Ludlum - Model 3IS

Ludlum Model 3-IS Intrinsically Safe General Purpose Survey Meter

The Ludlum Model 3-IS - The universal INTRINSICALLY SAFE survey meter.It was designed and tested to USA standards for instrinsic safety, permitting it to be used in potentially explosive atmospheres. The Model 3-IS can only be used with select detectors to sustain the intrinsic safety rating. The optional detectors for this application are:

  • Model 44-9:     15 cm2 GM pancake probe
  • Model 44-2:     2.5 x 2.5 cm (1 x 1 in.) NaI scintillator
  • Model 44-38:   energy compensated GM probe with beta window

The Ludlum Model 3 can be customized to suit any application. Universal meter body can be paired with any Ludlum probe. This meter can only be calibrated to one probe at a time.

The aluminum cast instrument housing with its separate battery compartment and accompanying metal handle offer an industrial robustness and quality that promote long-lasting protection and instrument life. The front-panel controls include a rotary switch for selecting the four-decade range, instrument shut-off, and battery test, an audio on/off switch, a fast/slow response switch, and a count reset button.
A one meter (39 in.) straight type detector cable with "C" style connector is included in the price of the instrument.

Meter Body:

Indicated Use Dependant on probe selection
Linearity Reading within 10% of true value with detector connected
High Voltage Adjustable from 400-1500 Vdc
Threshold fixed at 40 mV to 10 mV
Meter 6.4 cm (2.5 in.) arc, 1 mA analog type
  1. Rotary Selector: switches between instrument off, battery check, ranges: x0.1, x1, x10, x100
  2. Response Switch: toggles between FAST (4 seconds) or SLOW (22 seconds) from 10% to 90% of final reading
  3. Reset Pushbutton: to zero meter
  4. Audio Switch: for audio on/off, built-in unimorph speaker, greater than 60 dB at 0.6 meters (2 ft)
  5. Calibration Controls: accessible from front of instrument (protective cover provided)
Construction cast and drawn aluminum with beige powder coat
Temperature Range -20 to 50 °C (-4 to 122 °F), may be certified for operation from -40 to 65 °C (-40 to 150 °F)
Power Two "D" Cell Batteries
Battery Life Typically greater than 2000 hours with alkaline batteries
Size 16.5 x 8.9 x 21.6 cm (6.5 x 3.5 x 8.5 in.) (H x W x L), including handle