Key Considerations for Selecting Differential Pressure Transmitters for Mining Applications

In mining environments, differential pressure measurement is commonly used for dust collector filter bag differential pressure, ventilation duct pressure loss, auxiliary assessment of material level in silos, differential pressure in enclosed spaces, and liquid level measurement. Compared with ordinary industrial sites, mining equipment is typically exposed to high dust levels, continuous vibration, fluctuating temperature and humidity, and electromagnetic interference. Focusing solely on measuring range or accuracy often cannot ensure long-term stable operation.

Selection should simultaneously take into account the measured object, installation location, medium characteristics, hazardous area classification, and maintenance conditions. Particularly in underground coal mines, coal powder conveying systems, coal preparation workshops, or areas containing flammable gases and dust, the explosion-protection type must match the hazardous media on site, zone classification, and complete equipment certification requirements. Ordinary ingress protection ratings must not be used as a substitute for explosion-protection requirements.

For quality control and safety management personnel, a suitable solution is generally not one with the highest possible specifications, but one that strikes a balance among safety compliance, measurement stability, maintenance convenience, and life-cycle cost. Before procurement, it is advisable to define the normal differential pressure, maximum possible overpressure, medium temperature, dust particle size, vibration source, and signal connection method.

First Confirm the Measurement Task and Range Limits

Dust collector filter bag differential pressure is typically a low differential pressure application, with common control ranges of 0–1 kPa, 0–2 kPa, 0–5 kPa, or 0–10 kPa. If the selected range is too large, the actual operating point will be concentrated in the lower portion of the range, reducing display resolution and control sensitivity. If the range is too small, start-stop impacts, blockages, or pulse-jet cleaning processes may cause overpressure damage.

Generally, the normal operating differential pressure can be set within 30%–70% of full scale, with a transient pressure margin of no less than 1.5 times. For applications involving fan outlets, long-distance air ducts, and impulse piping, static pressure, differential pressure, and allowable overpressure on one side should also be distinguished to avoid directly equating the differential pressure range with pressure resistance capability.

A 4–20 mA output signal is preferably used, as two-wire loops offer strong interference resistance and are suitable for long-distance transmission in mining areas. Where connection to an intelligent control system is required, communication methods such as RS485 may be selected according to the system protocol. Power supply, cable shielding, grounding method, and isolator barrier configuration should all be confirmed during the instrument selection stage.

Structural and Installation Design for High-Dust Environments

Dust Protection Cannot Be Judged by IP Rating Alone

IP65, IP66, or higher protection ratings mainly indicate the ability of an instrument enclosure to protect against solid foreign objects and water, but they do not directly indicate that impulse ports, fittings, and internal piping will remain free from dust accumulation. Once mine dust enters the pressure chamber or impulse piping, it may gradually form blockages, causing delayed or drifting instrument output, or even a persistently incorrect reading.

For dry dust, short impulse piping with a clear routing may be used, with pressure taps positioned away from areas directly impacted by material flow, and isolation valves and purging provisions installed where appropriate. For conditions involving wet dust, slurry splashing, or a high risk of condensation, diaphragm seals, remote-mounted structures, or anti-blocking pressure tapping components should be evaluated to reduce the likelihood of media entering the sensor chamber directly.

The instrument installation location should avoid material discharge points, belt transfer points, and high-pressure cleaning areas. Enclosure cable entries should use explosion-proof glands or sealing fittings of matching specifications, and unused cable entry holes must be reliably sealed. For outdoor or washdown areas, the effects of rainwater ingress, condensation, and corrosive gases on wiring terminals must also be considered.

The Impulse Pressure System Requires More Regular Inspection Than the Transmitter Body

When a differential pressure transmitter measures inaccurately, the fault is not necessarily in the sensor itself. Unequal impulse line lengths, different degrees of dust accumulation, and unbalanced condensate levels can all introduce additional differential pressure. In low differential pressure applications, even an additional error of several tens of pascals may affect filter bag blockage assessment or airflow calculation results.

It is recommended to reserve drainage, condensate discharge, and calibration connections during the design stage, enabling maintenance personnel to inspect the piping without repeatedly removing the main unit. For dust collection systems with frequent pulse-jet cleaning, the pressure impact at the moment of pulsing should be carefully checked, and damping measures should be used where necessary to reduce the effect of pulsation on measurement components.

Maintenance intervals may be established based on dust concentration and equipment operating schedules. In high-load areas, impulse line flow passage may be inspected every 1–3 months, while routine areas may be covered during quarterly inspections. Once abnormal output fluctuations, zero drift, or clear inconsistency with site operating conditions is found, pressure tapping points and piping should be checked first rather than directly replacing the instrument.

How to Ensure Signal Stability Under Strong Vibration Conditions

Coordinated Control Through Installation Rigidity, Connection Methods, and Electronic Design

Near crushers, vibrating screens, fans, pump units, and belt conveyors, long-term mechanical vibration may cause fittings to loosen, solder joints to fatigue, and wiring terminals to make poor contact. Differential pressure transmitters should not be mounted directly on frames with strong vibration sources. Relatively stable brackets, walls, or independent instrument racks should be prioritized, and the mounting surface must have sufficient rigidity.

Where the installation cannot be located away from the vibration source, vibration-damping mounting brackets, metal flexible hoses, or reasonably sized impulse connections may be used. However, vibration-damping measures must not cause piping to swing, wear, or accumulate liquid. After installation, threaded connections, flange fastenings, and cable securing conditions should be rechecked to prevent vibration from being continuously transmitted to the transmitter body through piping and cables.

For the sensor itself, attention should be given to vibration and shock resistance ratings, zero temperature drift, long-term stability, and circuit potting processes. For control loops, shielded cables should be used and kept at a reasonable distance from power cables. Analog signal cables should avoid long parallel runs with variable-frequency drive output cables to reduce signal fluctuations caused by electromagnetic interference.

The Explosion-Proof Rating Must Correspond to Mining Area Conditions

Distinguish Between Flammable Gases, Combustible Dust, and Underground Coal Mine Requirements

Explosion-proof selection must first be determined based on the hazardous area classification and hazardous media on site, rather than being broadly specified simply because the application is “mining.” In locations containing explosive gases such as methane, the appropriate type must be matched according to gas explosion group, temperature class, and zone classification. Where combustible dust such as coal dust or mineral powder is present, dust explosion-protection requirements and equipment surface temperature limits must also be assessed.

Different explosion-protection types, such as intrinsic safety and flameproof enclosure, have different requirements for power supply, wiring, maintenance, and associated equipment. Intrinsically safe systems generally need to form a complete loop with a safety barrier or isolator, and associated parameters such as voltage, current, inductance, and capacitance must be verified. For flameproof types, particular attention should be paid to ensuring that the enclosure, entries, plugs, and installation method comply with certificate requirements.

Underground coal mine equipment may also involve mine product safety marking and project access requirements. Purchasers should obtain explosion-proof certificates corresponding to the actual model, product nameplate information, operating instructions, and necessary mining qualification documents from suppliers. The site safety management department should confirm the applicable scope to avoid inconsistencies in certificate rating, model, or configuration.

Explosion-Proof Configuration Checklist

During acceptance, the explosion-protection marking, ambient temperature range, ingress protection rating, power supply parameters, and output type on the nameplate should be checked. Explosion-protection performance is the result of the complete installation system. Certification of the instrument itself does not mean requirements will still be met after arbitrary wiring, modification of cable entries, or replacement with non-matching components.

For intrinsically safe circuits, check the safety barrier installation location, grounding requirements, loop parameters, and field cable length. For flameproof circuits, inspect whether flameproof joints are intact, fasteners are complete, and unused openings are sealed with specified sealing components. Any unauthorized dismantling or modification may compromise the equipment's original explosion-protection integrity.

When establishing an instrument register, models, ranges, installation locations, explosion-protection markings, certificate numbers, calibration dates, and maintenance records may be centrally managed. It is recommended to conduct a condition inspection at least every 12 months in accordance with site procedures. When the process medium, area classification, or installation method changes, applicability must be reassessed.

Develop an Actionable Mining Differential Pressure Selection Checklist

Complete inquiry and technical confirmation documentation should include, at a minimum, the medium name, design differential pressure, maximum static pressure, normal and maximum temperatures, connection specifications, installation orientation, environmental dust conditions, vibration source, power supply conditions, output signal, and hazardous area information. The more complete the information, the better it can prevent rework after delivery due to incompatible connections, certification, or measuring range.

Xi'an Shenghongchuang Instrumentation Co., Ltd., supported by the manufacturing and technical capabilities of Shaanxi Qinkong Sensor Technology Co., Ltd., can provide selection support for differential pressure range, protective structure, signal output, installation connections, and operating-condition compatibility for mining dust collection, ventilation, conveying, and equipment integration applications. For special pressure ranges, non-standard fittings, or system integration requirements, targeted confirmation can be carried out based on site parameters.

Before project initiation, equipment modification, or spare part replacement, please prepare photographs of existing instrument nameplates, installation location information, and site operating condition parameters. Technical personnel should jointly verify explosion-proof applicability, dust protection solutions, vibration-resistant installation methods, and measurement range before determining the mining differential pressure transmitter configuration.