Seametrics MJN-Series - Manual (Page 2)

Position. MJN-Series meters should be installed horizontally
with the register up. Vertical mounting will result in some de-
gree of under-measurement and shortened life of the bearings.
No upstream straight pipe is required.
Couplings. Male NPT threaded couplings are included with
each meter. The threads on the end of the meter are IPS
straight threads one size bigger than the meter size. Though
it is possible to thread a standard pipe coupling directly onto
the meter for close coupling, the included couplings are much
preferable because they provide a union connection for meter
service. Be sure to use the included gasket between the end
of the meter and the coupling.
Connections. MJNE and MJNR sensors are supplied with
a color coded output cable (see diagram, page 4). Optional
connectors can be ordered to plug directly into a Seametrics
control or LMI metering pump.
WARNING
DO NOT INSTALL
METER IN OVERHEAD
INDOOR PIPING OR
WHERE LEAKAGE
MAY CAUSE DAMAGE
GENERAL INFORMATION, INSTALLATION and MAINTENANCE
Page 2
GENERAL INFORMATION
MJN-Series meters use the internationally-accepted multi-jet
principle. A gear train drives the register totalizer dials. For
pulse output, one of the pointers is replaced by a magnet
arm, which is detected by an encapsulated sensor attached
to the outside of the lens.
MJNE meters use a solid-state, long-lasting Hall-effect sensor,
which requires power. They are suited for use with Seametrics
controls and metering pumps (LMI for instance) that have
sensor power.
MJNR meters use a reed switch. They provide a dry contact
closure and do not require power.
MJNT meters do not have a sensor, and they totalize only.
INSTALLATION
Pulse Output. Both MJNE and MJNR sensors respond
to a magnet that rotates on the face of the meter under
the lens. The sensor turns on and off once each time
the magnet passes under it. Sensors are designed for elec-
tronic control loads, and should not be used to switch power
loads or line voltages. See maximum current and voltage
ratings, under Specifications.
MAINTENANCE
Seametrics recommends all service to be performed by an
authorized distributor or the factory to maintain the integrity
of the protective tamper-proof wire-and-seal.
Inlet Strainer. Clean the strainer yearly, or as required, de-
pending on water condition. Pull out the strainer or backflush
the meter to loosen trapped particulates.
Calibration. Meters used for billing or billing exemp-
tion may be regulated by state or local authorities. New
meters are factory-tested to meet the AWWA C-708
Multi-Jet Meter accuracy specification. Some states
require retesting at various intervals, typically eight years for
3/4" meters, six for 1", and four for 1-1/2" and 2". Meters
used for control should be tested every 5-10 years. Testing
may be done by a local mobile meter service or in a private
or municipal meter shop. Changes in calibration should be
made at an authorized meter shop.
**CAUTION: Excessive flow can cause breakage.
Do not exceed recommended maximums.
Caution: These water meters are
not recommended for installation
in uninsulated suspended ceil-
ings where freezing is possible,
or in any overhead indoor piping
configuration where leakage may
cause damage.
SPECIFICATIONS*
6 mA at 12 Vdc (MJNE only)
105˚ F (40˚ C) max
150 psi operating
Eco-brass alloy
Engineered thermoplastic
Alnico
+/- 1.5% of reading
MJNE MJNR MJNT
Hall-effect Reed switch Totalizer only
20 mA 20mA
n/a
24 Vdc 24 Vdc or Vac n/a
12’ (4 m) standard (2000’ maximum run)
3/4” 1” 1-1/2” 2”
0.22 0.44 0.88 1.98
22 52 88 132
NSF-61-G
Power
Temperature
Pressure
Materials Body
Internals
Magnet
Accuracy
Pulse Output
Sensor
Max Current
Max Voltage
Cable Length
Flow Rates (GPM)
Minimum
Maximum
Regulatory
*Specifications subject to change
Please consult our website for current data (www.seametrics.com).