EVR series
The EVR-series are the robust vacuum Roots pumps.
Eurovacuum EVR-series pumps are robust vacuum Roots booster pumps that allow the user to operate the system with a much higher pumping speed in the lower vacuum range and to reach a much better ultimate vacuum level. These EVR-series Roots pump are useally combined with the pre-vacuum pumps of the following series: EV-series, EVD-series, EVSW-series and EVSL-series.
Operating principle
The figure-of-eight rotors are counter-rotating at a constant speed inside the pump housing for suction and exhaust of the gas. Two rotors are supported by two bearings and synchronized by a pair of gears, which ensure these two rotors in certain relative positions. They are near to another and to the housing without actual contacting, so lubrication is unnecessary in the working housing. The carefully balanced operating parts and high precision bevel wheels ensure the pump be operated stably and continuously under the condition of high-pressure difference. Dynamic seal part use our patent technology and high quality seals. The vibration of shaft and the shaft seals are controlled to less than 0,02mm against oil leaking. As an option a gravity valve can be installed between the suction and exhaust of the pump. The function of the gravity valve is as following, when the pressure difference between the suction and exhaust is over the weight of the valve, the valve opens automatically, which controls the pressure difference to a fixed value. This value is the allowable highest pressure difference to ensure a problem free working of the pump. The advantage is that the pump can be started at the same time as the pre-vacuum pump and will therefore have a higher pumping speed in the high pressure range. Because the roots pump has a free clearance inside and running without lubricant in the working housing there will be some back flow of gas, therefore these Roots pumps will need a pre-vacuum pump to reach the end-vacuum. To eliminate the change of leakage over the rotating sealing, cause by wear, we have some special version Roots pumps who have a magnetic Force system.
