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Information for Preparation
Dinosaur National Monument Scott Madsen-Fossil Preparator The dust evacuation system shown here was designed specifically to meet the needs and specifications of our lab. The room is 17ft x 54ft x 10ft (high). I believe the motor that runs this system was called "explosion-proof" (similar to those typically used in fume hoods) and works equally well to extract fumes of resins and solvents from the work area. The system is quiet as a mouse and the motor sits outside on vibration dampers to insure our microscopes are not affected by vibrations.	DUST AND FUME EVACUATION SYSTEMS FOR FOSSIL PREPARATION LABS MADSEN, S.K., Dinosaur National Monument, PO Box 128, Jensen, UT 84035 Many preparation activities, particularly the use of pneumatic percussion and grinding tools, generate huge amounts of airborne dust. Airborne particles may pose serious health risks including silicosis and cancer. These hazards tend to be taken lightly or ignored, since the threat is often invisible and the consequences long term. In 1989, a volunteer armed with a Geiger counter found indications of high radioactivity at an excavation within Dinosaur NM. This discovery spurred us to conduct 2 detailed Industrial Hygiene Surveys focusing largely on radon and dust sources. The surveys identified serious problems in the lab and storage areas, and suggested corrective measures. Over the next 4 years, DNM staff consulted with other museums as well as ventilation engineers to plan and design a user-friendly evacuation system to fulfill our needs. This effort culminated in the construction of a 5000cfm, 2-speed exhaust fan to which are attached 8 flexible hoses for point-source dust collection. Dust is evacuated directly outdoors, and make-up air provided by an integrated fan (heated by propane in winter). In addition, an independent re-circulating system in the lab filters total room air once every 5 minutes removing fine particles missed by the evacuation hoses.
Please note- I first sketched a schematic of how I thought our system should be configured for maximum efficiency and utility in the lab. I spent a lot of time discussing our needs with industrial hygiene specialists and engineers from the National Park Service prior to having the system built. I also talked with numerous vent system installers. Neither camp agreed on the specs the system should have to meet our needs. The size of the motor was the main bone of contention. The engineers thought the system would have so much drag in the ducts and hoses that it would not do the job. The installation companies thought the proposed system would "suck the keys out of our pockets" when we walked by. In the end we opted for a 2-speed 5000 cfm (maximum) motor and held our breaths when we first turned it on. I guess we lucked out as the lab didn't implode and the dust went up the tubes.
The motor mounted outside of the groundfloor laboratory.		We experienced a dramatic decrease in the amount of dust in our noses and on our desks, empirical evidence that the system worked. However, it was not until we had the lab environment tested by NIOSH that we truly knew the problem was solved. The NIOSH report by Ed Burroughs included here is a preliminary report and unpublished so I ask that it not be reproduced without permission. I include it here as a reference to demonstrate the potential usefulness of bringing in the pro's. Along with the report we also got a nifty video that graphically illustrates dust being generated with real-time overlays of data.
Our system was installed in 1996 for a cost of about $34,000. As we are a federal agency, the regulations required that hardware and installation had to go out for bid and all materials were bought new. It is very likely a similar system could be put together for far less money with some enterprising scrounging, or if your facility is located closer to big-city resources. The fan is a Greenheck, "backward inclined centrifugal utility fan" with a 3/4 Hp, 1725 motor. The fixed ductwork is tin. We used round duct where feasible and avoided right-angles as much as possible to reduce drag in the system. A removable hatch located at the junction of trunk lines allows access to the interior to check for dust buildup, though in 10 years this has not been an issue. Accumulated dust can be eliminated by running the fan on high and tapping the conduit.		Note the shutters for isolating individual air hoses.
I opted for 6" diameter, detachable flex-hoses instead of ones with internal armature. These allow for unlimited flexibility and can be placed at virtually any angle to maximize efficiency of the suction no matter which direction the air tool is pointed. Hose closures are guillotine-style and located at the attachment to the main trunk lines; hoses not in use can be easily removed and/or closed to increase overall efficiency of the system. Our hoses are 9-14 feet long and can reach any part of the lab. Movable cords are attached to the ceiling to help support and aim the hoses. In addition, the hoses can be attached to home made glove boxes or tents when using Airbrasive equipment.
The abstract included mentions an additional dust filter system in the lab. This is a ceiling mounted back-up system that filters all but the smallest particles of dust missed by the main point-source system- we felt that the added expense of a HEPA-quality filter was not worth the cost. The main system is quite efficient, so we seldom run it except when generating huge quantities of nuisance dust removing field jackets and the like. By the way, we still have to vacuum, but not as often as before. In addition, when running at high speed the system is strong enough to suck things like small brushes, cups of glue- and bone fragments- up the tube. Users beware.