Tinker & Rasor M/1 Low Voltage Holiday Detector

Tinker & Rasor Model M/1 Low Voltage Porosity Detector features regulated 67.5 v DC output voltage to locate pinholes in thin film coatings up to 20 mils thickness using the Wet Sponge Method in accordance with NACE RP0188.


Tinker & Rasor’s M/1 Low Voltage Holiday Detector is the classic wet-sponge detector for pinholes or bare spots in thin film coatings under 20 mils thick.  Equipped with six AA batteries, the Tinker & Rasor M-1 features on-board calibration verification, LED light on the front of the detector indicates unit calibration and detection of coating flaws, and a waterproof plastic housing protects electrical components from exposure to the elements. Compact and light-weight, the M/1 can be worn on the waist, leaving hands free for coatings inspection. Headphones may now be used to enable the inspector to hear the audio signal in noisy environments.

T & R M/1 is supplied with a 7” sponge electrode, with custom electrodes available in various lengths, as well as internal round sponges for flaw detection of internal pipe linings.

Tinker & Rasor M/1 is also available as M1/AC, using standard AC power supply for in-shop applications. The AC power makes it possible to run continuously without work interruptions to change batteries.

Tinker & Rasor M1/AC Low-Voltage Sponge Tester offers the same features as the Model M-1, but is powered by 110/120 volt, 60 Hz AC, producing regulated 67.5 volts DC output voltage, making the M1/AC ideal for in-shop operation without job interruptions to change batteries. A warning bell and indicator light alert detection of coating holidays. The audible alarm can be heard in most coatings application environments.

Features of the Tinker & Rasor M-1 Wet Sponge Porosity Detector includes:

  • Regulated 67.5v output
  • Push-button calibration check
  • 2 resistance settings:
    • 80Ω for tanks and pipe (factory setting)
    • 90Ω for coatings on concrete
  • Conforms to NACE RP0188, Standard Recommended Practice: Discontinuity (Holiday) Testing of New Protective Coatings on Conductive Substrates
Weight3 lbs
Dimensions20 × 9 × 5 in

The M-1 Low Voltage Holiday Detector Kit includes:

  • Detector with batteries
  • 18” wand with 6’ cable
  • 15’ ground wire
  • 7 x 2 x 2” sponge electrode (ships compressed; expands when water is added)
  • 4 oz bottle of Water Wetter
  • Instruction manual

Click here to download the Tinker & Rasor M/1 Datasheet

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