Why can't we configure the equipment accurately if we only give the cleanliness level?

In the procurement and selection of clean equipment, a situation often occurs: users only provide one cleanliness level, such as 'We want level 100' or 'ISO 5', and then hope that the supplier will directly provide equipment and quotations. However, the cleanliness level is only a target description, which does not include information such as area size, air flow pattern, pollution load, installation space and system resistance.

At the same level, the equipment configurations required in different scenarios may be completely different. With only one grade number, the supplier can only quote based on assumptions, and it is easy for configuration discrepancies or acceptance disputes to arise in the future.

The level only describes the concentration target and does not describe the conditions for achieving it.

Cleanliness levels describe the concentration of air particles in a specified area, specified particle size, and occupancy conditions. It is an outcome metric, not a device configuration scenario.

Level not specified:

• Area and boundaries of the region;

• Use unidirectional flow or non-unidirectional flow;

• where the pollution load comes from;

• Movement of personnel, materials and equipment;

• Installation space and maintenance conditions.

These conditions determine how much air supply, how much equipment, what level of filtration and how large a system is needed. The level is the same, but the implementation may be very different. The cleanliness level must indicate the particle size and state. For specific reasons, please refer to Why must the particle size be indicated in the cleanliness grade?。

The area and airflow pattern determine the air supply volume

For an area of ​​the same area, the calculation method of air supply volume is different whether it adopts unidirectional flow or non-unidirectional flow. Unidirectional flow areas are usually estimated based on effective air supply area and target wind speed; non-unidirectional flow areas are usually estimated based on volume and air exchange demand.

Only by giving the grade, it is impossible to determine which air flow form is used, and therefore the air supply volume cannot be calculated. For the relationship between area and air supply demand, please refer to How to convert the clean area area into air supply demand? , the selection of airflow form can refer to How to choose between whole room purification and local purification。

Pollution load affects the number of equipment

Pollution loads come from people, materials, equipment and processes. In an area of ​​the same level, a scene with dense personnel and a lot of dust-producing equipment may require higher air supply volume and equipment quantity than a scene with fewer people and low dust-producing equipment.

Only by giving a grade, it is impossible to judge the pollution load, and therefore it is impossible to determine whether the number of equipment is sufficient. To distinguish the sources of pollution, please refer to How to distinguish external and internal contamination when particles exceed the standard? , first understand the load source.

Installation space and interfaces limit equipment selection

Installation space, ceiling module, maintenance access and power supply conditions will all limit equipment selection. Targets of the same level may require different structures or different installation methods in space-limited scenarios.

Only the level is given, and it is impossible to judge whether the installation conditions allow a certain solution. To determine ceiling matching, please refer to How does the FFU appearance size match the ceiling module? , for maintenance space considerations, please refer to What later expenses will be increased due to insufficient maintenance channels?。

System resistance determines operating point

The actual capabilities of the equipment depend on the operating point at the system resistance, not the nominal maximum. Filter configuration, duct routing, and return air conditions all affect the operating point.

Only by giving a grade, it is impossible to judge the system resistance and working point, and it is impossible to confirm whether the equipment can meet the requirements under actual working conditions. For the selection method of working point, please refer to Why should we look at the complete performance curve when selecting FFU? , the influence of static pressure outside the machine can be referred to What does FFU external static pressure mean?。

The same level may correspond to different device combinations

Taking ISO 5 as an example, different projects may adopt:

• One-way flow scheme full of FFU;

• Plan for local EFU to protect key workstations;

• A combination plan of background area and local high-clean area.

These options differ in the number of devices, filtering configurations, control methods and costs. It is impossible to tell which solution should be adopted by only giving a grade. For the division of labor between the equipment side and the room side, please refer to How to divide the work between device-side EFU and room FFU。

Only by completing the conditions can an effective plan be formed

To ask the supplier to give an accurate configuration, you should add:

• Area boundaries and area;

• Air flow pattern requirements;

• pollution loads and activities;

• Installation space and interface conditions;

• System resistance and operating point conditions;

• Acceptance status and testing requirements.

The more complete this information is, the more comparable the plans and quotes will be. Please refer to the list of conditions that need to be clarified before making an inquiry. What cleaning conditions must be clarified before inquiry? , first sort out the requirements and then proceed to selection.

Project judgment example

A certain project only provides 'ISO 5', and the supplier quotes based on assumptions. After delivery, it was found that the quantity of equipment was insufficient and the wind speed at the workstation was low. Adjustment method: Supplement regional boundaries, pollution loads and airflow patterns, and recalculate the number of equipment and working points.

Another project provided area area, pollution load, installation conditions and acceptance status at the time of inquiry. The supplier configures the equipment according to the same caliber and passes the acceptance inspection once delivered.

These two situations illustrate that only the cleanliness level cannot accurately configure the equipment, and the area, load, space and system conditions need to be completed.

Key points for selection and acceptance inspection

Aili industrial equipment supporting support

By only giving one cleanliness level, the supplier cannot judge the air supply volume, number of equipment, working points and installation methods. Aili Industrial has collaborative capabilities in fans, motors, filters, control systems and complete machine assembly links. It can check the air flow form, equipment quantity, filtration configuration and operation settings based on the regional boundaries, pollution loads, installation conditions and acceptance requirements provided by the project, helping to transform grade goals into equipment solutions that match the site, rather than just quoting based on grade names.