Pumping installation for pumping out an enclosure containing gases which are mixed with solid particles or which generate solid condensates or particles

#The present invention relates to a pumping installation for pumping out an enclosure containing gases that may generate solid condensates or particles under certain temperature and/or pressure conditions, or that are mixed with solid particles from the outset.

#Industrial installations in which vacuum pumps are used to evacuate work chambers, e.g. when reactive gases are pumped in the semiconductor industry, include evacuation ducts leading to the outside and connected to the outlets of the pumps. It is not possible to allow the pumping unit to deliver inside the factory, in particular because of the noxiousness of some of the pumped gases. It is therefore absolutely necessary to evacuate the exhaust gases to the outside. This is done via a duct that often contains a purification system referred to as a "Scrubber" system, and an extractor fan.

#In order to dilute the pumped gases and so as to enable them to be evacuated more quickly at the outlet of the pump, the pumping unit, e.g. a multi-stage Roots pump, is equipped with a feed system for supplying an inert "purge" gas which is injected into the various ,stages of the pump. This enables improved evacuation of the above-mentioned condensates or particles, thereby protecting the inside of the pump. However, it does not prevent particles from being deposited in the evacuation duct whose cross-sectional area decreases over time with such deposition, thereby giving rise to excessive pressure at the outlet, which excessive pressure damages the pump. Furthermore, such particles also cause damage in the purification device, if there is such a device.

#An embodiment of the invention is described below with reference to the accompanying drawings, in which:

#FIG. 1 shows a pumping installation of the invention; and

#FIG. 2 is a plan view of the particle-separator device. However, in FIG. 2, the collecting receptacle is shown rotated through 90.degree. relative to its position in FIG. 1.

#The figures thus show an installation of the invention for pumping out an enclosure (not shown) containing gases which are mixed with solid particles, or which generate solid condensates or particles.

#The installation includes a pumping set 1 having a suction orifice 2 designed to be connected to said enclosure to be pumped out, and an exhaust orifice 3.

#The pumping set 1 is equipped with a feed system for supplying an inert purge gas, e.g. nitrogen, used to dilute and to entrain the gases. The system comprises a cylinder 4 of gas under pressure, the cylinder being equipped with a pressure-reducing valve 5 feeding the various stages of the pumping set 1 via narrow apertures 6, 7, 8, 9, and 10. In the embodiment shown, the pumping set is, for example a Roots pump which has five stages but which could be single-stage. The pumping set could also be another type of pump, such as a screw pump, a SCROLL pump, or even a molecular drag pump having an inert gas sweeping device.