Laboratory Facilities - Prudent Practices in the Laboratory - NCBI Bookshelf
Thus, laboratory buildings include spaces that encourage the production,  It is a space for scientists with specific conditions conducive to their role in a larger research cluster as well as their relationship with the surrounding area. . laboratories that are situated in a medical complex depend on the. Title: Space Management Policy Publication date: 3/8/ Effective date: guidelines for the management of Berkeley Lab space as a critical mission- readiness resource i. Lactation Accommodation Program; Medical Return-to- Work Policy - Dummy . Division directors or their designees assign office spaces to division. FA1: Clinical Laboratory and Pathology Phlebotomy Station Calculation. .. areas. The space planning criteria in this chapter apply to all Military Treatment Facilities relationship with other services of a medical facility.
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Yet some universal truths will apply in virtually all labs. For example, the goal is almost always to increase output without adding staff, and to improve productivity while controlling error rates. If a researcher or technician loses time unnecessarily in between individual steps of the experimental process, that is an increment of inefficiency that accrues each time the process repeats.
Awkward or inflexible arrangements of equipment in research spaces can lead to delays—very costly over the course of months or years of research—and can even increase errors, accidents and botched experimental trials. In other words, optimizing the space for efficiency of the experimental or technical process can yield increased return on investment ROI.
For that reason, lab design is essential to improved process management. Whatever the goal of the research organization and whether the client stakeholder is a corporate or institutional one, the field of scientific research is too competitive for the organization to forego the attention required to create an ergonomic, properly oriented and arranged workspace for the laboratory scientist.
The modern lab workspace As we begin to consider how to arrange lab furnishings and equipment to best suit the work that researchers are performing therein, it is vital that we address the trends affecting how research is conducted. As techniques, approaches and behaviors change, so too will functional relationships among equipment and furnishings, leading to new best-case adjacencies and proximities.
The most important such trend we are observing is the movement toward the bench space as a catchall space for nearly every aspect of the research process. Now more than ever, the lab is everything; more scientists are using the bench as the write-up space, to the point that bench and write-up space are one and the same.
This will not only affect the bench setup, but often greatly alters the traditional requirements for office and support spaces as a percentage of the facility footprint.
This trend is concurrent with another: Equipment technology for the lab is itself beginning to change in important ways. Energy-devouring equipment such as fume hoods and associated HVAC infrastructure are being designed for better efficiency, often leading to a smaller profile as well. Other types of equipment are also shrinking, thereby becoming more amenable to placement near the workbench rather than in specialized areas. And in some rarer instances, robotics and automation are finding their way to the bench, where they often assist with and even regulate the processing of samples, handling of glassware and more.
But perhaps most important is the overall change in space requirements. As bench areas remain steady, or in some cases decrease in overall footprint, separate equipment areas gain prominence and importance, with a concomitant increase in space. The traditional ratio of bench to equipment space had been 2: In these clusters, lab bench and floor space allocated to team members generally should be kept small to improve productivity: Lab desks, typically four feet or so in width, ideally are located within the open-plan lab or other lab area.
But input should be considered from a perhaps unexpected analogy, as well: By organizing these three elements into a triangle around the kitchen user, designers minimize the effort required to manage the work of cooking or cleaning up.
In fact, the decades-old golden triangle has been updated recently, as the paradigm of a single person in charge of all kitchen activity is replaced by one of multiple users. But the individual laboratory workspace is still typically occupied by a single researcher, and addressing the functional relationships of the most-used equipment—to arrange those elements into an efficient triangle or quadrangle, for example— will positively impact research efficiency.
Stakeholders should work together to plan an efficacious lab workspace by wrangling varying combinations of fume hood, storage, burner, freezer, incubator, centrifuge and the like. The key for the lab design team aiming to optimize the arrangement is to fully understand the work to be performed and the functional relationships of the equipment components to the work, the researcher and each other. The benefits of a thoughtfully constructed and arranged workspace are, in fact, several-fold.
If the space is designed with as many of the task specifics in mind as possible, we can optimize not only for efficient performance of process, but also for safety and sustainability. Arranging unique labs For startup firms and other smaller-budget research organizations, some of this may not be possible.
These groups may have to rent facilities and accept the existing layouts of benches, casework and equipment. But whenever possible, the design of a lab interior should begin with a pre-planning-phase workshop. The purpose of this period is to uncover all space needs and process elements, from facility owners and managers, executives or owners of the research organizations, the design team, and perhaps most important, the likely lab occupants.
By engaging the research scientists in this early design phase, designers can tailor the completed project to the requirements and process of the research in question.
Face velocities between and fpm have been recommended in the past for substances of very high toxicity or where outside influences adversely affect hood performance. However, energy costs to operate the chemical hood are directly proportional to the face velocity and there is no consistent evidence that the higher face velocity results in better containment. Face velocities approaching or exceeding fpm should not be used; they may cause turbulence around the periphery of the sash opening and actually reduce the capture efficiency, and may reentrain settled particles into the air.
With the desire for more sustainable laboratory ventilation design, manufacturers are producing high-performance hoods, also known as low-flow hoods, that achieve the same level of containment as traditional ones, but at a lower face velocity.
These chemical hoods are designed to operate at 60 or 80 fpm and in some cases even lower. Average face velocity is determined by measuring individual points across the plane of the sash opening and calculating their average.
A more robust measure of containment uses tracer gases to provide quantitative data and smoke testing to visualize airflow patterns. This type of testing should be conducted at the time the chemical hood is installed, when substantial changes are made to the ventilation system, including rebalancing and periodically as part of a recommissioning or maintenance program. These requirements should be incorporated into the laboratory's Chemical Hygiene Plan and ventilation system management plans see section 9.
When multiple similar chemical hoods are installed at the same time, at least half should be tested, provided the design is standardized relative to location of doors and traffic, and to location and type of air supply diffusers. Thirty to fifty percent of a face velocity of fpm, for example, is 30 to 50 fpm, which represents a very low velocity that can be produced in many ways.
The rate of 20 fpm is considered to be still air because that is the velocity at which most people first begin to sense air movement. Proximity to Traffic Most people walk at approximately fpm approximately 3 mph [4. If a person walks in front of an open chemical hood, the vortices can overcome the face velocity and pull contaminants into the vortex, and into the laboratory. Therefore, laboratory chemical hoods should not be located on heavily traveled aisles, and those that are should be kept closed when not in use.
Foot traffic near these chemical hoods should be avoided when work is being performed. This air usually enters the laboratory through devices called supply air diffusers located in the ceiling. Velocities that exceed fpm are frequently encountered at the face of these diffusers.
Normally, the effect is not as pronounced as the traffic effect, but it occurs constantly, whereas the traffic effect is transient. Relocating the diffuser, replacing it with another type, or rebalancing the diffuser air volumes in the laboratory can alleviate this problem.
Proximity to Windows and Doors Exterior windows with movable sashes are not recommended in laboratories. Wind blowing through the windows and high-velocity vortices caused when doors open can strip contaminants out of the chemical hoods and interfere with laboratory static pressure controls. Place hoods away from doors and heavy traffic aisles to reduce the chance of turbulence reducing the effectiveness of the hood.
Prevention of Intentional Release of Hazardous Substances into Chemical Hoods Laboratory chemical hoods should be regarded as safety devices that can contain and exhaust toxic, offensive, or flammable materials that form as a result of laboratory procedures. Just as you should never flush laboratory waste down a drain, never intentionally send waste up the chemical hood. Do not use the chemical hood as a means of treating or disposing of chemical waste, including intentionally emptying hazardous gases from compressed gas cylinders or allowing waste solvent to evaporate.
Laboratory Chemical Hood Performance Checks When checking if laboratory chemical hoods are performing properly, observe the following guidelines: Evaluate each hood before initial use and on a regular basis at least once a year to visualize airflow and to verify that the face velocity meets the criteria specified for it in the laboratory's Chemical Hygiene Plan or laboratory ventilation plan.
Verify the absence of excessive turbulence see section 9. Make sure that a continuous performance monitoring device is present, and check it every time the chemical hood is used. For further information, see section 9. Many factors can compromise the efficiency of chemical hood operation, and most are avoidable.
Be aware of all behavior that can, in some way, modify the chemical hood and its capabilities. Housekeeping Keep laboratory chemical hoods and adjacent work areas clean and free of debris at all times. Keep solid objects and materials such as paper from entering the exhaust ducts, because they can lodge in the ducts or fans and adversely affect their operation. The chemical hood will have better airflow across its work surface if it contains a minimal number of bottles, beakers, and laboratory apparatus; therefore, prudent practice keeps unnecessary equipment and glassware outside the chemical hood at all times and stores all chemicals in approved storage cans, containers, or cabinets.
Furthermore, keep the workspace neat and clean in all laboratory operations, particularly those involving the use of chemical hoods, so that any procedure or experiment can be undertaken without the possibility of disturbing, or even destroying, what is being done. Sash Operation Except when adjustments to the apparatus are being made, keep the chemical hood closed, with vertical sashes down and horizontal sashes closed, to help prevent the spread of a fire, spill, or other hazard into the laboratory.
Horizontal sliding sashes should not be removed. The face opening should be kept small to improve the overall performance of the hood. If the face velocity becomes excessive, the facility engineers should make adjustments or corrections.
For chemical hoods without face velocity controls see section 9. This range should be determined and marked during laboratory chemical hood testing. Do not raise the sash above the working height for which it has been tested to maintain adequate face velocity. Doing so may allow the release of contaminants from the chemical hood into the laboratory environment.
Chemical hood sashes may move vertically sash moves up and downhorizontally sash is divided in panes that move side to side to provide the opening to the hood interioror a combination of both. Although both types of sash offer protection from the materials within the hood and help control or maintain airflow, consider the following: Some experimentation requires the lab personnel to access equipment or materials toward the upper portion of the chemical hood.
If the chemical hood is equipped with a vertical sash, it may be necessary to raise the sash completely in order to conduct the procedure. Thus, the chemical hood must be tested in that position.
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The standard operating position for the vertical sash may be comfortable for the majority of users. However, shorter laboratory personnel may find that this position does not provide an adequate barrier from the materials within the chemical hood and may need to adjust downward.
Taller laboratory personnel may need to raise the sash more in order to comfortably work in the chemical hood. For chemical hoods with horizontal sashes, the intended operating configuration is to open the panes in such a way that at least one pane is between both arms, providing a barrier between the user and the contents of the chemical hood.
In addition, Do not remove panes.
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Permanently removing panes may decrease the safety afforded by the sash barrier and negatively affect containment and waste energy. Working with all panes moved to one side or through an opening in the center of the laboratory chemical hood provides no barrier between the user and the materials within the chemical hood.
The chemical hood is not intended to be used in this configuration. Sash panes should be equal width with a maximum of 15 in. Sash panes and viewing panes constructed of composite material safety glass backed by polycarbonate, with the safety glass toward the explosion hazard are recommended for chemical hoods used when there is the possibility of explosion or violent overpressurization e.
For all laboratory chemical hoods, the sash should be kept closed when the hood is not actively attended. Lowering or closing the sash not only provides additional personal protection but also results in significant energy conservation.
Some chemical hoods may be equipped with automatic sash-positioning systems with counterweighting or electronic controls see section 9. Constant Operation of Laboratory Chemical Hoods Although turning laboratory chemical hoods off when not in use saves energy, keeping them on at all times is safer, especially if they are connected directly to a single fan.
Because most laboratory facilities are under negative pressure, air may be drawn backward through the nonoperating fan, down the duct, and into the laboratory unless an ultralow-leakage backdraft damper is used in the duct. If the air is cold, it may freeze liquids in the hood. The ducts are rarely insulated; therefore, condensation and ice may form in cold weather.
When the chemical hood is turned on again and the duct temperature rises, the ice will melt, and water will run down the ductwork, drip into the hood, and possibly react with chemicals in the hood.
Chemical hoods connected to a common exhaust manifold offer the advantage that the main exhaust system is rarely shut down. Hence, positive ventilation is available on the system at all times. In a constant air volume CAV system see section 9. Some laboratory chemical hoods on variable air volume VAV systems see section 9. The setback may be triggered by occupancy sensors, a light switch, or a timer or a completely lowered sash.
Understand what triggers the setback and ensure that the chemical hood is not used for hazardous operations when in setback mode. They should only be turned off when they are empty of hazardous materials. An example of an acceptable operation would be a teaching laboratory where the empty chemical hoods are turned off when the laboratory is not in use. Testing and Verification The OSHA lab standard includes a provision regarding laboratory chemical hoods, including a requirement for some type of continuous monitoring device on each chemical hood to allow the user to verify performance and routine testing of the hood.
It does not specify a test protocol. Laboratory chemical hoods should be tested at least as follows: They should pass the low- and high-volume smoke challenges with no leakage or flow reversals and have a control level of 0. The test includes several components, which may be used together or separately, including face velocity testing, flow visualization, face velocity controller response testing, and tracer gas containment testing. These tests are much more accurate than face velocity and smoke testing alone.
Performance should be evaluated against the design specifications for uniform airflow across the chemical hood face as well as for the total exhaust air volume. Equally important is the evaluation of operator exposure.
The first step in the evaluation of hood performance is the use of a smoke tube or similar device to determine that the laboratory chemical hood is on and exhausting air. The second step is to measure the velocity of the airflow at the face of the hood. The third step is to determine the uniformity of air delivery to the hood face by making a series of face velocity measurements taken in a grid pattern.
Leak testing is normally conducted using a mannequin equipped with sensors for the test gas. As an alternative, a person wearing the sensors or collectors may follow a sequence of movements to simulate common activities, such as transferring chemicals. It is most accurate to perform the in-place tests with the chemical hood at least partially loaded with common materials e. For the ASHRAE leak testing, the method calls for a release rate for the test gas of 4 liters per minute Lpmbut suggests that higher rates may be used.
One-liter per minute release rate approximates pouring a volatile solvent from one beaker to another. Eight liters per minute approximates boiling water on a W hot plate. The 4-Lpm rate is an intermediate of these two conditions. If there is a possibility that the chemical hood will be used for volatile materials under heating conditions, consider a higher release rate of up to 8 Lpm for worst-case conditions.
If the laboratory chemical hood and the general ventilating system are properly designed, face velocities in the range of the design criteria will provide a laminar flow of air over the work surface and sides of the hood.
Higher face velocities fpm or morewhich exhaust the general laboratory air at a greater rate, waste energy and are likely to degrade hood performance by creating air turbulence at the face and within the chemical hood, causing vapors to spill out into the laboratory Figure 9. Velocity data are from a single traverse point on two separate hoods. An additional method for containment testing is the ENwhich is the standard adopted by the European Union and replaces several other procedures that were in place for individual countries.
Routine Testing At least annually, the following test procedures should be conducted for all chemical hoods: Analyze face velocity using the method and criteria described in section 9. Visualize airflow using smoke tubes, bombs, or fog generators.
Verify that continuous flow monitoring devices are working properly. Verify that other controls, including automatic sash positioners, alarm systems, etc. Check the sash to ensure that it is in good condition, moves easily, is unobstructed, and has adequate clarity to see inside the laboratory chemical hood. Ensure that the laboratory chemical hood is being used as intended e. Note any conditions that could affect laboratory chemical hood performance, such as large equipment, excessive storage, etc.
Take corrective actions where necessary and retest. Document the results in order to maintain a log showing the history of chemical hood performance.
Additional Testing Laboratory personnel should request a chemical hood performance evaluation any time there is a change in any aspect of the ventilation system. Thus, changes in the total volume of supply air, changes in the locations of supply air diffusers, or the addition of other auxiliary local ventilation devices e.
Face Velocity Testing Visually divide the face opening of a laboratory chemical hood into an imaginary grid, with each grid space being approximately 1 ft2 in area. Using an anemometer, velometer, or similar device, take a measurement at the center of each grid space.
Face velocity readings should be integrated for at least 10 seconds 20 is preferable because of the fluctuations in flow.
The measured velocity will likely fluctuate for several seconds; record the reading once it has stabilized. Calculate the average of the velocity for every grid space. The resulting number is the average face velocity. Such readings indicate the possibility of turbulent or nonlaminar airflow. Smoke tests will help confirm whether this is problematic. Traditional handheld instruments are subject to probe movement and positioning errors as well as reading errors owing to the optimistic bias of the investigator.
Also, the traditional method yields only a snapshot of the velocity data, and no measure of variation over time is possible. To overcome this limitation, take velocity data while using a velocity transducer connected to a data acquisition system and read continuously by a computer for approximately 30 seconds at each traverse point. If the transducer is fixed in place, using a ring stand or similar apparatus, and is properly positioned and oriented, this method overcomes the errors and drawbacks associated with the traditional method.
The variation in data for a traverse point can be used as an indicator of turbulence, an important additional performance indicator that has been almost completely overlooked in the past. Most laboratory chemical hoods are equipped with a baffle that has movable slot openings at both the top and the bottom, which should be moved until the airflow is essentially uniform.
Larger chemical hoods may require additional slots in the baffle to achieve uniform airflow across the face. These adjustments should be made by an experienced laboratory ventilation engineer or technician using proper instrumentation. Effect of baffles on face velocity profile in a laboratory chemical hood. One important factor to consider is acceptable sash position. However, one must understand how the chemical hood will be used to determine the range of sash positions needed.
Instrumentation Anemometers and other instruments used to measure face velocity must be accurate in order to supply meaningful data.
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Instruments should be calibrated at least once a year and the calibration should be National Institute of Standards and Technology traceable. Additional Exposure Monitoring If there is any concern that a laboratory chemical hood or other ventilation device may not provide enough protection to the trained laboratory personnel, it is prudent to measure worker exposure while the hood is being used for its intended purpose.
By conducting personal air-sampling using traditional industrial hygiene techniques, worker exposure both excursion peak and time-weighted average can be measured. The criterion for evaluating the hood should be the desired performance i. A sufficient number of measurements should be made to define a statistically significant maximum exposure based on worst-case operating conditions.
Direct-reading instruments may be available for determining the short-term concentration excursions that may occur in chemical hood use. Laboratory Chemical Hood Design and Construction When specifying a laboratory chemical hood for use in a particular activity, laboratory personnel should be aware of the design features. Assistance from an industrial hygienist, ventilation engineer, or laboratory consultant is recommended when deciding to purchase a chemical hood.
General Design Recommendations Construct laboratory chemical hoods and the associated exhaust ducts of nonflammable materials. Locate the utility control valves, electrical receptacles, and other fixtures outside the chemical hood to minimize the need to reach within the chemical hood proper.
Other specifications regarding the construction materials, plumbing requirements, and interior design vary, depending on the intended use.