Chlorination operations: Chlorine supply cylinders are commonly maintained around 38–40 °C in service. What operational problem does this prevent?

Introduction / Context:
Chlorine is typically stored as a liquefied gas. During dosing, heat input is needed to sustain evaporation; otherwise, refrigeration from vaporization can chill surfaces so much that frost and solid phases impede flow. Operators often maintain evaporators or water-baths at about 38–40 °C to stabilize gas withdrawal.

Given Data / Assumptions:

• Cylinders are used with vaporizers or water-bath heaters.
• Ambient conditions may be cool enough to cause icing and solidification phenomena at valves/evaporators.

Concept / Approach:

When chlorine vaporizes, latent heat is absorbed, lowering temperature. Without external heat, local cooling can cause icing and even formation of chlorine “hydrates” or crystals at valves/flow paths, restricting gas flow. Controlled heating counters this effect and ensures steady feed and accurate control.

Step-by-Step Solution:

Verification / Alternative check:

Equipment manuals for chlorinators specify water-bath temperatures in this range to avoid icing and flow instability.

Why Other Options Are Wrong:

• Combustion (“burning”) is not relevant; chlorine is not a fuel.
• Heating is not primarily for explosion prevention when systems are operated within rated pressures.
• Corrosion control is handled by materials selection, not by heating.

Common Pitfalls:

• Overheating beyond recommended limits can elevate internal pressure; always follow manufacturer settings.
• Confusing heater use for cold climates only—icing can occur from vaporization even in mild weather.

Final Answer:

Conversion of chlorine into crystals that impede gas withdrawal.