CSLB C-46 Solar ContractorSolar Thermal System InstallationMedium
A solar thermal installer is performing the initial fill of a closed-loop propylene glycol system. After filling the system and purging air, the installer needs to verify the freeze protection level of the glycol solution. What is the most accurate and common method to determine the freeze protection temperature of the glycol solution in the field?
- AComparing the color of the solution to a manufacturer's chart.
- BMeasuring the pH of the solution with litmus paper.
- CUsing a refractometer to measure the glycol concentration.
- DUsing a hydrometer to measure specific gravity.
Show answer & explanationAnswer & explanation
Correct answer: C. Using a refractometer to measure the glycol concentration.
A refractometer directly measures the refractive index of the glycol solution, which correlates precisely to its concentration and thus its freeze protection temperature. This is the most accurate field method. A hydrometer is less accurate, pH measures corrosion protection, and color is not an indicator of freeze protection.
Why the other options are wrong
- A. The color of the solution indicates the presence of dye or degradation, not the freeze protection level.
- B. pH measurement indicates the level of corrosion inhibitors, not freeze protection.
- D. A hydrometer measures specific gravity, which can be an indicator, but it's less accurate and temperature-dependent compared to a refractometer for glycol solutions.
Glycol Freeze Protection Verification
Verifying the freeze protection of a glycol solution in a solar thermal system ensures the fluid will not freeze and damage components at expected low temperatures.
- Crucial for system longevity and performance.
- Refractometers provide accurate field measurements.
- Concentration directly correlates to freeze protection temperature.
Memory trick: Refractometer's eye, tells the freeze point high.