# Engineering Controls Database

Minus

## Air Curtain Technology in a Rubber Milling Plant

| Problem:                                        | Production of rubber products involves subjecting heterogeneous mixtures of hundreds of chemicals to heat, pressure, and catalytic action during a variety of manufacturing processes. As a result, the work environment may be contaminated with dusts, gases, vapors, fumes, and chemical byproducts (e.g., Nnitrosamines). Workers may be exposed to these hazards through inhalation and skin absorption during rubber processing and product manufacturing                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
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| What this means to you:                         | Exposure to fumes, gas, dust, and chemical byproducts can lead to numerous health risks. Those include respiratory problems (chest tightness, shortness of breath, reductions in pulmonary functions, emphysema), dermatological problems (contact dermatitis, eczema, rashes), and many types of cancer.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| Description of control:                         | The investigated system consisted of an air curtain and an enclosure added to the existing control. The air curtain was located between the contaminant source and the mill operator to create an air barrier between the operator and the emission source. The enclosure covered the space between the exhaust hood and the mill’s back side to eliminate contaminant emission at this space and to increase hood face velocity at the operator side.This position also minimizes eddy effects caused by air blowing from and toward the worker.**Manifold located at safety bar****Manifold located at upper hood edge**The first image has the jet positioned at the manifold, which keeps the air contaminants out of the breathing zone of the worker. The second image has the jet positioned at the top of the opening which prevents even flow of the air contaminants to the exhaust system and into the breathing zone of the worker.   |
| Engineering and Physical Hazard Report Numbers: | 180-05-A; 180-05-B; 180-05-C; 180-05-D; 180-05-E; 180-05-F; 180-05-G; 180-05-H; 180-05-I; 180-05-J1; 180-05-J2; 180-05-K1; 180-05-K2; 180-05-L; 180-05-M; 180-05-N; 180-05-O; 180-05-P; 180-05-Q; 180-05-R; 180-05-S; 180-05-T; 180-05-U; 180-05-V; 180-11-A; 185-05-A; 185-05-B; 185-05-C; 185-05-D;                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| NAICS Codes:                                    | 33322                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| Keywords:                                       | rubberrubber manufacturingrubber millingrubber milling                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| How well does this control work?                | Performance of the air curtain ventilation system was first evaluated in the laboratory. The laboratory data showed that a significant (98%) reduction in the tracer gas concentration was achieved. Laboratory results were validated by field tests conducted at a plastic manufacturing plant’s drop mill and strip mill. Similar reductions of 98% in tracer gas concentration and 30%-70% in particulate emission were achieved when the air curtains were operating.                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |

November 16, 2018
National Institute for Occupational Safety and Health