Vacuum units that use water ring pumps as the primary pump offer advantages over other types of vacuum pumps. They overcome the drawback of low gas evacuation rate at low pressure, which is a problem when using a single water ring pump (the pressure ratio in the unit is much higher than that of the water ring pump). At the same time, they retain the benefits of Roots pumps, such as the ability to work with higher gas evacuation rates. This is especially beneficial for removing large volumes of condensable steam, particularly when mechanical vacuum pumps equipped with gas seals are inadequate for this task, or when the solvent used can degrade the pump oil, affecting performance, or when the vacuum system cannot tolerate oil contamination. Under the proper electrical and mechanical configurations and compliance with relevant regulations, they can also evacuate flammable and explosive gases. Therefore, Roots-water ring pump units are widely used in vacuum distillation, vacuum evaporation, and dehydration crystallization in the chemical industry; freeze-drying in the food industry; vacuum drying in the pharmaceutical industry; polyester chips in the light and textile industry; and vacuum evacuation systems for high-altitude simulation tests, etc.
Roots vacuum pumps (mechanical booster pumps) designed for higher vacuums cannot be directly discharged to the atmosphere. Direct discharge to the atmosphere would cause an excessive pressure difference between the intake and exhaust ports of the Roots vacuum pump, leading to overload. Simply increasing the motor power of the Roots vacuum pump would cause overheating, which in turn would rapidly expand the minute gaps between the pump rotors, resulting in them becoming jammed due to thermal expansion.
The inter-space. Therefore, a priming pump is used with the Roots vacuum pump to draw the system pressure within a specified range before starting the Roots vacuum pump, which helps prevent overloading of the Roots vacuum pump. The priming pump can be selected from various types of vacuum pumps that can directly exhaust into the atmosphere, such as water (liquid) ring vacuum pumps, scroll vacuum pumps, slide valve vacuum pumps, reciprocating vacuum pumps, etc.
In most cases, using a water ring pump as the primary pump in a vacuum unit is more advantageous than other types of vacuum pumps. This is primarily due to its ability to remove large quantities of condensable steam, particularly when the mechanical vacuum pump with gas-filled oil seals lacks sufficient condensable steam removal capacity, or when the solvent used can degrade the pump oil, affecting its performance, or when the vacuum system prohibits oil contamination.
Vacuum units are extensively used in vacuum systems for chemical industries, food sublimation drying, high-altitude simulation tests, and more.
