What Key Points Should Be Focused on When Using Pressure Transmitters in Boiler Systems

Boiler systems may appear to be conventional equipment, but their actual operating conditions are far from mild. High temperatures, vibration, steam condensation, and start-stop impacts can all affect pressure measurement results. If a pressure transmitter is selected incorrectly, the consequences may range from data drift to false interlock activation.

Therefore, when using pressure transmitters in boiler systems, it is not enough to consider only the measuring range and price. More important factors include the medium characteristics, installation location, temperature resistance, sealing method, and ease of subsequent maintenance. These details often determine whether on-site operation is trouble-free.

In practical applications, boiler feedwater, steam pipelines, steam drums, water tanks, and auxiliary equipment circuits do not have exactly the same requirements for pressure transmitters. If the selection approach is applied uniformly, the subsequent failure rate is usually higher.

Understand the Operating Conditions Before Selecting a Pressure Transmitter

The first step in selecting a pressure transmitter for a boiler system is not choosing a brand, but clarifying the operating conditions. It is necessary to first confirm whether the medium is steam, hot water, or heat transfer fluid; whether the pressure is stable or pulsating; and whether the temperature is continuously high or subject to periodic shocks.

The measuring range should have sufficient margin, but it should not be excessively large. If the range is too small, overpressure damage may occur easily. If it is too large, resolution in the low-pressure range will deteriorate, and the control signal will not be sufficiently precise. A common practice is to ensure that the normal operating pressure falls between one-third and two-thirds of the measuring range.

If water hammer, pump start-stop impacts, or instantaneous valve opening and closing occur on site, the pressure transmitter's overload capacity must also be considered. Many failures are not caused by long-term overpressure, but by instantaneous impact damaging the sensitive element.

• For steam pressure measurement, focus on temperature resistance and condensation protection.
• For feedwater pressure measurement, focus on pulsation and vibration resistance.
• For chemical solutions or media containing impurities, focus on diaphragm material and clogging resistance.
• For interlock control points, focus on long-term stability and signal reliability.

When the Medium Temperature Is High, a Pressure Transmitter Cannot Be Installed Directly

The most easily overlooked issue in boiler systems is temperature. Many pressure transmitters provide good accuracy at room temperature, but after being connected to a high-temperature steam pipeline, their zero point may drift rapidly, or even trigger false distortion alarms. This does not necessarily mean that the product itself has a problem; the installation method may simply be unsuitable.

When measuring steam pressure, a condensation loop or impulse tube is typically used to reduce the temperature, allowing the medium to cool before entering the pressure transmitter. This protects the sensitive core, delays aging, and reduces the impact of high temperature on the output signal.

If the on-site temperature remains high for long periods, the ambient temperature range of the housing and electronic components must also be confirmed. Many failure points are not at the pressure connection, but in the wiring chamber and circuit section. This issue is particularly apparent when the equipment room temperature is high in summer.

Several Practical Temperature-Related Checks

1. For steam measurement points, give priority to installing a condensation loop.
2. If the area near the connection is too hot to touch, direct installation is generally unsuitable.
3. When temperature fluctuations are significant, check the temperature drift specification.
4. In high-temperature areas, wiring should be routed away from heat radiation sources.

Only When the Installation Location Is Correct Can Pressure Transmitter Data Remain Stable

In a boiler system, the same pressure transmitter may show completely different readings when installed in different locations. Pulsation is stronger near the pump outlet. Local disturbances are greater near elbows, valves, and reducing sections. If the measurement point is poorly selected, it is difficult to compensate for the problem through later commissioning.

A more reliable approach is to install the pressure transmitter in a location where the medium flow is relatively stable, maintenance is convenient, and the unit is away from high-temperature and strong-vibration sources. This can improve data reliability while reducing the risk associated with disassembly and reinstallation.

In addition, the length of the impulse tube should not be determined solely by on-site convenience. If it is too long, the response will become slower. If it is too short, there will be insufficient space for heat dissipation. For steam pressure measurement points, consistent condensate-column conditions should also be maintained as much as possible to avoid measurement deviations.

Material, Sealing, and Signal Output Directly Affect the Subsequent Failure Rate

When using pressure transmitters in boiler systems, the wetted material must not be overlooked. For ordinary clean-water conditions, conventional stainless steel materials are generally sufficient. If the medium contains chemicals, impurities, or corrosive components, the diaphragm and connection materials must be rechecked to avoid pitting corrosion and leakage later.

The sealing method is also critical. Threaded connections must match the applicable on-site standard, and the sealing surface must be intact. Excessive wrapping tape should not be used to compensate for machining errors. Many leakage problems are not caused by the pressure transmitter itself, but by non-standard installation interfaces.

In terms of signal output, 4-20mA is common in boiler systems, while some applications connect to digital display instruments or control systems. In such cases, attention should be paid to the power supply, cable length, interference resistance, and grounding method. When on-site interference is significant, occasional signal fluctuations are not uncommon.

On-Site Inspection Can Follow These Items

• Check the connection thread, measuring range, power supply, and output.
• Inspect the sealing surface for scratches and burrs.
• Confirm that the cable routing is away from power cables.
• After wiring is completed, perform no-load and pressurized observation.

Do Not Focus Only on Accuracy; Long-Term Stability Matters More

Boiler systems have long operating cycles, and load changes can be significant when start-stop operations are frequent. In this scenario, the long-term stability of a pressure transmitter is often more valuable than laboratory accuracy specifications. Being accurate at initial installation does not mean it will remain accurate six months later.

If the pressure signal participates in interlocking, alarm, or automatic adjustment, even greater attention should be paid to zero drift, repeatability, and impact resistance. Short-term errors may only cause display deviations, while long-term drift can gradually distort combustion control, water-level coordination, and protection logic.

In practical operations, stable and reliable pressure transmitters can reduce false shutdowns and the frequency of manual verification, while also facilitating equipment management. For continuously operating environments such as boiler rooms, this is more valuable than specifications on paper.

Proper Daily Maintenance Helps Prevent Pressure Transmitter Problems

Installing a pressure transmitter does not mean that the work is finished. Boiler systems have complex operating conditions, so inspections should be made a routine task. For example, check whether the wiring is loose, whether the impulse tube is blocked, whether the connection is leaking, and whether the displayed value is fluctuating abnormally.

If the pressure transmitter reading fluctuates sharply, do not immediately conclude that the product is damaged. First check changes in valve opening, pump operating conditions, air accumulation in the pipeline, the condensate condition, and grounding issues. Many on-site failures actually result from changes in peripheral conditions.

Regular calibration is also necessary. For critical measurement points in particular, comparative inspections should be scheduled alongside planned shutdowns. Addressing faults at an early stage costs far less than waiting for an interlock alarm and then shutting down the boiler for corrective action.

Selecting the Right Pressure Transmitter Helps Ensure More Stable Boiler System Operation

In summary, when using pressure transmitters in boiler systems, the key is not to consider a single parameter, but to comprehensively assess the measuring range, temperature, medium, installation method, material, and stability. Only when every aspect is handled correctly can on-site operation remain stable.

Xi'an Shenghongchuang Instrumentation Co., Ltd. has long focused on the development and production of pressure sensors, pressure transmitters, and various industrial measurement and control products. For complex operating conditions such as boiler systems, the company places greater emphasis on product compatibility and performance in field applications.

If a boiler system is undergoing new installation, modification, or fault replacement, first clarify the conditions at the measurement point and the control requirements, and then match them with a suitable pressure transmitter. This generally helps avoid many unnecessary detours and is also more conducive to stable operation in the future.