In many industrial processes, measuring pressure at only one point cannot provide enough information. Engineers may need to compare pressure before and after a filter, monitor pressure across a flow restriction, or calculate liquid level inside a pressurized vessel. In these situations, the pressure difference between two points becomes an important process parameter.
TS301 Differential Pressure Transmitter is designed for this type of measurement. Instead of monitoring only one pressure value, it detects the difference between the high-pressure and low-pressure sides and converts the measured differential pressure into an electrical output for connection with industrial control or data acquisition equipment.
With multiple pressure ranges, output signals and connection options, this type of transmitter can be used in applications such as flow monitoring, tank level measurement, filter condition monitoring and general industrial process control.
Differential Pressure Measurement in Simple Terms
A differential pressure transmitter normally has two pressure connections. One side is connected to the higher-pressure point, while the other is connected to the lower-pressure point.
The basic calculation is:
Differential Pressure = High-Side Pressure − Low-Side Pressure
For example, when the high side is exposed to 500 kPa and the low side is exposed to 450 kPa, the measured differential pressure is 50 kPa.
Inside the transmitter, the sensing element responds to the pressure difference between the two sides. The resulting sensor signal is processed by electronic circuits and converted into an output signal that can be read by a controller, PLC, monitoring system or other compatible equipment.
This makes differential pressure useful when the relationship between two process locations provides more information than an individual pressure reading.
What Happens Inside a Differential Pressure Transmitter
The sensing element is a key component of the measurement system. Pressure applied to the two sides produces a physical response corresponding to the pressure difference. The electronics detect this response, apply signal processing and compensation, and generate the required output.
Sensor construction, calibration, temperature compensation and electronic design all influence the resulting measurement.
For applications involving relatively small pressure differences, these factors can become particularly important. External temperature changes, vibration, electrical interference and unexpected pressure conditions may affect measurement performance if the equipment is not appropriately designed for the application.
The TS301 uses a diffused silicon sensing element with dual-core technology. Its configuration includes pressure ranges such as 0–3 kPa and provides reverse overload capability.
Depending on the selected configuration, accuracy is specified as 0.25%FS or 0.5%FS. This makes the transmitter applicable to measurement tasks where monitoring relatively low differential pressure is important.
Using Differential Pressure to Monitor Flow
Flow measurement is one of the most familiar applications for differential pressure technology.
When fluid passes through an orifice plate, restriction or similar flow element, the pressure upstream and downstream of the restriction changes. The resulting pressure difference is related to the flow conditions.
A differential pressure transmitter measures this pressure difference and sends the resulting signal to a control or calculation system. The system can then use the measured value together with the appropriate flow calculation method.
The process can be summarized as:
Fluid movement → Pressure difference → DP measurement → Flow calculation
It is important to understand that the transmitter itself measures differential pressure rather than directly measuring volumetric or mass flow. Therefore, selecting the correct measurement span and considering the characteristics of the flow element are important parts of system design.
Static pressure, process temperature, fluid properties and installation conditions should also be reviewed before choosing the transmitter.
Differential Pressure for Tank Level Measurement
Pressure difference can also provide information about liquid level.
In an open tank, the pressure at a lower connection point is affected by the height and density of the liquid above it. By measuring the relevant pressure relationship, the control system can derive information about liquid level.
A closed tank introduces another factor: the pressure in the gas space above the liquid. If this pressure changes, it can affect the pressure measured at the bottom of the vessel. A differential pressure configuration can compensate for this effect by using appropriate high- and low-side connections.
The process connection arrangement therefore needs to correspond to the actual tank design.
For applications involving high temperature, corrosive materials, viscous media or difficult installation locations, a remote diaphragm seal and capillary arrangement may also be considered. The transmitter configuration should be selected according to the process rather than treating every tank application in the same way.
Monitoring Filter Loading Through Pressure Drop
Another practical use is monitoring the condition of filters.
A clean filter generally creates a relatively small pressure drop when fluid passes through it. As particles accumulate and the filter becomes increasingly restricted, the pressure difference across the filter can increase.
A differential pressure transmitter can continuously monitor this change.
The basic condition can be understood as:
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Clean filter: relatively low pressure drop
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Increasing loading: increasing differential pressure
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High pressure drop: inspection or maintenance may be required
This provides process personnel with a measurable parameter for evaluating filter condition. Instead of depending entirely on a predetermined replacement interval, maintenance decisions can be supported by actual operating data.
The appropriate alarm point depends on the filter design and process requirements. The transmitter's measurement range should therefore be selected so that normal pressure fluctuations and the expected filter pressure drop fall within a useful measurement span.
Different Configurations for Different Processes
Differential pressure transmitters are not limited to one mechanical configuration. Process connections and diaphragm arrangements can vary according to the installation environment.
Flange-Mounted Configuration
Flange-type designs can be used where the process equipment already incorporates standardized flange connections.
They may be suitable for vessels, pipelines and process equipment where a direct flange connection is required. In liquid-level applications, a flange arrangement can also help establish a defined pressure measurement point while separating the sensing element from the process.
Important factors include flange dimensions, pressure rating, diaphragm material, process temperature and medium compatibility.
Remote Seal and Capillary Configuration
A remote seal configuration can be useful when the transmitter cannot be mounted directly at the process connection.
The diaphragm seal creates a barrier between the process medium and sensing system, while the capillary transfers the pressure effect to the transmitter body.
This arrangement can be considered for hot, corrosive, viscous or difficult-to-access processes. It can also help when direct installation would expose the transmitter to unsuitable process conditions.
However, the complete assembly needs to be evaluated. Capillary length, temperature differences, mounting position and environmental conditions may influence the measurement, so the remote seal and transmitter should be considered as one measurement system.
Sanitary Differential Pressure Configuration
Hygienic processing applications require additional attention to process connections, wetted materials and cleanability.
Food, beverage, pharmaceutical and other sanitary processes may require connections and surfaces designed to reduce material accumulation and support cleaning procedures.
When selecting this type of equipment, engineers should review the sanitary connection, wetted material, surface requirements, cleaning method and process temperature in addition to the differential pressure range.
Important Factors When Selecting a DP Transmitter
A suitable transmitter should be selected based on the actual process conditions rather than simply choosing a model with the highest specification.
The first step is determining the expected differential pressure range. Selecting an unnecessarily large range can reduce the usefulness of measurement detail in applications where the actual pressure difference is relatively small.
The pressure reference should also be identified. Depending on the application, the system may require gauge, absolute or sealed gauge pressure measurement.
The measured medium is another critical factor. Materials exposed to the process should be compatible with the fluid or gas. Engineers should also consider temperature, corrosion, pressure cycling, vibration and environmental exposure.
Electrical compatibility is equally important. The TS301 supports 9–30V DC power and offers 4–20mA, 0–5V and 1–5V output options. Available pressure connections include M20×1.5, M18×1.5 and M12×1, with customized configurations available.
For industrial environments, the enclosure and electromagnetic compatibility should also be checked. The transmitter has an IP65 housing and is designed with resistance to interference from variable-frequency drives and RF signals. It complies with EN50081-1/-2 electromagnetic compatibility requirements.
Performance Goes Beyond Accuracy
Accuracy is an important specification, but it is not the only factor that determines whether a differential pressure transmitter fits an industrial application.
Long-term stability, response speed, overload capability, temperature characteristics and pressure-cycle durability can all affect practical performance.
The TS301 specifies a response time of 10 ms and long-term stability of ≤0.2% FS/year. Its pressure cycle life is rated at a minimum of 5 million cycles.
The stated safe pressure is 200% of span, while destructive pressure is 300% of span. These specifications are relevant for systems where the transmitter may experience pressure fluctuations or repeated operating cycles.
Temperature behavior should also be included in the selection process. The specified operating temperature range is -30 to 80°C, with a compensated temperature range of -10 to 60°C. Zero temperature drift is specified as ±0.02%FS/°C, while full-scale temperature drift is ±0.03%FS/°C.
These parameters give engineers more information for evaluating the transmitter under actual process conditions.
Quality and Traceability in Sensor Manufacturing
For industrial pressure measurement equipment, manufacturing consistency is closely connected with measurement performance. Sensor assembly, calibration, aging and final inspection all play a role in the finished transmitter.
Danrui Sensor (Suzhou) Co., Ltd. focuses on pressure and differential pressure sensing technologies and uses a digital quality management process covering production and inspection stages.
The company incorporates MES-based traceability into its manufacturing process, with an individual SN code used to connect sensor production and inspection information. Its testing capabilities include high-precision equipment, with some core testing equipment specified at a precision of 0.005%.
Danrui reports ISO 9001, ISO 14001 and ISO 45001 management system certifications as well as CE certification. Its pressure measurement products are applied in areas including process control, petroleum, chemical and power-related applications.
For buyers evaluating industrial transmitters, production traceability can be useful because it provides a way to associate individual sensor units with manufacturing and inspection records.
Matching Measurement Requirements With the Right Configuration
Although the basic operating principle remains the same, the selection requirements can vary considerably from one application to another.
For flow monitoring, the transmitter needs to accurately measure the pressure difference created by the selected flow element and communicate with the corresponding calculation or control system.
For tank level measurement, the process connection must correspond to the vessel structure, liquid characteristics and pressure conditions.
For filter monitoring, the measurement range should cover both normal operation and the pressure-drop level associated with filter loading.
When the process involves high temperatures, corrosive media or difficult access, remote seal or flange configurations may be considered. Hygienic processes require suitable sanitary connections and materials.
Electrical integration also needs to match the existing control architecture. Selecting the appropriate output signal and pressure connection can simplify system integration and reduce the need for additional signal conversion.
A Practical Approach to Differential Pressure Measurement
The most useful way to evaluate a differential pressure transmitter is to start with the measurement task.
Determine the expected pressure difference, identify the process medium, review temperature and environmental conditions, select the appropriate pressure connection, and then confirm that the output signal matches the acquisition or control equipment.
Performance specifications such as accuracy, temperature drift, response time, overload capability and long-term stability should then be compared against the operating requirements.
With multiple pressure and output configurations, IP65 protection, 9–30V DC power, rapid response and long pressure-cycle life, TS301 Differential Pressure Transmitter can be considered for a range of industrial measurement tasks involving flow, liquid level, filter pressure drop and process monitoring.
For engineers and industrial buyers looking for differential pressure measurement equipment, matching the sensing range, process connection, environmental conditions and electrical interface to the actual application is an important step toward building a reliable pressure monitoring system.
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