Gas-specific demand check fittings are not required on which type of indicators?

Gas-specific demand check fittings are designed to ensure that the indicator devices correctly measure and respond to the specific type of gas they are monitoring, providing safety and accurate readings. Zone valve pressure indicators are used to monitor the pressure in a specific area or zone where gases are used.

In this context, these indicators are generally operated at a constant pressure relative to the gas supply and are not required to have gas-specific fittings, as they are not measuring the properties of the gas itself, but rather the pressure status of the zone. Unlike other types of monitors, such as those for dew point or carbon monoxide, which directly interact with the gas being monitored, zone valve pressure indicators are more about maintaining and reporting consistent pressure within a system.

This distinction is key, as it highlights that while monitoring devices like dew point and carbon monoxide monitors require specific fittings to accurately perform their functions, zone valve pressure indicators function based on pressure levels and not on the chemical properties of the gas itself, thus making gas-specific demand check fittings unnecessary for them.