Another requirement for a vaporizer in a propane system is to:

• A. To increase tank capacity
• B. To increase tank pressure
• C. To decrease tank capacity
• D. To decrease tank pressure

Answer: (D)

The main idea here is how a vaporizer functions in a propane system. Propane is stored as a liquid under pressure, and when you open the gas line, the system must deliver propane as a gas at a usable pressure for appliances. The vaporizer’s job is to heat the liquid propane so it changes into a gas before it reaches the regulator and the downstream gas lines. This ensures the gas flowing to the system is in the proper phase and that the regulator can do its job of reducing the pressure to a safe, appliance-friendly level.

Because the regulator is what actually lowers pressure to the level needed by the appliances, the vaporizer itself doesn’t determine the tank’s pressure in normal operation. Tank pressure is dictated by the propane’s vapor pressure at the tank’s temperature, and pressure regulation for the system is accomplished downstream of the vaporizer. So the vaporizer’s role is about converting to vapor and maintaining a steady supply of gas, not about decreasing tank pressure.