When designing ventilation systems for clean rooms used in the production of microelectronics, laboratories of medical institutions, operating rooms, aseptic wards and departments, rooms with a 3D printer, etc. - it is necessary to follow SNiP standards and GOST requirements, based on the customer’s recommendations and the required cleanliness class.
Sanitary standards, technical specifications, manuals and installation rules
- Stages of ventilation design
- Hospital ventilation systems
- Reliable ventilation of medical laboratories
The main rule of a modern designer of “clean” ventilation is an individual approach, excluding standard solutions. The basis for organizing proper air exchange in “clean” rooms are the following requirements and standards:
- SNiP 41-01-2003(8), which determine the balance of supply and exhaust ventilation, taking into account the presence or absence of a transfer gateway (vestibule, window);
- GOST ISO 14644-1-2002, classifying 9 types of room cleanliness, depending on the size and number of particles suspended in the air.
Purpose and classification of “clean” ventilation systems
Modern design recommendations are based on mandatory requirement that the air prepared for the premises of medical institutions, laboratories, operating rooms and aseptic departments must be sterile. The implementation of such a project requires the installation of industrial antibacterial filters with a high lower threshold for filtration of harmful particles and microorganisms - HEPA and ULPA.
In microelectronics production, unidirectional and zonal ventilation is used. mixed type. The cleanliness class of such an object varies depending on the area - working, technological (maintenance), service.
A separate room is planned for a clean room with a 3D printer. Maintaining the required cleanliness is ensured by the installation additional devices air conditioning, transfer window or airlock.
Air exchange in complexes with “clean” rooms
In production, warehouse, office, medical complexes clean rooms and rooms, a modular ventilation scheme is used, including air distributors, air filters, transfer locks, boxes and windows, monitoring and automation system units. Ventilation equipment and air conditioning ducts are finished using special sealants. The construction of such objects is carried out from special materials - plastic, gypsum metal wall panels, sandwich panels for suspended ceilings, rounding baseboard profiles, sealed doors, windows and fixtures, floors with sticky mats. To minimize air pollution, metal furniture is selected. Clothes, shoes, and technological equipment are stored in isolated lockers and boxes.
An important aspect of the clean plant design process is proper industrial practice- GMP standard, which allows not only to calculate the cleanliness class for the technological environment of a room or premises, but also to responsibly carry out the installation of air conditioning and ventilation systems. A facility for the production of microelectronics, pharmaceuticals, medical equipment, food, etc. must not only undergo certification of climate control equipment, but also be subject to constant monitoring of its operation, including service maintenance, routine repairs, disinfection and cleaning.
Climate project of the medical center
When executing design work At the Moscow Doctor medical center, our company’s specialists performed the calculation, supply, and installation of ventilation and air conditioning systems for its clean rooms. GOST requirements were met in accordance with ISO-2002, taking into account ISO class 5 cleanliness for suspended particles.
The air supply was carried out by an intake device with industrial. SHUFT fan, which passes air through a multi-stage system with a HEPA filter. Heat recovery and air recirculation in the clinic's aseptic clean room were carried out with a Funke heat exchanger. The required degree of sterility was maintained by a transfer lock.
At the customer's request, 2 operating modes of ventilation equipment were prepared. The clean ventilation mode supplied air through a separate automation unit that was not connected to other rooms of the medical facility building. The second mode allowed control of air exchange from the control panel, for emergency notification purposes, in the absence of personnel in the building.
The purpose of the designed aseptic department in the medical center is an operating room and sterilization room. Procedures for the treatment of dermatitis were to be carried out in a clean room.
Perioral dermatitis
This type of dermatitis is a rare skin disease. Most often, this skin disease affects representatives of the fair half of humanity aged 20 to 40 years. Dermatologists sometimes call perioral dermatitis perioral dermatitis or perioral dermatitis. The last disease comes from the name of the place where it is located.
Symptoms of perioral dermatitis
Very often, the onset of perioral dermatitis is expressed by several pimples on the skin in the mouth area. Patients complain that the use of conventional hygiene products to prevent acne only makes it worse and the area of the affected area increases. You should immediately contact a medical center that specializes in skin diseases if you experience the following symptoms:
The skin on the chin and around the mouth is covered with a pronounced rash. Red rash, itching and burning of the affected skin. The skin seems to be tightened.
Pimples around the mouth do not occupy the entire area of the skin, but some areas. That is, they are located in localized areas.
Sometimes it is accompanied by pimples containing heads filled with clear liquid. When these heads burst, the liquid they contain leaks onto the skin. The red rash turns into ulcers over time.
The affected areas of the skin are covered with transparent scales, which periodically peel off from the surface and fall off. Similar symptoms may occur in other diseases of the human body.
Causes of perioral skin disease
Like any dermatitis, this one is caused by a decrease in protective function skin. The following factors can provoke disruptions in the skin’s immune system:
- Failure in the body's hormonal background (endocrine system).
- Reduced cellular immunity of skin tissues.
- Sudden climate change and prolonged exposure to direct skin sun rays. Ultraviolet radiation is bad for the skin.
- Allergies that are bacterial in nature.
- Allergic reactions to cosmetics and hygiene chemicals.
Skin reactions may occur from the use of allergenic medications. Before starting treatment for any disease, the doctor must make sure that the patient is not allergic to the constituent elements of the drug.
- Genetic predisposition to allergies.
- Rhinitis, asthma.
- Gynecological problems that cause a woman's hormonal imbalance.
- Increased sensitivity of the skin in the mouth and chin area.
- Dental dentures, cleaning pastes, especially fluoride-containing ones.
- Problems with the digestive system, especially in the gastrointestinal tract.
- Stressful situations, depressive states, that is, all situations that lead to disorders nervous system human body.
The cost of designing clean room ventilation is from 199 rubles. for 1 m2
“Clean” prices for turnkey clean room ventilation
The climate control company StroyEngineering LLC will carry out projects for facilities catering(canteens, cafes, restaurants), production shops (welding places, spray booths), workshops (jewelry, microelectronics), healthcare institutions (medical and preventive complexes, pharmacies, swimming pools, maternity hospitals, laboratories), office, server, residential, warehouse and retail premises (shopping centers, shops) - in accordance with modern requirements, according to GOST parameters and SNiP standards.
A high-tech, convenient and practical air purification scheme is required for private and public medical centers, rented and “own” clean rooms in Moscow and the region - with dispatching? We offer honest and “clean” prices (without markups) for design and installation work with subsequent service for construction and repair organizations, owners of sports clubs, tenants, healthcare institutions and catering establishments!
Our organization’s services include the selection and installation of specialized equipment for airlocks and transfer windows. Industrial air conditioners, filters, air distributors, control units, recuperators, etc. will create optimal conditions to perform any tasks at your “clean” facilities.
Development and implementation of clean room ventilation projects
- An example of installing ventilation in a clinic according to SanPiN
- Ventilation standards for ultrasound, x-ray, physiotherapy, massage rooms
- Ventilation requirements for dentistry with an X-ray machine
- SNiP pharmacy ventilation
- Example of gym ventilation with gym and a swimming pool
- Dry cleaning ventilation project at a consumer services enterprise
Previous material - ventilation of residential premises!
GOST R 56190-2014
NATIONAL STANDARD OF THE RUSSIAN FEDERATION
Clean rooms
Energy Saving Methods
Cleanrooms. Energy efficiency
OKS 13.040.01;
19.020
OKP 63 1000
94 1000
Date of introduction 2015-12-01
Preface
1 DEVELOPED by the All-Russian public organization"Association of Micropollution Control Engineers" (ASINCOM) with the participation of Open joint stock company"Research Center for Control and Diagnostics technical systems" (JSC "SRC KD")
2 INTRODUCED by the Technical Committee for Standardization TC 184 “Ensuring Industrial Cleanliness”
3 APPROVED AND ENTERED INTO EFFECT by Order of the Federal Agency for Technical Regulation and Metrology dated October 24, 2014 N 1427-st
4 INTRODUCED FOR THE FIRST TIME
The rules for the application of this standard are established in GOST R 1.0-2012 (section 8). Information about changes to this standard is published in the annual (as of January 1 of the current year) information index "National Standards", and the official text of changes and amendments is published in the monthly information index "National Standards". In case of revision (replacement) or cancellation of this standard, the corresponding notice will be published in the next issue of the information index "National Standards". Relevant information, notices and texts are also posted in information system for public use - on the official website Federal agency on technical regulation and metrology on the Internet (gost.ru)
Introduction
Introduction
Cleanrooms are widely used in electronics, instrumentation, pharmaceutical, food and other industries, medical devices, hospitals, etc. They have become an integral part of many modern processes and a means of protecting people, materials and products from contamination.
At the same time, clean rooms require significant energy consumption, mainly for ventilation and air conditioning, which can exceed the energy consumption in ordinary rooms by tens of times. This is caused by high air exchange rates and, as a consequence, significant needs for heating, cooling, humidification and dehumidification of air.
The current practice of creating clean rooms is focused on ensuring specified cleanliness classes without due attention to the tasks of saving energy resources.
Maintaining a given cleanliness in a room is a difficult and complex task. It is necessary to have precise knowledge of the particle emission characteristics and, based on them, to perform calculations of air flow and air exchange rates, which is not always possible. The concentration of particles in the air is probabilistic and depends on many factors: human influence, process, equipment, materials and products, which are difficult to estimate accurately, especially at the design stage. Because of this, design decisions are made with a large margin in order to guarantee the required cleanliness class during certification and operation.
A well-designed and constructed cleanroom has a margin of cleanliness. The current practice of certification and operation of clean rooms does not take this reserve into account, which leads to unnecessary energy consumption.
Another reason for excessively high air exchange rates included in projects is the application of regulatory requirements that do not apply to this facility. For example, Appendix 1 to GOST R 52249-2009 “Rules for the production and quality control of medicinal products” (GMP) establishes that the recovery time of a clean room during the production of sterile medicinal products should not exceed 15-20 minutes. To meet this requirement, the air exchange rate can significantly exceed the values required to ensure the cleanliness class in steady state.
The extension of requirements for the production of sterile medicines to non-sterile drugs and other products, including non-medical purposes, leads to significant waste of energy.
Guidance on energy savings in cleanrooms is given in UK standards BS 8568:2013* and Society of German Engineers VDI 2083 Part 4.2.
________________
* Access to international and foreign documents mentioned here and further in the text can be obtained by following the link to the website http://shop.cntd.ru. - Database manufacturer's note.
This standard provides requirements for determining the real power reserve at the stages of certification and operation based on the actual consumption of energy resources while guaranteeing compliance with a given cleanliness class. Energy savings should be provided not only at the design stage of cleanrooms, but also ensured during certification and operation.
________________
A.Fedotov. - "Saving energy in cleanrooms". Cleanroom Technology. London, August, 2014, pp.14-17 Fedotov A.E. "Energy saving in clean rooms" - "Cleanliness Technology" N 2/2014, pp. 5-12 Clean rooms. Ed. A.E. Fedotova. M., ASINKOM, 2003, 576 p.
When certifying and operating clean rooms, the actual emission of particles should be assessed and, based on this, the required air flow rate and air exchange rate should be determined, which may be significantly lower than the design values.
This standard provides a flexible approach to determining the air exchange rate, taking into account the actual particle emission and technological process.
1 Application area
This standard specifies methods for energy conservation in cleanrooms.
The standard is intended for use in the design, certification and operation of clean rooms in order to save energy resources. The standard takes into account the specifics of clean rooms and can be used in various industries(radioelectronic, instrument-making, pharmaceutical, medical, food, etc.).
The standard does not affect the requirements for ventilation and air conditioning established by regulatory and legal documents on the safety of working with pathogenic microorganisms, toxic, radioactive and other hazardous substances.
2 Normative references
This standard uses normative references to the following standards:
GOST R EN 13779-2007 Ventilation in non-residential buildings. Technical requirements for ventilation and air conditioning systems
GOST R ISO 14644-3-2007 Clean rooms and associated controlled environments. Part 3. Test methods
GOST R ISO 14644-4-2002 Clean rooms and associated controlled environments. Part 4. Design, construction and commissioning
GOST R ISO 14644-5-2005 Clean rooms and associated controlled environments. Part 5. Operation
GOST R 52249-2009 Rules for the production and quality control of medicines
GOST R 52539-2006 Air purity in medical institutions. General requirements
GOST ISO 14644-1-2002 Clean rooms and associated controlled environments. Part 1. Classification of air purity
Note - When using this standard, it is advisable to check the validity of the reference standards in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet or using the annual information index "National Standards", which was published as of January 1 of the current year, and on issues of the monthly information index "National Standards" for the current year. If an undated reference standard is replaced, it is recommended that the current version of that standard be used, taking into account any changes made to that version. If a dated reference standard is replaced, it is recommended to use the version of that standard with the year of approval (adoption) indicated above. If, after the approval of this standard, a change is made to the referenced standard to which a dated reference is made that affects the provision referred to, it is recommended that that provision be applied without regard to that change. If the reference standard is canceled without replacement, then the provision in which a reference to it is given is recommended to be applied in the part that does not affect this reference.
3 Terms and definitions
This standard uses terms and definitions in accordance with GOST ISO 14644-1, as well as the following terms with corresponding definitions:
3.1 recovery time: The time required for the particle concentration in the room to decrease by 100 times compared to the initial, sufficiently large particle concentration.
Note - The method for determining the recovery time is given in GOST R ISO 14644-3 (clause B.12.3).
3.2 air exchange rate N: Air flow ratio L(m/h) to room volume V(m), N=L/V, h.
3.5 air flow L: The amount of air supplied to the room per hour, m/h.
ventilation efficiency: Ventilation efficiency characterizes the relationship between the concentration of contaminants in the supply air, exhaust air and in the breathing zone (inside the operating area). Ventilation efficiency is calculated using the formula Where c- concentration of pollutants in the exhaust air; |
4 Principles of energy saving in clean rooms
4.1 Energy saving measures
Energy saving measures can be general for all buildings, industries and HVAC systems or specific for clean rooms.
4.2 General measures
General measures include:
- minimizing heat gain and loss, insulating buildings;
- heat recovery;
- air recirculation with bringing the proportion of outside air to a minimum, where this is not prohibited by mandatory standards;
- placement of energy-intensive industries in climatic zones, not requiring excessive high costs for heating and humidifying air in winter, cooling and dehumidifying in summer;
- use of highly efficient fans, air conditioners and chillers;
- exclusion of unreasonably strict ranges of temperature and humidity changes;
- maintaining air humidity in winter period at a minimum level;
- removal of excess heat from equipment primarily by local systems built into the equipment, rather than by means of ventilation and air conditioning, etc.
- use of protective equipment for workplaces and fume hoods that do not require the removal of large volumes of air when working with harmful substances(e.g. closed equipment, restricted access systems, isolators);
- use of equipment with power reserve (for example, air conditioners, filters, etc.), keeping in mind that equipment with a higher rated power consumes less energy to perform a given task;
Note - At the same air flow, a fan (air conditioner) with a higher rated power will have less energy consumption.
- other measures in accordance with 4.4.2.
4.3 Special measures
These measures take into account the characteristics of cleanrooms and include:
- reducing to a reasonable minimum the area of clean rooms and other air-conditioned premises;
- exclusion of setting unreasonably high cleanliness classes;
- justification of air exchange rates, avoiding excessively high values, including due to unreasonably stringent requirements for recovery time;
- use of HEPA and ULPA filters with low pressure drop, for example Teflon membrane filters;
- sealing leaks at the joints of enclosing structures;
- application of local protection when setting a high class in a limited area based on the requirements of the process;
- reducing the number of personnel or using unmanned technologies (for example, the use of closed equipment, isolators);
- reduction of air consumption during non-working hours;
- determination at the stages of certification and operation of the real value of the power reserve provided by the project;
- strict compliance with operating requirements, including clothing, personnel hygiene, training, etc.;
- determination of the really necessary air flow rates during testing and during operation and regulation of air flow rates to minimum values, based on these data;
- operation of a clean room with reduced energy consumption, subject to compliance with the requirements for the cleanliness class;
- confirmation of the ability to operate at reduced energy consumption through ongoing cleanliness control (monitoring) and repeated certifications;
- other measures in accordance with 4.4.2.
4.4 Energy saving steps
4.4.1 General
Energy resource requirements are assessed at the design, certification and operation stages.
The main factor determining the need for energy resources is air consumption (air exchange rate).
Air flow must be determined at the design stage. In this case, some reserve is provided to take into account uncertainty due to the lack of accurate data on the release of particles by equipment, process and for other reasons.
At the certification stage, the correctness of design solutions is checked and the real reserve of ventilation and air conditioning systems in terms of air flow is determined.
During operation, the compliance of the clean room with the specified cleanliness class is monitored.
NOTE This approach differs from current practice. Traditionally, air flow is determined at the design stage (in the project); in a constructed room, during certification, the compliance of the air flow with that specified in the project is checked, and this air flow is maintained during operation. In this case, the design provides for redundancy in air flow due to the presence of some uncertainty, but this redundancy is not revealed during testing. Further, the room is operated at excessively high air exchange rates, which leads to excessive energy consumption.
This standard provides for the determination of the real reserve in design solutions and the operation of clean rooms at actually required air flow rates, which turn out to be less than the design values by the amount of the reserve established during testing.
The standard provides a flexible procedure for determining air exchange rates.
4.4.2 Design
General and specific energy saving measures (see 4.2-4.3) should be taken taking into account real possibilities.
Along with this, the following should be provided:
- regulation of air flow by means of automation, including setting modes for working and non-working hours and providing microclimate parameters depending on specific conditions;
- transition from ensuring a cleanliness class throughout the entire room to local protection, in which the cleanliness class is set and controlled only in the work area, or a higher cleanliness class is provided in the work area than in the rest of the room;
- accounting for the operation of laminar flow cabinets and laminar flow zones. In this case, the air flow from the laminar flow cabinet (zone) is added to the air flow to ensure cleanliness from the air conditioner;
- for rooms where only local protection is required, the advisability of using a horizontal air flow instead of a vertical one should be considered. In some cases, it is possible to create an air flow at an angle, for example at an angle of 45° relative to the ceiling;
- reduction of resistance to air flow on all elements of the air flow path, including due to low air speed in the air duct.
Energy saving methods differ for rooms (zones) with unidirectional and non-unidirectional flow.
4.4.2.1 Unidirectional airflow
For zones with unidirectional flow key factor is the speed of air flow. It is recommended to maintain a unidirectional flow velocity of approximately 0.3 m/s, unless otherwise specified by regulations. In case of contradiction, the speed value established by regulatory documents is provided. For example, GOST R 52249 (Appendix 1) provides for a speed of unidirectional air flow in the range of 0.36-0.54 m/s; GOST R 52539 - 0.24-0.3 m/s (in operating rooms and intensive care wards).
4.4.2.2 Non-unidirectional air flow
For cleanrooms with non-unidirectional (turbulent) flow, the decisive factor is the air exchange rate (see section 5).
4.4.3 Attestation
Certification (testing) of clean rooms is carried out in accordance with GOST R ISO 14644-3 and GOST R ISO 14644-4.
In addition to this, it is necessary to check the possibility of maintaining the cleanliness class with a margin at reduced multiplicities and real particle emission values, i.e. determine the reserve of ventilation and air conditioning systems. This is done for the equipped and operating states of the cleanroom.
4.4.4 Operation
It is necessary to confirm the possibility of working with reduced air exchange rates in real mode when performing a technological process with a specified number of personnel, using this clothing, etc.
For this purpose, periodic and/or continuous monitoring of particle concentration is provided.
Measures should be taken to reduce the release of particles from all possible sources, the entry of particles into the premises and effective removal particles from the room, including from personnel, processes and equipment, clean room structures (convenience and efficiency of cleaning).
The main measures to reduce particle emissions are:
1) staff:
- use of appropriate technical clothing;
- compliance with hygiene requirements;
- correct behavior based on the requirements of cleanliness technology;
- education;
- use of sticky mats at the entrance to clean rooms;
2) processes and equipment:
- cleaning (washing, cleaning);
- use of local suction (removal of contaminants from the place of their release);
- the use of materials and structures that do not adsorb contamination and ensure efficiency and convenience of cleaning;
3) cleaning:
- the right technology and the required frequency of cleaning;
- use of equipment and materials that do not emit particles;
- control over cleaning.
5 Air exchange rate
5.1 Setting the air exchange rate
Taking into account the key role of air flow in energy consumption, air exchange rates should be assessed for all factors influencing them:
a) outdoor air requirements according to sanitary standards;
b) compensation for local exhaust (suction);
c) maintaining differential pressure;
d) removing excess heat;
e) ensuring a given cleanliness class.
Measures should be taken to reduce air flows not related to cleanliness ( listings a-d) to values less than necessary to ensure cleanliness (e).
To calculate the ventilation and air conditioning system, the multiplicity of the worst (largest) value is taken.
The required frequency of air exchange (air flow) depends on the requirements for the cleanliness class (maximum permissible concentration of particles in the air) and recovery time.
The method for calculating the air exchange rate to ensure cleanliness is given in Appendix A.
5.2 Ensuring cleanliness class
The classification of clean rooms is given in GOST ISO 14644-1.
Requirements for purity classes are set in accordance with regulatory documents (for the production of medicines - according to GOST R 52249, medical institutions- according to GOST R 52539) or design assignment ( terms of reference for the development) of a clean room based on the specifics of the technological process and by agreement between the customer and the contractor.
At the design stage, the intensity of particle emission can only be approximately estimated; therefore, a reserve of air exchange rates should be provided.
5.3 Recovery time
The recovery time is taken in accordance with regulatory requirements for the cases provided for therein. For example, GOST R 52249 sets a recovery time of 15-20 minutes for the production of sterile medicines. In other cases, the customer and contractor can set other recovery time values (30, 40, 60 minutes, etc.) based on specific conditions.
The methodology for calculating particle concentration reduction and recovery time is given in Appendix A.
Airborne particle concentrations and recovery times are strongly influenced by personnel clothing and other operating conditions (see example in Appendix B).
If there is an area with unidirectional air flow in the room, its effect on air cleanliness should be considered (see Appendix A).
Appendix A (informative). Dependence of particle concentration and recovery time on the air exchange rate
Appendix A
(informative)
The main source of contamination in a clean room is humans. In many cases, emissions of pollutants from equipment and structures are small compared to emissions from humans and can be neglected.
Particle concentration C in indoor air forced ventilation at a point in time t is calculated (in the general case) by the formula
Where C- particle concentration at the initial moment (when the ventilation system is turned on or after pollutants are introduced into the air) t=0, particles/m;
n- intensity of particle emission indoors, particles/s;
V- volume of the room, m;
k- coefficient calculated using formula (A.2);
k- coefficient calculated using formula (A.3).
where is the efficiency coefficient of the ventilation system, for clean rooms with non-unidirectional (turbulent) flow it is assumed = 0.7;
Q- supply air flow, m/s;
q- the volume of air penetrating into the room due to leakage (air infiltration), m/s;
- share of recirculated air;
- efficiency of filtration of recirculated air.
where is the efficiency of outdoor air filtration;
C- concentration of particles in the outside air, particles/m;
C is the concentration of particles in the air entering due to infiltration, particles/m.
Formula (A.1) includes two terms: variable C and permanent C.
C=C+C, (A.4)
Where ,
.
The variable part characterizes the transition process when the concentration of particles in the room air decreases after turning on ventilation or introducing pollutants into the room.
The constant part characterizes the steady-state process in which the ventilation system removes particles generated in the room (by personnel, equipment, etc.) and entering the room from the outside (with the supply air, due to infiltration).
In practical calculations the following is accepted:
- air infiltration equal to zero, q=0;
- filtration efficiency equal to 100%, i.e. =0 and =0.
Then the coefficients are equal
k=
Q=0.7Q,
k=0
Formula (A.1) is simplified
Where N- air exchange rate, h;
Q = N·V.(A.6)
Example A.1 Cleanroom in equipped condition (no personnel, no process in progress)
Consider a clean room with the following parameters:
- volume V =100 m
;
- ISO cleanliness class 7; equipped state; specified particle size 0.5 µm (352000 particles/m
);
0.5 µm indoors
=10
particles/s;
-
WITH
=10
particles/m
, particles with dimensions
0.5 µm;
- air exchange rate N, corresponds to the series 15*, 10, 15, 20, 30;
___________________
- air flow Q, m
/s, calculated using formula (A.6)
where 3600 is the number of seconds in 1 hour;
- the efficiency coefficient of the ventilation system for clean rooms with non-unidirectional (turbulent) flow is accepted
=0,7.
The reduction in particle concentration after time t is calculated using formula (A.5):
Where .
Note - When calculating, time should be expressed in seconds.
The calculation data is given in Table A.1.
Table A.1 - Variation of particle concentration with size
0.5 µm in the air depending on the frequency of air exchange over time in the equipped state
The data in Table A.1 is shown graphically in Figure A.1.*
___________________
* The text of the document corresponds to the original. - Database manufacturer's note.
From Table A.1 and Figure A.1 it is clear that the condition for a recovery time of less than 15-20 minutes (reducing the concentration of particles in the air by 100 times) is met for air exchange rates of 15, 20 and 30 hours
. If we allow the recovery time to be 40 minutes, then the frequency of air exchange can be reduced to 10 hours
. In operation, this means switching ventilation systems to operating mode 40 minutes before starting work.
Figure A.1 - Change in the concentration of particles with sizes of at least 0.5 µm in the air depending on the frequency of air exchange over time in the equipped state
Figure A.1 - Change in particle concentration with size
0.5 µm in the air depending on the frequency of air exchange over time in the equipped state
Example A.2. Clean room in operation
The clean room is the same as in example A.1.
Conditions:
- operating condition;
- number of personnel 4 people;
- intensity of release of particles with sizes
0.5 microns by one person is equal to 10
particles/s (cleanroom clothing is used);
- there is practically no emission of particles from the equipment, i.e. only the emission of particles by personnel is taken into account;
-n
=4·10
particles/s;
- WITH
=10
particles/m
.
Let us calculate the decrease in particle concentration over time using the formulas
,
The calculation results are shown in Table A.2.
Table A.2 - Variation of particle concentration with size
The data in Table A.2 is shown graphically in Figure A.2.
Figure A.2 - Change in the concentration of particles with sizes of at least 0.5 microns in the air depending on the frequency of air exchange over time (clothing for clean rooms is used)
Figure A.2 - Change in particle concentration with size 0.5 microns in the air depending on the frequency of air exchange over time (clean room clothing is used)
As can be seen from example A.2, with an air exchange rate of 10 hours
ISO class 7 is achieved 35 minutes after the ventilation system starts operating (if there are no other sources of pollution). Reliable maintenance of ISO cleanliness class 7 is ensured with a margin at an air exchange rate of 15-20 hours
.
Appendix B (informative). Assessing the impact of clothing on pollution levels
Appendix B
(informative)
Let's consider the effect of clothing on the concentration of particles in the air for the following cases:
- ordinary clothing for clean rooms - jacket/trousers, particle emission rate 10 particles/s;
- high-performance clothing - overalls for clean rooms, particle emission intensity 10 particles/s.
The data in Table B.1 was obtained using the methodology given in Appendix A.
Table B.1 - Concentrations of particles with a size of 0.5 microns in the air for various types of clothing for clean rooms at an air exchange rate of 10 hours
Note - It is assumed that personnel comply with the requirements of hygiene, behavior, dressing and other operating conditions of clean rooms in accordance with GOST R ISO 14644-5.
The data in Table B.1 is shown graphically in Figure B.1.
Figure B.1 - Concentrations of particles with sizes of at least 0.5 microns in the air for various types of clothing at an air exchange rate of 10 h_(-1)
Figure B.1 - Concentrations of particles with sizes of 0.5 microns in the air for various types of clothing at an air exchange rate of 10 hours
From Table B.1 and Figure B.1 it can be seen that the use of high-performance clothing can achieve ISO class 7 cleanliness levels with an air exchange rate of 10 h and a recovery time of 40 minutes (if there are no other sources of contamination).
Bibliography
Cleanroom energy - Code of practice for improving energy in cleanrooms and clean air devices |
||
VDI 2083 Part 4.2 | Cleanroom technology - Energy efficiency, Beuth Verlag, Berlin (April 2011) |
UDC 543.275.083:628.511:006. 354 | OKS 13.040.01; | |
Key words: clean rooms, energy saving, ventilation, air conditioning, air flow, air exchange rate |
||
Electronic document text
prepared by Kodeks JSC and verified against:
official publication
M.: Standartinform, 2015
FAVEA designs, supplies and installs ventilation and air conditioning systems for clean rooms, including control and dispatch units for these systems.
General principles
The main task of ventilation and air conditioning systems is to create and maintain the following parameters in clean rooms:
Air purification
Before being supplied to clean rooms, the air goes through a 4-stage filtration system. Coarse and fine filters are located in the central air conditioner. Ultra-fine filters, the so-called HEPA and ULPA filters, are located directly in the air distributors, i.e. before air enters the clean room. These filters are capable of capturing particles up to 0.01 µm in size.
Laminar air flow
Unidirectional (laminar) air flow is used to create local clean zones. In this flow, air movement occurs in one direction and “displaces” aerosol particles from the clean zone. Also, in a laminar flow there are no turbulences or mixing of air flows, which allows particles to remain in the flow field for a minimum time.
Laminar flow is ensured through the use of special laminar air distributors and laminar ceilings, which are part of the ventilation and air conditioning system.
Central air conditioner for clean rooms
The main element of any ventilation and air conditioning system is a central air conditioner - a device in which complete air preparation is carried out before supplying it to the premises.
For clean rooms, central air conditioners in a special “hygienic” design are used.
A standard central air conditioner consists of a housing that contains the following elements: a set of filters, heat exchangers for heating, cooling and dehumidifying air, a humidifier, fans for supplying air to and removing air from the room.
Automation and dispatching of ventilation and air conditioning systems
To control central air conditioners, as well as the entire ventilation and air conditioning system, the complex provides automatic regulation, control and dispatch systems.
The automatic regulation and control system allows:
- maintain and regulate basic system operating parameters, such as temperature, humidity, fan speed, pressure drops;
- protect the heat exchangers of central air conditioners from freezing during low temperatures outside air;
- signal the occurrence of emergency situations, such as fan failure or the need to replace the filter.
To organize the operation of such systems, various sensors, relays and programmable controllers are mainly used, which are an integral part of any modern ventilation and air conditioning system.
The dispatch system is used to display system operation data from controllers on the screen of a personal computer, with the ability to control from of this computer system parameters.
FAVEA implements dispatch control systems as part of automated systems and integrates with external systems, such as power supply, lighting, fire and security alarms, elevator equipment, etc. Dispatch systems provide, among other functions, multi-level user authorization, storage of parameters of all processes with maximum detail, constant monitoring of communication with controllers, the possibility of remote access via the Internet or local network without special additional software, and a multilingual interface.
Automated systems are built on the basis of modern controllers, sensors, control valves and drives and electrical components from the world's leading manufacturers, such as Siemens, Sauter, Schneider Electric, Eaton, Legrand, Danfoss, Belimo and many others. etc.
Our systems are highly energy efficient due to the great attention paid to the most precise adjustment of regulators, the use of modern control algorithms and the ability to set detailed operating schedules and automatically change set values.
Our specialists have extensive successful experience in solving non-standard automation problems for various equipment, developing concepts and complex control algorithms to satisfy all customer requirements and wishes.
Ventilation of clean rooms is one of the most important tasks in maintaining the working environment. Why does ventilation play such a big role? It is air purification that allows you to regulate the condition of the room, the standards of which are prescribed in GOST. There are several criteria by which a room is classified into one of nine cleanliness classes, each of which is characterized by the degree of air purification from impurities. Therefore, in technologically clean rooms ventilation should be used at several levels.
What should the air be like in a clean room?
Dust and bacteria are contained in any air in the form of aerosol particles. Ventilation of clean rooms allows maintaining the maximum permitted amount of dust and bacteria for a given class of premises.
Draft, dry air or high humidity- enemies of the clean room. Therefore, the ventilation system regulates the air condition, creating optimal conditions for working in this environment.
The air supply is regulated automatically, which means there should be no pressure differences caused by the transition of air from one room to another. Thus, the sterility and tightness of the premises is maintained automatically.
The air purification system in clean rooms is a complex automated group of filters. Clean room air filters are divided into coarse filters, fine filters and microfilters.
The air is filtered from coarse particles, finely purified, and then ultrafinely purified in microfilters. Thus, only air that meets GOST standards enters the room, which means it is 99.9% free from dust and microorganisms.
What is the mechanism of ventilation and air exchange?
In any room, sooner or later foreign impurities accumulate in the form of aerosol particles. A fresh portion of purified air enters the room in such a way that the flow of fresh air displaces impurities. It's called laminar flow, since it is directed in one direction. Several such flows create air exchange in the room. They are directed either parallel to each other, or, as is often the case in large rooms, in different directions so that the flows do not intersect. IN large rooms flows are adjusted so that air flows directly into work area. The air intakes are located lower, and “dirty” air moves towards them thanks to the ventilation created.
Supply and exhaust ventilation system Clean rooms also include heat exchange units and an air humidifier. They create a microclimate that is comfortable for humans and maintains an optimal working environment.
Ventilation allows you to maintain constant temperatures and humidity, eliminates dust and most microorganisms.
