Which device is NOT used for testing antifreeze solutions?

The spectrometer is not typically used for testing antifreeze solutions. In the context of antifreeze testing, devices such as refractometers and hydrometers are commonly employed. A refractometer measures the refractive index of a solution, which can help determine the concentration of antifreeze in water. Hydrometers measure the specific gravity of the fluid, allowing for the assessment of the antifreeze's effectiveness and concentration.

The manometer is used to measure pressure in liquids and gases, and while it plays an important role in system diagnostics, it does not assess antifreeze concentration or quality. In summary, the lack of application of a spectrometer in directly measuring the properties of antifreeze solutions justifies its selection as the device that is not used for testing in this context.