Calculation and monitoring method of air tightness of light-transmitting enclosure structure in Class III biosafety laboratory

Abstract

In view of the fact that the existing biosafety laboratory design methods cannot meet the regulatory requirements after the laboratory is built, and then compensatory measures such as leak detection and repair are required, which ultimately lead to consequences such as delays in work and time, increased comprehensive costs, and because it mainly relies on annual inspections or patrol inspections of the laboratory, the detection results are lagging, and the abnormal air tightness of the enclosure structure of this type of laboratory cannot be discovered in time. The method provides a method for calculating the air tightness of the light-transmitting enclosure structure of a third-level biosafety laboratory, which can avoid the possible failure of the air tightness verification of the biosafety laboratory to meet the regulatory requirements after completion and the resulting trial and error costs and comprehensive construction costs. At the same time, in view of the potential aging and shedding of the sealant used in the light-transmitting enclosure structure or other accidental damage that may cause abnormal air tightness of the laboratory as a whole, the present invention also provides a method for monitoring the air tightness of the light-transmitting enclosure structure of a third-level biosafety laboratory, which is convenient for timely discovery of abnormal air tightness problems of the enclosure structure of the biosafety laboratory. The invention discloses a method for calculating the air tightness of a light-transmitting enclosure structure of a level-three biosafety laboratory, which is characterized in that: the calculation method is based on the level-three biosafety laboratory being suitable for constant pressure detection, and includes an experimental data acquisition module and a design numerical calculation module; the method for monitoring the air tightness of a light-transmitting enclosure structure of a level-three biosafety laboratory includes an operation data analysis module.

Description

Technical Field

[0001] The invention relates to the technical field of air tightness control and monitoring of biosafety laboratory enclosure structures, in particular to an air tightness calculation and monitoring method for a light-transmitting enclosure structure of a level-three biosafety laboratory. Background Art

[0002] For Class III biosafety laboratories (i.e. Class B2 Class III biosafety laboratories) that cannot effectively utilize safety isolation devices to operate conventional amounts of airborne pathogenic biological factors, the good air tightness of their enclosure structures is an important guarantee for laboratory biosafety. Generally speaking, the enclosure structures of such laboratories are made of seamless and fully welded stainless steel composite plates to meet the mandatory requirements for air tightness verification of their enclosure structures. For specific use needs such as visits and natural lighting, when large-area unit combined light-transmitting enclosure components (such as airtight glass curtain walls, multi-sash combined airtight windows, single-sash airtight windows, airtight light-transmitting roofs, etc.) are used in such laboratories (i.e. Class B2 ABSL-3 laboratories) or in greenhouses of high-level plant biosafety laboratories (PBSL) with the same protection requirements, the overall air tightness of the laboratory will inevitably be affected by the airtightness of the light-transmitting enclosure components. The existing methods mainly rely on the "constant pressure method" after construction to test whether the overall air tightness of the laboratory meets the requirements of the specifications. This post-evaluation method objectively has the risk of not meeting the requirements of the specifications after construction, and then compensatory measures such as leak detection and repair are required, which ultimately leads to delays in work and time, increased comprehensive costs and other consequences. The "constant pressure method" detection process must strictly follow the relevant provisions of the "General Requirements for Laboratory Biosafety GB19489", and professional personnel and professional equipment must perform mechanical pressurization through the reserved pressure port, and the process requires the suspension of laboratory use, which is inefficient and undoubtedly increases the cost of detection and operation. In addition, since this process mainly relies on annual inspections or patrol inspections of the laboratory, its test results are lagging, and the abnormal state of the air tightness of the enclosure structure of this type of laboratory cannot be discovered in time. Summary of the invention

[0003] In view of the fact that the existing biosafety laboratory design methods cannot meet the regulatory requirements after the laboratory is built, and then compensatory measures such as leak detection and repair are required, which ultimately lead to consequences such as delays in work and time, increased comprehensive costs, and because it mainly relies on annual inspections or patrol inspections of the laboratory, the detection results are lagging, and the abnormal air tightness of the enclosure structure of this type of laboratory cannot be discovered in time. The method provides an air tightness calculation method for the light-transmitting enclosure structure of the third-level biosafety laboratory, which can avoid the possible failure of the air tightness verification of the biosafety laboratory to meet the regulatory requirements after completion and the resulting trial and error costs and comprehensive construction costs. At the same time, in view of the potential aging and shedding of the sealant used in the light-transmitting enclosure structure or other accidental damage that may cause abnormal air tightness of the laboratory as a whole, the present invention also provides an air tightness monitoring method for the light-transmitting enclosure structure of the third-level biosafety laboratory, which is convenient for timely discovery of abnormal air tightness problems of the enclosure structure of the biosafety laboratory.

[0004] The technical solution is as follows:

[0005] A method for calculating the air tightness of a light-transmitting enclosure structure of a level-three biosafety laboratory, characterized in that: the calculation method is based on the level-three biosafety laboratory being suitable for constant pressure method detection, and includes an experimental data acquisition module and a design numerical calculation module;

[0006] In the experimental data acquisition module, first, the volume V1 of the biosafety laboratory is obtained according to the design drawings of the laboratory, and the volume should include the volume of the air supply and exhaust ducts directly connected to the laboratory and to the closed valve; the sum of the volumes occupied by the facilities and equipment in the laboratory is calculated as V2, including the physical volume of the biosafety cabinet used, the physical volume of the culture rack, the volume occupied by the indoor part of the transfer window, the physical volume of the laboratory table and the volume of other equipment and facilities; then, the hourly leakage rates T1, T2, T3, T4, etc. of the equipment and components with leakage such as airtight doors, transfer windows, through-wall seals, and biosafety closed valves under a pressure difference of 250Pa are obtained through experimental testing or data provided by the manufacturer. The specific testing method is carried out in accordance with industry specifications, and the known biosafety laboratories are traversed to obtain the number N1, N2, N3, N4, etc. of equipment components such as airtight doors, transfer windows, through-wall seals, and biosafety closed valves. The leakage from the high-efficiency filter box and the biosafety closed valve to the laboratory pipeline is extremely small and can be ignored. The laboratory air pressure value P and the air temperature value T are recorded during the test. T is maintained as the upper limit of the indoor design temperature of the Class III biosafety laboratory.

[0007] The design of the numerical calculation module includes the following three steps:

[0008] According to the requirements of air tightness verification of Class III b2 biosafety laboratories, that is, Tf ≤ 10% (Tf is the hourly leakage rate, which represents the ratio of the air volume leaking through the gaps in the enclosure structure to the laboratory volume within a given time), calculate the allowable leakage volume Qy of a known biosafety laboratory;

[0009] Obtain the leakage air volume Q of the non-light-transmitting enclosure structure of a known biosafety laboratory under a given pressure difference f :

[0010]

[0011] Where Ti is the hourly leakage rate of equipment component i with leakage on the non-light-transmitting enclosure structure, and Ni is the number of such equipment components.

[0012] When it is known that the biosafety laboratory adopts a unit-combined light-transmitting enclosure structure, the airtightness index per unit area under the pressure difference of 250Pa is set as QA, and the surface area of ​​the gap of the light-transmitting enclosure structure is A (based on indoor measurement). Then, under the constant pressure test condition, the airtightness of the light-transmitting enclosure part and its area have the following inequality:

[0013] QA·A≤Qy-Q f

[0014] At this time, QA is the calculated value under the pressure difference of 250Pa. For the light-transmitting enclosure unit i with the same structure and the same method, its air permeability characteristics are constant, that is, the flow coefficient c and the flow index b are constant. Through the power exponential equation Q = c i △p bi The relationship between the air permeability QA' and QA of the light-transmitting enclosure unit when the pressure difference is 100Pa can be obtained:

[0015]

[0016] Where b i It is the flow index of the unit combined light-transmitting enclosure structure used, which is related to the flow velocity and flow state of the gas passing through the gap, and its value is between 0.5 and 1.0.

[0017] Then convert the result to standard state:

[0018]

[0019] Then, the air tightness index of the light-transmitting enclosure structure is calculated under the pressure difference of 10Pa. Integrating the above formulas, we can get:

[0020]

[0021] Where, qa is the known air tightness index per unit area of ​​the light-transmitting enclosure of the Class III biosafety laboratory, A is the surface area of ​​the light-transmitting enclosure structure, in square meters, P is the laboratory air pressure value during the test (in kPa), T is the laboratory air temperature value during the test (in K), V1 and V2 are in m3, T1, T2, T3, and T4 are the hourly leakage rates of airtight doors, transfer windows, through-wall closures, and biosafety closed valves, and b i It is the flow index of the unit combined light-transmitting enclosure structure used, and its value is between 0.5 and 1.0.

[0022] The above inequality relationship between qa and A as unknowns can provide designers with a design basis to control the surface area index A and unit area air tightness index qa of the known third-level biosafety laboratory translucent enclosure part, so as to ensure that the air tightness of the translucent enclosure structure meets the air tightness verification requirements of this type of biosafety laboratory;

[0023] The method for monitoring the air tightness of a light-transmitting enclosure structure of a Class III biosafety laboratory includes an operation data analysis module, which is characterized in that the operation data analysis module includes the following steps:

[0024] At the air supply and exhaust terminals of the Class III biosafety laboratory, high-precision flow meters (in L / min) are installed as close to the room as possible. When the laboratory is in a static state, that is, when the laboratory is completed, the process equipment is installed, the ventilation and air-conditioning system and equipment are operating normally but no one is operating, all passages except the air supply and exhaust vents (such as doors, transfer windows, etc.) are closed, and the air pressure in the rooms around the laboratory is ensured to be P and the temperature is T, and this state is maintained. In the early stage of the laboratory's construction, the flow index b value of the laboratory as a whole is obtained through multiple pressure tests. After the laboratory is officially put into use, when the laboratory is in a static state, that is, when the laboratory is completed, the process equipment is installed, the flow index b value of the laboratory as a whole is obtained through multiple pressure tests. When the air conditioning system and equipment are operating normally but no one is operating, close all passages (such as doors, transfer windows, etc.) except the supply and exhaust vents and ensure that the air pressure in the rooms around the laboratory is P and the air temperature is T. Maintain this state, monitor the values ​​online in real time and record them as Qs and Qp respectively. Use indoor temperature and pressure sensors to record the air temperature T0 and relative pressure difference P0 from 5 minutes to 10 minutes of the detection period. P0 and T0 are maintained at the upper limit of the design working value. Under this pressure difference condition, the hourly leakage air volume through the gap of the enclosure structure is Q = (Qp-Qs) × 60 / 1000; convert Q to the infiltration air volume Q' under the pressure difference condition of 250Pa through the power exponential equation, then This process can capture a portion of the time period for data collection each time the laboratory is started or before it is closed. When Q'>Qy appears continuously and stably, it indicates that the air tightness of the laboratory enclosure structure is abnormal and there is a potential risk of biosafety leakage. This process is analyzed online by the calculation program set by the computer data processing system of the laboratory monitoring and early warning center, and real-time display and alarm are displayed.

[0025] In view of the potential demand for the application of larger area translucent enclosure structures in Class III biosafety laboratories or the design and construction of plant biosafety greenhouses with the same protection requirements, this application aims to meet the airtightness verification. Through rigorous calculation processes and methods, the area index and airtightness index of the translucent enclosure structure are determined to guide the design and construction of such laboratories, reduce the risk of trial and error, and avoid the cost of trial and error. This method is targeted and operational.

[0026] At the same time, a monitoring method for abnormal air tightness of the enclosure structure of this type of laboratory is provided. Through real-time monitoring and online analysis of the laboratory supply and exhaust air volume, abnormal laboratory air tightness can be discovered in time without affecting the normal operation of the laboratory and without the need for mechanical pressure testing by professional inspectors, effectively ensuring laboratory biosafety with convenience and timeliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a block diagram of the method for calculating and monitoring the air tightness of the light-transmitting enclosure structure of a Class III biosafety laboratory suitable for constant pressure method detection in the present invention;

[0028] Figure 2 This is a schematic diagram of the greenhouse layout of a Class III plant biosafety laboratory suitable for constant pressure testing;

[0029] Figure 3 This is a schematic diagram of the cross-section of the greenhouse enclosure structure of the Level 3 plant biosafety laboratory.

[0030] In the figure: 1 airtight door, 2 transfer window, 3 wall-penetrating sealing part, 4 biosafety sealing valve, 5 high-precision flow meter, 6 differential pressure sensor, 7 temperature sensor, 8 light-transmitting enclosure component (glass component). DETAILED DESCRIPTION

[0031] The method for calculating the air tightness of the light-transmitting enclosure structure of the third-level biosafety laboratory of the present invention is characterized in that: the calculation method is based on the third-level biosafety laboratory being suitable for constant pressure method detection, and includes an experimental data acquisition module and a design numerical calculation module;

[0032] In the experimental data acquisition module, firstly, the volume V1 of the biosafety laboratory is obtained according to the design drawings of the laboratory. The volume should include the volume of the air supply and exhaust pipes directly connected to the laboratory and to the closed valve; the sum of the volumes occupied by the facilities and equipment in the laboratory is calculated as V2, including the physical volume of the biosafety cabinet, the physical volume of the culture rack, the volume occupied by the indoor part of the transfer window, the physical volume of the laboratory table and the volume of other equipment and facilities; then, the hourly leakage rates T1, T2, T3, T4, etc. of the equipment and components with leakage such as airtight doors, transfer windows, through-wall seals, and biosafety closed valves under the pressure difference of 250Pa are obtained through experimental testing or data provided by the manufacturer. The specific testing method is implemented in accordance with the industry specifications, and the known biosafety laboratories are traversed to obtain the number of equipment components such as airtight doors, transfer windows, through-wall seals, and biosafety closed valves N1, N2, N3, N4, etc. The leakage of the pipeline from the high-efficiency filter box and the biosafety closed valve to the laboratory is extremely small and can be ignored. The test room air pressure value P and air temperature value T are recorded during the test. T is maintained as the upper limit of the indoor design temperature of the Class III biosafety laboratory.

[0033] The design of the numerical calculation module includes the following three steps:

[0034] According to the requirements of air tightness verification of Class III b2 biosafety laboratories, that is, Tf ≤ 10% (Tf is the hourly leakage rate, which represents the ratio of the air volume leaking through the gaps in the enclosure structure to the laboratory volume within a given time), Tf is taken as 10%, and the allowable leakage Qy of a known biosafety laboratory is calculated;

[0035] Obtain the leakage air volume Q of the non-light-transmitting enclosure structure of a known biosafety laboratory under a given pressure difference f :

[0036]

[0037] Where Ti is the hourly leakage rate of equipment component i with leakage on the non-light-transmitting enclosure structure, and Ni is the number of such equipment components.

[0038] When it is known that the biosafety laboratory adopts a unit-combined light-transmitting enclosure structure, the airtightness index per unit area under the pressure difference of 250Pa is set as QA, and the surface area of ​​the gap of the light-transmitting enclosure structure is A (based on indoor measurement). Then, under the constant pressure test condition, the airtightness of the light-transmitting enclosure part and its area have the following inequality:

[0039] QA·A≤Qy-Q f

[0040] At this time, QA is the calculated value under the pressure difference of 250Pa. For the light-transmitting enclosure unit i with the same structure and the same method, its air permeability characteristics are constant, that is, the flow coefficient c and the flow index b are constant. Through the power exponential equation Q = c i △p bi The relationship between the air permeability QA' and QA of the light-transmitting enclosure unit when the pressure difference is 100Pa can be obtained:

[0041]

[0042] Where b i It is the flow index of the unit combined light-transmitting enclosure structure used, which is related to the flow velocity and flow state of the gas passing through the gap, and its value is between 0.5 and 1.0.

[0043] Then convert the result to standard state:

[0044]

[0045] Then, the air tightness index of the light-transmitting enclosure structure is calculated under the pressure difference of 10Pa. Integrating the above formulas, we can get:

[0046]

[0047] Where, qa is the known air tightness index per unit area of ​​the light-transmitting enclosure of the Class III biosafety laboratory, A is the surface area of ​​the light-transmitting enclosure structure, in m2, P is the laboratory air pressure value during the test (in kPa), T is the laboratory air temperature value during the test (in K), V1 and V2 are in m3, T1, T2, T3, and T4 are the hourly leakage rates of airtight doors, transfer windows, through-wall closures, and biosafety closed valves, dimensionless, and b i It is the flow index of the unit combined light-transmitting enclosure structure used, and its value is between 0.5 and 1.0.

[0048] The above inequality relationship between qa and A as unknowns can provide designers with a design basis to control the surface area index A and unit area air tightness index qa of the known third-level biosafety laboratory translucent enclosure part, so as to ensure that the air tightness of the translucent enclosure structure meets the air tightness verification requirements of this type of biosafety laboratory;

[0049] The method for monitoring the air tightness of a light-transmitting enclosure structure of a Class III biosafety laboratory includes an operation data analysis module, and the operation data analysis module includes the following steps:

[0050] High-precision flow meters (in L / min) are installed at the ends of the air supply and exhaust of the Class III biosafety laboratory (as close to the room as possible). When the laboratory is in a static state, that is, when the laboratory is completed, the process equipment is installed, the ventilation and air-conditioning system and equipment are operating normally but no personnel are operating, all passages except the air supply and exhaust vents (such as doors, transfer windows, etc.) are closed and the air pressure in the rooms around the laboratory is ensured to be P and the temperature is T. This state is maintained. In the early stage of the construction of the laboratory, the flow index b value of the laboratory as a whole is obtained through multiple pressure tests.

[0051] After the laboratory is officially put into use, when the laboratory is in a static state, that is, when the laboratory is completed, the process equipment is installed, the ventilation and air-conditioning system and equipment are operating normally but no personnel are operating, all other passages (such as doors, transfer windows, etc.) except the supply and exhaust vents are closed, and the air pressure in the rooms around the laboratory is ensured to be P and the air temperature is T. This state is maintained, and the values ​​are monitored online in real time and recorded as Qs and Qp respectively. The air temperature T0 and relative pressure difference P0 in the detection period of 5 minutes to 10 minutes are recorded by indoor temperature and pressure sensors. P0 and T0 are maintained at the upper limit of the design working value. Under this pressure difference condition, the hourly leakage air volume through the gap of the enclosure structure is Q = (Qp-Qs) × 60 / 1000; Q is converted into the infiltration air volume Q' under the pressure difference condition of 250Pa through the power exponential equation, then This process can capture a portion of the time period for data collection each time the laboratory is started or before it is closed. When Q'>Qy appears continuously and stably, it indicates that the air tightness of the laboratory enclosure structure is abnormal and there is a potential risk of biosafety leakage. This process is analyzed online by the calculation program set by the computer data processing system of the laboratory monitoring and early warning center, and real-time display and alarm are displayed.

[0052] The airtightness calculation method and airtightness monitoring method of the present invention are further described below in conjunction with the accompanying drawings and embodiments. The objects and scenarios targeted by this method are biosafety laboratories that need to use the "constant pressure method" to verify airtightness, and such laboratories use large-area non-openable unit combined light-transmitting enclosure components. The objects involved include Class III B2 biosafety laboratories and high-level plant biosafety laboratories with the same protection requirements. The light-transmitting enclosure components involved include non-openable unit combined airtight glass curtain walls or combined fixed airtight windows, non-openable unit combined airtight light-transmitting roofs, etc.

[0053] The invention comprises three main modules: experimental data acquisition, design numerical calculation and operation data analysis.

[0054] Data collection, first obtain the volume V1 according to the design drawings of this type of biosafety laboratory, such as Figure 2 As shown, taking the high-risk plant greenhouse 2 as an example, its net length and net width are 7.1m and 5.0m respectively, the net height of the ceiling is 2.8m, and the volume is 99.4m3, plus the volume of the pipeline between the closed valve is 99.5m3; the sum of the volumes occupied by the facilities and equipment entities in the laboratory is obtained from the corresponding experimental facility equipment manufacturers, calculated as V2, such as from the plane Figure 2 , which includes the physical volume of the culture rack, the physical volume of the lamp and the physical volume of the equipment belt, which is calculated as 0.9m3. The volume calculation should be as refined as possible.

[0055] Obtained through experimental testing or data provided by manufacturers Figure 3 The hourly leakage rates T1, T2, T3, and T4 of the existing airtight door 1, transfer window 2, through-wall seal 3, and biosafety seal valve 4 under the pressure difference of 250Pa are obtained, and the specific detection methods are carried out in accordance with the corresponding standards and specifications. During the detection, ensure that the gap sealing treatment is consistent with the actual project. The leakage of the high-efficiency filter box and the biosafety seal valve to the laboratory pipeline is extremely small, and this application ignores it. The ambient air pressure value during the detection is recorded as P = 101.1 kPa, and the air temperature value is T. T is 25°C, which is the upper limit of the indoor design temperature of the third-level biosafety laboratory. The airtight door T1, transfer window T2, through-wall seal T3, and biosafety seal valve T4 are obtained as 0.75%, 0.50%, 0.25%, and 0.25%, respectively. Traverse the known biosafety laboratories to obtain 1 airtight door, 1 transfer window, 2 through-wall seals, and 2 biosafety seal valves.

[0056] Design Numerical Calculation

[0057] According to the requirements for air tightness verification of Class III b2 biosafety laboratories (Tf≤10%, Tf is the hourly leakage rate, which represents the ratio of the air volume leaked through the enclosure structure to the laboratory volume within a given time), the allowable leakage volume Qy of a known biosafety laboratory is calculated, and its calculated value is:

[0058] Qy=T f (V1-V2) = 9.86m3 / h

[0059] See Figure 2 , Figure 3 The laboratory is equipped with one airtight door, one transfer window, two through-wall seals, and two biosafety seal valves. The leakage air volume Q of the non-light-transmitting enclosure structure of a known biosafety laboratory under a given pressure difference is obtained. f , which is calculated as:

[0060] Q f =(V1-V2)·(T1+T2+2×T3+2×T4)=2.2185m3 / h

[0061] Where Qf is in m3 / h, T1, T2, T3 and T4 are the hourly leakage rates.

[0062] When it is known that the biosafety laboratory adopts a unit-combined non-openable light-transmitting enclosure structure 8, under the pressure difference of 250Pa, the air tightness index per unit area is set as QA, and the surface area is A (which can be calculated based on the plane drawing). Then, under the constant pressure test condition, the air tightness of the light-transmitting enclosure part and its area have the following inequality:

[0063] QA·A≤Qy-Q f

[0064] At this time, QA is the calculated value under the pressure difference of 250Pa. For the light-transmitting enclosure unit i with the same structure and the same method, its air permeability characteristics are constant, that is, the flow coefficient c and the flow index b are constant. Through the power exponential equation Q = c i △p bi The air permeability QA' and QA of the light-transmitting enclosure unit when the pressure difference is 100Pa can be obtained, and the following relationship exists:

[0065]

[0066] This formula can be transformed into:

[0067] QA=2.5 bi ×QA'

[0068] Where b iis the flow index of the unit combined light-transmitting enclosure structure used, which is related to the flow rate and flow state of the gas passing through the gap, and the value is between 0.5 and 1.0. Here, bi is taken as 0.75 (the specific value depends on the specific product and is given by the professional manufacturer). Then convert the result into the standard state:

[0069]

[0070] Under the pressure difference of 10Pa, Integrating the above formulas, we can get:

[0071]

[0072] In the formula, qa is the airtightness index per unit area of ​​the light-transmitting enclosure of the known third-level biosafety laboratory, A is the overall area of ​​the light-transmitting enclosure structure used, and the surface area of ​​the light-transmitting enclosure component is 2.7×6.6+2.4×6.6=33.66㎡, P is the laboratory air pressure value during the test (unit kPa), which is 101.1kPa, T is the laboratory air temperature value during the test, which is 298.15K, V1 and V2 are 99.5m3 and 0.9m3 respectively, and the hourly leakage rates of the airtight door T1, the transfer window T2, the indoor wall panel seam T3, and the pipeline wall sealing piece T4 are obtained as 0.75%, 0.50%, 0.25%, and 0.25% respectively. Traversing the known biosafety laboratory, 1 airtight door, 1 transfer window, 2 wall sealing pieces, and 2 biosafety sealing valves are obtained. b i is the flow index of the unit combined light-transmitting enclosure structure used, where b i Take 0.75 (the specific value depends on the specific product and is given by professional manufacturers). Substituting the numerical value into the formula, we can get:

[0073] qa×A≤17.5287

[0074] When A=33.66㎡, it is calculated that qa≤0.5208m3 / (h·㎡), which is the allowable value of the air tightness index of the light-transmitting enclosure structure. If this value is exceeded, the overall air tightness of the laboratory will be difficult to meet the 10% hourly leakage rate required by the specification. A certain amount of redundancy is generally reserved during design, so the air tightness index value of the light-transmitting enclosure structure should be slightly smaller than the calculated value.

[0075] The above inequality about the surface area A of the light-transmitting enclosure component and the air-tightness index qa is used to provide a design basis for designers, and then the area index A and the air-tightness index per unit area qa of the light-transmitting enclosure part of the known third-level biosafety laboratory are controlled to ensure that the light-transmitting enclosure structure meets the air-tightness verification requirements of this type of biosafety laboratory.

[0076] 1. Run data analysis:

[0077] High-precision flow meters (unit L / min) are installed at the ends of the air supply and exhaust of the Class III biosafety laboratory (as close to the room as possible). When the laboratory is in a static state (referring to the state when the laboratory is built, the process equipment is installed, the ventilation and air conditioning system and equipment are operating normally but no personnel are operating), all other passages (such as doors, transfer windows, etc.) except the air supply and exhaust vents are closed and the air pressure in the surrounding rooms of the laboratory is ensured to be P and the air temperature is T, that is, the atmospheric pressure is 101.1 kPa and the air temperature is 298.15 K, and this state is maintained. When the temperature T1 inside the laboratory remains unchanged, when the pressure difference between the indoor and outdoor is P1 = 40Pa and P2 = 80Pa, the difference between the air supply and exhaust volume per unit time of the laboratory is obtained and recorded as Q1 and Q2 respectively, Q1 is 1.896m3 / h, and Q2 is 3.301m3 / h. This process is carried out in the early stage of the laboratory construction. We assume that the sealing performance of the sealant has not changed, that is, the overall air tightness of the laboratory enclosure structure has not changed. The following relationship exists through the power exponential equation:

[0078]

[0079] The flow index b value of the laboratory enclosure structure as a whole can be obtained through this relationship. The average value of the b value can be obtained through multiple times of the above-mentioned pressure difference transformation process. At this time, the b value is 0.800.

[0080] After the laboratory has been put into use for a period of time, as the airtightness of the equipment (such as airtight doors and transfer windows) deteriorates or the sealant of the light-transmitting enclosure fails due to aging or other unexpected circumstances, the difference between the supply and exhaust air volume of the laboratory will gradually expand. When the laboratory is in a static state (referring to the state when the laboratory is completed, the process equipment is installed, the ventilation and air-conditioning system and equipment are operating normally but no personnel are operating), close all other passages except the supply and exhaust vents (such as doors, transfer windows, etc.) and ensure that the air pressure in the rooms around the laboratory is P and the air temperature is T. Maintain this state, monitor the values ​​online in real time and record them as Qs and Qp respectively. The air temperature and relative pressure difference during the monitoring time period (5 to 10 minutes) are recorded by indoor temperature and pressure sensors. During the time period, they remain unchanged at the design working values ​​T0 and P0 specified in the specification. At this time, T0=T=25℃, P0=P1=40Pa, then the air volume leaking through the gaps in the enclosure structure under this pressure difference condition is Q was measured to be 2.424m3.

[0081] The power exponential equation is used to convert Q into the infiltration air volume Q' under the pressure difference of 250Pa. The calculated value of Q' = 10.501m3 is greater than the allowable leakage of the laboratory. This process can be performed by intercepting a part of the time period for data collection after each laboratory startup or before shutdown. When Q'>Qy appears continuously and stably, it indicates that the air tightness of the laboratory enclosure structure is abnormal and there is a potential risk of biosafety leakage. This process is automated through online analysis, real-time display and alarming by the calculation program set by the computer data processing system of the laboratory monitoring and early warning center.

[0082] Figure 3 Among them, 10 is the downward delivery and upper side return air duct in the low temperature zone, 11 is the downward delivery and upper side return air duct in the normal temperature zone, 12 is the downward delivery and upper side return air duct in the high temperature zone, 13 is the negative pressure corridor, 14 is the high-risk plant laboratory 1, 15 is the high-risk plant laboratory 2, 16 is the high-risk plant laboratory 3, 17, 18, 19, and 22 are buffer zones respectively, and 9, 20, and 21 are duct aisles respectively.

Claims

1. The calculation method of air tightness of the light-transmitting enclosure structure of the third-level biosafety laboratory is characterized by: The calculation method is based on the three-level biosafety laboratory being suitable for constant pressure detection, and includes an experimental data acquisition module and a design numerical calculation module; In the experimental data acquisition module, first, the volume V1 of the biosafety laboratory is obtained according to the design drawings of the laboratory, and the volume should include the volume of the air supply and exhaust ducts directly connected to the laboratory and to the closed valve; the sum of the volumes occupied by the facilities and equipment in the laboratory is calculated as V2, including the physical volume of the biosafety cabinet used, the physical volume of the culture rack, the volume occupied by the indoor part of the transfer window, the physical volume of the laboratory table and the volume of other equipment and facilities; then, the hourly leakage rates T1, T2, T3, T4, etc. of the equipment and components with leakage such as airtight doors, transfer windows, through-wall seals, and biosafety closed valves under a pressure difference of 250Pa are obtained through experimental testing or data provided by the manufacturer. The specific testing method is carried out in accordance with industry specifications, and the known biosafety laboratories are traversed to obtain the number N1, N2, N3, N4, etc. of equipment components such as airtight doors, transfer windows, through-wall seals, and biosafety closed valves. The leakage from the high-efficiency filter box and the biosafety closed valve to the laboratory pipeline is extremely small and can be ignored. The laboratory air pressure value P and the air temperature value T are recorded during the test. T is maintained as the upper limit of the indoor design temperature of the Class III biosafety laboratory. The design of the numerical calculation module includes the following three steps: According to the requirements of air tightness verification of Class III b2 biosafety laboratories, that is, Tf ≤ 10% (Tf is the hourly leakage rate, which represents the ratio of the air volume leaking through the gaps in the enclosure structure to the laboratory volume within a given time), calculate the allowable leakage volume Qy of a known biosafety laboratory; Obtain the leakage air volume Q of the non-light-transmitting enclosure structure of a known biosafety laboratory under a given pressure difference f : Where Ti is the hourly leakage rate of equipment component i with leakage on the non-light-transmitting enclosure structure, and Ni is the number of such equipment components. When it is known that the biosafety laboratory adopts a unit-combined light-transmitting enclosure structure, the airtightness index per unit area under the pressure difference of 250Pa is set as QA, and the surface area of ​​the gap of the light-transmitting enclosure structure is A (based on indoor measurement). Then, under the constant pressure test condition, the airtightness of the light-transmitting enclosure part and its area have the following inequality: QA·A≤Qy-Q f At this time, QA is the calculated value under the pressure difference of 250Pa. For the light-transmitting enclosure unit i with the same structure and the same method, its air permeability characteristics are constant, that is, the flow coefficient c and the flow index b are constant. Through the power exponential equation Q = c i △p bi The relationship between the air permeability QA' and QA of the light-transmitting enclosure unit when the pressure difference is 100Pa can be obtained: Where b i It is the flow index of the unit combined light-transmitting enclosure structure used, which is related to the flow velocity and flow state of the gas passing through the gap, and its value is between 0.5 and 1.

0. Then convert the result to standard state: Then, the air tightness index of the light-transmitting enclosure structure is calculated under the pressure difference of 10Pa. Integrating the above formulas, we can get: Where, qa is the known air tightness index per unit area of ​​the light-transmitting enclosure of the Class III biosafety laboratory, A is the surface area of ​​the light-transmitting enclosure structure, in square meters, P is the laboratory air pressure value during the test (in kPa), T is the laboratory air temperature value during the test (in K), V1 and V2 are in m3, T1, T2, T3, and T4 are the hourly leakage rates of airtight doors, transfer windows, through-wall closures, and biosafety closed valves, and b i It is the flow index of the unit combined light-transmitting enclosure structure used, and its value is between 0.5 and 1.

0. The above-mentioned inequality formula with qa and A as unknowns can provide designers with a design basis to control the surface area index A and the air tightness index qa per unit area of ​​the light-transmitting enclosure part of the known third-level biosafety laboratory, so as to ensure that the air tightness of the light-transmitting enclosure structure meets the air tightness verification requirements of this type of biosafety laboratory.

2. A method for monitoring the air tightness of a light-transmitting enclosure structure of a Class III biosafety laboratory, comprising an operation data analysis module, characterized in that: The operation data analysis module comprises the following steps: At the end of the air supply and exhaust of the Class III biosafety laboratory, high-precision flow meters (in L / min) are installed as close to the room as possible. When the laboratory is in a static state, that is, when the laboratory is completed, the process equipment is installed, the ventilation and air-conditioning system and equipment are operating normally but no personnel are operating, all other passages except the air supply and exhaust vents (such as doors, transfer windows, etc.) are closed and the air pressure in the surrounding rooms of the laboratory is P and the temperature is T. This state is maintained. In the early stage of the construction of the laboratory, the flow index b value of the laboratory as a whole is obtained through multiple pressure tests. After the laboratory is officially put into use, when the laboratory is in a static state, that is, when the laboratory is completed, the process equipment is installed, the ventilation and air-conditioning system and equipment are operating normally but no personnel are operating, all other passages (such as doors, transfer windows, etc.) except the supply and exhaust vents are closed, and the air pressure in the rooms around the laboratory is ensured to be P and the air temperature is T. This state is maintained, and the values ​​are monitored online in real time and recorded as Qs and Qp respectively. The air temperature T0 and relative pressure difference P0 in the detection period of 5 minutes to 10 minutes are recorded by indoor temperature and pressure sensors. P0 and T0 are maintained at the upper limit of the design working value. Under this pressure difference condition, the hourly leakage air volume through the gap of the enclosure structure is Q = (Qp-Qs) × 60 / 1000; Q is converted into the infiltration air volume Q' under the pressure difference condition of 250Pa through the power exponential equation, then This process can capture a portion of the time period for data collection each time the laboratory is started or before it is closed. When Q'>Qy appears continuously and stably, it indicates that the air tightness of the laboratory enclosure structure is abnormal and there is a potential risk of biosafety leakage. This process is analyzed online by the calculation program set by the computer data processing system of the laboratory monitoring and early warning center, and real-time display and alarm are displayed.

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