A number of factors need to be considered to properly size and specify a vacuum pump. In some of our previous posts, we’ve discussed topics like how to determine the right flow rate for your new pump. Considerations such as this are readily evaluated through the use of calculators such as those we have posted on our website.
However, there are also a number of more subjective issues that should also be considered when evaluating vacuum pumps. For example, the durability of the pump and its maintenance requirements have a signficant impact on both maintenance costs (parts, labor) and future equipment costs (pump life and subsequent replacement pumps). By virtue of their design, some pumps require regular maintenance and rebuilds whereas other types of pumps are relatively low maintenance and durable. The pump’s wetted materials significantly affect the durability if the pump is exposed to aggressive gasses and chemical vapors. The type of pump selected can also result in large differences in operating costs (electricity, water, disposal charges for water/oil, etc.)
Another subjective factor to consider when evaluating different pumps is whether the pump is compatible with your process. Many processes – manufacturing of APIs, for example – are highly sensitive to contamination, whereas other processes are less so. To be used in sensitive operations, liquid sealed pumps often require additional equipment to prevent backstreaming which contaminates the product. In contrast, a dry pump allows for a relatively simpler installation as no additional equipment is need to prevent backflow.
A third factor that is often overlooked is the pump’s noise level. Noise generated by equipment can be quite disruptive and make for a challenging working environment – especially in scale-up or lab settings. With regard to vacuum pumps, some types of pumps are inherently noisier than others, so selecting a quieter pump that meets the performance specs can have a meaningful impact on the background noise in a facility. For example, all things being equal, a diaphragm pump will generally be quieter than an equivalent piston pump. Additionally, well-designed pumps tend to run more quietly as a result of a variety of design features. For example, a pump that is designed well will generally be more efficient; that is, the same pump performance can be achieved with less work from the pump’s motor. This allows the motor to operate at lower speed, or for a smaller motor to be used; in either case the result is a quieter pump. Finally, by ensuring that the pump is installed properly and that air leakage into the pump is minimized, pump noise level can be further mitigated.