Final answer:
To find the nitrogen cylinder regulator setting for an ATG system, consult the system's manual for the specific pressure range. Gauge pressure readings on these systems, which read zero at atmospheric pressure, correspond to pressure above the atmosphere when positive and below when negative.
Step-by-step explanation:
When inspecting automated tank gauging (ATG) systems, the specific pressure range for the nitrogen cylinder regulator setting can vary depending on the system's design and the manufacturer's recommendations. It's crucial to consult the manual or technical documents for the accurate pressure range for a given system. Most pressure gauges are calibrated to read zero at atmospheric pressure, indicating that the reading shown is the gauge pressure, which is the pressure relative to the atmospheric pressure. When dealing with compressed gases such as nitrogen, a common gauge setting might be within the safe operating pressure recommended for the tank and system, but specific numbers should always be derived directly from the pertinent documents associated with the ATG system being used.
In general, gauge pressure is positive for pressures above atmospheric pressure and negative for pressures below it. Remember that when you see a gauge reading such as 34 psi, this value is the gauge pressure above atmospheric pressure. For absolute pressure, which includes the atmospheric pressure, you would add approximately 14.7 psi (the value of standard atmospheric pressure at sea level) to the gauge pressure.