AbsolutAire MS-221 Installation Manual

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]

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, adjustable dampening of output sig­nal (with optional display) and the ability to select a square root
output for use with Pitot tubes and other similar flow sensors.
Along with these features, magnetic sensing technology pro­vides exceptional long term performance and 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. The
diaphragm must be vertical to minimize gravity effects on the
diaphragm.
Mount the transmitter using #8 x 1/2˝ pan head sheet metal
screws in the mounting flanges. Do not over tighten.

Duct Mount:

The transmitter should be mounted away from fans, corners,
heating and cooling coils and other equipment that will effect
the measurement of the pressure.

1. To mount the transmitter, drill a .562 (12.70) diameter hold
into the duct.

2. Insert transmitter probe into the duct.

3. Mark location of three mounting holes on duct using mount­ing flange as template. Drill holes.

4. Attach mounting flange to duct with (3) #8 x 1/2 pan head
sheet metal screws. Do not overtighten screws.

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.

Series MS Magnesense®Differential Pressure Transmitter

Specifications - Installation and Operating Instructions

Bulletin A-26

SPECIFICATIONS

Service: Air and non-combustible, compatible gases.
Wetted Materials: Consult Factory.
Accuracy: ±1% for 0.25” (50 Pa), 0.5” (100 Pa), 2” (500 Pa), 5”

(1250 Pa), ±2% for 0.1” (25 Pa), 1” (250 Pa) and all bi-directional
ranges.

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 or 3-wire, 0 to 10 V.
Response Time: Adjustable 0.5 to 15 sec. time constant.

Provides a 95% response time of 1.5 to 45 seconds.

Zero & Span Adjustments: Digital push button.
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: Diaphragm in vertical position.
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

2-41/64
(67.07)

2-11/64
(55.17)

2-9/16

(65.09)

21/32

(16/67)

8-1/8

(206.38)

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

Ø35/84 (13.87)

1/2

Ø3-7/16

(Ø87.31)

1/2 NPT

Electrical Connection:
2-Wire Operation, continued:

The connections to the transmitter are made through a two circuit
European style terminal block TB1 located at the bottom left of the
main PB board. Polarity is indicated by + and – signs on the P.C.
board.

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 (R

L

) 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

.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.

3-Wire Operation:

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

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 V+ and the negative connected to Com. 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 Com and V+. 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%).

Figure 3

The output of Vo is 0 to 10 VDC. As much as 10 mA may be drawn
from Vo 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

the leads less than 0.1% of the value of RL. 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.

Figure 4

Select Operation Mode and Range:

The operating modes and ranges are controlled by two shorting
jumpers on a pair of jumper blocks, PJ3 and PJ5. These two
jumper blocks are shown in Fig. 5.

Bulletin A-26

Page 2

TOTAL RECEIVER RESISTANCE ( )

–
+

1500
1400
1300
1200
1100
1000

900
800
700
600
500
400
300
200
100

50

TB1

5101315

0

+

POWER
SUPPLY
10-35V

RL MAX =

–

RECEIVER

L

R

MAXIMUM VALUE (1250 )

V

ps - 10.0

20mA DC

OPERATING

REGION

20 25 30 35 40

POWER SUPPLY VOLTAGE

TB1

V+
Vo

COM

RECEIVER

L

R

POWER SUPPLY

17 TO 36 VDC

OR

21.6 TO 33 VAC

PJ1 PJ2

PJ1

PJ2

LOW

SW1
SW2

TB1

HIGH