2.7 Conduit Seal and Pressure Relief
In accordance with the National Electrical Code (NEC) ANSI/NFPA 70, Article 501-5(f)(3), the
flowmeters include a conduit entry seal and pressure relief to prevent the process fluid from entering
the electrical conduit system. This safety feature is avai;able for NPT fittings only and considers the
remote possibility of a primary seal failure, in which case, the secondary seal will prevent the process
from entering the electrical conduit system. The secondary seal consists of the following:
Integral Converter - Feed-through’s between the electronics housing and field wiring
(customer connection) junction box.
Remote Primary - Conduit entry cable seal on meter customer connection box.
It is the user’s responsibility to properly install the conduit entry cable seal fitting supplied with the
signal cable provided with the remote mounted signal converter. This will ensure proper performance
of this safety feature. See Figure 2-22.
A pressure relief is provided in the electronics housing for the integrally mounted signal converter
and in the customer connection box on the remote mounted Flowmeter. In both housings, the
pressure relief is located in the center of the cover joint on the side opposite from the conduit
connection. If the primary seal should fail, the pressure relief will vent the process preventing an over
pressurization and potentially dangerous failure of the electronics housing.
It is the user’s responsibility to be aware of this safety feature and to consider the unlikely event of its
functioning. Based on knowledge of the process and meter application, the user should consider the
installation orientation of the meter and possible use of deflectors to safely direct the vented process.
FIGURE 2-22. CONDUIT ENTRY SEAL INSTALLATION
Series 10DX3000 Magnetic Flowmeter Instruction Manual
2-27
