—A Complete Selection Guide

Pressure transmitters are among the most critical sensing devices in industrial automation. They convert physical pressure from gases, liquids, or vapors into standardized electrical signals—typically 4-20 mA—that enable accurate monitoring, control, and safety interlocking across countless applications. Whether you are monitoring pipeline pressure in an oil field, controlling reactor pressure in a chemical plant, or managing steam pressure in a power station, selecting the right pressure transmitter is essential for ensuring accuracy, reliability, and safety.

This guide walks you through the key decisions you need to make when selecting a pressure transmitter, presented from the perspective of Anhui Tiankang (Group) Co., Ltd.—a leading manufacturer with nearly five decades of experience in industrial instrumentation.

Step 1: Define Your Measurement Requirements

Before diving into technical specifications, start by clarifying the basics:

• What is the purpose of the measurement? Monitoring (keeping the operator informed), control (providing input to a control loop), or safety (initiating shutdowns or alarms)? Control applications generally need the highest accuracy, while safety applications demand reliability above all else.

• What is the normal working pressure? The operating range should fall within the device's most accurate range, typically around the middle of the scale.

• What are the highest and lowest pressures expected during normal operation? Accuracy may degrade at extremes, but the device must remain repeatable and survive without damage.

• What is the maximum pressure the device will experience? The transmitter must withstand the pressure rating of the vessel or pipe to which it is attached without bursting.

Tiankang recommendation: For most industrial applications, choose a transmitter with a range 1.5–2 times higher than your maximum operating pressure. This provides a safety margin for pressure spikes while maintaining measurement resolution in the normal operating range.

Step 2: Understand Pressure Measurement Types

Pressure transmitters come in several measurement configurations, and selecting the wrong type will render the device unusable for your application:

Industry insight: Gauge pressure is the most common measurement, as most industrial processes operate relative to atmospheric conditions. Differential pressure transmitters are especially valuable for inferring flow and level measurements where direct measurement is impractical. For vacuum measurement and applications where atmospheric pressure changes would distort readings, choose absolute pressure.

Tiankang offering: Anhui Tiankang manufactures a complete range of gauge (GP), absolute (AP), and differential pressure (DP) transmitters. For high-static-pressure applications such as refinery flow measurement and power plant high-pressure systems, our TK1151HP series offers robust performance with overpressure capability up to 32 MPa.

Step 3: Select the Right Accuracy Class

Accuracy is often the most discussed but also the most misunderstood parameter in pressure transmitter selection. Accuracy is the difference between the true value and the indicated measurement, typically expressed as a percentage of full scale (%FS). Common industrial accuracy classes include 0.05%, 0.1%, 0.2%, 0.5%, and 1.0%.

General guidelines:

• 0.05–0.1% FS: High-precision applications such as custody transfer, laboratory measurement, critical process control loops, aerospace

• 0.2–0.25% FS: Most industrial process control, chemical plants, oil refineries, power generation

• 0.5% FS: General monitoring, utility services, non-critical pressure indication

• 1.0% FS or higher: Cost-sensitive applications, rough indication only

Important nuance: Accuracy specifications can be expressed as FS (full scale) or BFSL (best fit straight line). A 0.25% FS accuracy means the maximum error is 0.25% of the full output scale at any point, while BFSL refers to deviation from a calibrated best-fit line and may appear more favorable. Always compare like terms.

Beyond initial accuracy, long-term stability matters equally. A pressure transmitter with poor stability will gradually deviate from true values during long-term operation, even if it has high initial accuracy.

Tiankang offering: Our intelligent pressure transmitters deliver accuracy from ±0.075% to ±0.5% FS, with long-term stability of ≤±0.2% per year. After six months of operation, the transmitter does not exceed the basic error limit—this stability is field-verified across thousands of installations.

Step 4: Evaluate Process Media Compatibility

The process fluid—whether gas, liquid, vapor, slurry, or aggressive chemical—directly determines which materials can safely contact the media. These are called "wetted parts," including the diaphragm, flange adapter, and other components exposed to the process.

Critical consideration: If the process media is corrosive or contains abrasive particles, the diaphragm material must be upgraded accordingly. For highly corrosive or high-temperature applications, a remote seal diaphragm transmitter isolates the sensor body from the aggressive process.

Tiankang offering: We provide a comprehensive selection of wetted materials for our pressure transmitters, including 316L stainless steel, Hastelloy C-276, Monel, and tantalum. For viscous, crystallizing, or sanitary applications, we offer flange-mounted remote diaphragm seal configurations. Our high-static-pressure differential pressure transmitters feature specialized high-static-pressure capsules, reliable for flow and level measurement in high-pressure systems.

Step 5: Consider Environmental and Installation Conditions

Industrial environments can be punishing. Temperature extremes, vibration, humidity, electromagnetic interference, and hazardous atmospheres all affect pressure transmitter performance and longevity.

Temperature range: The operating temperature includes both the process medium temperature and the ambient temperature around the transmitter. Standard industrial transmitters typically operate from -30°C to 85°C. For higher process temperatures:

• >85°C up to 120°C: Install a cooling element (heat sink) between the process and transmitter

• >120°C up to 315°C: Use a remote seal transmitter with capillary tubing, filled with high-temperature silicone oil

• >315°C: Special high-temperature designs with extended cooling sections are required

Vibration and shock: Piezoresistive and thin-film sensing technologies perform well under vibration. Some transmitters are rated for vibration up to 50G. For high-vibration areas such as compressor stations and pump houses, select transmitters with rugged construction and appropriate mounting.

Hazardous areas: When the installation is in an area where explosive vapors or dusts may be present, the pressure transmitter and its power supply must be certified for such environments. Two common protection methods are:

• Intrinsically safe (Ex ia): Limits electrical energy in the circuit to a level below that which can ignite a hazardous atmosphere. Suitable for Zone 0, 1, and 2 (gas) and Zone 20, 21, 22 (dust).

• Flameproof/explosion-proof (Ex d): Encloses components that could ignite an explosion, allowing the explosion to occur inside the enclosure without propagating to the outside atmosphere.

Tiankang offering: Our transmitters are available in both flameproof (Ex d II BT4-6) and intrinsically safe (Ex ia II CT5) configurations, suitable for Zone 1 and Zone 2 hazardous areas. With IP65 or higher ingress protection ratings, they withstand harsh industrial environments, including dust, moisture, and occasional wash-down.

Step 6: Determine Output Signal and Communication Protocol

The output signal from your pressure transmitter must be compatible with your control system—whether a PLC, DCS, SCADA, or cloud-based IIoT platform. Common options include:

Market context: The global HART pressure transmitter market reached $2.26 billion in 2026, growing at 7.3%. 4-20 mA with HART remains the dominant standard, offering backward compatibility with legacy 4-20 mA loops while enabling digital communication capabilities.

Tiankang offering: Our pressure transmitters offer flexible output options. The standard configuration is 4-20 mA two-wire output with HART protocol digital communication. For specialized requirements, we offer voltage outputs (0-5 V, 0-10 V) and low-power versions for battery-operated or remote applications.

Step 7: Evaluate Turndown Ratio and Rangeability

The turndown ratio is the ratio between the maximum calibrated span and the minimum calibrated span of a transmitter. It directly affects how many transmitter models you need to stock and how flexibly you can adapt to changing process conditions.

Turndown = nominal range of the device / set span of the device

For example, a transmitter with a nominal range of 100 psi and a set span of 25 psi has a turndown ratio of 4:1.

Why turndown matters:

• Inventory reduction: A high turndown ratio allows you to stock fewer transmitter models, as one transmitter can cover multiple pressure ranges

• Process flexibility: You can re-range a single transmitter to adapt to changing process conditions

• Cost efficiency: Reduces capital expenditure and spare parts inventory

Performance consideration: Extremely high turndown (e.g., 100:1) is available from many modern transmitters, but accuracy degrades at very high turndowns because accuracy is typically specified as a percentage of the calibrated span or upper range limit. Carefully evaluate the turndown/accuracy trade-off for your specific application.

Tiankang offering: Our intelligent pressure transmitters feature up to 100:1 turndown capability, allowing one device to cover multiple process conditions and significantly reducing inventory requirements for plant maintenance departments. For applications requiring even greater flexibility, we offer 5:1 customer-accessible turndown adjustments via on-board potentiometers.

Step 8: Understand Sensing Technology Options

Different sensing technologies offer different performance characteristics:

Tiankang offering: Our pressure transmitters are built around advanced capacitive sensing technology for the TK1151 and 3051 series, delivering excellent accuracy and long-term stability. For special applications requiring high corrosion resistance, we offer ceramic sensor variants.

Step 9: Installation and Process Connection Considerations

How the pressure transmitter connects to your process affects ease of installation, maintenance access, and measurement accuracy.

Common process connections:

• Threaded (NPT, BSP, Metric): In-line mounting, direct connection to a single pressure port (gauge/absolute). Light weight, no mounting bracket may be required. Suitable for most gauge and absolute pressure applications.

• Flanged: For remote diaphragm seal transmitters, connects to tank nozzles or pipe flanges. Preferred when media are viscous, crystallizing, or corrosive.

• Coplanar: Two process connections at the bottom (for DP). Modern design enabling measurement of differential, gauge, and absolute pressures with a single connection.

• Sanitary (Tri-clamp, DIN 11851, etc.): Flush diaphragm design, crevice-free construction for hygienic applications.

Installation tips:

• For vertical pipes, install the transmitter above the tapping point to prevent liquid from siphoning back into the impulse lines

• Ensure impulse lines slope downward from the tapping point to the transmitter to prevent gas bubbles

• For steam service, fill impulse lines with condensate before operation

• Use manifolds (2-valve, 3-valve, or 5-valve) to allow transmitter isolation, zeroing, and calibration without process shutdown

Tiankang offering: Our pressure transmitters can be factory-assembled with manifolds, tested for leaks, and calibrated before delivery—significantly reducing field installation time and labor costs. We provide both in-line (NPT 1/2 or M20×1.5) and flange-mount configurations to suit diverse installation requirements.

Step 10: Account for Special Applications

Some industrial applications impose additional selection constraints:

Why Choose Anhui Tiankang Pressure Transmitters?

With nearly 50 years of manufacturing experience and a distinguished reputation in the Chinese instrumentation industry, Anhui Tiankang (Group) Co., Ltd. has become a trusted supplier for oil & gas, petrochemical, chemical, power generation, pharmaceutical, and many other industrial sectors worldwide.

Extensive product portfolio:

• TK1151 series: A widely accepted industrial pressure transmitter family offering DP, GP, AP, HP, and remote seal configurations. Full-featured performance with external zero/span adjustment, damping adjustment, and LCD/LED display options. Widely used in petroleum, chemical, power, food, paper, pharmaceutical, and brewing industries.

• 3051 series intelligent transmitters: Advanced capacitive sensing technology with HART digital communication, up to 100:1 turndown, accuracy as high as 0.05–0.075%, and 60-month long-term stability of 0.25%. Supports gauge, absolute, differential, flange, and high-temperature configurations (process temperature up to 191°C).

• Specialized configurations: High-static-pressure differential pressure (32 MPa withstand pressure, for refinery and power plant applications) and absolute pressure transmitters (for vacuum measurement, degasification systems, evaporators, and crystallizers).

• Intelligent transmitters: CPU-based digital circuit with HART protocol communication, local LCD display, self-diagnostics, and EEPROM data retention.

Quality and certifications:

• ISO 9001, ISO 14001, GJB 9001B certified

• Flameproof (Ex d II BT4-6) and intrinsically safe (Ex ia II CT5) for hazardous area use.

• CNAS-accredited laboratory for full performance testing, including electromagnetic compatibility (IEC61000-4-4 Class IV)

• IP65 or higher ingress protection

Global presence:

• Exported to Russia, Iran, Kazakhstan, Saudi Arabia, Italy, Brazil, and more than 40 other countries and regions

• Long-term supplier to major state-owned enterprises in China and international engineering, procurement, and construction firms worldwide

Customer-focused engineering:

• Factory-assembled manifolds with leak testing and calibration before delivery

• Customized configurations based on customer drawings or specifications

• Full-process technical support from specification to commissioning

• All wetted materials available: 316L stainless steel, Hastelloy C-276, Monel, and tantalum.

Selection Summary Checklist

Before finalizing your pressure transmitter selection, confirm:

Conclusion

Selecting the right pressure transmitter is not about chasing the highest specifications—it is about aligning technical capabilities with your specific application requirements. Start with the fundamentals: measurement type, pressure range, and process media compatibility. Then move to environmental factors, accuracy needs, and output compatibility. Finally, consider long-term stability, turndown requirements, and total cost of ownership.

With nearly five decades of experience and a complete range of pressure measurement products, Anhui Tiankang (Group) Co., Ltd. is ready to help you make the right choice for your industrial application.

For project-specific pressure transmitter selection advice or quotations, please email us at [email protected] or visit http://www.tiankang-global.com/. The Tiankang Instrument Engineering Technology Department is ready to provide professional, customized solutions for your pressure measurement needs.