Cleanroom FAQs

Here are some common questions we get asked by cleanroom facility managers regularly. We hope this information helps you or your facility and invite you to contact us for a free phone or email consultation to discuss your needs in further detail.

Cleanrooms

How do I certify my new cleanroom for ISO 14644?

Prior to live production or testing in any cleanroom it is recommended that you get your critical environment decontaminated and certified by a professional certification company such as SET3.

How often am I supposed to get my cleanroom validated?

ISO 14644-2 specifies that a cleanroom that is ISO class 5 or cleaner needs to have their testing procedures done every 6 months. For any cleanrooms less stringent (class 6 through 9) it is only necessary once per year.


Strategic Testing: (Table 1) Schedule of Tests to Demonstrate Continuing Compliance.

Test Parameter Class Maximum Time Interval Test Procedure
Particle Count Test < or = ISO 5 6 Months ISO 14644-1 Annex A
> ISO 5 12 Months
Air Pressure Difference All Classes 12 Months ISO 14644-1 Annex B5
Airflow All Classes 12 Months ISO 14644-1 Annex B4


Strategic Testing: (Table 2) Schedule of Additional Optional Tests.

Test Parameter Class Maximum Time Interval Test Procedure
Installed Filter Leakage All Classes 24 Months ISO 14644-3 Annex B6
Containment Leakage All Classes 24 Months ISO 14644-3 Annex B4
Recovery All Classes 24 Months ISO 14644-3 Annex B13
Airflow
Visualization
All Classes 24 Months ISO 14644-3 Annex B7

What is involved in cleanroom certification?

Cleanroom certification involves checking the cleanroom for specific parameters to ensure that it is built to the proper set of requirements. The room is also routinely retested to the same factors to ensure the quality has not changed during operations conducted in the cleanroom space.

When a cleanroom is certified to a specific class, it must operate according to standards that meet or exceed the ISO parameters of that class under a specific occupancy status.

    This includes:

  • Particle Count Testing – Test procedure ISO 14644-1 Annex A
  • Testing for Air Pressure Difference – Test procedure ISO 14644-1 Annex B5
  • Airflow Testing – Test procedure ISO 14644-1 Annex B4
  • Installed Filter Leakage Testing – Test procedure ISO 14644-1 Annex B6
  • Containment leakage Testing – Test procedure ISO 14644-1 Annex B4
  • Recovery – Test procedure ISO 14644-1 Annex B13
  • Airflow Visualization Test – Test procedure ISO 14644-1 Annex B7

Is cleanroom monitoring and cleanroom certification the same thing?

No. Cleanroom certification involves checking the room for various parameters to ensure that it has been built according to the proper requirements set out in ISO 14644. The room is also routinely retested to confirm continued success of the original standards the building was built to achieve.

On the other hand, cleanroom monitoring applies a broader approach – helping to show trends in particles and airflow in day-to-day processes. Continued monitoring can help pinpoint potential issues that are starting to occur or are getting worse – allowing the management to fix the protocol, filter or equipment issues that would affect future certification results and or product yield.

Is it better to use disposable cleanroom garments or reusable cleanroom garments?

The answer is based on the following factors:

  • Product manufactured
  • Process used during manufacturing
  • Ability of the cleanroom garment laundry to service the customer with reusable garments
  • The number of garments required during cleanroom manufacturing

Disposable apparel is used during cleanroom manufacturing of toxic or biohazardous products or if the process uses hazardous chemicals such as acids or alkali. Disposable apparel is used if a reusable garment system and service is not readily available or the limited number of garments required for the cleanroom manufacturing application does not make the use of reusable cleanroom garments cost effective. Reusable garments are preferred in all other cleanroom manufacturing applications.

What is a Facility Monitoring System?

Facility Monitoring Systems (FMS) are used to allow all of your particle counters, manifolds, sensors, samples and other assessment equipment to communicate with each other within a central monitoring system.  This process allows you to collect and analyze the particle data.  This allows you to correlate the particle counts with actions like a filter failure or an open door.  Facility Monitoring Systems are typically used in cleanrooms and associated areas.  Although a FMS cannot be used to classify an area, they perform a monitoring function to provide evidence that an area’s environmental conditions have been maintained within the required specifications.  The FDA and other regulatory agencies accept that if you’re using a Facility Monitoring System, the period of reclassification can be extended (ISO 14644-2).

How do I determine how many particle counters or monitoring locations I need?


This can be calculated by determining the square root of the square meters of the room you’re monitoring.  An example would be a room that is 25 square meters.  Square root (25) (square meters) = 5M² or 5 monitoring points.  Always round up.

How can I collect particles in one area and count them in another area?


Particles can be counted from another area by using a tube or duct.  You should remember that 2 things happen when a sample medium is conducted from the sampling area to the particle counter by tubing:

1) you will experience some loss of pressure
2) some particles will adhere to the tubing.

Constant monitoring is essential for ensuring the integrity of a cleanroom environment. To determine the best system for cleanroom particle monitoring, you must understand the two kinds of continuous particle monitoring systems. These systems are real-time and sequential particle monitoring.

Real-Time Particle Monitoring

With real-time particle monitoring, a single particle counter or sensor is used at a specified location. Each event is detected and counted, and there are no gaps in the particle counting data. And particles are monitored in particles per cubic foot or per cubic meter. This system is best suited at very critical or sensitive operations, where events can occur suddenly or without warning.

There are several kinds of particle counters available. One type is a stand-alone portable particle counter that comes equipped with a display and built-in carbon vane vacuum pump. The remote counter, on the other hand, has no display and should be connected to a computer, a facility monitoring system or data acquisition system. Vacuum for sampling with the remote counters are furnished via a separate centralized carbon vane vacuum pump that serves several, or all, particle monitor sensors.
Whether a single particle counter or sensor or several sensors are used, real-time monitoring offers a number of important benefits. For example, it provides for the continuous detection of all particle events and emergency reaction to those events. It is also ideal for crucial monitoring, as well as watching equipment for failure and preventive maintenance. Real-time particle monitoring allows for immediate notification or alarming of yield-destroying particle levels, feedback to staff when procedures are not being followed, and feedback after shut down/evacuation procedures to determine if the area is in specification.

Sequential Particle Monitoring

Sequential particle monitoring is also known as Pneumatically Multiplexed Particle Counting and, more simply, manifold particle counting. This type of monitoring involves the addition of a sequential manifold sampler that connects the particle counter to multiple sample tubes. Each tube is sampled in sequence one at a time.

During the sampling process, air is constantly being pulled through the sample tubes through a blower. When the manifold switches to the next tube being sampled, the particle counter stops counting and pauses to allow any air from the previous sample to be purged. This eliminates any “air hammering” that may free particles in the sample tubing due to the starting and stopping of the air flow. Particles are monitored in particles per cubic foot or per cubic meter, as they are with real-time monitoring.

The frequency of each sample is based on the number of points. Each location is generally sampled for one minute and then purged for 10 seconds, as the sampling arm moves to the next location. The ordered nature of manifold particle monitoring offers a number of advantages. For example, fewer counters can be used to cover a specific area. This, in turn, translates in decreased costs, greater sensitivity per cost and easier service. Sequential particle monitoring is excellent for trending the overall performance of a cleanroom.

Real-Time vs. Sequential

Comparing real-time and sequential particle monitoring reveals distinct differences between the two systems. Real-time monitoring allows for the detection of every single event in the cleanroom regardless of how short the duration. It continuously detects everything with no loss in the data. The system uses multiple sensors, and the sensor points can be located anywhere, as tubing distance is not a factor.

However, more sensors require more calibration and overall service. Operation and maintenance costs are also higher with real-time monitoring because of the individual counters involved.

Sequential particle monitoring, in contrast, has a lower cost for the same coverage area. Fewer sensors are used, which means less calibration and service. However, detection can be made only to events that happen over a longer span. Short events are missed and reported only when sampled. Sequential particle monitoring can only detect trends, not single events.

Cleanroom standards require that a number of factors be kept under tight control, including airborne particles. Selecting the most appropriate monitoring system can make the process of particle monitoring much easier to manage. Continuous cleanroom particle monitoring and cleanroom automation reduces process and product defects and contributes to refining quality control.

How can I avoid particle dropout?


The rule of thumb for this is “the shorter the sampling tube, the more accurate the reading”.  Ideally, if you’re using .1 CFM, don’t allow the sampling tube to be longer than 2 feet.  With 1 CFM, you can go up to 10 feet, but it is better to keep it between 3-4 feet.

Does particle size matter?


Yes, depending on your particular application, particle size range may be important because they may cause specific types of damage during your process.

What is the difference between Real Time particle monitoring and Sequential particle monitoring?


Using Real Time particle monitoring involves placing a single cleanroom particle counter or particle sensor at a specific location in your cleanroom. The sensor is committed to monitor particles only at a designated location, where every event is detected and counted. There are no gaps in the particle counting data and particles are monitored in particles per cubic foot or per cubic meter. The Real Time system is well suited for use at critical locations where sensitive processes can be adequately monitored. You can use a stand-alone particle counter that is a dedicated counter with a built-in vacuum pump. Another option is a remote particle counter. This instrument has no display; a process vacuum is provided for sampling or you can use a separate pump dedicated to particle counting.

Sequential Particle Monitoring is also referred to as Pneumatically Multiplexed Particle Counting or a Manifold Monitoring System. This system involves using a single particle counter to monitor multiple points. This can be accomplished by adding a Sequential Manifold Sampler that connects the particle counter to different sampling tubes. Each individual tube is sampled in sequential order; when a tube is sampled, the manifold moves to the next tube to be sampled.

During this tube change, the particle counter stops counting particles until the change is complete, then it delays to allow any air from the prior sample to be purged. A blower continuously pulls air through all the sample tubes, avoiding any “air hammering” that may free particles in the sample tubing from the start and stop of the airflow. The number of monitoring points determines the frequency of each sample. In a typical application, each location is sampled for 60 seconds then purged for 10 seconds as the sampling arm moves to the next location.

What things should I consider when determining what type of monitoring system to use?

  • The number of points you want to monitor
  • The size of the particles that need monitoring – between .5-5 micron
  • How critical the location is in your process
  • Product volume at your monitoring location
  • Amount in your budget
  • What are you going to do with the particle counter monitoring system data?  (interface?, pulse out?, MODBUS?).

What are the advantages of Real Time particle monitoring?

  • Excellent for sensitive monitoring at lower detection limits > 0.1 micron
  • Provides continuous detection of all particle events
  • Works well for equipment monitoring for failure and preventative maintenance at higher detection limits > 0.2 micron
  • Provides immediate notification of yield destroying particle excursions
  • Allows for emergency reaction to particle events
  • Provides immediate feedback after shut down to verify of the area is in spec

What are the advantages of Sequential (Manifold) particle monitoring?

  • Central location of the particle counter offers easier service
  • Fewer particle counters can be used to cover a specific area
  • Low calibration costs
  • No need to correlate data between particle counters

How many filters should I install in my cleanroom?

HEPA & ULPA filters used in most stringent cleanrooms are generally built in ceiling and can be installed in groups housed in a proprietary modular pressure plenum system. They can also be installed in single filter housings, individually ducted, suspended in an inverted “T” grid support system, and sealed to prevent unfiltered bypass air from entering the cleanroom.  Cleanroom design conventionally follows the following guidelines for filter coverage.

ISO Class

Fed 208

Controls

HEPA Coverage as % of Ceiling

1

Stringent 100

2

Stringent 100

3

1 Stringent 100

4

10 Stringent 100

5

100 Stringent 100

6

1,000 Intermediate 33   – 40

7

10,000 Intermediate 10   – 15

8

100,000 Less   Stringent 05   -10

How many air changes per hour should my cleanroom have?

Airflow is usually specified either as average air velocity within the room or as air changes per hour.  HEPA & ULPA filters used in most stringent cleanrooms are generally built in ceiling and can be installed in groups housed in a proprietary modular pressure plenum system. They can also be installed in single filter housings, individually ducted, suspended in an inverted “T” grid support system, and sealed to prevent unfiltered bypass air from entering the cleanroom. Cleanroom design conventionally follows the following guidelines for filter coverage:

ISO Class

Fed 208

Controls

Air Velocity at table level in FPM

Air Changes Rate per Hour

1

Stringent 70   – 130 >750

2

Stringent 70   – 130 >750

3

1 Stringent 70   – 130 >750

4

10 Stringent 70   – 110 500   – 600

5

100 Stringent 70   – 90 150   – 400

6

1,000 Intermediate 25   – 40 60   – 100

7

10,000 Intermediate 10   – 15 25   – 40

8

100,000 Less   Stringent 3   – 5 10   – 15

Who is responsible for confirming proper cleaning according to ISO 14644 standards?

Since cleaning affects everyone and everything in a clean room according to ISO 14644 standards, everyone who has any job in a data center or clean room has a responsibility to confirm that all proper standards are met and upkeep is regular keep them that way. Typical positions in a data center include:

 

DATA CENTERS

IT Manager
Software Engineer
Systems Engineer
Database Administrator
Network Administrator
Network Engineer
CIO
Subject Matter Expert
DC Manager
Facilities Program Manager
Technical Program Manager
Electrical Engineer
Mechanical Engineer
Data Center Specialists
Environmental Technician
Data Center Technician
Hardware Planner
Smart hands technician
Computer Operations Manager
Computer Operations Director
Data Center Facilities Manager
Hardware Specialist
Data Center Operator
Data Center Drones
Colo Expert
Colo Technician
CLEANROOMS
Cleanroom Technician
Cleanroom Manager
cleanroom Engineer
Cleanroom Systems Engineer
Cleanroom Administrator
Cleanroom Product Administrator
Cleanroom Engineer
CIO
Cleanroom Expert
Facilities Program Manager
Technical Program Manager
Electrical Engineer
Mechanical Engineer
Cleanroom Specialists
Cleanroom Planner
Cleanroom Operations Manager
Cleanroom Operations Director
Cleanroom Facilities Manager
Product Line Operator
Cleanroom Operator