THE PROPERTIES DIRECTORS HANDBOOK
PROPS for the THEATRE
An absolute must-have in any prop shop is an adequately sized dust collection and ventilation system. The crew will spend less time cleaning up, shop motors will last longer, and the air will be free of dust or spray that could settle on cleaned props. But most importantly, the environment will be far less hazardous to the health of everyone working in the shop.
Sawdust can be hazardous to the health of theatre artisans. For many years this topic was debated and various OSHA compliance programs established but all too often theatre shops seemed exempt from this safety and health priority perhaps due to the sporadic nature of the work and the use of other materials that do not create a dust hazard. However, all woods have a variety of resins, alkaloids, and toxic organic and inorganic particles when inhaled as dust can cause a wide variety of allergic reactions, skin problems, and respiratory ailments. Plywood, MDF, and particleboard, often used in theatre work, are especially problematic due to the glue resins necessary for their manufacture.
Dust collection at the tool source is important, keeping
the air quality of the shop acceptable and pulling the sawdust away to a collection unit.
Tools with a factory-installed collar have the size of port determined by the manufacturer as necessary for adequate exhaust.
Each tool should be 
fitted with an open/shut port called a blast gate allowing for each access point to be controlled and the system volume to be maximized.
Some theatres have a whole building/ shop dust collection plan configured by an air handling system expert. This is recommended especially when designing a new space to allow for appropriate duct sizing /runs and safe configuration / installation of the air handling units. Installation of the motors and collection units outside of the shop area can help create a buffer from the motor noise of the units as well as making access for cleaning and maintenance easier and separate from the shop work area.
In other situations, adding in a stand-alone system similar to what one would find in a home workshop may be the best solution. In either case, knowing the volume of air needing to be moved or air volume in cubic feet per minute (CFM) divided by the amount of branches in the system open and working at one time allows for an adequate system to be installed. Most dust collection companies will have grids showing the performance ratings available on their systems and most tool manufactures will give a minimum CFM or FPM (velocity of air in feet per minute) required to evacuate the dust from the tool. Wood dust requires approximately 4000 FPM in the branches to adequately pull the dust to the main duct. Depending on how many tools are hooked up to the system and the length of the runs, one or several units may be required.
Proper installation and grounding of the collection system and especially the duct work is important to prevent static electricity from developing and to plan for appropriate negative pressure from the air ventilation. Like any other tool, consider cost, performance, safety, ease of use, ease of maintenance, and quality of construction in determining which unit to purchase.
Complete and detailed information on selecting and installing a dust collection or air filtration system is available on-line, in many woodworking shop books, or from most tool companies that sell wood dust collection systems.
One excellent site is: Air handling systems
Stopping the majority of airborne dust at the source is the first step but each shop should also have an air filtration system. While most shops are part of an overall air system associated with the building, having additional units that can be activated when dust-producing work is occuring allows for the quick removal of small particulates from the air that a building system would not dissipate quickly enough.
Properly located and sized, these filtration units can circulate the air in a room eight times per hour. Small units that could clear a small shop (5000 – 7000 cu.ft.) are available for around $300.
Many filtration units contain permanent washable pre-filters that capture most particles 3 microns or larger. Smoke pre-filters are also available that capture even smaller particles. Electrostatic pre-filters recently came on the market enhancing the performance of air cleaners and extending the life of the bag filter by working on the principle of static electricity removing dust and mold from the air. Electrostatic filters are washable.
Inside the filtration unit is a disposable bag/s depending on the size of the unit. These internal bag filter/s capture particles 1 microns or larger. The combination of the fan on these units with the pre-filter and capture bag filter allows most airborne particles to be efficiently removed from the air and it is recommended units be installed in both the “dirty” shop and “crafts” area. Units are available through many tool companies and can be installed by simply hanging in an appropriate work area and plugging them into a standard outlet. Some are available with a work light as part of the unit making them a good choice for installation above a worktable for illumination as well as air filtration. Some units come with a remote control allowing installation in practically any location.
The crafts area workhorse for ventilation should be a local exhaust ventilation system that traps toxic spray, mists, gases, fumes, smokes, or dusts and filters them to an outside air source. Appropriate clean make-up air must be provided to allow the system to work properly. The common configuration for most shops is a spray booth with a hood to surround the work area, a large air filter grid holding the contaminants, and a fan to pull the air from the work space through the filter and out the exhaust ducting.
This type of ventilation is controlled by a switch that may also operate an explosion proof light source in the spray booth as well as activating the air source providing fresh make-up air. Artisans working in the space must remember to keep the work piece between them and the filter screen. Airflow in the booth is directional pulling from outside the booth to the filter and artisans standing between the work piece and the screen will be exposed to contamination. Local building codes often specify mandatory fire suppression requirements for all types of spray booths, and local authorities may perform periodic inspections of this equipment to check for maintenance, cleanliness, and safety compliance as they make the rounds on annual building inspections in all areas of the theatre facility.
Keeping a clean workspace inside the booth is important to prevent spills or contaminates from one project getting on another. An explosion proof waste receptacle encourages the safe disposal of oily rags and debris but should be emptied daily. A separate plastic trash can should be provided for empty aerosol cans so they can be disposed of properly according to local hazardous waste policy. Many organizations have a hazardous waste policy for liquids requiring a chemically appropriate, usually plastic, removal container for any liquid that should not be disposed down the drain. Disposal of non-hazardous or self-combustible materials can be accommodated through the normal and usual trash can disposal methods.
Click here to view sub-topics:
Electrical Floor Surfaces Water Work Flow
Ventilation and Dust Collection
Click to see next “chapter”: Health and Safety
When purchasing a system to install in a wood shop, a two-stage collector is recommended.
A two-stage system has a first stage cyclone cone into which the air first enters allowing the coarse sawdust to settle out and removing the fine dust through a central outlet into the blower and on into the second stage after-filter. Allowing the coarse sawdust to settle out lessens the load on the blower and filters are not filled as rapidly since they are receiving primarily only fine dust.
Larger shops may have a walk-in variety where entire work pieces can be moved into the space and the back wall of the spray booth is covered with filters for the air to be exhausted. Smaller "bench" style vent booths are also available and work effectively in smaller shops where less space is available.
Various adaptors, transitions, and reducers are available to convert from a metric outlet, from a rectangular outlet to the round duct branch, or to increase/decrease size. For those tools lacking a dust collection port, seek out an accessory adaptor or manufacture a third party unit to allow it to be connected to the shop collection system.
