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Flinn Scientific recommends you ventilate your chemical storage area a minimum of four air changes per hour. The best type of design is to have a fan mounted on an exterior wall of your chemical storeroom. Have sheet metal ductwork extend down from the fan to within 12" from the floor. The ductwork should be a minimum of 12" wide and 8" deep. See Figure.
The purpose for this design is to have ceiling to floor ventilation. Most organic vapors are heavier than air and sit at floor level. It only makes sense that the air to be ventilated be drawn from floor level.What is the maximum number of students you should have in your science laboratory? How much lab space should be available for each science student?
These are two of the most frequently asked questions we receive each year. The frequency of these questions points out the safety consciousness of today's science teacher. This article is intended to provide you with guidelines on how to help solve the problem of overcrowding in the science laboratory. We hope you and your administration will evaluate and adopt these guidelines in an effort to provide a safer working and improved learning environment for teachers and students.
Many school districts are experiencing budget problems. Any and all solutions to reduce school spending are being considered. One of the many solutions school administrators are considering to help "ease" budget problems is to increase the number of students in each class. Increasing class size not only delays the need to hire additional teaching staff, but also postpones the need to provide additional classroom space. For the science laboratory this solution creates major problems.
Health and Safety Concerns
Science teachers sense that overcrowded conditions in their science laboratories contribute to lab accidents. Their safety sense has not failed them! Overcrowding in the science laboratory is a major contributing factor to the safety problems school science departments face today.
In 1988, a report published in the Florida Science Teachers Magazine, Spring Edition, 1988, by Phillip Horton entitled "Class Size and Lab Safety in Florida" documented that over 55% of the science classes had enrollments teachers considered to be "potentially unsafe" for lab work. The average class size in these "unsafe" classrooms was 31 students. Of the 45% of the science classrooms teachers considered to be "safe", the average class size was 23 students. One high school teacher surveyed had two classes where the number of students was within the designed enrollment capacity, and three classes where enrollments exceeded the room capacity. He said "Contrasting the number of accidents between the first two periods and the last three ... class size does make a significant difference in traffic flow, individual monitoring, and understanding of the students!" The facts are clear, increasing the number of students in a science laboratory increases the likelihood of accidents. A high pupil/teacher ratio constitutes a threat to laboratory safety.
While we are concerned about the safety of the students, let's not forget that overcrowded conditions in the science laboratory also present an unsafe working environment for the science teacher as an employee of the school district. Most science laboratories are designed to accommodate 24 students, an accepted professional standard. When class sizes are larger than 24 students, it becomes very difficult for the science teacher to safely handle, transport and use laboratory chemicals and equipment. Increased class size puts "at risk" the health and safety of the science teacher.
Academic Concerns
Though student safety in the science laboratory is a major reason for limiting class size, another consideration is the ability to provide quality laboratory instruction. Many laboratory experiences require a high degree of student-teacher interaction. The fewer students there are in a laboratory, the greater the opportunity for students to ask questions and for teachers to clarify procedures and encourage the development of reasoning skills.
The amount of personal instruction provided each student must be considered. As one teacher who was teaching in an overcrowded science laboratory put it, "There is simply not enough teacher to go around and give sufficient time to each student."
The type of layout you ultimately select depends on many factors. No one design works well for all sciences. Here are a few thoughts we have on lab layout.
The lab layout you select will be used for the next 25-30 years. Think about how much science has changed from the 1960's to today. You need to think about what science will look like in the year 2020. What influences will technology and computers have on the way we teach science. How will integrated science affect the lab space you're designing? Will team teaching be a common method of teaching? The demands to have more hands-on science will continue to grow. How will this growth affect the lab that you're designing?
The questions can go on and on. All we ask is that you think about what science will look like in 20-25 years. Now that we've started you thinking about the future, let's give you a few recommendations that we feel strongly about.
We recommend that you select a furniture company who will "earn your business". The furniture companies are the people with the most expertise in lab design. They design labs on a daily basis and know what will or won't work based on your needs. It's simply a matter of finding which company really wants to put forth the effort to help you.
Below is a list of laboratory companies you should contact when designing a chemistry laboratory.
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Kewaunee Scientific |
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Sheldon Division, |
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Leonard Peterson & Co., Inc. |
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Campbell Rhea |
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Diversified Woodcrafts, Inc. |
Yes, we strongly recommend a fume hood be placed in all chemistry, A.P. Biology and integrated science labs. Typically, one 4'-6' fume hood per lab is plenty if you have "great" ventilation in the laboratory. (See Frequently Asked Question #1.)
For rooms where you may someday wish to install a fume hood, I would plan ahead and have the necessary design elements built into the building so the fume hood could be installed at a later date. Design elements would consist of allowing space to install ductwork and designing the roof to accommodate the motor/blower set and vent stack. All low-cost items during construction, but very expensive to do after the fact
Not all fume hoods are the same. For instance, if you are purchasing a 4' fume hood, make sure the hood can overcome a maximum external static pressure of 0.259 H2O at 100 fpm face velocity (720 cfm). All the other bells and whistles that come with a fume hood are to be selected based on your curriculum needs and local building codes.Three different types of tabletops are available. Select the tabletop which best fits your intended use and needs. We strongly recommend the epoxy resin tabletop.
Plastic Laminate
Economically priced top for use in general science classes. Wears exceptionally well under normal use. Has superior resistance to scratching with limited resistance to high temperatures, organics, and concentrated acids and bases.
ChemGuard®
Specifically designed for the science laboratory. Excellent alternative to the more expensive epoxy resin tops. Has excellent resistance to scratching and heat. ChemGuard® should not be subjected to open flames or temperatures exceeding 275 °F.
Epoxy Resin
Your best choice for a laboratory tabletop. Epoxy resin has excellent resistance to chemicals, heat and scratching. Surface is simple to clean and if maintained properly will look "brand new" for years.
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Characteristic |
Plastic Laminate |
ChemGuard® |
Epoxy Resin |
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Scratch Resistance |
Good |
Fair |
Excellent |
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Heat Resistance |
Fair |
Fair |
Excellent |
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Chemical Resistance |
Fair |
Good |
Excellent |
From various school projects we've helped out with and in discussion with architects, we have determined that a new science room costs about $150.00 per sq. ft. For remodeling and renovation we have been told $80.00 per sq. ft.
Please remember these prices are only estimated. The scope of the project and where you are located will greatly influence the cost of the project.
The National Fire Protection Association (NFPA) does not recommend the ventilation of flammable cabinets for fire protection purposes. Instead of ventilating individual chemical safety storage cabinets, we suggest you ventilate your entire chemical storage area a minimum of four air changes per hour, seven days a week. This type of ventilation system will provide needed ventilation for all chemicals contained in a storeroom.
Some states and/or local municipalities require chemical safety storage cabinets to be ventilated. If your cabinet must be ventilated, please contact Flinn Scientific for ideas on how to safely ventilate individual cabinets.
1. Tops should be thoroughly cleaned of oil, wax, or residue, using lacquer thinner.
2. Existing finish should then be thoroughly sanded with an 80-grit sandpaper to feather edge any nicks, scratches, etc., and remove any buildup of residue.
3. Tops should then be thoroughly sanded with a fine abrasive 150-grit to 180-grit sandpaper to prepare them for the new finish.
4. Apply a primer coating by brush and/or roller. The primer coating should be formulated to be compatible with the epoxy finish coat.
5. After the primer coating is thoroughly dry (8 to 10 hours), sand with a fine grit sandpaper, 180- to 200-grit.
6. Remove all sanding dust with a tack rag and apply the epoxy finish coat with brush and/or roller.
7. If a second coating is required to obtain desired finish, repeat steps 5 and 6.
8. Primer and epoxy coating are available from Flinn Scientific, Inc.
9. The above procedure is a recommendation only. Due to the many possible variations of materials used for tabletops, Flinn Scientific is not able to warranty the final results or accept any liability for failure of the applied finish.
