Demand for differential pressure gauges in Thang Long Industrial Park

Thang Long Industrial Park I is located in the Dong Anh area of Hanoi and accommodates a large concentration of manufacturers. Its tenant base includes companies involved in electronics, components, mechanical products, industrial equipment and supporting industries. Major manufacturers associated with the industrial park include Canon, Denso, Yamaha, HOYA and many Japanese manufacturing companies.

Factories operating cleanrooms, precision-assembly areas, dust-controlled rooms and central air-handling systems commonly need to monitor differential pressure.

A differential pressure gauge can be installed between two rooms, between a cleanroom and a corridor, upstream and downstream of a filter or between two locations in an air-distribution system.

The instrument helps operators identify changes associated with airflow, door conditions, filter resistance and HVAC balance. If the measuring range is unsuitable or the installation is incorrect, the gauge may operate but fail to provide a clear or representative reading.

Factories and cleanroom contractors in Thang Long Industrial Park should therefore select a supplier capable of reviewing the actual application rather than only supplying a product model.

What is a differential pressure gauge?

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

The displayed value is the difference between the two pressure levels. The instrument does not directly measure cleanliness, airborne particle concentration or airflow volume.

In cleanrooms, differential pressure gauges are commonly used to monitor pressure relationships between areas. In AHUs and filter housings, they are used to measure pressure loss across a filter.

The instrument may be a mechanical dial gauge or a digital gauge. Mechanical gauges provide local visual indication, while electronic instruments can display numerical values, activate alarms or transmit signals to a PLC or building-management system.

Why factories monitor differential pressure

Air tends to move from an area of higher pressure to an area of lower pressure. This principle is used to establish the intended airflow direction between rooms.

In product-protection applications, the cleaner room is commonly operated at a higher pressure than the adjacent space. When a door opens or leakage paths are present, air tends to move outward rather than allowing uncontrolled air to enter.

In areas where dust, chemicals or potentially hazardous substances must be contained, the room may be maintained at a lower pressure than the surrounding area.

The correct differential pressure should not be based on a single value applied to every project. It depends on the production process, cleanliness requirements, room tightness, number of doors, door-opening frequency, supply airflow, return airflow and contamination-control objectives.

The gauge enables operators to confirm that actual pressure remains within the intended range. It does not automatically regulate pressure unless it is connected to a controller, variable-speed drive or automation system.

Cleanroom pressure-monitoring applications

In factories within Thang Long Industrial Park, differential pressure gauges may be installed between a production room and a corridor, between a cleanroom and an airlock or between two areas with different cleanliness classifications.

The gauge should be positioned where operators can read it easily without exposing the pressure tap to direct supply airflow. The measuring point should represent room static pressure rather than high-velocity or turbulent airflow.

When the differential pressure falls below its limit, the facility should inspect door status, wall and door sealing, supply airflow, return airflow, dampers and fan operation.

When pressure rises unexpectedly, potential causes include restricted return airflow, closed dampers, increased supply volume or changes in door position.

The gauge provides only part of the operating information. Its reading should be interpreted together with HVAC status, airflow measurements and door conditions.

HEPA filter monitoring

Differential pressure gauges are commonly installed upstream and downstream of HEPA filters to monitor pressure loss.

As air passes through the filter media, the filter creates resistance. Dust accumulation may increase this resistance over time and change the differential-pressure reading.

Recording the initial pressure drop of a new filter is important. The value should be measured after correct installation, system stabilisation and normal airflow have been established.

During operation, new readings can be compared with the initial value and the recommended final pressure drop provided by the filter manufacturer. Trend monitoring is generally more useful than relying on one isolated reading.

A high reading does not automatically indicate a damaged filter. It may be caused by dust loading, increased airflow, blocked pressure tubing or unsuitable pressure-tapping locations.

A low reading does not prove that the filter remains effective. A torn filter, poor sealing or bypass airflow may reduce resistance while compromising particle-retention performance.

HEPA filter evaluation should therefore combine differential-pressure monitoring with integrity testing, leakage testing, airflow velocity and airflow-volume measurements.

AHU and HVAC applications

An air-handling unit commonly includes several filtration stages, such as prefilters, medium-efficiency filters and fine filters. Each stage has a different initial pressure drop and final replacement limit.

Differential pressure gauges help maintenance teams monitor dust loading on individual filter stages. As resistance increases, airflow may fall unless the fan system automatically compensates for pressure changes.

The same measuring range should not be used for every filtration stage. Prefilters, bag filters, fine filters and HEPA filters have different pressure-drop characteristics.

If the range is excessively high, pointer movement is limited and changes become difficult to observe. If it is too low, the pointer may exceed full scale or the instrument may be operated outside its intended range.

Pressure tubing should be firmly installed, leak-free, free from kinks and arranged to prevent condensation. The pressure taps should be positioned correctly upstream and downstream of the filter section being monitored.

Applications on cleanroom equipment

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

On a dynamic pass box, the gauge may monitor pressure loss across the filter or the pressure condition inside the chamber.

On dispensing booths and laminar airflow units, it is commonly used to monitor the condition of the HEPA filter. More advanced equipment may use an electronic transmitter for alarms or automatic fan-speed control.

Each equipment type has a different filter area, airflow volume, chamber configuration and pressure loss. The supplier should review the equipment design before recommending a gauge range.

Common measuring ranges

Low measuring ranges are generally preferred for cleanroom-pressure monitoring because they make small variations easier to observe. Common reference ranges include 0–30 Pa, 0–60 Pa, 0–100 Pa and 0–125 Pa.

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

For HEPA filters and clean-air equipment, ranges such as 0–250 Pa, 0–500 Pa, 0–750 Pa or 0–1,000 Pa may be considered, depending on design resistance.

For AHUs, the range should be selected according to the initial pressure drop, final pressure drop and operating airflow of each filtration stage.

The correct range is not necessarily the largest range available. It should cover the maximum expected pressure while still allowing operators to observe meaningful changes clearly.

Mechanical or digital differential pressure gauge

A mechanical differential pressure gauge is suitable where local visual indication is sufficient. It is relatively simple, easy to read and does not require an electrical supply for basic operation.

Mechanical gauges are commonly installed on cleanroom walls, AHUs, filter housings and clean-air equipment.

A digital gauge or transmitter is appropriate 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.

Where operators only need periodic local readings, a mechanical gauge may offer a practical and economical solution.

For critical points requiring continuous monitoring or deviation investigation, an electronic transmitter provides greater functionality. The total project cost should also include power supply, signal wiring, control-panel integration, programming and calibration.

How to select a supplier in Thang Long Industrial Park

Application-based technical advice

The supplier should determine whether the instrument is intended for room pressure, HEPA filter monitoring, AHU filtration or cleanroom equipment.

Each application has different operating conditions. Selecting a gauge only according to dial diameter or price can result in an unsuitable measuring range.

Understanding of cleanrooms and HVAC systems

Differential-pressure readings are affected by supply airflow, return airflow, room tightness, door status, dampers, fans and filter condition.

The supplier should understand these relationships to recommend the correct measuring range, pressure-tapping position and installation method.

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, documentation requirements and actual operating conditions.

Clear technical documentation

Project documentation may include catalogues, technical data sheets, installation instructions, certificates of origin, quality certificates and calibration certificates.

Contractors should agree on documentation requirements during the material-approval stage. This reduces the risk of supplying an instrument that is technically suitable but cannot be accepted because its documentation is incomplete.

Installation and troubleshooting support

Many incorrect readings are caused by reversed pressure ports, tubing leakage, blockage, condensation or unsuitable tapping locations rather than by instrument failure.

A competent supplier should provide connection guidance, zero-setting instructions and troubleshooting support when readings are unstable.

Coordinated supply capability

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

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

Calibration certificates and acceptance documentation

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

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

The calibration interval should be determined according to the criticality of the measuring point, quality-management requirements, manufacturer recommendations and historical instrument stability.

Not every gauge necessarily requires the same interval. A critical production-room measuring point may require stricter control than an instrument used only as a reference on a supporting utility.

Common installation mistakes

The most common mistake is reversing the high-pressure and low-pressure ports. The pointer may fail to rise or may move in the wrong direction.

Kinked, leaking or blocked tubing can also cause incorrect readings. In humid environments, condensation may accumulate in the tubing and create unstable indication.

Some mechanical gauges must be installed in the intended orientation. Incorrect mounting or an unstable surface may shift the zero point.

The pressure tap should not be positioned too close to a supply grille, fan or high-velocity airflow. Dynamic pressure in these areas may prevent the reading from representing room static pressure.

Pre-commissioning checks

Before commissioning, the project team should verify the model, measuring range, engineering unit, mounting location and pressure-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 differential-pressure value.

For electronic instruments, the power supply, output signal, alarm thresholds, display and PLC or building-management-system connection should also be tested.

A calibrated instrument can still provide an incorrect field reading if pressure tubing is leaking, blocked or connected incorrectly. Acceptance testing should therefore evaluate the complete measuring loop.

Frequently asked questions

Where can factories in Thang Long Industrial Park buy differential pressure gauges?

Factories should choose a supplier with cleanroom and HVAC experience that can recommend the correct range, installation method, connection accessories and calibration documentation.

Can a room-pressure gauge be used to monitor a HEPA filter?

Only when its measuring range and pressure limit are suitable. In practice, room-pressure gauges usually have a lower range than gauges used across HEPA filters.

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

Not necessarily. Both pressure ports should be equalised, and the tubing, condensation, mounting position and zero-setting mechanism should be checked before replacement.

How often should a differential pressure gauge be calibrated?

The interval depends on the measuring point’s criticality, the quality-management system and the historical stability of the instrument. The frequency should be based on risk rather than automatically applying the same interval to every gauge.

Can a differential pressure gauge confirm cleanroom classification?

No. It only measures pressure difference. Cleanroom classification must be determined through airborne particle counting and other applicable environmental tests.

Differential pressure gauge consultation for Thang Long Industrial Park

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

Vietnam Cleanroom Equipment supplies differential pressure gauges for cleanrooms, AHUs, HVAC systems, HEPA filters, pass boxes, dispensing booths and other controlled-air equipment in Thang Long Industrial Park.

Defining the application correctly from the beginning helps select the appropriate model, reduces changes during installation and improves project acceptance.