What precautions should be taken when replacing the cooling water in a three-roll mill?

I. Pre-Replacement Preparation
‌1. Shutdown and Cooling
‌Wait for at least 30 minutes to avoid injury from splashing high-temperature cooling water.
‌Confirm that the roller temperature has dropped below 50°C before proceeding.
‌2. Tool Preparation
‌Prepare distilled/purified water (conductivity <50 μS/cm), a funnel, a wrench, and a water collection container.
‌Check that the cooling water piping is intact (focus on the copper pipe connections).
‌II. Replacement Operation Key Points
‌1. Drainage Procedures
‌First, open the drain valve at the bottom of the water tank, then loosen the drain bolt (counterclockwise).
‌Observe the condition of the old water: If rust or sediment is found, thoroughly flush the system.
‌2. System Flushing
‌Circulate clean water 3-5 times until the water is clear (you may briefly start the water pump for assistance).
‌After flushing, drain any remaining water (recommended). Compressed air is recommended for purging.
3. Water Filling Standards
Use a funnel to slowly fill with distilled water to the liquid level mark (avoid creating bubbles).
In winter, add 30%-50% ethylene glycol antifreeze (when the ambient temperature is <0°C).
III. Safety Precautions
1. Protective Measures
Wear acid- and alkali-resistant gloves and goggles when handling (coolant may contain corrosive substances).
2. Water Quality Management
Tap water is strictly prohibited (it can easily cause scale buildup and clog pipes).
Test the water conductivity monthly; replace immediately if it exceeds the standard.
3. System Venting
After filling with water, run the equipment idle for 5 minutes, check the liquid level, and refill to the standard.
IV. Maintenance Recommendations
Create a cooling water replacement record (record date, water quality parameters, and operator).
Check the sealing of cooling water pipes quarterly.