Why Do Quotes for Custom Differential Pressure Sensors Vary with Measurement Range

When purchasing custom differential pressure sensors, customers often find that products with similar appearances and identical output types may have significantly different quotes simply because the measurement range is adjusted from several hundred pascals to several tens of kilopascals. This is not simply a matter of adding or reducing the price according to the measuring range; changes in range directly affect the sensing element, structural strength, calibration difficulty, and operating-condition adaptation solution.

Differential pressure sensors are used to measure the pressure difference between two pressure ports. Typical applications include air pressure monitoring in air ducts, filter blockage alarms, differential-pressure-based level conversion, liquid level control in sealed vessels, flow measurement, and equipment differential pressure protection. Different applications have different requirements for low-range resolution, overload capacity, and long-term stability.

For example, a 0–500 Pa range is typically used for cleanrooms, ventilation systems, or pressure differential detection across filter sections; 0–10 kPa and 0–100 kPa ranges are more commonly used in industrial equipment and in level- and flow-related operating conditions. The closer the range is to the actual operating range, the higher the measurement effectiveness is generally, but the corresponding selection and production control must also be more precise.

Xi'an Shenghongchuang Instruments Co., Ltd., supported by the production base of Shaanxi Qinkong Sensor Technology Co., Ltd., can provide non-standard customization solutions based on the medium, range, static pressure, connection, output signal, and installation environment. The core of quote evaluation is not simply looking at a range value, but confirming whether the product can operate stably and accurately and remain suitable for the site over the long term at that range.

Four Key Factors Through Which Range Affects Pricing

Range Matching and Manufacturing Requirements of the Sensing Element

The sensing element is the core of a differential pressure sensor. Low differential pressure products need to maintain sufficient sensitivity to minor pressure changes, requiring more stringent diaphragm design, strain structure, signal amplification, and temperature compensation. For measurements in the tens or hundreds of pascals, zero drift and environmental disturbances may affect actual readings.

Higher-range products place greater emphasis on pressure resistance and safety margin. For example, with a measurement range of 0–100 kPa, the product must not only cover the rated differential pressure but also account for transient shocks, one-sided pressure loading, and pressure fluctuations caused by system start-up and shutdown. If higher static pressure must be withstood, requirements for the sensing element and isolation structure will increase further.

Even with the same 4–20 mA output, the sensing element sensitivity and full-scale output adjustment range used for 0–1 kPa and 0–100 kPa are different. Sensing elements are not simply shared and then modified by changing parameters, particularly when accuracy classes reach 0.5%FS, 0.25%FS, or even higher requirements. Range matching directly determines the cost basis of the product.

Accuracy, Stability, and Calibration Workload

Differential pressure sensor accuracy is typically expressed as a percentage of full scale. Taking 0.5%FS as an example, the allowable error for a 0–1 kPa product is approximately ±5 Pa, while that for a 0–100 kPa product is approximately ±0.5 kPa. Although low-range products have smaller absolute errors, achieving this requirement presents greater challenges for controlling zero point, linearity, and repeatability.

Custom products require zero calibration, full-scale calibration, linearity calibration, and output verification. Models with intelligent compensation, digital display, RS485 communication, or alarm control functions also require program configuration and complete unit commissioning. The more specialized the range span and the higher the accuracy requirement, the more calibration points and testing time are generally required.

In actual quotations, a distinction should also be made between “short-term accuracy at room temperature” and “long-term overall performance.” If the on-site temperature varies from -20℃ to 80℃, or if equipment operates continuously throughout the year, temperature drift control, aging screening, and stability verification of the sensor become important cost factors and cannot be judged solely by initial accuracy under laboratory conditions.

What Customization Requirements Beyond Range Can Also Change the Price

Static Pressure and Overload Capacity Cannot Be Overlooked

A small differential pressure range does not mean that the pressures at both ends of the system are low. For example, when the two sides of equipment are respectively at 0.8 MPa and 0.81 MPa, the actual differential pressure is only 10 kPa, but the static pressure borne by the sensor is close to 0.8 MPa. In this case, selecting a product suitable only for low-pressure air environments may result in zero shift, seal failure, or even sensing element damage.

During valve switching, pump start-up and shutdown, pipeline blockage, or incorrect operation, the differential pressure sensor may also be subjected to one-sided overpressure. Customers should provide information on normal operating pressure, maximum static pressure, allowable transient shock, and possible reverse differential pressure to determine the isolation diaphragm, structural material, and overload protection solution.

For corrosive media, viscous media, particle-containing media, or high-temperature steam, wetted materials such as 316L stainless steel, Hastelloy, and PTFE, as well as supporting structures such as impulse tubes, condensation bends, and isolators, must also be considered. After materials and protection solutions are upgraded, the custom quote will also change even if the range remains unchanged.

Output, Installation, and Protection Rating Must Also Be Clearly Defined

Standard output options include 4–20 mA, 0–10 V, 0–5 V, RS485, or switching output. 4–20 mA is suitable for long-distance transmission in industrial sites; RS485 facilitates connection to PLC, DCS, and IoT data acquisition systems; models with LED or LCD displays, upper and lower limit alarms, and relay control require additional circuitry and functional testing.

Installation methods also affect manufacturing costs. Threaded connections, flange connections, clamp connections, panel mounting, and DIN rail mounting have different requirements for housings, fittings, and sealing structures. Where site space is limited, structural adjustments can also be made according to dimensions, cable length, wiring direction, and display orientation.

The protection rating must match the operating environment. Conventional protection designs are generally suitable for dry indoor environments; for humid, dusty, or outdoor applications, protection requirements such as IP65 and IP67 should be considered. For use in chemical explosion-hazardous areas, the explosion-proof type and related supporting requirements should be further confirmed to avoid repeated investment caused by later redesign.

How to Determine a Reasonable Range and Avoid Selection Deviations

Reserve a Margin Based on the Actual Operating Range

A larger range is not always better. If the range is too large, the actual operating differential pressure may account for only a small proportion of full scale, potentially reducing signal resolution and control accuracy; if the range is too small, it can easily be exceeded under fluctuating or abnormal operating conditions. Selection can generally be made by considering normal differential pressure, maximum differential pressure, and short-term shock conditions together.

For example, if the normal pressure differential across a filter is 0.3 kPa and the blockage alarm point is 1.2 kPa, 0–1.6 kPa, 0–2 kPa, or a similar customized range may be evaluated first. If the differential pressure may reach 3 kPa during fan start-up and shutdown, dynamic shock capacity should be further confirmed rather than selecting solely on the basis of normal operating values.

For projects involving differential-pressure-based level or flow conversion, changes in density, temperature, and pipeline losses in process calculations should also be noted. The sensor range should correspond to the process calculation results. When necessary, instrument technicians should verify the pressure tapping point location, impulse line conditions, and actual zero migration requirements.

To obtain a custom differential pressure sensor quote better suited to site conditions, you may provide Xi'an Shenghongchuang Instruments Co., Ltd. with the differential pressure range, medium name, static pressures on both sides, temperature, accuracy, power supply and output, installation connection, and quantity required. Technical personnel can use this information to confirm the sensing element and structural solution and provide corresponding selection recommendations and quotation information.