
IM 61A01A01-01E-A
4th Edition
Model MLD
Loop Powered Process Indicator
User’s
Manual
IM 61A01A01-01E-A

MLD Field Mounted Loop Indicator (Digital)
2” Horizontal Pipe
2” Vertical Pipe (or wall mount)
Cast Aluminum Alloy - (Standard Housing)
SUS316 Cast Stainless Steel and ASTM CF-8M
ANSI ½ NPT female, without blind plug
ANSI ½ NPT female, 316 Stainless Steel blind plug
ISO M20 female, without blind plug
ISO M20 female, 316 Stainless Steel blind plug
FM Explosion Proof
CSA Explosion Proof
Epoxy resin coating
Polyurethane-Epoxy Anti-corrosion coating
/P1
/P2
/P3
/P4
/P5
/P6
/P7
Light Blue (RAL # 5012)
Orange (RAL # 2008)
Red (Munsell # 7.5 R4/14)
Mint Green
Silver (RAL # 9006)
Yellow (RAL # 1018)
Gray (RAL # 7046)
Engineering Unit Calibration (MLD Only)
Stainless Steel tag screw attached to housing
Stainless Steel tag wired to housing
1. PREFACE
The Model MLD field mounted indicator receives a DC current signal from electronic transmitters and
indicates process measurement values. This instruction manual gives instructions on handling, mounting,
and wiring of the MLD indicator.
2. MODEL CODE AND SPECIFICATIONS
STANDARD SPECIFICATIONS
Voltage Drop:
1.8V typ., 2V max.
Scale:
0- 1999 w/decimal
Accuracy:
± 0.05% of full scale (1999) ±1 count
Operating Temperature Range:
-20 to 60°C
Temperature drift: ±0.3 Count/°C
Insulation
terminals and case 100 Mohm at 500 V DC
Dielectric
and case: 1000 VAC for 1 minute.
Mounting:
surface.
Explosion Protection Type:
EXPLOSIONPROOF
A,B,C,D,
GROUPS E,F,G
Case and Cover: Die cast aluminum or 316
Stainless Steel, baked polyurethane paint. Moss
Green (Stainless Steel is unpainted); NEMA 4X
Electrical
M20 x 1.5
Weight: 2.7 lbs
ORDERING INSTRUCTIONS
Example Ordering Instructions:
MLD-A1/1/00/FF1/ENG/SST Field Mounted Indicator (Digital), 4 to 20 mA DC, 2” Horizontal Pipe, FM Explosion Proof
0-200 InH2O Scale in Engineering Units. Please specify Scale and Engineering units when ordering /ENG
FT-201 Specify Tag Number when ordering /SST or /SSW
Resistance: Between input
Strength: Between input terminals
Nominal 2” (50mm) pipe mount or
FM, CSA,
CL1, DIV1, GROUPS
DUST-IGNITIONPROOF
Connection: ½ x 14 NPT or
1. Model and Suffix codes.
2. Option Codes
CLII / III,

DIMENSIONS
3. INSTALLATION
The Loop Powered Indicator can be mounted on a wall or a 2” pipe. The housing is a NEMA 4X Explosion Proof housing so it c an be mounted
outside in the field.
Do not install the unit in the following conditions:
• Extreme Temperatures beyond the temperature rating of the instrument.
• High vibration areas above the vibration rating of the instrument.
• Extremely corrosive environments.
MOUNTING EXAMPLES

4. WIRING
The loop powered indicator series is powered by the current output loop and does not require external power. All devices must be wired in series
with the current loop. Twisted pair shielded cable is recommended.
The following is an example of the MLD Loop Indicator connected to an EJA Pressure Transmitter (Note: The EJA Transmitter below can be
replaced with any 4-20mA 2 wire device.)
The Loop Indicator is available in FM Explosion Proof and CSA Explosion Proof types for hazardous locations. Wire sealing is required for these
approvals. The following diagrams show som e wire sealing examples .
For Flameproof type, use Flameproof Packing Adapter or Flameproof Conduit in connection above.

MOUNTING IN HAZARDOUS LOCATIONS

5. CALIBRATION
Calibration of MLD Units
(1) The MLD model ships with a calibration range of 0-100% unless ordered with the /ENG
Engineering Units option.
(2) If adjustments are needed the 2 screws holding the plate will need to be removed
(3) Connect unit to a Current Standard (red to +, black to -). Current Standards can be purchased
through Yokogawa Corporation of America. Recommended models are CA310 (Voltage/Current
Calibrator) or CA71 (Multifunction Calibrator).
(4) Set range switches based on the following table (for standard 0-100% unit set SW1 and SW8 to
ON):
(5) Set the Decimal value as follows:
a. If tenths (ex. XXX.X) set SW8 on.
b. If hundredths (ex. XX.XX) set SW7 on.
c. If thousandths (ex. X.XXX) set SW6 on.
(6) The values to check are shown in the table below.
(7) Set the Current standard to the 0% value. Adjust the Zero Pot (top one) to read the minimum value
needed.
(8) Set the Current Standard to the 100% value. Adjust the Span Pot (bottom one) to read the
maximum value needed.
(9) Check all points in the table above and verify unit is within specification.

6. ROTATING DISPLAY DIRECTION
The loop indicator display is designed so that it can be rotated in 90 degree increments. This is
accomplished by ordering the unit as a horizontal pipe mount or a vertical pipe mount. However there
may be the need for the customer to change the angle of the display. The following are procedures for
the display rotation:
Display Rotation:
(1) Remove power from the unit.
(2) Remove the glass cover from the display side.
(3) Remove the 2 screws holding the mounting plate to the standoffs.
(4) Rotate the display to the desired position (can be rotated in 90 degree increments).
(5) Replace and tighten firmly the 2 screws into the standoffs.
(6) Replace the glass cover.