Water aspirators, once a staple in many biology and chemistry labs, are becoming an increasingly uncommon sight. These pieces connect to a lab faucet, and as water flows through a tube inside the aspirator, its velocity increases, creating a vacuum in the connected sidearm. Their historic popularity stemmed mainly from their low purchase price. But a closer look at the performance, environmental impact, and lifetime cost of a water aspirator may help convince aspirator devotees that it’s time to switch to a vacuum pump.
Performance
Water aspirators produce a moderate vacuum, in some cases reaching as low as 10 torr. While suitable for use in rotary evaporation or filtration systems using funnels or solid-phase extraction cartridges, water aspirators do not reach the deep-level vacuum required for certain applications, such as evaporating high-boiling-point solvents. Another drawback of water aspiration is the end vacuum depends on the water pressure of the faucet and the water temperature. The water pressure from the faucet may go down when there are simultaneous users, and that, along with seasonal water temperature changes, can create an inconsistent vacuum.
Environment
Environmental impact is really where water aspirators fall short. Intensive water use is a major concern with water aspiration, which requires a continuous flow of water from the tap. With moderate daily use of the device wasting an estimated 50,000 gallons of water per year, water aspiration is subject to increasing regulation. Also, water aspiration often leads to water contamination, as these devices can draw up volatile solvents, which then get carried through the device and down the drain. A recirculating water aspirator can help mitigate wastage. However, these devices still pose a contamination risk and require that the resulting water be treated as hazardous waste.
Cost
A simple aspirator can be purchased for as little as $50. But the real cost lies in the cost of ownership—the copious use of running water and having to dispose of hazardous waste. Additionally, water aspirators run the risk of causing lab flooding if a sink drain gets blocked during use, which could result in an enormous cost.
The Alternative
Vacuum pumps solve many of the problems associated with water aspirators. An environmentally friendly alternative, vacuum pumps completely avoid the issues of water waste and contamination. And by eliminating the water use and treatment costs associated with an aspirator, the initial cost of a vacuum pump potentially can be recovered in a few years.
Where water aspirators fail to provide a deep enough vacuum for certain uses, vacuum pumps deliver. A simple dry lab pump can reach about 1 torr, which is deep enough to handle most lab applications. Use of a vacuum pump provides the user with greater control over the vacuum, which leads to improvements in key lab applications; for example, a vacuum pump reduces bumping during evaporation.
While the initial cost of a vacuum pump can be more than the initial cost of a water aspirator, the flexibility, performance, reliability, and environmental impact are strong arguments for making the change and adopting a well-established solution in the industry.
We, at BaneBio, would love to help you keep your laboratory current and up-to-date. When you decide to replace your water aspirator, we have several affordable vacuum pumps available for purchase. Click here to browse our diverse selection.
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Reference: Erica Tennenhouse (2016). Vacuum Pumps to Replace Your Water Aspirator. Retrieved from Lab Manager: http://bit.ly/2ibnYGr