Dwyer Instruments MS Magnesense Series Specifications-installation And Operating Instructions

Bulletin A-26P

Series MS Magnesense®Differential Pressure Transmitter

Specifications - Installation and Operating Instructions

The Series MS Magnesense®Differential Pressure
Transmitter is an extremely versatile transmitter for monitoring

pressure and air velocity. This compact package is loaded with
features such as: field selectable English or metric ranges, field
upgradeable LCD display and the ability to select a square root
output for use with Pitot tubes and other similar flow sensors.
Also, a single digital push button simultaneously calibrates
both zero and span reducing installation and setup time. These
features along with exceptional long term performance

®

enables the Magnesense

to be the solution for a myriad of

pressure and air flow applications.

INSTALLATION
Mounting:

The transmitter should be mounted on a vertical surface with
the connections directed down to prevent moisture fr om enter­ing either the pressure ports or the electrical cable entry.
Mount the transmitter using #8 x 1/2˝ pan head sheet metal
screws in the mounting flanges. Do not over tighten.

Electrical Connection:
2-Wire Operation:

CAUTION: DO NOT EXCEED SPECIFIED SUPPL Y
VOLTAGE RATINGS. PERMANENT DAMAGE
NOT COVERED BY WARRANTY WILL RESULT.
2-WIRE UNITS ARE NOT DESIGNED FOR AC
VOLTAGE OPERATION.

2-41/64
(67.07)

2-11/64
(55.17)

2-9/16

(65.09)

21/32

(16/67)

21/32

(16/67)

29/32

(12.70)

(23.02)

57/64

(22.62)

(3) 3/16 (4.76) HOLES
EQUALLY SPACED ON A

4.115 (104.52) BC

1/2

Ø3-7/16

(Ø87.31)

1/2 NPT

SPECIFICATIONS

Service: Air and non-combustible, compatible gases.
Wetted Materials: Consult Factory.
Accuracy: ±1% @ standard conditions
Stability: ±1% F.S./ year.
Temperature Limits: 0 to 150°F (-18 to 66°C).
Pressure Limits: 1 psi maximum, operation; 10 psi, burst.
Power Requirements: 2-wire, 10 to 35 VDC; 3-wire, 17 to

36 VDC or isolated 21.6 to 33 VAC.

Output Signals: 2-wire, 4 to 20 mA; 3-wire, 0 to 10 V.
Response Time: 300 msec
Pressure Calibration: One Digital push button set both zero &

span simultaneously.
Loop Resistance: Current Output: 0-1250 Ohm max. Voltage
Output: min. load resistance 1 k OhmΩ.

Current Consumption: 40 mA max.
Display (optional): 4 digit LCD.
Electrical Connections: 4-20 mA Units: 2-Wire: European Style

Terminal Block for 16 to 26 AWG; 0-10 V Units: 3-Wire:
European Style Terminal Block 16 to 22 AWG.
Electrical Entry: 1/2˝ NPS Thread.

Accessory: Cable Gland for 5 to 10 mm diameter cable.
Process Connections: 3/16˝ (5 mm) ID tubing. Maximum
OD 9 mm.

Enclosure Rating: NEMA 4X (IP65).
Mounting Orientation: Insensitive to mounting orientation
Weight: 8.0 oz (230 g).
Agency Approvals: CE.

The following standards were used for CE approval:

CENELEC EN 61000-4-2: 2001
CENELEC EN 61000-4-3: 2002
CENELEC EN 61000-4-4: 1995
CENELEC EN 61000-4-5: 2001
CENELEC EN 61000-4-6: 2003
CENELEC EN 61000-4-8: 2001
CENELEC EN 55011: 2003
CENELEC EN 61326: 2002
89/336/EED EMC Directive

DWYER INSTRUMENTS, INC.

Phone: [phone] www.dwyer-inst.com

P.O. Box 373 • Michigan City, IN 46361-0373, U.S.A. Fax: [phone] e-mail: [e-mail]

Bulletin A-26P

Page 2

Electrical Connection:
2-Wire Operation, continued:

The connections to the transmitter are made through a two circuit
European style terminal block CONN6 located at the bottom of the
main PCB board. Polarity is indicated by + and – signs on the PCB
board. Do not connect to the (V) terminal.

P.S.

–

+

V

+
–

RL

Figure 1

An external power supply delivering 10 to 35 VDC with a minimum
current capability of 40 milliamps must be used to power the con­trol loop in which the Magnesense

®

transmitter is connected. Refer
to Fig. 1 for connection of the power supply , transmitter and receiv­er. The range of appropriate receiver load resistances (RL) for the

power supply voltage available is given by the formula and graph
in Fig. 2. Shielded two wire cable is recommended for control loop
wiring and the negative side of the loop may be grounded if
desired. Note also that the receiver may be connected in either the
negative or positive side of the loop, whichever is most convenient.
Should polarity of the transmitter or receiver be inadvertently
reversed, the loop will not function properly but no damage will be
done to the transmitter.

1500
1400
1300
1200
1100
1000

900
800
700
600
500
400

TOTAL RECEIVER RESISTANCE ( )

300
200
100

50

0

RL MAX =

5101315

MAXIMUM VALUE (1250 )

V

ps - 10.0

20mA DC

OPERATING

REGION

20 25 30 35 40

POWER SUPPLY VOLTAGE

Figure 2

The maximum length of connecting wire between the transmitter
and the receiver is a function of wire size and receiver resistance.
That portion of the total current loop resistance represented by the
resistance of the connecting wires themselves should not exceed
10% of the receiver resistance. For extremely long runs (over 1,000
feet), it is desirable to select receivers with higher resistances in
order to keep the size and cost of the connecting leads as low as
possible. In installations where the connecting run is no more than
100 feet, connecting lead wire as small as No. 22 Ga. can be used.

The connections to the transmitter are made through a three cir­cuit European style terminal block. Connect the power and signal
leads to the corresponding terminals as shown in Fig. 3. When
using a DC supply, the positive of the supply should be connected
to (+) and the negative connected to (-). Connecting the leads in
reverse will not damage the device but it will not operate. The DC
supply should be capable of providing 20 mA or more of current
per Magnesense

®

transmitter.

When using an isolated AC supply, either leads of the supply may
be connected to (-) and (+). The input diode of the device half wave
rectifies and filters the applied AC voltage. A small DC current of
less than 20 mA is thus drawn through the transformer. The trans­former used for the AC supply must be capable of handling this
small DC current. Use a UL 1584 Class 2 rated transformer rated
between 24 V and 30 VAC, 40 VA or larger, 50/60 Hz. UL 1584
Class 2 rated transformers are limited to 30 VAC maximum under
any conditions at nominal line. The AC input voltage to the device
is thus limited to a minimum of 21.6 at low line (24 V-10%) and 33
V at high line (30 V+10%).

CONN6

+
V
Ø

RECEIVER

R

L

POWER SUPPLY

17 TO 36 VDC

OR

21.6 TO 33 VAC

Figure 3

The output of (V) is 0 to 10 VDC. As much as 10 mA may be drawn
from (V) without affecting accuracy. This limits the minimum load

RL connected to Vo to 1 KΩ or higher. Remember to keep the
wiring resistance between the output and the receiver R

L

low com­pared to value of RL. While the voltage at the terminals remains
unchanged with a 10 mA current flow, resistive losses in the wiring

do cause errors in the voltage delivered to RL. For a 1% accurate
gauge, a good rule of thumb would be to keep the resistance of

L

the leads less than 0.1% of the value of R

. This will keep the error

caused by current flow below 0.1%.
To minimize noise in the signal use shielded cable. The common

line may also be grounded.

Pressure Connections

Two integral tubing connectors are provided. They are designed to
fit 3/16˝ (5 mm) ID tubing. Connect the high pressure to the High
side as shown in Fig. 4. Be sure the pressure ratings of the tubing
exceed that of the operating ranges.

3-Wire Operation:

CAUTION: DO NOT EXCEED SPECIFIED SUPPLY
VOLTAGE RATINGS. PERMANENT DAMAGE NOT
COVERED BY WARRANTY WILL RESULT.

HIGH LOW

Figure 4

Select Operation Mode:

The operating modes and ranges are controlled by a shorting
jumper on jumper block J2. This jumper block is shown in Fig. 5.

Figure 5, Mode Programming Jumpers

Bulletin A-26P

FULL SCALE ANALOG OUTPUT

Model English Metric

MS-X

31 10 in w.c. 2 kPa

MS-X

41 15 in w.c. 3 kPa
51 25 in w.c. 5 kPa

MS-X

Table 2

Page 3

Jumper block J2 primary function is to control the operating mode.
There are two operating modes, Normal and Velocity. The Normal
operating mode provides for zero pressure to corr espond to 0 V or
4 mA output. This mode is selected by placing the supplied short­ing jumper for J2 on the pins next to the letter “N”. The jumper for
J2 is factory installed to the Normal Mode. If no jumper is installed
on J2, the device defaults to the “N” selection.

The Velocity mode provides the ability for the unit in conjunction
with a Pitot tube or similar flow sensor with known K factor to give
a direct output in air velocity. This mode is selected by placing the
supplied shorting jumper for J2 on the pins next to the letter “V”.
If the optional display is present, this mode prompts the display to
read in air velocity. The current or voltage output is modified such

that full scale output is 4004* K* √(ΔP) feet per minute or its met­ric equivalent in meters per second depending upon which units
are selected. The factory programming for the K factor is 1.00 but
may be adjusted (see Adjust K Factor). The velocity displayed for
the various models can be found in Table 1.

Velocity Displayed

Model English Metric

3X K* 12.66 x 1000 fpm K* 57.7 m/s

MS-X
MS-X

4X K* 15.51 x 1000 fpm K* 70.7 m/s

MS-X5X K* 20.02 x 1000 fpm K* 91.2 m/s

Table 1

SETUP
Set Measurement Units:

Magnesense

TM

transmitters can be easily set to operate in either

English or metric units.
The programming jumper is CONN3. A representation of this

jumper is shown in Fig. 6. English units are selected by placing the
provided shorting jumper on the lower two pins of the block. Metric
units are selected by placing the provided shorting jumper on the
upper two pins of the block. If no jumper is present English units
are selected by default.

Install Optional Display:

The A-435 LCD conversion kit allows any non display model to
have the LCD added at a later time. The kit contains an LCD dis­play and replacement cover with LCD window. The optional dis­play may be set to read pressure either in Inches Water Column or
Kilopascal. The optional display can be also set to display air
velocity in X1000 feet per minute or meters per second when used
with a Pitot tube or similar flow sensor with a known K factor.

®

The optional display for the Magnesense

is mounted on the main
board by connectors CONN4 and CONN5. The display is proper­ly mounted when CONN4 and CONN5 on the display are con­nected to the corresponding CONN4 and CONN5 on the main
board. See Fig. 4. Installing the display upside down causes no
harm the display or the main board. The display just simply reads
upside down.

Label (Included with display):

The optional LCD display does not contain engineering unit indica­tion. So that the display may be appropriately marked, four adhe­sive labels have been provided with the units. The unit labels are
INWC, kPa, X1000 fpm, and M/S. Attach the appropriate provid­ed units label above the display window on the cover of the device
to indicate to which units the display has been set.

Adjust K Factor:

If the optional display is present, the K factor used in velocity mea­surements may be adjusted. This is done by activating the K fac­tor adjustment function of the unit. To activate the K factor adjust­ment function, take the shorting jumper from programming block
J2 and place it on the upper two terminals next to the letter “K”.
See Fig. 5. The display will now show the programmed Pitot tube
K factor. The K factor can be adjusted up and down by using the
up and down buttons as up and down buttons. Once the desired
K factor has been set, replace the shorting jumper on J2 to its
velocity position (“V”). The shorting jumper must not be left in the
“K” position for proper operation of the unit. The factory setting for
the K factor is 1.0 and it is adjustable from 0.5 to 3.

English

Metric

CONN3

Figure 6, Measurement Units Programming Jumper

In addition to the obvious change in the scale of the LCD display,
the full scale range and corresponding analog outputs are also
affected by the measurement units selection. The analog output
goes to full scale output (10 volts or 20 mA depending on model)
of the selected range and units. See Table 2.

One button pressure calibration – Leaving the hose barbs vent­ed, press and hold the “Zero/Up” switch for about 4-5 seconds.
The zero point should now be set and if the display is present, the
display will read zero. Span is also simultaneously adjusted at the
time the zero is set. No further calibration is required. It does not
matter if in metric or English unit made when performing this “one
button” calibration of both zero & span.

Bulletin A-26P

Page 4

MAINTENANCE

Annual recalibration is suggested. No lubrication or other periodic
servicing is required. Keep exterior and cover clean. Occasionally
disconnect pressure lines to vent both sides of gauge to atmos­phere and re-zero. Do not use solvent to clean transmitter. Use
only plastic compatible cleaners or water.

The Series MS is not field serviceable and should be returned if
repair is needed (field repair should not be attempted and may void
warranty). Be sure to include a brief description of the problem plus
any relevant application notes. Contact customer service to receive
a return goods authorization number before shipping.

©Copyright 2007 Dwyer Instruments, Inc. Printed in U.S.A. 1/07 FR# 01-443337-20 Rev.1

DWYER INSTRUMENTS, INC.

P.O. Box 373 • Michigan City, IN 46361-0373, U.S.A. Fax: [phone] e-mail: [e-mail]

Phone: [phone] www.dwyer-inst.com