Check with your bath manufacturer before using this salt to make sure your equipment is compatible. Hart offers three standard bath models and custom-designed units for use with this salt. It's important to understand a few specifications before selecting a bath fluid. We've seen bath fluids advertised with a temperature range that spans from the freezing point to the flash point or beyond. It's a viscosity issue, not a freezing-point issue.
Usable range is the question.
Suitability for calibration work is the specification that counts. The usable viscosity range is determined by your bath's stirring or pumping design. Hart baths can be operated using fluids with up to 50 centistokes viscosity. This gives you additional usable range in the lower temperature levels of the fluid. Some baths advertised as calibration baths require fluids with 10 centistokes or less viscosity to operate properly.