Can High-Strength Differential Pressure Sensors Withstand Pipeline Pressure Surges

During pump start-up and shutdown, rapid valve opening and closing, compressor pulsation, hydraulic actuator reversal, and similar scenarios, short-term pressure surges may occur in pipelines. For high-strength differential pressure sensors, the ability to withstand such conditions reliably depends not only on the rated differential pressure range, but also on the static pressure rating, one-sided overload capacity, bidirectional overload capacity, diaphragm structure, medium characteristics, and on-site installation method.

A differential pressure sensor measures the pressure difference between the high-pressure and low-pressure sides, but actual failure risks often arise from unbalanced pressure applied to the two sides. For example, if the pressure on the high-pressure side rises suddenly while the low-pressure side responds with a delay, or if an impulse line blockage prevents pressure from being transmitted promptly on one side, the sensing element may be subjected to transient loads far exceeding the normal measuring differential pressure.

Therefore, high strength does not mean unlimited resistance to water hammer or gas hammer. Only by maintaining sufficient safety margin between the sensor's rated operating pressure, allowable overload range, and pressure surge peak, while applying correct pressure tapping, valve manifold, and damping measures, can measurement accuracy, equipment service life, and pipeline system safety all be ensured.

I. First Distinguish Differential Pressure Range from Pressure Resistance

The Differential Pressure Range Does Not Represent the Pressure Each Side Can Withstand

The differential pressure range usually indicates the pressure difference range that the sensor can measure accurately, such as 0–10kPa, 0–100kPa, or 0–1MPa. This value mainly relates to output signal linearity, accuracy class, and resolution; it does not directly indicate the pipeline static pressure or transient surge that the high- and low-pressure sides of the sensor can withstand.

Taking low-range differential pressure measurement as an example, a differential pressure transmitter with a range of 0–10kPa may, if designed with a high-static-pressure structure, allow both sides to withstand a common pressure of several MPa or even higher. Conversely, an ordinary low-pressure differential pressure element with the same range may not be suitable for installation on a high-pressure main pipeline. During selection, the “differential pressure range” and “maximum operating static pressure” must be verified separately.

When the high- and low-pressure sides rise simultaneously while the differential pressure remains essentially unchanged, the sensor is subjected to a static pressure test; when the pressures on the two sides change asynchronously, it faces a differential pressure overload risk. Pipeline pressure surges often exhibit both characteristics, particularly during rapid valve operation, when the transient differential pressure may be far greater than the normal operating differential pressure of the system.

Four Types of Parameters That Require Particular Verification

In engineering selection, burst pressure may only serve as the final reference for structural safety and cannot replace the rated pressure resistance specification. Even if the surge peak does not reach the burst value, long-term repeated loading may still cause diaphragm fatigue, zero drift, reduced sensitivity, or deteriorated sealing performance.

For liquid pipelines with evident water hammer, on-site pressure waveforms should be obtained as a priority, or at least the peak pressure under start-stop conditions should be estimated. The surge may last only tens of milliseconds, but its peak can reach 1.5 times, 2 times, or even more than the normal operating pressure; selection must not be based simply on steady-state pressure.

Xi'an Shenghongchuang Instrumentation Co., Ltd. can match appropriate differential pressure sensor structures and supporting protection solutions according to the actual medium, pipe diameter, operating pressure, differential pressure range, and installation conditions, avoiding application risks caused by selecting only according to conventional ranges.

II. Factors Determining Resistance to Pressure Surges

The Sensing Element and Isolation Structure Are Key

The impact resistance of a high-strength differential pressure sensor depends first on the material of the sensing core, diaphragm thickness, stress design, and the quality of welded sealing. Different technical approaches, such as diffused silicon, ceramic capacitive, and metal capacitive technologies, have different strengths in pressure resistance, response speed, temperature adaptability, and overload resistance, and should be selected according to operating conditions.

For corrosive liquids, particle-containing slurries, or high-temperature media, stainless steel isolation diaphragms, corrosion-resistant wetted materials, or remote seal structures are generally required. If the wetted material is incompatible with the medium, corrosion thinning of the diaphragm will significantly reduce its surge resistance service life, even if the original pressure resistance design is relatively high.

If the sensor is equipped internally with mechanical stops or overload protection structures, excessive deformation of the sensing element can be limited when the differential pressure rises suddenly. Such designs have a positive effect on short-term surges, but they must still be used according to the product technical specifications and must not be regarded as a basis for long-term overpressure operation.

Sources of Surges and Risk Assessment

It should be noted that pressure surges depend not only on peak value but also on repetition frequency. Short-term surges occurring only 1 to 2 times per hour have a completely different effect on diaphragm fatigue life from high-frequency pulsations occurring dozens of times per minute. For high-frequency conditions, the product's cyclic durability data should be confirmed as a priority.

Temperature also affects surge resistance. High temperatures can alter the performance of seals and fill fluids, while low temperatures may increase medium viscosity or cause impulse lines to freeze. The actual operating temperature should remain within the sensor's specified range, with allowance for day-night temperature differences, heat tracing fluctuations, or abnormal operating conditions.

In complex sites such as chemical, energy, and metallurgical applications, it is recommended to provide technical personnel with the medium corrosiveness, solid particles, temperature, pressure rating, and number of surge events together. Complete operating condition information is more helpful in selecting a reliable differential pressure measurement solution than providing only the “pipeline pressure.”

III. Correct Installation Is More Important Than Increasing the Range

Avoid Asynchronous Pressure Transmission on Both Sides

When installing a differential pressure sensor, the impulse paths on the high- and low-pressure sides should be as symmetrical as possible. The length, inner diameter, and routing of the impulse lines should not differ excessively. If one line is too long, contains accumulated liquid or gas, or becomes blocked, the two sides will respond asynchronously during pressure fluctuations, causing the sensor to withstand additional transient differential pressure.

When measuring liquid media, gas accumulation in the impulse lines should be prevented; when measuring gaseous media, condensate should be prevented from entering the pressure tapping lines. For steam or high-temperature media, condensate bends, condensate pots, or isolation devices should be arranged according to the characteristics of the medium to keep pressure transmission conditions consistent on both sides.

A three-valve manifold or five-valve manifold not only facilitates start-up, shutdown, and calibration, but also reduces one-sided pressure surges caused by incorrect operation. During commissioning, follow the principle of first opening the equalizing valve, then slowly opening the high- and low-pressure shutoff valves, and finally closing the equalizing valve; when shutting down, first open the equalizing valve and then close the shutoff valves on both sides.

On-Site Protection Measures

For pipelines with pronounced liquid water hammer, buffers, dampers, or flow-restricting orifice plates may be installed near the pressure tapping points to reduce the speed at which instantaneous pressure waves are transmitted directly to the sensor. The aperture of damping elements must not be reduced blindly, otherwise response lag may occur and affect the control system's assessment of the actual differential pressure.

The sensor body should be kept away from areas of severe turbulence, such as pump outlets, elbows, reducers, and downstream locations of valves. Where conditions permit, pressure tapping points should be arranged on straight pipe sections with relatively stable flow conditions and secured with supports to prevent pipeline vibration from being transmitted directly to the instrument housing and wiring sections.

In a system with a normal operating pressure of 1.0MPa, if on-site records show transient peaks close to 2.0MPa, the rated pressure resistance of the sensor and accessories should not be configured based only on 1.0MPa. The specific safety margin should be determined in combination with surge frequency, system criticality, and manufacturer technical documentation, and critical loops should preferably undergo actual testing and verification.

After installation is completed, zero stability, full-scale output, fitting sealing performance, and valve manifold operating status should be checked. If frequent output fluctuations, continuous zero shift, leakage at wetted areas of the housing, or abnormal impulse line vibration are found, the source of the surge and installation issues should be investigated promptly; faults must not be concealed merely through software filtering.

IV. Recommendations for Selection and Maintenance of High-Strength Differential Pressure Sensors

Establish a Selection Checklist Based on Actual Operating Conditions

Before selection, the normal differential pressure, maximum differential pressure, normal static pressure on both sides, expected surge peak, medium temperature, medium corrosiveness, and installation orientation should be clarified. For low differential pressure applications such as filter blockage monitoring and fan air-pressure monitoring, particular attention should be paid to whether reverse differential pressure or full pressure loading on one side may occur at the high- and low-pressure ports.

The range selected should generally not be too small, to prevent normal fluctuations from approaching the upper limit; nor should it be expanded without limit in pursuit of surge resistance, as this would reduce measurement resolution in low differential pressure ranges. A reasonable solution is to select a product with suitable overload capacity and an adequate static pressure rating while meeting accuracy requirements.

For non-standard interfaces, special media, high-temperature and high-pressure conditions, or high-vibration environments, non-standard customization can be adopted to match wetted materials, thread specifications, output signals, display methods, process connections, and protection ratings. During customization, pressure surge conditions should be included as key technical requirements in the confirmation documents.

Operation and Maintenance Determine Long-Term Reliability

After commissioning, inspections and calibration are recommended according to the equipment management cycle. For applications with frequent surges, the zero point, sealing condition, and impulse line flow continuity may be checked once every 3 months to 6 months; for conventional systems with stable operating conditions, periodic verification or calibration should also be performed in accordance with the enterprise's metrology management requirements.

When a fixed deviation persists in the differential pressure signal, first check the valve manifold position, impulse line blockage, condensate level, and fouling at the pressure tapping ports before determining whether sensor drift is present. Many issues that appear to be instrument failures actually result from imbalance in the pressure tapping system or damage to accessories after pressure surges.

Relying on the production base of Shaanxi Qinkong Sensor Technology Co., Ltd., Xi'an Shenghongchuang Instrumentation Co., Ltd. can provide industrial measurement and control products and technical services for pressure, differential pressure, level, flow, and more. For requirements involving pipeline pressure surges, high static pressure, low differential pressure, corrosive media, and complex installation spaces, it can assist with product selection, parameter confirmation, and application solution matching.

If your pipeline system experiences water hammer caused by pump start-up and shutdown, rapid valve switching, filter backwashing, or high-frequency pressure pulsation, please compile the operating pressure, maximum surge pressure, medium parameters, differential pressure range, and interface dimensions, and contact the technical personnel of Xi'an Shenghongchuang Instrumentation Co., Ltd. for targeted high-strength differential pressure sensor selection recommendations and supporting protection solutions.