B T U team members have experience in the design and install complex cleanroom HVAC systems incorporating cooling, heating and dehumidification required in cleanrooms. Integration of HVAC hard wares with controls soft wares will be carefully designed to ensure system accuracy and stability is part of our forte. The HVAC system is designed to meet specific requirements on room differential pressures, air changes, temperature and humidity, particles and microbial level.


Our pursuit of technology application is manifested through our persevering commitment to offer the most cost effective solution for each and every project undertaken. No problem is viewed as simple and no solution is viewed as optimum until our dedicated project teams are satisfied that all feasible options have been considered and our customer’s critical requirements are met.

Clean rooms are required for various manufacturing, life care and research applications. As the name indicates, the clean rooms are having extremely clean air. Parameters such as air particles, dust, the composition of air, mold particles in the air, microbes etc. are controlled to meet the required levels. Also, temperature and humidity will be at controlled levels. Ex. in a pharmaceutical manufacturing industry, we require clean rooms to manufacture medicines. There should not be any particles contaminating the medicines during the manufacturing process. We regulate the air pressure also so that air particles do not enter the room from outside.

Clean room monitoring systems

A typical clean room monitoring systems consists of most of the following systems. Based on your specific requirement, you can select the desired parameters

  1. Airborne particle counters

    This is, of course, the most important parameter since a clean room is defined by the number and size of the particles. Airborne particles are measured by sampling the air within the room regularly. This is displayed in ppm as well as the size of the particles.Modular cleanroom particle monitoring

  2. Liquid and moisture counters

    The liquid particles in the air are also equally important. Hence continuous sampling and counting takes place for liquid particles.

  3. Air microbe counters

    Microbes are small organisms found in common air. If left uncontrolled this can form mold and will encourage bacterial growth. The microbe counters are called microbial air samplers.

  4. Chemical vapor monitoring

    Chemical vapor monitoring may be important in certain industries, especially in manufacturing plants involving chemical processes. It may not be required to monitor numerous chemical vapors. You can shortlist the possible chemical vapors and install monitoring system for the same.

  5. Temperature monitoring

    Temperature monitoring is a standard requirement and hence we can easily implement same. We have to place couple of high accuracy temperature sensors around the clean room for continuous recording and alert.

  6. Aerosol sampling counter

    Aerosol is fine suspended particles in the air. Aerosol counting is not a standard requirement for a clean room. Hence, you can install an aerosol sampling counter based on your requirements.

  7. Humidity monitoring

    Humidity monitoring is a standard requirement since moisture causes a lot of other adverse factors inside a clean room. Clean room humidity monitoring is simple by a couple of humidity sensors. Normally a dehumidifier removed fresh air before intake. However, it is better to install a clean room humidity monitoring system with alert.environment-monitoring-system-for-clean-rooms

  8. Differential pressure monitoring

    The clean room will have its own pressure requirements. The air handling system maintains this particular pressure inside the clean room. It is essential to have a pressure monitoring system for such cases.

  9. Real-time environment monitoring for clean rooms

    Environment monitoring is a general term covering most of the above parameters. Essentially temperature and humidity are part of an environment monitoring system.

Type of clean rooms

Various industries such as aerospace, semiconductor, electronic manufacturing, pharmaceutical manufacturing etc. require clean rooms. The standards of cleanliness are defined by Cleanroom Standards ISO 14644-1 and BS 5295. Few of the examples of classification are as below:

  1. Class ISO 1 permits maximum 10 particles of size less than or equal to 0.1 µm per cubic meter.
  2. Class ISO 2 permits maximum 100 particles of size less than or equal to 0.1 µm per cubic meter.
  3. Class ISO 3 permits maximum 1000 particles of size less than or equal to 0.1 µm per cubic meter.
  4. Class ISO 4 permits maximum 10000 particles of size less than or equal to 0.1 µm per cubic meter.
  5. Class ISO 5 permits maximum 100000 particles of size less than or equal to 0.1 µm per cubic meter.



BS EN ISO 14644- 1:1999.
table 1: selected airborne particulate cleanliness classes for cleanrooms and clean zones

Number (N)
Maximum concentration limits (particles / m3 of air) for
particles equal to and larger than the considered sizes below
  0.1µm 0.2µm 0.3µm 0.5µm 1µm 5µm
ISO Class 1 10 2            
ISO Class 2 100 24 10 4        
ISO Class 3 1000 237 102 35 8   1 C
ISO Class 4 10000 2370 1020 352 83   10 D
ISO Class 5 100 000 23 700 10 200 3520 832 29 100 E (F)
ISO Class 6 1 000 000 237 000 102 000 35 200 8320 293 1000 H (G)
ISO Class 7       352 000 83 200 2930 10 000 J
ISO Class 8       3 520 000 832 000 29 300 100 000 K
ISO Class 9       35 200 000 8 320 000 293 000    


ANNEX 1 (2008)
airborne particulate classification

Maximum permitted number of particles/m3 equal to or above
Grade At rest In operation
  0.5µm 5µm 0.5µm 5µm Class
A 3 520 20 3 520 20   29 5, 4.8
B 3 520 29 352 000 2 900    2 930 7, 7
C 352 000 2 900   2 930 3 520 000 29 000   29 300 8, 8
D 3 520 000 29 000   29 300 not defined not defined  


recommended limits for microbiological monitoring of clean areas during operation

Recommended limits for microbial containment
Grade Air sample cfu/m3 Settle Plates
(diam.90mm) cfu/4 hours
Contact plates
(diam.55mm) cfu/plate
Glove print 5
fingers cfu/glove
A <1 <1 <1 <1
B 10 5 5 5
C 100 50 25
D 200 100 50