Laboratory equipment can be a significant contributor to workplace noise levels, which the US Occupational Health and Safety Administration (OSHA) has identified as a serious health concern. Depending on the type of lab, noise can come from many sources, all of which have a cumulative effect on workers. A chemical lab for example, might have fume hoods, instrumentation, refrigerators, nitrogen generators, compressors and freezers. A biochemistry or clinical lab might employ ultracentrifuges, large automated analyzers, tissue homogenizers and stirrer motors. More specialized labs may use additional noise producing equipment. For example, a geology laboratory might include a rock crusher while a quality assurance lab could have pneumatic sample injectors on the gas chromatography or liquid chromatography equipment.
The good news for lab managers is that equipment noise is something over which they have at least some control — unlike noise coming from external sources such as nearby building construction or vehicular noise if the lab is located in a high traffic area. One logical option is simply to choose quieter equipment. Two devices that perform identical functions may produce significantly different levels of noise. One may employ noise mitigating features, such as a sound dampening enclosure, which the other does not. Or, one may perform its function in an entirely different way, and produce lower noise levels. In other words, it’s quieter by design.
A Low Noise Lab Equipment Design
Selecting low noise producing equipment is one way for lab managers to control noise levels in the laboratory. A good example of this is a nitrogen generator. Nitrogen is commonly used with Liquid Chromatography/Mass Spectroscopy (LCMS) instrumentation to displace all of the oxygen in the mass spectroscopy chamber. While Nitrogen gas can be obtained in a number of ways (e.g. tank gas or liquid nitrogen) many laboratories use a nitrogen generator as it is safer, less costly, and more convenient than delivered supplies. Most nitrogen generators with internal compressors are quite noisy – typically in the range of 55-60 dBA. However, nitrogen generators that employ an oil-less rotary scroll system, are much quieter. The Parker Nitroflow60 Nitrogen Generator for example, produces a noise level of only 49 dBA.
A rotary scroll system consists of two identical spirals that are offset 180° with respect to each other so the scrolls mesh. One scroll is orbited around the fixed scroll, trapping and compressing gas pockets as they move to the center of the fixed scroll. The compressed gas discharges from the pump through the center outlet to an air cooled “after cooler,” which includes a series of cooling fins and a high output fan. The cooling features allow the scrolling mechanism to operate at lower temperatures and also extend bearing, tip seal and grease life. Another benefit of this design is that no oil is introduced into the LC/MS system.
This is the third part of a three part series on Noise Pollution in the Laboratory.
Why Audit Laboratory Noise Sources? Part 2 of 3
Peter Froehlich, PhD., was contracted by Parker to author the white paper. He was assisted by Kim Myers, Product Manager, Parker Hannifin.