What is the recommended withdrawal of chlorine in pounds from a 100 or 150 lb cylinder in a 24-hour period to prevent freezing?

The recommended withdrawal of chlorine from a 100 or 150 lb cylinder in a 24-hour period to prevent freezing is 40 pounds. This guideline is established to ensure that the liquid chlorine does not reach temperatures low enough to freeze, which could potentially block the line and disrupt disinfection processes.

Withdrawing 40 pounds over a 24-hour period maintains the cylinder's temperature and pressure by allowing adequate vaporization while ensuring a steady supply of chlorine for treatment processes. It helps balance the pressure within the cylinder and avoids the rapid cooling that can occur with excessive withdrawal rates. Proper management of chlorine use is critical in wastewater treatment to maintain effective disinfection while also ensuring safety and operational efficiency.

The other options suggest withdrawal amounts either too low, which may not be sufficient for operational needs, or too high, which could cause temperature drops leading to freezing. Thus, adhering to the 40 pounds recommendation is essential for optimal performance and safety.