Propylene Glycol

Propylene Glycol has been used as an industrial ultrasonic couplant since the early 1960’s. Because of its low
viscosity, it is most suited to horizontal surfaces. Propylene Glycol is often the couplant choice for laboratory
work and calibration of test blocks.


Compatible with a broad range of materials including most metals, plastics and composites.

  • Broad operating range -40 °F to 250°F (-40°C – 482 °C)
  • Low toxicity – propylene glycol is often added to food products and is used in injectable medicines.
  • Water soluble: easierto removethan most ultrasonic couplants by wet or dry wiping or water wash.
  • Slow Drying at ambient temperatures
  • Good Surface wetting due to low surface tension and solvent properties.

Auto Ignition: while propylene glycol has a high auto-ignition temperature, its relatively low flash point of 220° F (104° C) limits the upper temperature range in many applications to 175° F (80° C)

Contains no glycerin which can interfere with subsequent penetrant inspection.

Environment and operator friendly – no formaldehydes, nitrates, nitrites or glycol ethers.

Lower residue than most UT couplants.

Removal: Wipe with wet or dry paper or cloth rag or water wash.

pH: 7.0

Operating Temperature: -40 °F to 250°F (-40°C – 482 °C)

Halogens and Sulfur: less than 50 ppm

Acoustic Impedance 1.61 x 105 g/cm2/s

Auto ignition Temperature 700 F (371 C)

Flash Point 220°F (104.4°C)

Surface Tension 36 dynes/cm (mN/m), 77°F (25°C)

  • PG-4CTN: Carton of (12) 4-oz/118 ml bottles
  • PG-1: 1-gallon/3.8 liter cubitainer, one refillable bottle
  • PG-5: 5-gallon/18.9 liter cubitainer, two refillable bottle