Hello everyone, an old engineer who has been struggling in the cleanroom industry for twenty years.

I often encounter bosses who come to me with budgets of tens of millions to design production lines, with a desire for wealth shining in their eyes. When it comes to the site selection for building a factory, they look confused and say, "Yi Gong, we have a good view of the land. It's located right next to the city center, with convenient transportation and a large number of talents. As for the environment... if it gets dirty, we'll clean it up. If it doesn't work, we can just open a few FFUs (fan filter units)

At that moment, I really wanted to throw the CAD drawing in his face on the spot.

Brothers, the essence of cleanroom engineering is not to "clean up dirty things", but to "firmly guard the door to the microscopic world".

Today, let's not talk about the boring HEPA filter parameters, let's talk about the source - site selection. This thing is definitely the first level that determines the life and death of your factory.

Many people have a huge misunderstanding of "cleanliness". In their eyes, the clean room is like a huge air purifier, as long as the machine is powerful enough, you can drink hot tea inside even with a knife outside.

absolutely wrong.

There is an extremely straightforward sentence in the "Code for Design of Cleanrooms": "The factory site with a cleanroom should be selected in an area with low atmospheric dust concentration

How do you understand this? Let's take a look at the group data, which comes from authoritative measured data:

How many dust particles with a particle size of ≥ 0.5 microns are present per cubic meter of air in urban industrial areas? 3.5 × 107 to 1.1 × 108! Translated into human language, it means tens of millions to hundreds of millions!

Above the sea: how many are the same standards? 1.1 × 104 to 2.5 × 104. That's just over ten thousand.

Did you see? The dust concentration in industrial areas is ten thousand times higher than that in the ocean!

I received a painful case before. A biopharmaceutical company purchased an abandoned factory area located on the edge of the old city area to save time. That place used to be a chemical factory, and although it has been relocated, the base of chemical particles and dust in the soil and air is still large.

In the early stages of production, they did install top-notch air conditioning purification systems and barely met the indoor cleanliness standards through self testing. But every autumn and winter when the wind blows, or when the neighboring construction site starts work, their sterile filling workshop will inexplicably sound an alarm.

Why?

Because the outdoor atmospheric dust concentration has exploded, comparable to the scene of a "sandstorm". The peripheral protective structure of the factory building, new air vents, and even the cooling tower of the air conditioning system are constantly bringing the "billion level army" from outside into the house. Once the filter exceeds the load, it will instantly break down.

In the end, in order to make up for the deficiencies in the site selection, they had to double the air exchange rate, causing a surge in energy consumption, and the expansion of the air conditioning main room cost several million more. This is a typical example of 'choosing a location for a while and putting a crematorium into operation'.

So, Lao Yi advises that the countryside, the outskirts, and the shores of the water are the true parents for you to maintain high purity. Don't be too hard in urban industrial areas, the air there is too expensive, so expensive that your filter cannot be replaced.

In addition to dust in the air, invisible vibrations are also details that must be picked with a magnifying glass when selecting a site.

Many bosses in the semiconductor, precision optics, and high-end medical equipment industries have no concept of "anti vibration". They believe that as long as the building is sturdy and the machines are placed steadily, there will be no problem.

But reality often feels very fragile.

The standard clearly states that if there are precision equipment and instruments in the clean room, the impact of surrounding vibration sources must be evaluated.

I have seen a laboratory for photoresist research and development, built in a seemingly standard research building. No one paid attention to the site selection, as there is a city expressway several hundred meters away and several large punch press workshops.

After the factory building was completed, the first batch of imported laser interferometers were unable to adjust accurately. The data jumping on the screen is as wild as an electrocardiogram. We invited German experts to come and inspect it, pointing out the window and saying, "Your precision requirement is at the nanometer level, and the ground vibration caused by heavy trucks passing by on that road is tens of micrometers. What does this mean? It's like you're on a plane at an altitude of tens of thousands of meters, sewing a spacesuit with embroidery needles

What should we do in the end?

We can only smash walls, dig foundations, and build floating floors up to tens of meters deep, turning the entire laboratory into a completely isolated "island" from the outside world. This renovation project cost more money than the initial purchase of land.

Do you understand? Vibration cannot be filtered by later purification equipment. During the site selection stage, do not avoid railways, main highways, forging workshops, and large motor rooms. In the later stage, you will be doing useless work for the building.

As an experienced person, I am well aware of the difficulties of building a factory. Good plots are located in the city center, with convenient transportation and complete supporting facilities; In remote suburbs, although the air is good, it is difficult to recruit people and logistics are expensive.

This leads to a game: Should we trust the backend purification system or respect the natural environment of the frontend?

My answer is: never test the limits of the purification system for the core production area.

You can build your office in a bustling city and your R&D center in the CBD, but please place your core cleanroom in that calm and peaceful place where birds don't poop.

Because dust and vibration are physical laws that are not subject to human will. You cannot change the dust discharge of the neighboring factory, nor can you stop heavy trucks from passing by. The only thing you can control is to use a professional eye to eliminate these thunderstorms at the moment of site selection.

Conclusion:

There is a saying in the cleanroom industry that goes, "It's easy to get in, but difficult to get out

When you ignore the strict requirements for site selection in order to save on temporary land costs or construction cycles, you will have to repay this debt with several times the maintenance cost, loss of yield rate, and endless arguments in the next few years.

Respecting the environment means respecting your product. Don't let your ambition be destroyed in one breath of air.

I am Lao Yi, follow me and take you through the mist of the cleanroom.

What have you encountered in a project where a "rollover" occurred due to improper site selection? Welcome to share in the comment section, let's avoid pitfalls together!