Network Meter Block Installation, Operation, & Maintenance Manual
Installation 10
After installing your NMB, the qualified installer must indicate the type of environment in which the NMB
was installed using a stamping die (such as an “x”) in the box next to the appropriate zone type on the
housing’s name plate.
Class I, Division 1, Zone 1 areas are identified as Ex db IIB T6 Gb -40 °C ≤ Ta ≤ 60 °C
Class I, Division 2, Zone 2 areas are identified as Ex ec IIB T6 Gc -40 °C ≤ Ta ≤ 60 °C
3.1.3 Installing the NMB or NMT on a Turbine Meter
To communicate meter information, the NMB is designed to be easily connected to a turbine meter using
traditional low voltage pickup coils. The following options are available for connecting the NMB with a
turbine meter, depending on your NMB model:
• Models beginning with “NMB” directly interface with a digital meter pulse signal; for example, the
output of a preamplifier, such as the Smith Meter PA-6 or PA-11 Preamplifier, (see Figure 9: Meter
Pulse Inputs from a PA-6 Transmitter (NMB Models Only) for connections).
• Models beginning with “NMT” include a preamplifier front end so it can connect directly to a low voltage
pickup coil (see Figure 12: Wiring the NMT Directly to Pickup Coils in Sentry, Guardsman, and MV
Turbine Meters for connections).
All Smith Meter turbine meters with pickup coils are supplied with a 1-inch NPT pickup boss. The NMB’s
instrument housing may be directly mounted to the 1-inch NPT boss using a male/female (M/F) conduit
union.
3.1.3.1 Pulse Transmission
If long-distance pulse transmission is required to connect with other non-communicating ancillary
equipment, we recommend using the NMB with a Smith Meter PA-6 or PA-11 Preamplifier, which can be
purchased as accessories with an NMB. The pulse output from a preamplifier is used to send the meter
pulse signal to the NMB’s pulse input and to other pulse input ancillary devices in parallel.
If long-line pulse transmission is not required, a 5 volt, peak-to-peak, 1:1 pulse output is available.
This direct-mounting method only allows access to one pickup coil. If you require access to both pick-up
coils (such as for flow direction detection), remote mounting of the NMB is recommended so the signals
are derived directly from the individual preamplifiers.
Figure 3: NMB Housing Directly Mounted to Smith Meter G Series Turbine Meter
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