The DMK331 ceramic diaphragm pressure transmitter is for general purpose applications requiring a pressure range between 0.4 and 600 bar, including vacuum ranges and absolute range from 0.6 bar.
This pressure transmitter can be supplied with a PVDF process connector so that it can be used to measure the pressure of acids and other corrosive chemicals. There is also the option for a Oxygen service version for pressure ranges up to 25 bar with a FKM seal, or 15 bar with a EPDM seal.
The industrial pressure transmitter DMK 331 features a high-grade ceramic sensor engineered specifically for demanding industrial applications involving pasty, polluted, or highly aggressive media, as well as low-pressure oxygen applications. Offering a wide nominal pressure range from 0…400 mbar up to 0…600 bar, this versatile instrument provides reliable performance with an accuracy of 0.5% FSO according to IEC 61298-2. With multiple options for electrical interfaces, mechanical process connections, housing types, and specialized safety certifications like intrinsic safety and SIL 2 rating, it delivers a highly customizable solution tailored to complex process monitoring and control requirements.
Product Parameters
- Nominal pressure range: Available from 0…400 mbar up to 0…600 bar in gauge or absolute configurations to accommodate low to high-pressure regimes.
- Accuracy rating: Maintains a standard accuracy of 0.5% FSO according to IEC 61298-2 for precise process control.
- Output signals: Supports 2-wire loops with 4 … 20 mA or 3-wire configurations with 0…20 mA and 0…10 V electrical outputs.
- Diaphragm material: Features a robust 96% aluminum oxide (Al2O3) ceramic diaphragm providing exceptional chemical and mechanical resistance.
- Process connection types: Offers G1/2″ DIN 3852, G1/2″ EN 837, G1/4″ DIN 3852, G1/4″ EN 837, as well as 1/2″ NPT and 1/4″ NPT threads.
- Safety certifications: Optional intrinsically safe explosion protection (Ex ia for gases and dusts) and SIL 2 safety integrity level according to IEC 61508 / IEC 61511.
- Permissible temperatures: Operates within environmental temperatures of -20 to 60 °C in explosive zone 0 and -40 to 70 °C in standard or zone 1 environments depending on configuration.
Product Description
The DMK 331 series industrial pressure transmitter is designed to bridge the gap between heavy industrial resilience and high-accuracy measurement instrumentation. At the core of its design is a capacitive or piezoresistive ceramic sensing element composed of 96% pure Al2O3, which ensures total separation between the electronic transduction circuitry and corrosive or abrasive process fluids. This makes the transmitter exceptionally well-suited for challenging media that would typically degrade standard stainless steel diaphragms, including viscous sludges, chemically aggressive fluids, and high-purity oxygen systems.
Configurability is a primary advantage of this instrument series. Users can choose between multiple electrical connection architectures, ranging from standard ISO 4400 plug connectors to heavy-duty compact stainless steel field housings or direct factory-sealed cable outlets with ventilation tubes for atmospheric reference. Mechanical versatility is achieved through multiple process connection threads and styles, such as open ports or semi-flush designs that prevent pasty or particulate-laden media from clogging the pressure port channel.
For deployment in safety-critical and hazardous locations, the transmitter can be specified with intrinsic safety approvals (ATEX and IECEx) for both gas and dust environments. When integrated into safety-instrumented systems, the transmitter is available in a SIL 2 certified version conforming to international standards IEC 61508 and IEC 61511. This ensures that design and process engineers can seamlessly standardize on a single transmitter line across non-hazardous utility systems and critical safety loops alike.
Product Features
- Chemical resilience: Utilizes a high-purity 96% ceramic diaphragm that stands up to aggressive acids, bases, and abrasive chemical compounds.
- Anti-clogging process ports: Available with a G1/2″ flush or open port option specifically intended for pasty, polluted, or high-viscosity media.
- Oxygen system compatibility: Specifically prepared and certified options for low-pressure oxygen applications, including BAM-approved FKM O-rings.
- High overpressure tolerance: Designed with substantial overpressure and burst pressure margins to prevent mechanical failure during process pressure spikes.
- Hazardous area compliance: Certified ATEX and IECEx intrinsically safe zone ratings for reliable deployment in explosive gas or dust atmospheres.
- Functional safety compliance: Certified for use in SIL 2 safety loops, helping plant operators meet rigorous risk-reduction targets.
- Premium field housing: Can be outfitted with a robust stainless steel 1.4404 compact field housing to resist extreme environmental elements and washdowns.
Product Applications
- Plant and machine engineering: Monitoring hydraulic fluid pressures, cooling loops, and pneumatic systems in heavy machinery fabrication.
- Energy and utility monitoring: Tracking liquid and gas pressures within power generation facilities, distribution hubs, and auxiliary boiler plant lines.
- Wastewater and sewage treatment: Measuring pump discharge and line pressures for heavily polluted fluids, sludges, and recycling streams.
- Chemical process processing: Regulating line pressures for aggressive chemical reagents, acidic solutions, and caustic processing fluids.
- Medical and laboratory technology: Managing medical gas supply pressures, specialized process plumbing, and clean room chemical utilities.
- Industrial oxygen handling: Ensuring precise pressure transmission in low-pressure oxygen enrichment lines and gas delivery manifolds.
Calcium Chloride
A DMK331 built with a ceramic diaphragm, PVDF process connection and FKM seals is compatible with a calcium chloride solution.
- SKU ID: s1-dmk331-0008
- Part No: 251-1002-1S-5-TA0-H00-1-B-2-000
- Pressure Range: 0 – 10 bar absolute
- Output: Intrinsic Safety, SIL2, 4 – 20mA / 2 wire
- Electrical Connection: IP66 cable outlet with 2m of PVC cable
- Process Connection: G 1/2″ DIN 3852 open port
- Process Connection Material: PVDF
- Seal Material: FKM
- Diaphragm Material: Aluminium Oxide
- Accuracy: 0.5% FS
- IP Rating: 65
- Thermal Errors (TZS & TSS): 0.02% FSO / °C
- Media Operating Temperature Range: -30 to +60°C
- Electronics Housing Operating Temperature: -40 to +85°C
Saline & Sulphuric Acid Solutions
Measure the pressure of water pipes containing salts and sulphuric acid solutions. Reverse Osmosis is used to remove salts from water, and sulphuric acid is used as a dosing agent to remove scaling, caused by the salt, from the membrane.
- SKU ID: s1-dmk331-0007
- Part No: 250-4001-1-5-850-H00-1-B-2-000
- Pressure Range: 0 – 4 bar g
- Output: 4 – 20mA / 2 wire
- Supply Voltage: 12 – 36V dc
- Electrical Connection: Field housing stainless steel IP67
- Process Connection: G 1/2″ DIN 3852 open port
- Process Connection Material: PVDF
- Seal Material: FKM
- Diaphragm Material: Aluminium Oxide
- Accuracy: 0.5% FS
- IP Rating: 65
- Thermal Errors (TZS & TSS): ±0.02% FSO / °C
- Media Operating Temperature Range: -30 to +60°C
- Electronics Housing Operating Temperature: -40 to +85°C
Oxygen clean 1 bar g
Oxygen service intrinsically safe pressure transmitter for measuring pressure of Oxygen gas from 0 to 1 bar gauge.
This transmitter is suitable for use on Oxygen because it has a dry sensing cell which excludes any hydrocarbons based fluids which would otherwise be a flammable/explosion risk if the cell was damaged and leaked fluid into the Oxygen.
The internal surfaces of the process connection have been cleaned to very high standard to remove traces of oil & grease left behind during the manufacturing process.
- SKU ID: s1-dmk331-0003
- Part No: 250-1001-E-5-100-N40-1-1-2-007
- Pressure Range: 1 bar gauge
- Accuracy: 0.5% FS
- Output Signal: 4-20mA, ATEX / IECEx IS, (2 wire)
- Supply Voltage: 10-28Vdc
- Electrical Connection: DIN43650A plug and socket
- Pressure Connection: 1/4 NPT male
- Media Compatibility: Stainless steel 1.4404 (316L) port, Ceramic diaphragm, FKM O ring seals
- Optional Extras: Oxygen clean
Acidic water pressure up to 300 psi
Pressure sensor for use on acidic water from underground mines up to a pressure of 300 psi. This sensor has a 4-20mA output and a 1/2 inch thread for installing on a pipe.
- SKU ID: s1-dmk331-0004
- Part No: 250-P300-1-5-100-H00-1-B-2-000
- Pressure Range: 0 – 300 Psi G
- Output: 4 – 20mA / 2 wire
- Supply Voltage: 12 – 36V dc
- Electrical Connection: Large Plug & Socket to ISO 4400
- Process Connection: G 1/2″ DIN 3852 open port
- Process Connection Material: PVDF
- Seal Material: FKM
- Diaphragm Material: Aluminium Oxide
- Accuracy: 0.5% FS
- IP Rating: 65
- Thermal Errors (TZS & TSS): ±0.02% FSO / °C
- Media Operating Temperature Range: -30 to +60°C
- Electronics Housing Operating Temperature: -40 to +85°C
Ethylene & Acetylene gases up to 1 bar absolute
Intrinsically safe pressure sensor for use on ethylene and acetylene gas with a measurement range of 0 to 1 bar absolute and a 4 to 20 milliamp transmitter signal.
- SKU ID: s1-dmk331-0005
- Part No: 251-1001-E-5-100-300-1-1-2-000
- Pressure Range: 0 – 1 Bar Abs
- Output: 4 – 20mA / 2-wire
- Supply Voltage: 14 – 28 V dc
- Electrical Connection: Large Plug & Socket to ISO 4400
- Process Connection: G1/4″ male DIN 3852
- Process Connection Material: Stainless Steel 1.4571 (316Ti)
- Seal Material: FKM
- Diaphragm Material: Aluminium Oxide
- Accuracy: 0.5% FS
- IP Rating: 65
- Thermal Errors (TZS & TSS): ±0.02% FSO / °C
- Media Temperature: -25 to +135°C
- Operating Temperature: -25 to +85°C
- Special Options: None
- Approvals: ATEX (II 1 G Eex ia IIC T4)
Product Specifying Guide
Step 1: Select measurement type and pressure range
Determine whether your application requires gauge pressure reference to atmosphere or absolute pressure reference to a sealed vacuum. Then choose the appropriate nominal pressure range from the available options between 0…400 mbar and 0…600 bar, ensuring that the maximum system pressure spikes do not exceed the specified overpressure limits.
Step 2: Choose the output signal and electrical interface
Select a 2-wire 4…20 mA loop for long-distance transmissions and standard industrial loops, or a 3-wire voltage output (0…10 V) or current output (0…20 mA) for direct PLC analog integration. Pair this with the required physical interface, such as an ISO 4400 plug for quick disconnect or a compact field housing for high environmental ingress protection.
Step 3: Configure mechanical connections and seals
Review your medium characteristics to choose the ideal process connection. Pasty or polluted fluids require a flush or open G1/2″ port, while clean thinner fluids can use standard G1/4″ connections or NPT options. For aggressive chemicals not compatible with stainless steel choose the PVDF plastic port option. Select a compatible seal material, opting for standard FKM, EPDM for specific temperature bounds, or BAM-approved seals for specialized oxygen use.
Step 4: Determine safety and regulatory requirements
Identify whether the installation zone is classified as a hazardous area requiring intrinsic safety (Ex ia) for gases and dusts. If the transmitter is being integrated into an emergency shutdown or critical monitoring loop, specify the certified SIL 2 functional safety option to satisfy plant compliance protocols.
Part Number Builder
Generate or decode DMK 331 ordering code & request quote
Configuration Rules & Restrictions
To ensure high reliability, safety, and compatibility with aggressive, pasty, or high-pressure media, this configurator automatically enforces several manufacturing and engineering logic rules from the technical datasheet. Below is an overview of the structural dependencies used to validate your part number:
Chemical Compatibility & Pressure Port Materials
- PVDF (Code B): This option is specifically designed for highly aggressive chemical environments.
- Mechanical Connection Constraint: The PVDF pressure port is only physically available with the G1/2″ DIN 3852 open pressure port (Code H00). If you choose PVDF (B), the configurator will automatically lock the mechanical connection to H00.
- Pressure Limitations: Due to structural limits of the plastic material, PVDF pressure ports cannot be used for high-pressure configurations. It is entirely restricted and hidden for all nominal pressure ranges greater than 60 bar (e.g., ranges 100 bar up to 600 bar).
Mechanical Connection Limitations
- G1/2″ DIN 3852 Semiflush Sensor (Code F00): This mechanical design is intended for pasty or heavily contaminated media to avoid clogging. However, it is structurally restricted to lower and medium pressures. It is disabled and hidden for any measurement range greater than 60 bar.
- Absolute Pressure vs. Semiflush: According to factory specifications, the semiflush connection (F00) is not a standard option for absolute pressure. Therefore, if Absolute (251) is chosen under Pressure Type, the F00 option is disabled.
Pressure Type (Gauge vs. Absolute)
- Absolute Pressure (Code 251): Absolute pressure measurement requires special reference cell configurations. It is not available for very low pressure ranges or vacuum configurations. Specifically, it is disabled for the 0…0.40 bar (4000) range and the -1…0 bar vacuum (X102) range.
Elastomer Seal Material Selection
- EPDM (Code 3): EPDM is excellent for water applications, food processing, and certain chemical environments. However, it is restricted for ultra-high-pressure applications and cannot be selected for nominal ranges greater than 160 bar (250 bar to 600 bar).
- Oxygen Application Restriction: EPDM seals are strictly incompatible with oxygen-enriched environments due to chemical safety hazards. If the Oxygen application (007) special version is selected, EPDM is disabled, and the unit defaults to FKM (1).
Special Versions (Oxygen Cleaned)
- Oxygen Application (Code 007): For media safety, oxygen transmitters undergo specialized cleaning and oil-free assembly. This specialized safety standard is only applicable up to a specific safety threshold. It is disabled for all pressure ranges greater than 25 bar (40 bar up to 600 bar).
Electrical Connections & Cable Outputs
- Standard Plug Connections: Choosing industrial connectors like the Plug ISO 4400 (100), Binder 723 (200), M12x1 (M10), or Compact Field Housing (850) renders the custom cable options inapplicable.
- Integrated Cable Outlets: Selecting either Cable outlet IP67 (TA) or Cable outlet IP68 with vent tube (TR) will dynamically unlock the Cable Type and Cable Length fields.
- Default Length: A standard 2-meter length is supplied by default and will not alter the suffix of the base part number.
- Custom Length Suffix: If you change the length input box to any integer other than 2, the configurator automatically appends a length suffix to the final generated ordering code (e.g., (5m) for 5 meters) to communicate the custom requirement to our engineering team.
Installation & Operation Guide
Mechanical connection installation
Ensure the process line is completely depressurized before starting installation. Thread the transmitter manually into the matching process port mating boss, then finalize tightening using a calibrated wrench applied strictly to the hex flats (SW27) of the transmitter body. Avoid overtightening to protect the threads and process seals.
Electrical wiring integration
Wire the transmitter according to the specific configuration chosen during ordering. For standard 2-wire current loops, connect the positive supply voltage to pin 1 and the negative loop line to pin 2 of the electrical interface. Ensure any shield or ground wires are terminated correctly according to local industrial grounding codes to eliminate electrical noise interference.
Venting and atmospheric reference
If utilizing a version outfitted with an integrated connecting cable, verify whether your pressure range requires atmospheric referencing via an internal ventilation tube. Ensure the open end of the reference ventilation tube terminates inside a clean, dry junction box free from moisture or liquid ingress to prevent capillary action from drawing liquid into the internal transmitter reference cavity.
Product Help
Overpressure limits explanation
What is the difference between nominal pressure, overpressure, and burst pressure on this transmitter?
Nominal pressure is the maximum calibrated operational range where the transmitter maintains its 0.5% FSO accuracy. Overpressure represents the maximum pressure limit the device can survive without sustaining permanent calibration shift or mechanical deformation. Burst pressure indicates the ultimate structural destruction limit of the housing and sensor assembly.
3500 mbar range for Oxygen service
I’m looking for a pencil pressure transmitter to measure up to 3500 mbar with a 1/2 inch thread size. The pressure transmitter must also be suitable for Oxygen service.
Below is a suggested spec which is Oxygen clean and with a pressure range scaled to 0-3500 mbar g.
- SKU ID: s1-dmk331-0006
- Part No: 250-3501-E-5-TA0-H00-1-1-2-007
- Pressure Range: 3500 mbar gauge
- Accuracy: 0.5% FS
- Output Signal: 4-20mA, ATEX / IECEx IS, (2 wire)
- Supply Voltage: 10-28Vdc
- Electrical Connection:IP67 seal with 2m of cable
- Pressure Connection: G1/2 DIN3852 open port male
- Media Compatibility: Stainless steel 1.4404 (316L) port, Ceramic diaphragm, FKM O ring seals
- Optional Extras: Oxygen clean
Oxygen application compliance
What special precautions must be taken when ordering this device for oxygen lines?
For oxygen lines, the device must be specified with a dedicated oxygen configuration that utilizes a specific FKM Vi 567 O-ring seal holding official BAM approval. This option restricts the permissible nominal pressure range to a maximum of 25 bar to guarantee safe operational margins within oxygen systems.
Sulfuric acid H2SO4 50% conc & 50°C max up to 2 bar
We are looking for pressure transducers that are capable for working with sulfuric acid (H2SO4) with a concentration which is always below 50% and a temperature always below 50°C. The other specification requirements are a nominal pressure range of 0 to 2 bar gauge and an output signal of 4-20mA.
The DMK331 can be manufactured with a PVDF process connections to make it compatible with acids along with the Ceramic diaphragm and FKM o ring seals.
- SKU ID: s1-dmk331-0001
- Part No: 250-2001-1-5-100-H001-B-2-000
- Pressure Range: 2 bar gauge
- Accuracy: 0.5% FS
- Output Signal: 4-20mA (2 wire)
- Supply Voltage: 8-32Vdc
- Electrical Connection: DIN43650A plug and socket
- Pressure Connection: G1/2 DIN3852 male open port
- Media Compatibility: PVDF port, Ceramic diaphragm, FKM O ring seals
- Media Operating Temperature Range: -30 to +60°C
- Electronics Housing Operating Temperature: -40 to +85°C
Viscous media port selection
Which process connection style should be selected if my fluid contains suspended particulates or sludge?
For applications involving thick, pasty, or highly polluted media, you should select the G1/2″ flush or open pressure port style. This design removes restricted or narrow entry channels, allowing the process fluid to directly contact the flat ceramic diaphragm without accumulating solids that could plug standard pressure cavities.
Acetic & Hydrobromic acid
I have a requirement for a 10 bar pressure transmitter for use on corrosive process fluid which is a mixture of Acetic acid, Hydrobromic acid & water.
We would suggest a DMK331 with a PVDF process connection and EPDM seals for compatibility with the acid solution you will be measuring.
- SKU ID: s1-dmk331-0002
- Part No: 250-1002-1-5-100-H00-3-B-2-000
- Pressure Range: 10 bar gauge
- Accuracy: 0.5% FS
- Output Signal: 4-20mA (2 wire)
- Supply Voltage: 8-32Vdc
- Electrical Connection: DIN43650A plug and socket
- Pressure Connection: G1/2 DIN3852 male open port
- Media Compatibility: PVDF port, Ceramic diaphragm, EPDM O ring seals
- Media Operating Temperature Range: -30 to +60°C
- Electronics Housing Operating Temperature: -40 to +85°C
Max media & ATEX Tamb temperature
Is the DMK331 ATEX rated up to 85 °C? The maximum temperature limit stated on the data sheet says 125 °C but could you confirm the level at which the ATEX rating fails.
The DMK311 maximum media temperature rating is 125°C, The maximum ATEX ambient temperature rating (Tamb) is 85 degC for the surrounding environment.
Plastic pressure port limits
When should I select the plastic PVDF pressure port, and what are its physical constraints?
The PVDF open port process connection is an excellent choice for highly aggressive chemical media that would attack stainless steel. However, it is restricted to nominal system pressures up to 60 bar, and its medium temperature range must be restricted to between -30 and 60 °C due to the mechanical boundaries of the plastic material.
250-X102-1-5-100-F00-1-1-2-000
What is the product configuration for a DMK 331 with the part number 250-X102-1-5-100-F00-1-1-2-000?
- SKU ID: s1-dmk331-6-16255
- Part No: 250-X102-1-5-100-F00-1-1-2-000
- Pressure Range: -1 to 0 bar gauge
- Accuracy: 0.5% FS
- Output Signal: 4-20mA (2 wire)
- Electrical Connection: DIN43650A plug and socket
- Pressure Connection: G1/2 male DIN3852 with semi-flush diaphragm
- Media Compatibility: Stainless steel 1.4404 (316L) port, Ceramic diaphragm, FKM O ring seals
Intrinsically safe wiring rules
What are the barrier limits when wiring the intrinsically safe version of this transmitter?
The intrinsically safe version requires connection through an approved safety barrier or galvanic isolator conforming to the transmitter’s maximum safety values: maximum input voltage (Ui) of 28 VDC, maximum input current (Ii) of 93 mA, and maximum input power (Pi) of 660 mW. Internal capacitance and inductance are negligible at approximately 0 nF and 0 µH.
250-X102-1-5-100-300-1-1-2-000
What is the product configuration for a DMK 331 with the part number 250-X102-1-5-100-300-1-1-2-000?
- SKU ID: s1-dmk331-0009
- Part No: 250-X102-1-5-100-300-1-1-2-000
- Pressure Range: -1 to 0 bar gauge
- Accuracy: 0.5% FS
- Output Signal: 4-20mA (2 wire)
- Electrical Connection: DIN43650A plug and socket
- Pressure Connection: G1/4 male DIN3852
- Media Compatibility: Stainless steel 1.4404 (316L) port, Ceramic diaphragm, FKM O ring seals