Air Shower Acceptance & Inspection Guide
Air shower room acceptance: Don't equate "the equipment can operate" with "the equipment is effective"
The acceptance of the air shower room is often just a formality: the equipment is installed, the door is closed, the fan is making noise when blowing, and the signature is made. Whether it's installed or not is never the problem. The problem is whether the air shower installed still works. cleanroom air shower is one of the few. The operating state and the effective state are completely two different things. The equipment. The fact that the fan is running, the light is on and the door is locked doesn't mean it is working.
When is it really useful A qualified air showers has to accomplish two core tasks: The first step is to blow off the particles adhering to the surface of the person's clean suit. The second one acts as an air lock, relying on two interlocked doors at the front and back to prevent air from the non-clean area from directly flowing into the clean area. This cleanroom air shower is truly useful only when both things are met. The debate in the industry that "air shower room is useless" mostly stems from this: some people only evaluate it based on one thing. It's no use saying so. What's being tested is the dust removal effect. What's useful is whether the door is still locked or not.
① Dust removal function
When it comes to dust removal, there is a premise that is often overlooked: The air shower blows recirculated air. The air comes out from the built-in filter of the device, hits the person, and is then sucked back through the return air grille. If this filter is not of the high-efficiency level, the air sprayed out will be dirty in itself, which is equivalent to hitting unfiltered air onto a clean suit. The harder you blow, the dirtier it gets.
② Double-door interlock (air lock function)
The logic behind the interlocking of the two doors is that during the air shower process, both doors are locked and no one can pull them open. After blowing, delay for a few seconds before placing the inner door - these few seconds allow the particles blown up to settle down and be carried away by the return air. The interlock fails, or someone keeps one side door open for convenience all the time. As a result, the air shower room degenerates from an air lock into an ordinary passage, and the pressure difference between the clean area and the outside is directly short-circuited.
Under what circumstances is it just for show
There are three common situations where air showers become ornaments:
1. The supply air does not come with a high-efficiency filter
As mentioned earlier, at this time, the cleanroom air shower is not discounted in effect; instead, it makes things worse.
2. The wind speed at the nozzle has dropped
Wind speed is a hard indicator of dust removal effect. JG/T 296-2010 classifies the nozzle wind speed according to the nozzle diameter. The smaller the diameter, the higher the requirement: the minimum for 28mm nozzles is 29 m/s, for 32mm nozzles it is 25 m/s, and for 38mm nozzles it is 21 m/s. Only an airflow of this speed can peel off the particles adhering to the fabric. Below 18 m/s, it is basically just a psychological comfort to blow on people. The failure of air shower usually does not occur suddenly. After a period of time, the resistance of the high-efficiency filter increases, the air volume drops, and the air velocity at the nozzle gradually decreases. The lights are still on, the door is still locked, and the program is running as usual. The dust removal capacity is no longer sufficient. No one regularly uses an anemometer to measure," The equipment can rotate And "; "Blow clean" The gap between them has never been noticed.
3. The grade of the clean area itself is not high
In an ISO level 8 workshop, the influence of people on cleanliness is already limited. At this time, the marginal value of cleanroom air shower is low. Whether it's worth installing or not depends on the specific situation, but the criterion for judgment is the same: What else can it do, dust removal or gas isolation? Only when something can be accomplished can it be considered equipment. If neither of them can be accomplished, it's just for show.
What is tested for acceptance and how is it judged
There's no need to complicate things. Just go through each item one by one.
| Item | Test Method | Judgment Standard |
|---|---|---|
| Nozzle Wind Speed | Use anemometer to test each nozzle, focus on corner positions | Refer to JG/T 296‑2010 grading values by nozzle diameter; Disqualify if below grading value or obvious overall attenuation |
| Double‑door Interlock & Delay | Pull each door during air shower; Use stopwatch to check delay after blowing | Both doors cannot be opened during blowing; release with delay. Disqualify if any door can be pulled open |
| Blowing Time Setting | Check setting value matches working condition | Not less than 20s, recommended 20‑40s; extend appropriately for cold‑weather heavy‑clothing scenarios |
| Nozzle Angle | Visual inspection for every nozzle | Aim toward human body; realign and record if adjustable nozzles point toward wall or ceiling |
| Filter Condition | Check initial resistance, current resistance and replacement records | Read differential pressure gauge; perform scan leak test after replacement or when leakage is suspected |
| Noise | Measure at 1m outside the door | Not exceeding 68 dB(A) |
When measuring wind speed, don't just measure the middle few. The nozzles in the corners are the most likely to fail. Pick a few from the entire batch. "Representativeness" The inspection is the most common form of cutting corners in the acceptance process. Wind speed attenuation is not something that equipment alarms can monitor for you - no controller will shut down just because the nozzle wind speed drops from 25 to 18; it will simply complete the process as usual.
After the interlock test, take the opportunity to check if there is any bypass. Some workshops have bypass doors that can bypass the air shower room. The requirements for fire evacuation are understandable, but there should be management measures to control this opening on a regular basis. Otherwise, no matter how well the interlock is done, it will be in vain. Setting the air shower time is a management issue. The lower limit of JG/T 296-2010 is 20 seconds, and 20 to 40 seconds are recommended. Settings are not a one-off matter: It's quite common for factory default Settings to remain untouched once installed. When the working conditions change (for instance, wearing thick clothes to enter the workshop in winter), the time should be adjusted accordingly. How long to blow for enough depends on the thickness of the clothes and the composition of the personnel. There is no one-size-fits-all rule for this.
For the filter, you need to ask three questions: what is the initial resistance? What is the current resistance? When should it be replaced? The root cause of wind speed attenuation is mostly in the filter. Measuring only the wind speed without checking the resistance is equivalent to checking the symptoms but not the root cause, which is also the core reason why most air showers performance attenuation goes unnoticed.
So next time someone asks ";" Is "cleanroom air shower" really useful? Don't rush to answer - first look at this air shower: Can the particles still be blown down? Is the door still locked? If both things can still be accomplished, they will be useful. If neither of the two items can be accomplished, write "unqualified" for acceptance. Don't write "..." "Installed" .