SIEMENS SITRANS P DS III series pressure transmitter



SIEMENS SITRANS P DS III series pressure transmitter

Product positioning and core functions

Product model: Covering three sub series: 7MF4.33., 7MF4.34., and 7MF4.35., suitable for pressure measurement of corrosive, non corrosive, and hazardous gases, vapors, and liquids.

Measurement type:

Basic measurements: Gauge Pressure, Absolute Pressure, Differential Pressure;

Extended measurement: Through parameter configuration and additional components such as flow orifice plates and remote seals, liquid level, volume, mass, volumetric flow, and mass flow measurements can be achieved.

Core output: Always a 4-20mA load independent DC signal, supporting three communication protocols: HART, PROFIBUS PA, and Foundation Fieldbus.

Explosion proof features: Provides two explosion-proof versions: intrinsic safety (Ex i) and explosion-proof (Ex d), compliant with ATEX 94/9/EC directive, can be installed in hazardous environments in zones 0/1/2, and has an EC type inspection certificate.

Safety warning system (core emphasis)

1. Risk grading standards

The document adopts a four level risk warning system, clarifying the definitions and response requirements for different risk levels:

Warning level identification, risk description, typical scenarios

DANGER red safety warning symbol. Failure to take measures may result in death or serious personal injury. Failure to ventilate during toxic medium leakage

Warning red safety warning symbol. Failure to take measures may result in death or serious personal injury. Use of non explosion proof equipment in hazardous areas

CAUTION yellow safety warning symbol. Failure to take measures may result in minor personal injury from contact with equipment surfaces above 70 ℃

NOTICE unsigned failure to take measures may result in property damage and unauthorized modification of equipment

2. Key safety requirements

Personnel qualifications: Only "qualified personnel" are allowed to operate, and the following abilities are required:

Master the knowledge of safety protection for electrical circuits, high-voltage equipment, and hazardous media;

Familiar with electrical operation standards in hazardous areas;

Able to use protective equipment and possess first aid skills.

Special requirements for hazardous areas:

Explosion proof type selection: The appropriate explosion-proof version (Ex i/Ex d/nA) should be selected based on the hazardous area level (such as Zone 0, Zone 1, Zone 2), and non corresponding explosion-proof components should be prohibited;

Electrostatic protection: When operating in hazardous areas, close the key cover and tighten the screws to avoid static electricity accumulation and explosion;

Wiring specifications: Use B-type RCD (trip limit 300mA), the power supply must comply with SELV (safety isolation ultra-low voltage) requirements, and shielded cables must only be grounded at one end.

Equipment modification restrictions: Only modifications according to document instructions are allowed. Unauthorized modifications will result in the invalidation of warranty and the invalidation of explosion-proof certification.

Installation specifications (mechanical+electrical)

1. Preparation before installation

Arrival inspection:

Check the packaging and equipment for any transportation damage. If there is any damage, immediately claim compensation from the shipping company and keep the damaged parts;

Compare the order with the shipping documents to confirm the integrity and correctness of the equipment model and accessories (such as flanges and seals);

Prohibit the use of damaged or incomplete equipment (especially in hazardous areas, which may cause explosions).

Environmental conditions: The following environmental requirements must be met, otherwise it may affect equipment performance or cause safety accidents:

Remarks on Environmental Parameter Requirements

Operating temperature -40~85 ℃ (Ex i/T6 version -40~60 ℃) Avoid direct sunlight, and additional heat dissipation is required in high-temperature environments

Storage temperature -50~85 ℃. The packaging only provides limited moisture-proof protection and requires additional protection

Humidity ≤ 95% (no condensation). Moisture proof devices need to be installed in condensing environments

Vibration acceleration ≤ 9.8m/s ² (in accordance with DIN IEC 68-2-6) Keep away from strong vibration equipment (such as pumps and compressors)

The output current drops to 80% when the altitude is ≤ 2000m (over altitude requires reduced capacity)

2. Mechanical installation specifications

General requirements:

Installation method: Only vertical installation is allowed to avoid shell rotation (which may damage the measuring unit);

Explosion proof gap: The distance between the explosion-proof surface of explosion-proof equipment and fixed components should be ≥ 40mm to prevent explosions caused by high-temperature gas leakage;

Sealing selection: The flange seal should be compatible with the process medium (such as PTFE seal used in FDA compliant scenarios), and the seal should be centered without obstructing the movement of the diaphragm.

Scenario based installation differences: According to the measurement medium state, the equipment installation position and pipeline layout need to be designed differently:

Measurement medium installation position pipeline requirements

The gas transmitter is higher than the pressure tapping point and the pipeline is inclined towards the pressure tapping point, which facilitates the discharge of condensed water

The liquid/steam transmitter is located below the pressure tapping point and the pipeline is inclined towards the pressure tapping point for easy gas discharge (a condensation tank needs to be installed for steam)

The flange of the liquid level (open container) is lower than the minimum measured liquid level, and the negative pressure chamber is open to the atmosphere. The open interface needs to be protected to prevent pollution

The flange of the liquid level (closed container) is lower than the minimum measured liquid level, and in strong condensation scenarios, negative pressure pipelines need to be filled and condensation tanks need to be installed

3. Electrical installation specifications

Grounding requirements:

Grounding must be carried out according to IEC 536 Class 1 standard, and the cross-sectional area of the PE wire must not be smaller than that of the power wire;

Explosion proof equipment requires equipotential connection (excluding Ex i type) to avoid explosion caused by compensating current;

Grounding through the "+" terminal is prohibited, and grounding through the "-" terminal is required (otherwise it may damage the equipment).

Wiring specifications:

Cable selection: High temperature environments (≥ 60 ℃) require the use of cables with a temperature resistance of ≥ 80 ℃, and shielded cables must meet EMC requirements;

Cable gland: Only use gland compatible with explosion-proof type, and the tightening torque must comply with technical specifications (such as M20 gland torque of 2.5Nm);

Cable separation: Power cables (power+motor) and control cables need to be wired separately (in different cable trays/conduits) to avoid EMI interference.

Special wiring in hazardous areas:

IT power supply system: It is necessary to remove the internal "Y" capacitor of the equipment and install an output reactor;

Conduit system: A spark barrier should be installed at a designated distance from the equipment input port, in compliance with national regulations and explosion-proof certification requirements.

Debugging process (scenario based steps)

1. Preparation before debugging

Power on preheating: After the equipment is powered on, it needs to be preheated for 5 minutes to ensure stable measurement values;

Parameter verification: Confirm that the equipment nameplate parameters (such as range, power supply, explosion-proof level) are consistent with the actual operating requirements;

Tool preparation: Select the appropriate tool (HART communicator, SIMATIC PDM, BOP/AOP panel) based on the communication protocol.

2. Scenario based debugging steps

(1) Gas medium debugging

Close all valves and apply range starting pressure (such as 0mbar) to the transmitter through the testing interface;

Check if the output signal is 4mA, and calibrate if there is a deviation;

Close the test valve, open the pressure tap valve, and then slowly open the process valve;

Adjust to the end pressure of the range, confirm that the output signal is 20mA, and complete the debugging.

(2) Liquid medium debugging

Close all valves, open the pressure tap valve and balance valve;

If the transmitter is located below the differential pressure sensor, open the drain valve to release air (until no bubbles of liquid flow out); If it is above, open the exhaust valve to release air;

Close the drain/exhaust valve, open the positive pressure side differential pressure valve and exhaust valve (close after emptying the bubbles);

Repeat step 3 on the negative pressure side and close the differential pressure valve;

Open the positive pressure side differential pressure valve 1/2 turn and calibrate the zero point (0 bar corresponds to 4mA);

Close the balance valve, fully open the differential pressure valve, and complete the debugging.

(3) Steam medium debugging

Close all valves, open the pressure tapping valve and balance valve, and wait for the differential pressure pipeline and the steam in the condensing tank to completely condense;

Open the differential pressure valve and exhaust valve on the positive pressure side (close after draining the condensate until there are no bubbles);

Repeat step 2 on the negative pressure side and close the differential pressure valve;

Open the positive pressure side differential pressure valve 1/2 turn and calibrate the zero point (0 bar corresponds to 4mA);

Close the balance valve and fully open the differential pressure valve;

Temporarily open the drain valve to clean the pipeline (close before steam leakage) and complete the debugging.

Maintenance and troubleshooting

1. Regular maintenance

Maintenance cycle: The cycle should be defined based on the corrosiveness of the medium and the concentration of environmental dust (such as once every 3 months for strong corrosion scenarios and once every 6 months for cleaning scenarios).

Core maintenance project:

Precautions for maintaining project steps

Sealing inspection 1. Clean the shell and seal; 2. Check for cracks/damage; 3. Lubrication or replacement of differential pressure equipment seals requires Siemens authorized personnel to operate

Anti static tools should be used in hazardous areas where the dust layer on the surface of the dust cleaning and removal equipment is greater than 5mm to avoid the accumulation of static electricity

Use a soft brush and an appropriate solvent to clean film deposits. Do not use sharp tools to avoid scratching the film

Parameter calibration: Regularly verify the range and zero point (e.g. every 6 months) using a standard pressure source and record calibration data

2. Fault handling

Fault indication method:

SDP panel: indicates faults through a combination of on/off/flashing of 2 LEDs (such as alternating flashing of dual lights=RAM fault);

BOP/AOP panel: displays Fxxx fault codes (such as F0001=ground fault) or Axxx alarm codes (such as A0002=over range alarm);

HART/PA/FF: View detailed fault information (such as sensor disconnection, EEPROM failure) through communication tools.

Common troubleshooting solutions:

Fault code, fault type, possible causes, and solutions

F0001 grounding fault 1. Motor power does not match equipment; 2. Cable grounding; 3. Equipment overload: 1. Check P0307 (motor power); 2. Check the insulation of the cable; 3. Reduce load

F0002 DC bus overvoltage 1. Input voltage exceeds the range; 2. The slope descent time is too short; 3. The regenerative energy of the load is high. 1. Check the power supply voltage (which should be between 10.5-45V DC); 2. Increase P1121 (slope descent time); 3. Install a braking unit

F0051 EEPROM fault EEPROM read/write failure 1. Perform factory reset (P0010=30+P0970=1); 2. Replace the electronic unit (if reset is ineffective)

Fault reset method:

Power off and restart the device;

Press the reset button on the BOP/AOP panel;

Trigger reset through digital input 3 (parameters need to be configured in advance).

Technical specifications (core parameters)

1. Pressure range (HART/PA/FF universal)

Measurement Type Range Maximum Operating Pressure (MAWP) Maximum Test Pressure

Gauge pressure 0.01~700bar g 0.04~800bar g 0.06~800bar g

Absolute pressure 8.3mbar~100bar a 1.5~160bar a 6~250bar a

Differential pressure 1mbar~30bar 32~420bar 32~600bar

2. Temperature range

Temperature Type Range Remarks

The ambient temperature is -40~85 ℃ for Ex i/T6 version and -40~60 ℃ for Ex d/T4 version

Process temperature -40~250 ℃ can reach 250 ℃ with cooling extension, and -40~100 ℃ without extension

Storage temperature -50~85 ℃, limited moisture-proof packaging, requires additional protection

3. Electrical and communication parameters

Parameters: HART PROFIBUS PA/Foundation Fieldbus

Supply voltage DC 10.5~45V (Ex i type 10.5~30V) Bus supply DC 9~32V (Ex i type 9~24V)

Current consumption - maximum 15.5mA (in case of fault)

Output signal 4-20mA (load independent) digital signal (compliant with PROFIBUS PA/FF specifications)

EMC compatibility complies with EN 61326, NAMUR NE 21 complies with EN 61326, NAMUR NE 21

4. Certification and Protection

Protection level: IP65/IP68 (EN 60529), NEMA 4X;

Explosion proof certification: ATEX（PTB 99 ATEX 1160）、FM（Certificate of Compliance 3008490）、CSA（Certificate of Compliance 1153651）；

Compliance directives: EMC 2004/108/EC, ATEX 94/9/EC, PED 97/23/EC.