limit of the detonator which can potentially trigger explosives.
To ensure safety, meters must be labelled as a “blasters ohm meter”, “blasters multi-meter” or “blasting galvanometer” with an Original Equipment Manufacturer label. Meters without a “blasters” or “blasting” label should not be used.
Surface Safety Testers are designed specifically for digital circuit, multi-stage detonators. Each tester is manufactured specifically to the detonator’s manufacturer.