What should I do if the residual pressure of the ULPA fan is insufficient?

Insufficient residual pressure usually manifests itself as: the air volume cannot be adjusted up, the fan is already running at high speed but the pressure difference is still insufficient, or the air volume gradually decreases after running for a period of time.

In this case, don't rush to change the fan, and don't directly increase the speed. The reason for insufficient residual pressure may be the system pressure loss, the fan selection, or the filter element resistance exceeding expectations. Depending on the direction, the approach is very different.

First locate the cause clearly, and then decide whether to adjust the speed, change the filter element or turn the fan. For specific calibration methods, please refer to the relevant instructions for calibrating the fan residual pressure according to the final resistance.

First check the design input and measured pressure loss

To judge whether the residual pressure is insufficient, the premise is to know 'how much is needed' and 'how much is there now'.

Are there any problems with design input? Are the air volume, system pressure loss, and filter element resistance used in the original design consistent with the current actual operating conditions? If the equipment has been modified, the pipeline has been adjusted, or the filter element model has been changed, the design input may be outdated.

Whether the measured pressure loss exceeds expectations. Measure the actual pressure difference in each section of the system - filter element, pre-filter, air duct, box, and terminal. Whichever segment is higher than expected is the problem. If the filter element resistance is normal, but the pressure loss in the air duct or box far exceeds the design value, the root cause of the insufficient residual pressure may be the system rather than the fan.

What is the actual output of the fan. What are the air volume and static pressure at the current speed? Compare the fan curve to confirm whether the fan is already operating at the capacity boundary. If the fan still has reserve but is not exerting its power, it may be a problem with the control settings or pipeline resistance, not necessarily a deficiency in the fan itself.

Only by checking these three items clearly can you determine whether the insufficient residual pressure is a system problem, a filter element problem, or a fan problem. involving HEPA/ULPA air filter items , the pressure loss decomposition method is the same. For

Processing direction one: speed adjustment

If the fan still has room for speed adjustment, increasing the speed is the most direct way.

Provided the motor and controller allow it. As the speed increases, current, power, noise and vibration will all change. It is necessary to confirm the allowable range of motor specifications, driver output and control system. Operating beyond the design range may affect the life of the motor and may also trigger protection.

Pay attention to changes in energy consumption and noise. As the rotational speed increases, the energy consumption increases and the noise also increases. If the equipment has requirements for noise or runs for a long time, this account must be calculated in advance. For specific energy consumption calculation methods, please refer to the relevant instructions on operating energy consumption.

Speed ​​adjustment is a short-term remedy, not a long-term solution. If the residual pressure is insufficient because the filter element resistance exceeds expectations or the system pressure loss is high, relying on speed regulation to compensate will only push the problem back. When the filter element accumulates dust during operation, the rotation speed may have reached its peak, but the air volume will still drop.

Supporting For the FFU fan filter unit system, speed adjustment is relatively straightforward. Device-side applications such as The EFU equipment-side fan filter unit has a compact internal space, a small range of fan options, and limited room for speed adjustment.

Processing direction two: Optimize filter elements and channels

If the fan is already at the capacity boundary, or speed adjustment is not feasible, you can start by reducing system resistance.

Choose a low-resistance filter model. On the premise of meeting the filtration grade and sealing requirements, choose a ULPA structure with a larger effective filtration area, or a model with lower resistance in the same size. The premise is that the interface and installation conditions match, and you cannot just look at resistance as an indicator.

Expand filter area. If the installation space allows, use a larger size filter element. When the wind speed is reduced at the same air volume, the resistance will naturally decrease. This solution does not sacrifice the filtering effect, but requires installation space support. For the specific relationship between surface wind speed and service life, please refer to the relevant instructions.

Optimize system channels. Check the air inlets, air outlets, air duct elbows and valves to see if there is any space where the resistance can be reduced. Restricted inlets, blocked air ducts, or improperly designed plenums may affect the operating point more than the filter element. This type of change usually does not require replacement of parts, but requires the cooperation of the equipment.

Optimize front-end protection. If the resistance of the pre-filtration section is high, replacing or adjusting the front-stage filter can also reduce the total resistance of the system. For specific configuration, please refer to the instructions related to pre-filtering.

Processing direction three: adjust the fan

If neither of the first two directions can solve the problem, consider moving the fan.

First analyze where the bottleneck is. Is it because the fan static pressure is not enough or the air volume is not enough? The two are handled differently. Simply replacing the motor does not necessarily increase the effective air supply pressure - the aerodynamic characteristics of the fan are determined by the impeller and volute, and the motor only provides power. If the impeller design itself has insufficient static pressure, the effect of replacing the motor will be limited.

The selection should match the system. The PQ curve of the new fan must cover the entire working range from initial resistance to final resistance, and have a reasonable margin near the design air volume. You cannot select a model based only on a certain working condition point.

The installation conditions need to be confirmed. The size, interface, power supply and control method of the new fan must be compatible with the original system. The device-side application also needs to confirm whether the internal space can accommodate it.

Debugging after replacement cannot be spared. After the new fan is installed, the air volume, pressure difference and noise must be measured again to confirm that the working point is within a reasonable range. Relevant records are updated to the maintenance ledger. involving ULPA ultra high efficiency filter or When selecting a HEPA high-efficiency filter , it is recommended to check the fan parameters together.

Project judgment example

When the ULPA system of a certain equipment is running, the air volume is always low, and the fan speed is close to the upper limit, but the air volume still does not reach the design value.

Troubleshooting process: First measure the pressure loss of each section. The filter element pressure difference is normal and the pre-filtration pressure difference is normal, but the pressure loss in the air duct inside the equipment is about 40% higher than the design value. Further inspection revealed that a section of the air duct inside the equipment was partially blocked by the cable tray during renovation, and the effective ventilation area was reduced.

Treatment method: Adjust the position of the cable tray and restore the ventilation area of ​​the air duct. After adjustment, the total resistance of the system decreased, the air volume returned to the design range, and the fan speed also returned to normal levels.

The key point in this case is: insufficient residual pressure does not necessarily lie in the fan or filter element. Additional resistance somewhere in the system may also make the fan appear 'underpowered.' Decompose and measure the pressure loss first, and then decide on the treatment direction.

Selection and Acceptance Checklist

About Aili Industrial’s system matching package

The solution to insufficient residual pressure is often not a problem of a single component, but a problem of system matching. Fans, filters, air ducts and control systems need to be checked under the same working conditions.

Aili Industrial has independent manufacturing capabilities in fans, motors, control systems and filters. When doing ULPA projects, the filter element resistance curve, system pressure loss and fan PQ curve can be evaluated together. When air supply equipment such as FFU and EFU are matched with filters in the same system, the matching of filter element resistance and fan operating point can be confirmed during the planning stage. For renovation projects with insufficient residual pressure, you can also combine the original system parameters and new filter element specifications to check whether it is necessary to adjust the fan, replace the low-resistance filter element, or optimize the system channel.

When enquiring, provide the design air volume, measured pressure loss, existing fan parameters and installation space to help confirm the appropriate treatment plan. The specific configuration is subject to the technical documents and test results confirmed by the project.