Network Meter Block Installation, Operation, & Maintenance Manual
Installation 8
3 Installation
3.1 Physical Installation
The following sections provide guidelines on installing your NMB when purchased as a standalone unit
(without a Smith Meter Turbine or PD meter). Standalone NMBs can be panel mounted on a DIN rail or,
when purchased with an explosion-proof instrument housing, directly mounted to a meter.
3.1.1 Installing a Panel-Mounted NMB
You can install a standalone NMB (without an enclosure) in nonclassified areas remotely from the meter,
assuming the meter transmits pulses to an existing device, such as a flow computer or batch controller.
The NMB’s inputs can accept an amplified meter pulse train (such as those sent to a flow computer). The
NMB’s meter pulse inputs have sufficient impedance that operation of an existing flow computer should not
be affected by sending pulse data into the NMB in parallel.
A standalone NMB can be wired the same as a meter-mounted NMB with a pulse transmitter included
(such as Smith Meter’s PA-6 Preamplifier; see Section 3.2.5: Typical Wiring Diagrams).
The NMB can be mounted directly to a panel using the two through-holes. Optionally, it can be purchased
with an 35-mm DIN rail mounting kit, designed specifically for a single panel-mounted meter block.
When planning a custom DIN rail layout, you must allow adequate spacing for air circulation around each
NMB sharing the same DIN rail; a minimum of 6 mm (.24 inch) is recommended. Adequate spacing also
should be allowed between any adjacent, parallel DIN rails for cable runs; a minimum center-to-center
distance of 120 mm (4.7 inches) is recommended. The center-to-center distance used should also factor in
the minimum spacing requirements for any other equipment mounted on the DIN rail.
The NMB is certified to allow installation into Class I, Division 2, Zone 2 hazardous locations when it is
installed in an appropriate electrical enclosure with a minimum ingress protection (IP) rating of IP54.
It is the installer’s responsibility to ensure that all applicable local electrical safety codes are followed
when integrating the Smith Meter NMB into a custom enclosure. It may be required that the complete
electrical enclosure system be certified by a national authority.
The NMB also may be installed in ordinary, non-hazardous locations and has been evaluated to
Underwriters Laboratories (UL) 508 – Industrial Control Equipment, a standard regarding fire and shock
safety. This standard also is used to satisfy the requirements of European Union (EU) Directive 2014/
35/EU regarding low voltage.
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