Seametrics MJN Operating Manual

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MJP/MJN-Series

Pulse Meter Instructions

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ISO

9001:2008

MJP/MJN-SERIES INSTRUCTIONS

General Information

General Information ...................................................................................................................................................Page 3

Features ...........................................................................................................................................................................Page 3

Specications ................................................................................................................................................................Page 4

Dimensions ....................................................................................................................................................................Page 5

Pulse Rates .....................................................................................................................................................................Page 5

Shipping Weight ..........................................................................................................................................................Page 5

Pressure Drop Curve ...................................................................................................................................................Page 5

Installation and Operation

Position ............................................................................................................................................................................Page 6

Couplings ........................................................................................................................................................................Page 6

Connections ...................................................................................................................................................................Page 6

Pulse Output ..................................................................................................................................................................Page 6

Setting Pulse Rate .......................................................................................................................................................Page 6

Reading Meter ..............................................................................................................................................................Page 7

Maintenance

Inlet Strainer ..................................................................................................................................................................Page 7

Calibration ......................................................................................................................................................................Page 7

Parts ..................................................................................................................................................................................Back

Seametrics • 253.872.0284 Page 2 seametrics.com

GENERAL INFORMATION

MJP/MJN-SERIES INSTRUCTIONS

MJP-Series and MJN-Series meters use the multi-jet
principle, which has been an internationally-accepted
standard for many years. This type of meter is known for its
wide range, simplicity, and accuracy in low-quality water.
The Seametrics MJP-Series and MJN-Series are certied to
NSF/ANSI 61. The impeller is centered in a ring of jets, with
inlet jets on one level and outlet jets on another. A gear train
drives the register totalizer dials. For pulse output, one of
the pointers is replaced by a magnet, which is detected by
an encapsulated sensor attached to the outside of the lens.
Pulse rate is determined by the dial on which the magnet
is placed, and by the number of sensors (single or double).

Changing the pulse rate requires no special tools and can

be done in the eld.

Features

The MJP-Series has a plastic body and is available in 3/4”,
1”, and 1 1/2” versions.

The MJN-Series has a brass body and is available in 3/4”,
1”, 1 1/2” and 2” versions.

MJPE & MJNE meters use a solid-state, long-lasting Hall­effect sensor, which requires power. It is suited for use with
Seametrics controls and metering pumps that have sensor
power.

MJPR & MJNR meters use a two-wire reed switch. They
provide a dry contact closure and do not require power.

MJPT& MJNT meters totalize only and do not have a
sensor.

The MJPE/MJNE or MJPR/
MJNR sensor fastens to
lens without removing top

Plastic body (MJP) or
Brass body (MJN)

Union end couplings
for easy service

Calibration plug seal wire
for tamper evidence

MJP-Series

(plastic body)

MJN-Series

(brass body)

Seametrics • 253.872.0284 Page 3 seametrics.com

GENERAL INFORMATION

MJP/MJN-SERIES INSTRUCTIONS

Specications*

Power 6 mA at 12 Vdc (MJPE & MJNE only)

Temperature 105˚ F (40˚ C) max

Pressure 150 psi operating (10.3 Bar)

Materials Body Plastic (MJP) or Eco-brass alloy (MJN)

Internals Engineered thermoplastic

Magnet Alnico

Fittings Lead-free tail piece

Accuracy ±1.5% of reading

Pulse Output MJPE/MJNE MJPR/MJNR MJPT/MJNT

Sensor Hall-effect device Reed switch Totalizer only

Max Current 20 mA 20 mA n/a

Max Voltage 24 Vdc 24 Vdc or Vac n/a

Cable Length 12’ (4 m) standard (2000’ maximum run)

Flow Rates (GPM)** 3/4” 1” 1 1/2” 2” (MJN only)

Minimum 0.25 0.75 1.5 2.0

Maximum 20 50 100 160

Regulatory NSF/ANSI 61, complies with Federal Public Law 111-380

Standards ISO4064 Class B, AWWA C708

*Specications subject to change • Please consult our website for current data (www.seametrics.com).
** Caution: Excessive ow can cause breakage. Do not exceed recommended maximums.

Seametrics • 253.872.0284 Page 4 seametrics.com

GENERAL INFORMATION

20

15

10

5

0

2.557.510152025

5101520253035404550

10 20 30 40 50 60 70 80 90 100

3/4"

1"

1

-1/2"

13 26 39 52 65 78 91 104 117 1302"

12.5

17.5 22.5

(MJN only)

MJP/MJN-SERIES INSTRUCTIONS

Dimensions

C

A

B

MJP 3/4” 1” 1 1/2”

A (body)

B (w/couplings)

C (IPS thread)

D (NPT thread)

MJN 3/4” 1” 1 1/2” 2”

A (body)

B (w/couplings)

C (IPS thread)

D (NPT thread)

7 1/2” 10 1/4” 11 3/4”

11 5/8” 15” 17”

1” 1 1/4” 2”

3/4” 1” 1 1/2”

7 1/2” 10 1/4” 11 3/4” 11 3/4”

11 5/8” 15” 17” 17 5/8”

1” 1 1/4” 2” 2 1/2”

3/4” 1” 1 1/2” 2”

Pulse Rates

3/4” 1” 1 1/2” 2”

D

Pulses per
Gallon

Gallons per
Pulse

Cubic Feet
per Pulse

Pulses
per Cubic
Meter

Liters per
Pulse

20*

10

4†

2*

1

1
5*
10

50*
100

1
5*
10

1
10

100

1
10

100

4†
2*

1

1

5*

10
50*
100

1
5*
10

1
10

100

1
10

100

50*
100

100

100

*MJPR/MJNR dual reed switch meters only
†MJPR/MJNR single reed switch meters only

4†
2*

5*

10

5*
10

10

10

(MJN only)

4†
2*

1

1

1

1

5*

10
50*
100

1

1
5*
10

1

1
10

100

1

1
10

100

Shipping Weight

MJP MJN

lb kg lb kg

3/4”

1”

1 1/2”

2”

3 1.4 6 2.7

4.5 2 8 3.6

7.5 3.4 13 5.9

n/a n/a 16 7.3

Pressure Drop Curve

Pressure drop in P.S.I.

Rate of ow in gallons per minute (GPM)

Seametrics • 253.872.0284 Page 5 seametrics.com

INSTALLATION & OPERATION

MJP/MJN-SERIES INSTRUCTIONS

Position

MJP/MJN-Series meters should be installed horizontally
with the register up. Vertical mounting will result in some
degree of under-measurement and shortened life of the
bearings. No upstream straight pipe is required.

Caution: These water meters

WARNING

DO NOT INSTALL

meter in overhead

indoor piping or where

leakage

may cause damage

are not recommended for
installation in uninsulated
suspended ceilings where
freezing is possible, or in
any overhead indoor piping
conguration where leakage
may cause damage.

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. If connecting a plastic meter to
metal pipe, you can use brass tail pieces, but you MUST use
the plastic coupling nuts.

Column 1 Column 2 Column 3

Pulse Rate

*20 P/G (3/4” only) x0.01 2

10 P/G (3/4” only) x0.01 1

†4 P/G x0.1 1

*2 P/G x0.1 2

1 P/G x0.1 1

*5 G/P x1 2

10 G/P x1 1

*50 G/P x10 2

100 G/P x10 1

1 CF/P x0.1 1

*5 CF/P x1 2

10 CF/P x1 1

1 P/CM x0.1 1

10 P/CM x1 1

100 P/CM x10 1

1 L/P x0.1 1

10 L/P x1 1

100 L/P x10 1

*MJPR/MJNR dual reed switch meters only
†MJPR/MJNR single reed switch meters only. A special magnet

(available from the factory) is required to achieve a rate of 4 pulses per
gallon. It should be placed on the x0.1 dial, with non-magnetic pointers
on the remaining dials. Otherwise, the procedure is the same.

Magnet Pointer Dial

Position

Connection Diagram

#

Connections

MJPE/MJNE and MJPR/MJNR sensors are supplied with a
color coded output cable (see diagrams to right). Optional
connectors can be ordered to plug directly into a Seametrics
control or metering pump.

Pulse Output

Both MJPE/MJNE and MJPR/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
electronic control loads, and should not be used to switch

power loads or line voltages. See maximum current and
voltage ratings, under Specications.

Setting Pulse Rate

The pulse rate is determined by which sensor was ordered
from the factory and by the dial on which the magnet
pointer is located. The pointer is set at the factory, but can

be changed in the eld as follows.

1. Find your desired pulse rate (Column 1)

2. Note the magnet pointer position (Column 2)

3. Move the magnet pointer to the appropriate dial

position (see detailed instructions on next page)

4. Use the appropriate Connection Diagram (from
Column 3) to wire the sensor to your remote device
(using diagrams at right).

Diagram 1: Single Sensor

Blue (No connection)
Black - Common
Red - N O

Black ( - )
White - (Signal)
Red ( + )

MJPR/MJNR:

Reed Switch

MJPE/MJNE:

Hall-Effect

Diagram 2: Dual Sensor

NOTE: The Dual Sensor is distinguished by a red stripe on the
cable at the base of the sensor.

Black - Common
Red - N O
Blue - N O

MJPR/MJNR:

Reed Switch

To Distinguish Single Sensor From Dual:

Single: (if new from factory) blue wire is cut back on cable

end.

Dual: A red mark will be on cable near sensor.

Note: Dual sensor can be used as a single sensor also ­use either the red OR the blue wire w/black. If using it as
a dual sensor then connecting red and blue together will
produce two pulses with every revolution of magnet.

Seametrics • 253.872.0284 Page 6 seametrics.com

INSTALLATION & OPERATION/MAINTENANCE

MJP/MJN-SERIES INSTRUCTIONS

Moving the Magnetic Pointer

NOTE! When removing the large meter nut,
Seametrics recommends using a 24” pipe
wrench. Larger or smaller pipe wrenches
may damage the nut on plastic units!!

Remove meter top and lens, taking care not to lose the

sealing ring. With ngers, lift the magnet pointer off its

shaft and remove the plain pointer from the target dial.

Reverse their positions and press them rmly into place.

Securely seat the sealing ring and replace the lens,
matching the tab on the lens to the notch on the meter to
align the sensor with the magnetic pointer dial. Thread the
meter top on and tighten.

†NOTE: A special magnet (available from the factory) is
required to achieve a rate of 4 pulses per gallon. It should

be placed on the x0.1 dial, with non-magnetic pointers on

the remaining dials. Otherwise, the procedure is the same.

Sample Set-Up

A 1” meter is shown with the magnet pointer set at the x10

dial, with a pulse rate of 100 Gallons per Pulse (that is, 10

increments on the x10 dial, or 10x10=100 Gal/Pulse).

1” Meter

100 Gal/Pulse

Reading Meter

The Total Flow that has passed through your meter is

read by starting at the top of the register with the Six-

Digit Totalizer, and then reading clockwise around the

small dials. In the example below, the Six-Digit Totalizer
reads 13,800 (138 x 100), and the dials read 60 (6 x 10),
2 (2 x 1), and .4 (4 x .1) respectively. The Total Flow is

13,862.4 gallons.

1” Meter

100 Gal/Pulse

Six-Digit Totalizer

(reads 138x100)

x10 Gal Dial
(reads 6x10)

x1 Gal Dial
(reads 2x1)

x0.1 Gal Dial
(reads 4x0.1)

25mm

40˚C

1 3 8

U.S. GALLONS

NSF

®

Certied to

NSF/ANSI 61-G

X1

X0.1

X100

X10

(NOTE: Disregard the color of the numbers on the totalizer
when reading your total.) The “ones” digit is signicant but the
fact that it is red is not.

25mm

40˚C

U.S. GALLONS

NSF

®

Certied to

NSF/ANSI 61-G

X1

X0.1

X10

Special Congurations

X100

20mm

U.S. GALLONS

40˚C

X0.01

NSF/ANSI 61-G

X0.1

The 3/4” meter has a fourth dial,
as shown above. The x0.01 dial is
used for 20 P/G and 10 P/G rates.
Note: The 3/4” meter has a 5 digit
totalizer.

NSF

Certied to

X10

®

X1

X100

Magnet Pointer

x10 Dial

(10 x 10=100 G/P)

[With the magnet pointer
on the x1 dial, the pulse
rate would be 10x1=10
Gal/Pulse. With the
magnet pointer on the x0.1
dial, the pulse rate would
be 10x.1=1 Gal/Pulse.]

25mm

U.S. GALLONS

40˚C

NSF

Certied to

NSF/ANSI 61-G

X0.1

®

The 4 P/G rate requires
a special magnet, placed
on the x0.1 dial, as shown
above.

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, depending on

water condition. Pull out the strainer or backush the

meter to loosen trapped particulates.

Calibration

X100

X10

Meters used for billing or billing exemption may

be regulated by state or local authorities. New
meters are factory-tested to meet the AWWA C-708

X1

Multi-Jet Meter accuracy specication. 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.

Seametrics • 253.872.0284 Page 7 seametrics.com

MJP/MJN-Series Parts

MJP/MJN-SERIES INSTRUCTIONSMAINTENANCE

¾” 1”

1 Lid and Hinge Pin Assembly 101068 101069

2 Lens Gaskets (O-ring & slip ring) 101071 101072

a Internal Assembly (gallons) 103677 103678

b Internal Assembly (cubic feet) 103681 103682

3

c Internal Assembly (cubic meters) 103685 103686

d Internal Assembly (liters) 103689 103690

Brass Coupling Assembly w/Gasket

a

(incl 2 sets)

4

Plastic Coupling Assembly w/Gasket

b

(incl 2 sets)

5 Coupling Gasket (incl 2) 101081 101082

6 Lens 101004 101004

7 Sensor Screw 101045 101045

a Single Reed Switch Sensor (MJP/MJR) 100980 100980

b Double Reed Switch Sensor (MJP/MJR) 100993 100993

8

c Single Hall-Effect Sensor (MPE/MJE) 101065 101065

a Register (gallons) 103302-001-075 103302-001-100

b Register (cubic feet) 103302-002-075 103302-002-100

9

c Register (cubic meters) 103302-003-075 103302-003-100

d Register (liters) 103335-075 103335-100

10 Internal Strainer 101016 101043

11 Tubular Strainer 101029 101030

12 Register Gasket 101013 101027

103239-075 103239-100

103924-075 103924-100

Internal Parts Replacement. All of the internal
parts of an MJP/MJN-Series meter lift out as a unit,
after the top has been unscrewed. The lens can then
be removed and the internal assembly lifted out. If
necessary, turn the meter upside down and tap one
end lightly on a counter top to loosen the internals.
The assembly can be separated by hand.

1

6

2

7
8 a-c

9a,b,c,d

1½” 2” (MJN only)

1 Lid and Hinge Pin Assembly 101070 101070

2 Lens Gaskets (O-ring & slip ring) 101085 101085

a Internal Assembly (gallons) 103679 103680

b Internal Assembly (cubic feet) 103683 103684

3

c Internal Assembly (cubic meters) 103687 103688

d Internal Assembly (liters) 103691 103692

Brass Coupling Assembly w/Gasket

a

(incl 2 sets)

4

Plastic Coupling Assembly w/Gasket

b

(incl 2 sets)

5 Coupling Gasket (incl 2) 101083 101084

6 Lens 101004 101004

7 Sensor Screw 101045 101045

a Single Reed Switch Sensor (MJP/MJR) 100980 100980

b Double Reed Switch Sensor (MJP/MJR) 100993 100993

8

c Single Hall-Effect Sensor (MPE/MJE) 101065 101065

a Register (gallons) 103302-001-150 103302-001-200

b Register (cubic feet) 103302-002-150 103302-002-200

9

c Register (cubic meters) 103302-003-150 103302-003-200

d Register (liters) 103335-150 103335-200

10 Internal Strainer 101044 101044

11 Tubular Strainer 101031 101032

12 Register Gasket 102228 102228

103239-150 103239-200

103924-150 n/a

3a,b,c,d

12

10

4

11

5

Seametrics • 19026 72nd Avenue South • Kent, Washington 98032 • USA

(P) 253.872.0284 • (F) 253.872.0285 • 1.800.975.8153 • seametrics.com

LT-14383r1.0-20161012

10/12/16