Siemens SITRANS 7MF1570 User manual

USER'S MANUAL
Siemens
Energy & Automation
UMMPS-1
Rev. 2
January 2003
Supersedes Rev. 1
MG00420a
Pressure Transmitter for
Level Measurement
Model 7MF1570

UMMPS-1 Contents
January 2003 i
Table of Contents
Title Page
Introduction ...................................................................................................................................................................1
Operation .......................................................................................................................................................................2
Installation .....................................................................................................................................................................3
Wiring............................................................................................................................................................................4
Calibration .....................................................................................................................................................................4
Maintenance ..................................................................................................................................................................5
Model Designation ........................................................................................................................................................5
Specifications ................................................................................................................................................................6
Junction Box..................................................................................................................................................................7
Cable Hanger .................................................................................................................................................................8
Product Support .............................................................................................................................................................8
Warranty......................................................................................................................................................................10

Contents UMMPS-1
January 2003ii

UMMPS-1 Installation and Maintenance
January 2003 1
Introduction
The Siemens Model 7MF1570 pressure transmitter is used for hydrostatic liquid level measurement. Typical
applications include wastewater treatment and water supply, and many other applications in a variety of industries.
The transmitter measures hydrostatic pressure using the formula:
p = ρ* g * h
with:
ρ- density of the liquid
g - acceleration due to gravity
h - height of the liquid column
Hmax
Hmin
L
MG00414a
Transmitter
Junction Box
(Cable Connections)
Cable
(4-20 mA,
Vent Pipe, &
Support)
Open Vessel
Cable to Process
Instruments
Cable Hanger
FIGURE 1 Typical Application
The transmitter and cable are a single assembly. Transmitter range and cable length are determined by the model
ordered. Range and other transmitter information are printed on the sensor housing.
The transmitter has a sealed stainless steel housing that includes all pressure-to-current circuitry and is suitable for
use in corrosive liquids. Pressure is sensed by a flush-mounted stainless steel diaphragm connected to a bridge-
configured piezo-resistive sensor. The diaphragm is protected by a cap with perforations that allow the process
liquid to act on the diaphragm. Temperature compensation allows the transmitter to provide an accurate
measurement over a wide range of process temperatures.
The cable contains two wires to carry the 4-20 mA signal, a cable sheath ground wire, a cord to support the sensor,
and a vent pipe to supply atmospheric pressure to the sensor.
Note the following points when selecting an application and when using the device:
• Do not exceed the maximum permissible pressure p max of the transmitter. See the Specifications section.
• The transmitter can be damaged if the process medium in contact with the transmitter exceeds 80°C (176°F).
• The transmitter can be damaged if ice forms on the diaphragm.
• Measuring accuracy will be affected by clogging of the perforations in the protective cap.
• Measuring accuracy will be affected if the vent pipe is obstructed.

Installation and Maintenance UMMPS-1
January 20032
Operation
The hydrostatic pressure felt by the sensor is proportional to submersion depth. The pressure of the process medium
deflects the stainless steel diaphragm at the tip of the transmitter. This deflection is sensed by a piezo-resistive
bridge. The diaphragm and bridge also sense the atmospheric (barometric) pressure supplied through a vent pipe in
the connecting cable.
U
Const.
U
IEM
Diaphragm
Sensor
Vent Pipe
Shield
+ Brown
- Blue
Io, UB
p
MG00415b
Cable Jacket
FIGURE 2 Block Diagram
The bridge output voltage is a pressure differential signal that is then converted to a 4-20 mA output current. The
circuit board is sealed in the housing.
The transmitter is powered from a user-supplied 10-36 Vdc source. Diodes at the transmitter input protect against
reverse polarity and over voltage.
An optional junction box provides screw terminals for cable termination and for connecting to a receiving
instrument, such as a Siemens Model 353 Process Automation Controller. The cable shield is connected to the
housing and is connected by the user to earth ground. Within the junction box, the vent pipe is exposed to
atmospheric pressure.

UMMPS-1 Installation and Maintenance
January 2003 3
Installation
The transmitter is installed suspended on the cable. The cable is routed through a cable hanger and into the junction
box as shown in figure 1. Figure 3 shows transmitter dimensions.
+ Brown
Vent Pipe
Cord, White
- Blue
Shield
158 mm
6.22 in. L
Protective Cap Cable Sheath
27 mm
1.06 in.
MG00416b
1. Dimensions are in millimeters and inches.
2. Cable sheath 8.3 mm / 0.23 in. diameter; black, HFFR
3. Flexible cable with 0.5 mm2/ 10 AWG cross-section
4. Vent pipe 1 mm / 0.04 in. inner diameter
5. Protective cap with 4 x 3 mm / 0.15 x 0.12 in. diameter holes; black, PA
FIGURE 3 Transmitter Dimensions
In a moving medium, transmitter location must be fixed to prevent measuring errors. To minimize movement, install
a guide tube, add a weight on the transmitter (maximum tensile force on the cord is 65 lbs), or install a bracket
between the transmitter and the vessel.
Anchor the cable above the vessel with the cable hanger; see the Cable Hanger section later in this manual. Connect
the cable leads to the junction box; see the Junction Box section later in this manual. Mount the junction box in a
location compatible with its degree of protection (IP 54).
There are four inlet holes in the protective cap at the diaphragm end of the transmitter. These holes must be open to
the medium and free of congealed material and contaminants (e.g. dust, dirt, grease) to ensure transmitter accuracy.
If gelled or solidified material is likely to accumulate at the bottom of the vessel, the tip of the sensor should be
elevated above the level at which the vessel will be drained and cleaned.

Installation and Maintenance UMMPS-1
January 20034
Wiring
WARNING
Electrical shock hazard
Hazardous voltage can cause death or serious injury.
Remove power from all wires and terminals before working
on this equipment.
1. Remove power from all wires and terminals to eliminate any electrical shock hazard.
2. Route the transmitter cable through the cable hanger and into the junction box.
3. Connect the transmitter cable to the junction box. See Figures 3 and 4.
Blue wire to Terminal 1 (-)
Brown wire to Terminal 2 (+)
Shield wire to Ground
1
2
1
2
Blue
Screen
Brown
Transmitter
Vent Pipe
To Atmospheric Pressure
++
__
Junction Box
User-Supplied
10-36 Vdc
Power Supply
+
_
Controller,
Recorder, or
other process
instrument
MG00417a
GND
FIGURE 4 Electrical Connections
4. Clamp the cord between the two screws provided in the box.
5. Find the end of the vent pipe. This end of the pipe must be open and exposed to atmospheric pressure.
6. Connect a user-supplied 10-36 Vdc power supply to terminals 1 and 2 in the junction box. The resistance value
for the maximum load depends on the voltage UB. It is determined by the following equation:
UB - 10 V
R max = ————— (kOhm)
20 mA
Calibration
The transmitter has been calibrated at the factory to the user-specified measuring range. It cannot be re-calibrated.

UMMPS-1 Installation and Maintenance
January 2003 5
Maintenance
The transmitter requires no periodic or scheduled maintenance.
Transmitter accuracy and responsiveness can be degraded should gelled or solidified material plug or partially plug
the holes in the protective cap or accumulate within the cap and coat the diaphragm. To remove this material, lift the
transmitter from the vessel. Apply a low-pressure stream of clean water to unplug the holes and wash material from
inside the cap. A mild detergent that will not leave a residue may be added to the water.
The protective cap may be unscrewed from the transmitter body for cleaning. If the cap is difficult to unscrew and
additional leverage is needed, carefully insert a 1/8" (3.2mm) diameter metal rod through two opposing holes in the
cap. Do not scratch the diaphragm while inserting the rod.
When installing the cap, be careful not to damage the threads in the cap. Use your hands, no tools, and feel for
proper thread engagement.
CAUTION
Do not scratch the transmitter diaphragm.
Harsh solvents may damage the protective cap.
Do not use the transmitter without the protective cap.
Model Designation
Each transmitter has a nameplate with the transmitter’s model designation printed on it. The following table lists the
available transmitter models. If ordering, select the desired measuring range, read across the table to the Range
Character (*) and insert that character into the model number at the head of the column.
Example: 7MF1570-1MA01
SITRANS P Pressure Transmitter, MPS Series (Submersible Sensor),
Two-Wire System 7MF1570-1*A01
Measuring Range Cable Length (L) * Range Character
0-6 ft WC 32.8 ft (10 m) K
0-12 ft WC 32.8 ft (10 m) L
0-20 ft WC 82.0 ft (25 m) M
0-30 ft WC 82.0 ft (25 m) N
0-60 ft WC 82.0 ft (25 m) P
Accessories
Junction Box (to connect transmitter cable to field wiring) 7MF1570-8AA
Cable Hanger (to mount/hand the transmitter) 7MF1570-8AB

Installation and Maintenance UMMPS-1
January 20036
Specifications
Input
Measured variable Pressure
Measuring range Overload limit
0-6 ft WC 47 ft WC
0-12 ft WC 47 ft WC
0-20 ft WC 100 ft WC
0-30 ft WC 100 ft WC
0-60 ft WC 200 ft WC
Output
Output signal 4-20 mA
Accuracy
Error in measurement (includes non-linearity,
hysteresis and repeatability, at 25°C (77°F))
0.3% of full scale value
Zero and span temperature effect
Temperature compensation
Between 6 and 12 ft H2O
20 ft H2O and greater
0°to +70°C (+32° to +158°F) referenced to +35°C (+95°F)
0.3%/10°C of full scale value
0.2%/10°C of full scale value
Zero and span long term stability
Between 6 and 12 ft H2O
20 ft H2O and greater
0.25% of full scale value/year
0.2% of full scale value/year
Vibration effect 0.05% of full scale / g from 10-500 Hz in any axis
Power supply effect 0.01% of full scale / V
Rated operating conditions
Ambient conditions
Operating temperature
Storage temperature
-30°to +85°C (-22°to +185°F)
-50°to +100°C (-58°to +212°F)
Degree of protection to DIN EN 60 529 IP68 (EN 60529)
Explosion Protection ATEX II 2G Eex ia IIC T4, FM, and CSA1
Electromagnetic compatibility
Noise immunity2
To DIN EN61326, NAMUR NE21
Design
Weight
Transmitter
Cable
0.4 kg (0.9 lbs)
0.1 kg/m (0.073 lbs/ft)
1Pending. Certifications had not been received at the time this manual was printed. Contact the factory for latest
information.
21.25% deviation with HF-conducted disturbance between 20-30 MHz