Demand for differential pressure gauges in VSIP Bac Ninh

VSIP Bac Ninh Industrial Park accommodates manufacturers operating in electronics, components, precision engineering, industrial equipment, food processing, pharmaceuticals, cosmetics and supporting industries. These factories increasingly require stable production environments, controlled airflow and reliable monitoring of pressure, dust, temperature and humidity.

In cleanrooms and controlled manufacturing areas, differential pressure gauges measure the pressure difference between two locations. They can be installed between rooms, between a cleanroom and a corridor, across a filter or on clean-air equipment.

Maintaining and monitoring the correct pressure differential helps control airflow direction, reduce contamination risks and identify changes in HVAC performance.

For cleanroom contractors, selecting the correct gauge during the design stage reduces the risk of replacement during commissioning. A product may have the correct appearance and dimensions but still be unsuitable if its range, accuracy or documentation does not meet project requirements.

What is a differential pressure gauge?

A differential pressure gauge measures the difference in pressure between two points. It normally has a high-pressure port and a low-pressure port connected to the measuring locations through pressure tubing.

The displayed value is the difference between the two pressure levels rather than the absolute pressure at one point. This makes the instrument suitable for room-pressure monitoring, filter-resistance indication and HVAC system evaluation.

Differential pressure gauges are available as mechanical dial gauges and digital instruments. A digital gauge or transmitter may also send data to a PLC, building-management system or environmental-monitoring system.

Why factories monitor differential pressure

Differential pressure is an important parameter for controlling airflow direction. Air naturally tends to move from a higher-pressure area to a lower-pressure area.

In product-protection cleanrooms, the cleaner area is often maintained at a higher pressure than the adjacent space to reduce the entry of uncontrolled air.

In containment areas involving dust, chemicals or hazardous substances, negative pressure may be applied to keep contaminants inside the controlled room.

The required pressure differential depends on the process, room classification, enclosure tightness, number of doors, door-opening frequency, supply airflow, return airflow and contamination-control strategy.

The gauge allows operators to verify that the room remains within the intended pressure condition. However, the instrument only measures and displays pressure. It does not regulate the room unless integrated into an automatic control system.

Cleanroom pressure monitoring

In factories located in VSIP Bac Ninh, gauges may be installed between a cleanroom and a corridor, between rooms with different cleanliness levels or between a manufacturing room and an airlock.

The installation position should allow operators to read the gauge without affecting the cleanroom wall construction. Mechanical gauges are commonly flush-mounted on cleanroom panels or installed on equipment surfaces.

Where alarms and data recording are required, an electronic differential pressure sensor may be used instead of, or together with, a local display.

A falling pressure differential may be associated with an open door, poor door sealing, reduced supply airflow, fan-performance deterioration, damper changes or an imbalance in return airflow.

An abnormally high differential may be caused by changes in door position, restricted return airflow, damper closure or increased supply airflow.

Pressure readings should therefore be assessed together with the actual HVAC operating condition.

HEPA filter monitoring

Differential pressure gauges are commonly installed upstream and downstream of HEPA filters to monitor resistance during operation.

As air passes through the filter media, a pressure drop is created. Dust accumulation may gradually increase this resistance.

Monitoring the pressure trend helps maintenance personnel plan inspections and filter replacement. However, filter condition should not be determined from a single pressure reading alone.

A high differential pressure may indicate dust loading, but it can also result from increased airflow, blocked tubing or unsuitable tapping points.

A low reading does not prove that the filter is in good condition. A damaged filter, poor sealing or bypass airflow may reduce resistance while compromising particle-control performance.

HEPA filter evaluation should combine differential pressure with integrity testing, leakage testing, airflow velocity, airflow volume and other applicable qualification tests.

AHU and HVAC applications

Air-handling units commonly contain several filtration stages, including prefilters, medium-efficiency filters and fine filters. Each stage has a different pressure-drop characteristic and may require a separate gauge range.

A range that is too high makes small resistance changes difficult to observe. A range that is too low may cause the pointer to exceed full scale or expose the instrument to unsuitable pressure.

Pressure taps must be installed upstream and downstream of the intended filter section. Tubing should be secured, leak-free, free from kinks and arranged to avoid water accumulation.

After installing a new filter and stabilising the system at normal airflow, the initial pressure drop should be recorded. This value becomes an important reference for monitoring filter loading over time.

Cleanroom-equipment applications

Differential pressure gauges are also installed on dynamic pass boxes, air showers, laminar airflow units, dispensing booths, sampling booths, biosafety cabinets, HEPA filter boxes and standalone filtration modules.

On a dynamic pass box, the gauge may monitor filter resistance or chamber pressure.

On dispensing booths and laminar airflow units, it commonly indicates the pressure drop across the HEPA filter.

On AHUs and terminal filter housings, it helps operators observe changes in filter resistance.

Each equipment type has a different airflow rate, filter area, chamber design and operating resistance. A supplier should understand the equipment principle before recommending a specific model.

Common measuring ranges

Low ranges are generally preferred for cleanroom-pressure monitoring because they allow small variations to be observed more clearly. Common options may include 0–30 Pa, 0–60 Pa, 0–100 Pa and 0–125 Pa.

For areas that may operate under both positive and negative pressure, bidirectional ranges such as -30 to +30 Pa or -60 to +60 Pa may be used.

For HEPA filters, dispensing booths, laminar airflow units and filtration modules, ranges such as 0–250 Pa, 0–500 Pa, 0–750 Pa or 0–1,000 Pa may be considered.

For AHU filters, the range should be selected using the initial pressure drop, recommended final pressure drop and actual operating airflow.

The best range is not the largest available range. It should cover the maximum expected pressure while still allowing operators to identify meaningful changes.

Mechanical or digital gauge

A mechanical dial gauge is suitable where local observation is sufficient. It is simple, easy to read and does not need an electrical supply for basic indication.

A digital gauge or transmitter is more suitable where alarms, data recording or signal transmission are required. Depending on the model, outputs may include 4–20 mA, 0–10 V, relay contacts or communication protocols.

If operators only need to check the value periodically, a mechanical gauge may provide a practical and economical solution.

If the measuring point is critical and requires continuous trending or deviation investigation, an electronic transmitter provides greater functionality.

Digital instruments also require a power supply, signal wiring, control integration, calibration and maintenance. These costs should be considered during project budgeting.

How to select a supplier in VSIP Bac Ninh

Application-based technical selection

The supplier should confirm whether the gauge will be used for room pressure, a HEPA filter, an AHU or cleanroom equipment.

The expected operating pressure, maximum pressure, required resolution, display type and installation conditions should be reviewed before selecting a model.

Understanding of cleanrooms and HVAC systems

A differential pressure gauge does not operate independently from the system. Its reading is affected by airflow, room tightness, doors, dampers, fans and filter condition.

The supplier should understand these relationships to avoid recommending an unsuitable measuring range or installation position.

Vietnam Cleanroom Equipment, also known as VCR Cleanroom, supplies differential pressure gauges and cleanroom equipment to cleanroom contractors, MEP companies, system integrators and industrial factories. Product selection is based on the application, technical requirements and actual operating conditions.

Clear technical documentation

Required documents may include product catalogues, technical data sheets, installation instructions, certificates of origin, quality certificates and calibration certificates.

Documentation requirements should be agreed during the material-approval stage, particularly for projects operating under strict quality-management requirements.

Installation and troubleshooting support

Many incorrect readings are caused by tubing, pressure taps or installation rather than the gauge itself.

An experienced supplier should support identification of the high- and low-pressure ports, zero adjustment and troubleshooting when readings are unstable.

Coordinated cleanroom-equipment supply

For cleanroom projects, sourcing gauges together with HEPA filter boxes, pass boxes, laminar airflow equipment, door interlocks and related equipment can reduce technical coordination risks.

It also helps contractors coordinate drawings, technical submissions, delivery and after-sales support.

Calibration-document considerations

A calibration certificate should clearly identify the instrument, model, serial number, measuring range, calibration points, errors and test conditions.

A quality certificate or factory inspection report does not fully replace an individual calibration certificate.

For critical measuring points, the calibration interval should be determined according to risk, internal procedures, manufacturer recommendations and historical instrument stability.

Not every gauge needs the same calibration interval. A critical production-room measuring point may require tighter control than a gauge used only for reference on a utility system.

Common installation mistakes

The first common error is reversing the high-pressure and low-pressure ports. The pointer may fail to rise or may indicate in the wrong direction.

The second error is kinked, leaking or blocked pressure tubing, which prevents the pressure signal from reaching the instrument correctly.

The third error is placing a pressure tap too close to a supply grille or high-velocity airflow. Dynamic pressure may affect the result and prevent it from representing room static pressure.

The fourth error is allowing condensation to accumulate in the tubing, which can cause unstable or incorrect readings.

The fifth error is installing the gauge in an unsuitable orientation or failing to check zero before operation.

Pre-commissioning checks

Before commissioning, the project team should verify the model, measuring range, engineering unit, installation location and port connections.

When both ports are exposed to equal pressure, the gauge should return to zero within its allowable tolerance.

The system should then be operated to confirm pointer direction and the actual pressure differential.

For digital instruments, the power supply, output signal, alarms, display and connection to the PLC or building-management system should also be tested.

A calibrated instrument can still provide an incorrect field reading if the tubing leaks, becomes blocked or is connected to unsuitable pressure taps. Commissioning should therefore evaluate the complete measuring loop.

Frequently asked questions

Where can factories in VSIP Bac Ninh buy differential pressure gauges?

Factories should select a supplier with practical cleanroom and HVAC experience that can recommend the measuring range, installation method, calibration documentation and accessories.

Can the same gauge be used for room pressure and HEPA filters?

Only when its measuring range is suitable for both applications. In practice, room-pressure gauges normally have a much lower range than gauges used across filters.

Is a gauge defective if it does not return to zero?

Not necessarily. The pressure on both ports should first be equalised, and the tubing, mounting position, zero adjustment and mechanical movement should be checked.

Can a differential pressure gauge measure cleanroom cleanliness?

No. It only measures the pressure difference between two points. Cleanliness must be determined by airborne particle counting and other applicable environmental tests.

When should a digital gauge be selected?

A digital gauge is appropriate when alarms, signal transmission, data recording or continuous monitoring are required. A mechanical gauge may be more suitable where only local indication is needed.

Differential pressure gauge consultation for VSIP Bac Ninh

When requesting a quotation, factories and contractors should provide the installation location, expected pressure range, display type, output signal, quantity and documentation requirements.

Vietnam Cleanroom Equipment supplies differential pressure gauges for cleanrooms, AHUs, HVAC systems, HEPA filters, pass boxes, dispensing booths and clean-air equipment in VSIP Bac Ninh Industrial Park.

Defining the requirement accurately from the beginning helps select the correct model, reduces changes during installation and improves project acceptance.