Understanding the Use of Magnetic Level Gages and ASME Code Compliance on Power Boiler Applications
A Magnetic Level Gage may be an excellent addition to the drum level instrumentation on your Power Boiler application. However, in order to properly apply a Magnetic Level Gage on a Power Boiler, you must first understand the specific minimum requirements for water level instrumentation in the ASME Boiler and Pressure Vessel Code. A functional water gage glass is required on all boilers and it must be in service at all times on applications operating up to 400 PSIG (3MPa). For boilers operated at greater pressures, the Code permits the minimum use of two remote (indirect reading) level indicators on continuous display for the operator combined with a water gage glass. The use of a magnetic type level indicator has a Code limit of 900 PSI (6 MPa). Furthermore, when two remote indicators are in service, the gage glass may be isolated, but must be kept in good working condition. Gage glasses are often used to confirm the actual water level in the drum and for comparison with other instruments, especially at start-up.
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