本帖最后由 老张 于 2013-11-19 06:19 编辑
A SMALL FOOD MICROBIOLOGICAL TESTING LABORATORY
The general guidelines for design of the chemical laboratories apply to microbiology laboratories too. However, the microbiology laboratory design needs special attention due to the nature of the test material handled. The design of a microbiology laboratory needs to pay attention to the following general characteristics of microorganisms: The microorganisms are invisible; they could be present in the air, on various surfaces or carried by humans working in the laboratory; and they could grow into large populations, since they are live and active entities. When testing microorganisms, the laboratories provide highly conducive conditions for microbial growth. The laboratories therefore need to develop techniques to manage areas of high microbial populations, precautionary controls to prevent their release into environment, and mechanisms to prevent them entering aseptically protected areas. The initial design of a microbiology laboratory therefore needs to include the physical separation of spaces to carryout functions and to meet the environmental and other requirements identified in Table 1.
Table 1- Basic physical infrastructure requirements for a microbiological testing laboratory
Identity & space (square metre) [min-max] | | | Testing laboratory [30-50] | | Temperature and humidity controlled; maintain specified microbiological quality of air; used by staff only during testing; floor and bench surfaces cleaned on a daily basis; house testing equipment only. | Media Preparation room [15-25] | Preparation of microbiological media & storage | Meet the conditions specified above for testing laboratory; house media preparation equipment only; may include storage facility for unused microbiological media. | | | Temperature maintained below 33 degrees Celsius; house only incubators operating at temperatures between 10 to 45 degrees Celsius; microbiological quality of air monitored less rigorously. | Reference culture room [10] | Maintaining reference cultures | Temperature and humidity controlled; maintain specified microbiological quality of air; used only for reference culture work; floor and bench surfaces cleaned before and after work each time; house lamina hood and a refrigerator. | Decontamination room [15-25] | Washing and decontaminating glassware | House only washing and decontamination equipment; cleaned on daily basis; disposal of used test materials after decontamination on a daily basis. | Reference culture maintenance room [10-15] | Maintaining reference cultures | House only a lamina hood used solely for this purpose and a refrigerator to keep the cultures under storage. | Sample receipt room [15-25] | | Conveniently located for public access and away from testing laboratories, with a refrigerator and a freezer. | Tested sample store [15-20] | | Located away from testing facilities, with refrigerator and freezer. | Store room for purchased media [0-10] | | Temperature controlled around 15 degrees Celsius; may use cupboards in the media preparation room in small laboratories. | | | Handling all the documents with communication and printing facilities; need to carry safety lockers to store test reports and confidential documents. | | | Room for the technical manager with visibility to testing laboratories through transparent partitioning. | | | Room for staff to rest and carry on duties when not engaged in bench work | | | Space to keep cleaning equipment for the laboratories | | | On the passage to the testing laboratories | Wash room facilities [15-20] | | Separate female and male facilities at a ratio of 1 unit per 8 staff members |
Development and layout
It is important in developing a laboratory and preparing the layout to recognize the required work capacity of the laboratory, the number of staff engaged in testing, the services (electricity, water, gas) required and the mechanisms to control inadvertent release of microorganisms to the environment as well as cross contaminations. Two layouts for a small capacity laboratory and an optimal capacity laboratory are described below.
General guidelines for a small microbiological testing laboratory Where funds and human resource are limited, it is advisable to establish microbiological laboratories of minimum capacity, with the possibility of future expansion as demand and funds increase. Three essential separate works spaces need to be identified, and an office space. Small laboratories will expect to have around four technical staff. Let us take a microbiological testing laboratory with a minimal capacity of 70 sq. m. It will have a separate room in the vicinity which allows public access for receiving and storing samples. This room may be adjacent to the laboratory or some distance from it, depending on the general layout of the institution and its areas of public access. The sample receipt room may serve as a common facility for other testing laboratories (chemical etc). The space suggested for each activity in a small laboratory is as follows:
| | | | | | Washing/decontamination room | | | | | | | |
The layout plan in (Fig. 1) shows an arrangement of the different areas used to carryout functions preventing contamination. There are locations for the main testing laboratory, a media preparation room, glassware washing and an office and other facilities. The design specifications are given below in Fig 1-4. The planned testing laboratory is 5.5 x 4.5 meters. The media preparation room and the glassware washing room, the office room and changing room need to be separated as indicated in Fig. 1. The guidelines given below indicate the constructions and modifications required to meet the technical standards expected in a testing laboratory.
◆ Partition the area as indicated in Fig 1 using aluminium and glass paneling. Alternately, use aluminium or cement brick up to 1.2 meters from the floor and then put glass up to the ceiling. At ceiling level all the panels should fit tightly and be sealed with appropriate material to prevent air leaks that may lead to contaminations. ◆ Construct a workbench projecting into the middle of the laboratory, as indicated in the layout diagram (Fig. 2). The proposed dimensions for the bench are 90 cm (height), 400 cm (length)) and 125 cm (width) with a sink, power outlets and gas outlets as indicated in Figure 3. ◆ Construct workbenches along the walls of the testing laboratory. One bench is to be located along the north wall, 90 cm (height), 95 cm (width) and 510 cm (length) and the other bench of the same height and width, and length 200 cm to be located along the south wall in the testing laboratory. The locations of the sinks are indicated in Figure 2. ◆ The center writing table in testing laboratory should be 100 cm x 100 cm x 75 cm (height). ◆ The workbench in the washing room to be 510 cm (length), 75 cm (width) and 90 cm (height), and the one in the media preparation room to be 510 cm (length), 90 cm (width) and 90 cm (height). ◆ The testing laboratory and the media preparation room need to be air-conditioned, to maintain the temperature at 25 oC and RH (55 + 5)% ◆ The floor of the testing laboratory and the media preparation room should be laid with vinyl material (epoxy resin). Floor tiles are suitable for other areas. ◆ Fit an exhaust fan in the washing room. ◆ All ceilings should be smooth. There should be no ceiling fans in laboratories. ◆ All laboratory doors to open outward as indicated in Fig. 1. ◆ The locations for electricity outlets for 5 amps, 15 amps and 30 amps supply, the gas outlets and the location of sinks are indicated in the Fig.3. The sink in the corner of the central workbench in the testing lab to be fixed at 70 cm height for washing hands. ◆ Stainless steel sinks are preferred. In the washing room a sink with a draining board will be more useful. It is preferable to fix two-way or three-way laboratory type taps for the sinks. ◆ The gas lines should carry two-way or four-way taps. The gas supply tank to be located outside the laboratory protected and fixed with external control valves. ◆ All exhaust water down pipes from the sinks should be of 50 mm diameter leading to 100 mm diameter horizontal pipes with no bends and opening out of the lab so that they can be cleaned from outside. ◆ All surfaces where dust could accumulate (window panes) and sharp corners in the floor need to be curved in the testing laboratory and media preparation room. ◆ The pipelines if laid on the surface of the floor and conduits along the walls in the laboratories, they should be covered with cement to avoid accumulation of dust and dirt. It is preferable to embed them in the walls and floor. ◆ Storage cupboards under workbenches and above 1.6 meters to be arranged in appropriate locations in the washing room and media preparation room for storage of glassware and chemicals. ◆ The glass windows in the walls to be tinted to prevent direct sunlight entering the laboratory. ◆ Lighting as done in all rooms with double fluorescent bulbs, fixed at the level of ceiling leaving no room for accumulation of dust on their upper surfaces and providing a light intensity of 750 lux. ◆ It is preferable to use enamel paints on the walls ◆ The locations for equipment in the laboratory are given in Fig. 4. FIG 1 - LAYOUT PLAN FOR A SMALL FOOD MICROBIOLOGICAL TESTING LABORATORY
FIG 2 - LAYOUT PLAN FOR WORK BENCHES IN A SMALL FOOD MICROBIOLOGICAL TESTING LABORATORY
FIG 3 - LAYOUT PLAN FOR ELECTRICITY AND GAS SUPPLIES IN A SMALL FOOD MICROBIOLOGICAL TESTING LABORATORY
FIG 4 - LAYOUT PLAN FOR EQUIPMENT FOR A SMALL FOOD MICROBIOLOGICAL TESTING LABORATORY | 
发表于 2013-11-19 05:23:47
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