NFPA 2015
5.1.8.1.1 Pressure indicators and manometers for medical gas piping systems shall be cleaned for oxygen service.
5.1.8.1.2 Gauges shall comply with ANSI!ASME B40.100,
Pressure Gauges and Gauge Attachments.
5.1.8.1.3* The scale range of positive pressure analog indicators shall be such that the normal operating pressure is within the middle third of the total range [e.g., an indicator of 0 to 2070 kPa (0 to 300 psi) would have a lower third of 0 to 690 kPa (0 to 100 psig), a middle third of 690 kPa to 1380 kPa (100 psig to 200 psig), and a top third of 1380 kPa to 2070 kPa (200 psig to 300 psig)].
5.1.8.1.4 The accuracy of digital indicators shall be ±5 per- cent of the operating pressure at which they are used.
5.1.8.1.5 The scale range of vacuum indicators shall be 0 to 760 mm (0 to 30 in.) gauge HgY. Indicators with a normal range display shall indicate normal only above 300 mm (12 in.) gauge HgY.