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				           		VD精炼炉的真空抽气泵工作时蒸汽压力稳定而流量具有周期性,间断使用。
						        					            	 The pressure of the steam used in the vacuum pump of VD refining furnace is stable, but its flow is periodic.
								    										 
								    				            	 youdao 
- 
				           		VD精炼炉的真空抽气泵工作时蒸汽压力稳定而流量具有周期性,间断使用。
						        					            	 The pressure of the steam used in the vacuum pump of VD refining furnace is stable, but its flow is periodic.
								    										 
								    				            	 youdao