Question

13 multiple choice 1 point
why is natural gas used to maintain the constant pressure for the fuel gas system?
because atmospheric changes can affect other gases
because fluctuations in temperature do not affect it
because refinery off - gas or fuel gas may be variable based upon unit operations
because of variance in the quality of fuel gas
14 multiple choice 1 point
what should be done to a compressed air system to ensure that water vapor is not entrained in utility and instrument gas systems?
operate at dewpoint temperatures lower than ambient down to - 112 degrees fahrenheit.
flush the system out with nitrogen.
flush the system out with helium.
add lubricant to the system.

Explanation:

For question 13: Fuel gas from refinery operations can vary in supply based on unit processes, so natural gas acts as a stable source to keep pressure constant.
For question 14: Lowering the system to a dew point below ambient (down to -112°F) removes water vapor by condensing it, preventing entrainment in utility/instrument systems.

Answer:

1. C. Because refinery off-gas or fuel gas may be variable based upon unit operations
2. A. Operate at dewpoint temperatures lower than ambient down to -112 degrees Fahrenheit.