Overview
The JZWLW oil-free vertical vacuum unit is primarily equipped with a Roots vacuum pump (also known as a Roots booster pump) as the main pump, complemented by a WLW type oil-free vertical vacuum pump as the preliminary pump. It utilizes electrical contact pressure and vacuum gauges to achieve automatic start/stop, protection, and safety for both the Roots vacuum pump and the oil-free vacuum pump. This unit is widely used in the vacuum distillation, crystallization, drying, and polyester film steam adhesion processes in industries such as electronics, vacuum coating, chemical fiber, metallurgy, heat treatment, welding, and chemical engineering.
It features certain characteristics of general Roots vacuum pump units, but due to the use of oil-free vacuum pumps (this product utilizes oil-free lubrication and sealing technology in the overflow section as the primary pump, which enhances vacuum purity and allows for clean vacuum. It is particularly suitable for industrial processes that require removal of gases that react with oil, as well as non-condensable and non-compressible solids (such as CO2/cyclopentadiene, benzene, alcohols, etc.).
Working Principle and Structural Features
The JZJW-type oil-free reciprocating vacuum pump set consists of two main parts: the pump section (suction section) and the power control section. The pump section of the four-stage JZJW model is composed of three Roots vacuum pumps and one WLW-type oil-free reciprocating vacuum pump, connected in series in four stages. The oil-free vacuum pump is called the preliminary pump, the Roots vacuum pump connected to the suction vessel is called the main pump stage, and the Roots vacuum pump connected to the preliminary and main pump stages is called the intermediate stage. If one Roots vacuum pump in the intermediate stage is removed, it forms a three-stage JZJW model; if two Roots vacuum pumps in the intermediate stage are removed, it forms a two-stage JZJW model. The ultimate vacuum of this two-stage model is 133Pa, the ultimate vacuum of the three-stage model is 15Pa, and the ultimate vacuum of the four-stage model is 1Pa.
Due to the fact that standard Roots vacuum pumps cannot start under atmospheric conditions, they must be pre-evacuated to a vacuum at the exhaust end before starting. Therefore, a preliminary vacuum pump (abbreviated as the preliminary pump) is required at the outlet of the Roots vacuum pump. For the JZJW four-section unit, the preliminary pump for the main pump stage is the 2nd Roots vacuum pump, the preliminary pump for the 2nd Roots pump is the 1st Roots vacuum pump, and the preliminary pump for the 1st Roots vacuum pump is an oil-free vacuum pump. For the JZJW three-stage unit (excluding the 2nd Roots vacuum pump), the preliminary pump for the main pump stage is the 1st Roots vacuum pump, and the preliminary pump for the 1st Roots pump is an oil-free vacuum pump. For the ÷ZW two-stage unit (excluding two intermediate pumps), the preliminary vacuum pump for the main pump stage is an oil-free vacuum pump.
The suction speed ratio between different vacuum pumps (the suction speed of the downstream pump compared to the upstream pump) should conform to a certain proportion. Considering the insufficient power and exhaust suction capacity of the upstream pump under high suction speed ratios, which can adversely affect the downstream vacuum pump, it is generally advisable not to exceed a suction speed ratio of 3, with a ratio of around 2 being preferable.
The Roots vacuum pump boasts excellent gas evacuation characteristics (large evacuation rate at low pressure) and, when used as a secondary vacuum pump within the Roots vacuum pump's ultimate vacuum range, it can always achieve a significantly higher vacuum level than the primary vacuum stage (e.g., if the primary vacuum is 10Pa without the Roots pump, it can be improved to 10Pa with the Roots pump, and so on). Due to the absence of mechanical contact between the rotors and the pump chamber in the Roots vacuum pump, lubrication is not required, resulting in notably lower power loss compared to other types of mechanical vacuum pumps with the same evacuation rate. Furthermore, the use of an oil-free vacuum pump with no lubrication in the primary vacuum pump is particularly suitable for industrial processes that require the removal of gases and exhaust gases that react with oil and necessitate recovery.
Note: 1. The table above lists recommended standard models in the industry, which can also be customized with non-standard designs according to specific customer requirements.
2. Technical specifications for the single pump are detailed in the performance parameters of each pump.
