What are the main parameters of the fan box? Air volume, external static pressure and power should be viewed in pairs
When looking at the fan box parameters, don’t just look at an air volume number. The air volume must be paired with the corresponding external static pressure and the input power of the whole machine. Otherwise, it cannot be judged whether the equipment can be used after it is installed in the system. Noise should also describe the measurement distance and working conditions. The interface size, power supply, and speed adjustment method also affect whether the project can be implemented.
Aili Industry is discussingWhen configuring the fan box , the first thing to check is the air volume under the specified external static pressure and the input power of the whole machine, and then look at the noise, power supply, size, interface and speed adjustment conditions.
Performance parameters must have common working conditions
The nominal maximum air volume is mostly obtained under specific test conditions and does not necessarily correspond to the external static pressure of the project. The selection table should contain at least three parameters: 'air volume, external static pressure, and machine input power' at the same time. If necessary, a performance curve should also be provided. The intersection of the fan performance curve and the system resistance curve is the expected operating point.
If you only write 'air volume 5000m³/h', it does not indicate the external static pressure under which this air volume is achieved, and this number has no engineering significance. The same Typhoon chassis may deliver 5000m³/h when connected to a short air duct, but may only deliver 3000m³/h when connected to a filter section and a long air duct. The difference is not in the fan, but in the system resistance.
The noise value should also indicate the measurement distance and operating conditions. The noise measured 1 meter away from the unit cannot be directly compared with the value measured 3 meters away. At different speeds, the noise will also change. When selecting, the supplier should be asked to indicate the test conditions instead of just giving a decibel number.
The 'wind pressure' in the parameter table needs to be clarified.
Some materials state full pressure, some state static pressure, and some manufacturers directly state that external static pressure can be used. The three cannot be replaced at will. Total pressure is the sum of static pressure and dynamic pressure; static pressure is the pressure of gas on the pipe wall; external static pressure is the pressure at the outlet of the fan box that can be used to overcome the resistance of the external pipeline.
When enquiring, the supplier should be asked to clarify the measurement boundaries and whether the pressure loss of the internal accessories of the unit has been deducted. What engineers ultimately want to use is the pressure that can still be supplied to the air duct after installation, rather than the isolated fan sample peak. If the parameter table says full pressure, but the system requires external static pressure, and there is still an outlet dynamic pressure difference between the two, the selection will be biased.
For systems with filter sections, it should also be clarified whether the external static pressure includes the initial or final resistance of the filter. System end configurationWhen using HEPA/ULPA high-efficiency filters , both the initial resistance and the resistance at the end of use should be included in the calculation of the working point. When the process requirements are higher, it can be evaluatedDoes the ULPA ultra-high efficiency filter meet the requirements?
The overall machine power and the motor power are not the same number
The rated power of the motor is used to define the continuous output capability of the motor itself under standard working conditions and is the upper limit of the motor's capability. The input power of the whole machine is the actual power consumption of the fan box under specific air volume, external static pressure and rotation speed, and includes the comprehensive result of motor loss, driver loss and fan aerodynamic efficiency.
The rated power of the motor of a wind turbine box may be 1.5kW, but under certain common operating conditions, the input power of the whole machine may be only 0.9kW because the motor is not running at the rated point. Conversely, if the system resistance is high and the fan operating point is far from the high efficiency area, the input power of the whole machine may be close to or even exceed expectations. When comparing energy consumption, the supplier should be required to provide the input power of the complete machine under the same air volume and external static pressure, and indicate the rotation speed, filter status and valve opening during the test.
Interface parameters will affect engineering construction
The length, width and height of the cabinet, the size and direction of the air inlet and outlet, flange specifications, equipment weight, power supply mode, control terminals and access surfaces should all be reflected in the drawings. Even if the performance of the two units is the same, as long as the access door faces the wall or the air outlet does not match, it may not be usable on site.
If the project adopts a DC speed regulation solution, the speed regulation signal type, driver installation location and heat dissipation conditions must also be confirmed. Clean room ceiling air supply is comparableFFU fan filter unit ; centralized management of multiple devices can be matchedFFU computer group control system . Protection of single process equipment can be consideredEquipment-side fan filter unit (EFU) . The final filtered air supply at the end of the air duct can beHigh-efficiency air supply outlet (HEPA BOX) . The division of labor between these equipment and the fan box should be clearly stated on the system flow chart.
One more resistance calculation for clean applications
If the system served by the fan box has a high-efficiency filter, the change in resistance of the filter section and the replacement path need to be considered. After the filter accumulates dust, the resistance rises, and the fan operating point moves to the direction of small air volume. If the terminal air volume is insufficient, the operator may increase the speed to compensate, resulting in increased energy consumption. When selecting the model, the working point should be calculated based on the pressure difference allowed before maintenance, rather than just the clean state.
Ai Li industrialThe fan box plan can discuss the fan, motor and box structure based on these parameters. It is not recommended to place an order based on the rated power or dimensions alone. Specific structure and configuration options can be found inIt is confirmed in the fan box product catalog that non-standard projects should provide equipment or machine room drawings, and then shape them based on the determined working points and on-site interfaces.
