Ludlum - Model 25-IS-1 Dosimeter

Ludlum Model 25-IS-1 Digital Dosimeter

The Model 25-IS-1 is an intrinsically safe, small-sized device designed to warn users any time they are in a potentially harmful radiation situation within an explosive gaseous environment. The design was specifically designed to warn emergency personnel entering into unknown environments but will equally serve anyone working near radioactive sources as in industrial type applications.

The unit will automatically alarm with a loud audible signal and a blinking display when either the dose rate (0.001 mSv/h to 9.99 Sv/h) or accumulated dose (0 to 1999 Sv) setpoints are exceeded. The dose is recorded until manually reset and is for use as reference only; it is not intended for legal dose recording.  This small device can be worn on a belt, a lanyard, or armband, and is very simple to use and operate.



Indicated Use Dosimetry
Display Range
.001 mSv/h to 9.99 Sv/h
Energy Range
60 keV to 2 MeV
Threshold Fixed at 40 mV to 10 mV
  • Dose rate alert
  • Dose rate (hi)
  • Accumulated dose alert
  • Accumulated dose (hi)
  • Time remaining to allowed dose (hi)
  • Detector failure
  • Low-battery notice when only 8 hours remain
LCD Display
3½ digit LCD with large 12.7 mm (0.5 in.) digits, cpm, cps, low battery indicator
Gamma Response
typically 18 cpm per mR/hr (1800 cpm per mSv/h)
Temperature Range -40 to 65 °C (-40 to 150 °F)
Power Two Lithim coin cell batteries
Battery Life Typically 6000 hours with alkaline batteries
Size 7.6 x 5.4 x 1.7  (3.0 x 2.1 x 0.69 in.) (H x W x L)