The detection of air volume in central air conditioning ducts can be fully achieved through the use of air pressure transmitters. Differential pressure serves as a reliable data basis for converting real-time air volume. The Longlv PTL802S digital display air differential pressure transmitter comes with an on-site display, catering to both precise measurement of micro-differential pressure and building automation linkage requirements. It is suitable for various central air conditioning duct conditions in shopping malls, office buildings, and factories. It not only enables online real-time conversion of air volume but also synchronizes monitoring of filter blockage faults. It serves as a supporting monitoring instrument for intelligent and energy-saving operation and maintenance of central air conditioning systems.

1、 Why can a transmitter detect the airflow in a duct based on the correspondence between wind pressure and airflow

When the airflow inside the supply and return air ducts of central air conditioning is flowing, a stable pressure difference will be formed in the front and rear of the air duct, the air valve or the air volume detection section under the premise of fixed duct section and air speed. There is a corresponding pattern between air volume and pressure difference: the larger the air volume, the higher the pressure difference caused by air flow resistance; When the filter screen accumulates dust, the air duct is blocked, and the air valve opening is insufficient, the pressure difference will change synchronously.

By relying on a wind pressure transmitter to collect real-time values of air duct pressure difference, combined with the unit control system conversion, real-time air volume can be obtained. It can not only determine whether the current air supply volume meets the standard, but also synchronously monitor problems such as filter blockage, abnormal air duct resistance, and insufficient fan output. It can be fully used as the core instrument for online monitoring of air duct volume in central air conditioning.

The traditional method of estimating air volume solely based on the rated parameters of the fan has a huge error. Manual handheld instruments can only perform periodic sampling to measure air volume, and cannot be monitored 24/7. On the other hand, wind pressure transmitters can continuously collect data 24 hours a day, achieving digital control of air volume.

2、 Difficulties in monitoring the working conditions of central air conditioning ducts

The central air conditioning duct belongs to a typical micro pressure difference working condition, and the normal operating pressure difference value is relatively small; Continuous vibration of the fan in the computer room and turbulent flow in the air duct bends can easily cause fluctuations in wind pressure values; Dust and flocculent substances accumulate in the air duct all year round, and the pressure inlet is prone to clogging; The maintenance space for some ceiling ducts is narrow, making it inconvenient to check the values on site. There are special requirements for the display, stability, and installation adaptability of the transmitter.

3、 Advantages of using Longlv PTL802S digital differential pressure transmitter for central air conditioning air volume monitoring

Equipped with local digital display, on-site reading is intuitive and convenient

Different from ordinary non display transmitters, this device integrates a local display screen and can directly read real-time pressure difference without going to the central control room. It can be installed in the ceiling machine room or next to the air conditioning unit. Operation and maintenance inspections do not require carrying detection tools, and can quickly determine the air volume and filter blockage situation. It is suitable for distributed air duct point monitoring of central air conditioning.

Accurate measurement of micro pressure difference and small error in air volume conversion

For the optimization and calibration of low-pressure air ducts in central air conditioning, even slight pressure differences can be clearly identified, and the converted air volume data is in line with actual working conditions. The air volume attenuation caused by slight filter dust accumulation can be captured in advance to avoid insufficient air supply and imbalanced indoor temperature control.

Equipped with signal filtering to suppress airflow fluctuations in the air duct

The airflow pulse vibration generated by the operation of the fan and the adjustment of the air door will be filtered by an internal filtering mechanism, and the pressure difference reading will be stable without jumping. The central control system will convert the air volume curve smoothly, and there will be no frequent fluctuations or false alarms in the air volume value.

Suitable for dusty environments with air conditioning, easy to maintain

The whole machine has a compact structure, and the pressure interface is not easily clogged with dust. With a simple blowing structure, it can clean the dust in the pipeline; The body protection adapts to changes in temperature and humidity in the computer room, and long-term installation in suspended ceilings and air conditioning rooms is less likely to cause zero drift, reducing the frequency of regular calibration.

Dual signal adaptation air conditioning automatic control system

Output standard universal signals, which can be directly connected to central air conditioning DDC and PLC building automation systems, allowing real-time monitoring of pressure difference on the local screen while synchronously uploading data to the building monitoring platform. The system converts air volume based on pressure difference, sets two-level warnings for insufficient air volume and clogged filter screen, and links the fan frequency conversion to adjust the speed, achieving energy-saving operation of the air conditioner.

Flexible installation to adapt to narrow ceiling spaces

The body is compact in size and supports various methods such as wall mounting and side installation of air ducts. It can be installed in narrow positions on the ceiling interlayer and unit side. The renovation of new and old central air conditioning projects does not require extensive disassembly and assembly of air ducts, making construction simple and time-saving.

4、 Implementation Plan for Complete Monitoring of Air Volume in Central Air Conditioning Ducts

Layout of monitoring points

Install transmitters in the main return air duct section of the central air conditioning system, at both ends of the unit filter, and in the branch air volume detection section. The high and low pressure taps should avoid bends and fan outlet vortex areas to ensure uniform pressure transmission and accurate air volume conversion.

Wind volume logic and warning settings

The system establishes a pressure difference air volume conversion model based on the specifications of the air duct:

First level reminder: The pressure difference slightly increases, the air volume slightly decreases, and the filter screen begins to accumulate dust. Arrange for regular cleaning;

Level 2 alarm: The pressure difference significantly exceeds the standard, the air volume is seriously insufficient, and an alarm reminder is pushed to clean the filter screen and repair the fan in a timely manner to ensure the indoor cooling and heating effect.

Energy saving value of operation and maintenance

Through real-time air volume monitoring, avoid long-term ineffective operation of the fan at full load, adjust the fan frequency as needed, and reduce the energy consumption of central air conditioning; There is no need to manually inspect the air volume section by section on a regular basis, reducing the cost of manual operation and maintenance, and avoiding the problem of high load on air conditioning units and increased equipment loss caused by insufficient air volume in advance.