原文:
涡轮分子泵抽气系统的基本操作方法:
一个装有单独粗抽管路的涡轮分子泵抽气系统的操作方法与扩散泵抽气系统相似。在开始粗抽以前,高真空阀和粗抽阀是关着的,而前级管道阀是打开的。
1、首先关闭前级阀,启动粗抽泵(兼前级泵),打开粗抽阀开始对真空室进行抽气。在真空室内的压力降到150~100Pa时关闭粗抽阀,打开前级管道阀,
2、再启动涡轮分子泵(需先接通冷却系统)。如果分子泵入口处装有液氮冷阱,则应在泵加速到额定转速后(一般需5~10min)加注液氮。粗抽系统的配置随真空室的容积的大小而有所不同。对500L/s或更小的涡轮分子泵来说,可采用一台双级旋片泵;1000L/s以上的涡轮分子泵则采用以机械泵为前级泵的罗茨泵机组。在压力为100到150Pa时关闭粗抽阀,把真空室切换到涡轮分子泵上。对某些泵,这样做会引起轻微而滞后的瞬时减速,但这对抽气并无影响。正如扩散泵抽气系统那样,涡轮分子泵系统中的最主要的物质是水蒸气,其抽气时间将受液氮冷阱抽速的支配。如果不用液氮冷阱,那么这个系统抽除水蒸气的速度就会比同样抽速的无冷阱扩散泵略慢一些。在高真空抽气过程的起始阶段,泵的很大的未经烘烤的内表面会吸附水,然后再在较低的压力下重新释放出来。这种效应在无阀门的系统中更为明显,因为它可能比未暴露在压力高于150Pa的空气环境的有阀门的系统吸附更多的水蒸气。
3、系统停机时,先关闭高真空阀,如果有液氮冷阱的话,还要将冷阱加热。在冷阱达到平衡温度后,关掉前级管道阀,再切断涡轮分子泵电动机的电源使分子泵的转子减速。一般来说,到泵转子xx停止需要十分钟或更长的时间。在分子泵转子减速期间,来自前级管道的碳氢化合物和涡轮分子泵的润滑油蒸气会迅速地向泵的进气口上方区域扩散。为了防止
机械泵油蒸气和涡轮分子泵润滑油蒸气的返流,在切断涡轮分子泵电动机的电源后,要用一股干燥的反向气流对分子泵进行放气。例如,应该在泵转子速度下降到{zd0}转速的50%左右时,在泵进气口上方的某处或在转子组件上部连续充入氩气或氮气,直到泵内压力达到大气压。通过从阀门3(见图1)充入气体就可适当地完成这一操作。当涡轮分子泵以额定速度运转时,不应经常充入压力为大气压的气流。这样做对轴的寿命是不利的。当前级管道阀关闭后,即可关掉机械泵系统,并用放气阀对机械泵内进行放气。停机后应立即关掉冷却水以防止内部冷凝。在正常工作时,可把水温调节到略高于露点来xx泵体外部可能形成的冷凝物。启动系统要先接通冷却水流,打开前级管道阀门,再同时启动机械泵和涡轮分子泵。在泵加速到额定转速(一般为5到10min)后,就可加注液氮冷阱。此后就可按上节所介绍的步骤对真空室进行抽气。
4、下面一种所给出的是不用高真空阀门的抽气系统的操作要比有阀门的抽气系统简便得多。操作时:先打开冷却水和前级管道阀,并同时启动机械泵和涡轮分子泵。如粗抽泵选择得当使真空室的粗抽时间等于加速时间,那么真空系统就能在没有泵油蒸气返流的情况下把真空室抽到其本底压力。
5、无阀门系统在放气和停机:
1)首先关闭前级管道阀,等泵转速下降到{zd0}转速的50%时再在泵的上方充入干燥气体。当系统充到大气压时应关闭放气阀门,否则会造成真空室过压。
2)然后按上述介绍的方法关掉机械泵并停掉冷却水。没有单设粗抽管路的涡轮分子泵系统的操作:先打开分子泵冷却系统和前级管路阀,并同时启动前级(粗抽)机械泵和涡轮分子泵。如果粗抽泵(前级泵)选择得当,使真空室的粗抽时间等于分子泵的加速(启动)时间,则真空系统就能在没有泵油蒸汽返流的情况下把真空室抽到其本底压力。
3)该系统在停机前,要先关闭前级管路阀,然后切断分子泵电源和关闭冷却水。等分子泵转速下降到额定工作转速的一半时,再在泵的入口处充入干燥气体,当系统充到大气压力后,应关闭放气阀门。根据需要在前级阀关闭后的任何时候停掉前级泵系统。
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译文:
Turbo molecular pump exhaust system basic operation method: A crude
extract of the pipeline with a separate turbo molecular pump
exhaust system operating methods and ventilation systems similar to
the diffusion pump. Before pumping crude at the beginning of the
high vacuum valve and Roughing valve is closed, while the former
class pipe valve is open. 1, first close the valve before the class
to start pumping crude (and before the pump), open the valve to
begin pumping crude for pumping chamber. In a vacuum chamber when
the pressure dropped to 150 ~ 100Pa closed Roughing valve, pipe
valve opens before the class, 2, and then start the turbo
molecular pump (you must first connect the cooling system). If the
molecular pump equipped with a liquid nitrogen cold trap at the
entrance, should be accelerated to the rated speed of the pump
after the (usually takes 5 ~ 10min) filling liquid nitrogen.
Roughing the configuration of the system with the vacuum chamber
the size of the volume vary. On 500L / s or less for the turbo
molecular pump, can use a two-stage rotary vane pump; 1000L / s
turbo molecular pump is more than mechanical pumps used to pump the
former stage Roots pump unit. 100 to 150Pa pressure to close
Roughing valve, the vacuum switch to the turbo molecular pump. Some
pumps, this would cause minor transient deceleration delay, but no
effect on the exhaust. As the diffusion pump exhaust system, as
turbo molecular pump system, the material is the most important
water vapor, the extraction time by the liquid nitrogen cold trap
pumping speed of disposal. If you do not have liquid nitrogen cold
trap, then the system extraction rate of water vapor pumping speed
than if the same non-cold trap diffusion pump a little slower. In
the high-vacuum pumping the initial stage of the process, the pump
within a large baking surface without adsorbed water, and then
again at a lower pressure release. This effect in the absence of
the valve system was more obvious than it is not exposed to the air
pressure is higher than 150Pa valve system environment are adsorbed
more water vapor. 3, system shutdown, turn off the high vacuum
valve, liquid nitrogen cold trap if the words, but also heating the
cold trap. Balance in the cold trap temperature, turn off the valve
before the stage pipeline, and then cut off the turbo-molecular
pump motor power supply to make molecular pump rotor deceleration.
In general, to completely stop the pump rotor need 10 minutes or
longer. In the molecular pump rotor during deceleration, the
pipeline from the former level of hydrocarbons and steam
turbo-molecular pump of the oil will quickly pump inlet to the top
of the regional spread. In order to prevent mechanical pumps and
turbo molecular pump oil vapor lubricant vapor reflux, in the turbo
molecular pump motor cut off the power, the use of reverse flow of
a dry molecular pump deflation. For example, the pump rotor speed
should be reduced to about 50% of the maximum speed when the pump
inlet at the top of the rotor component somewhere in the top row or
in argon or nitrogen filled until the pump pressure to atmospheric
pressure. Through 3 from the valve (see Figure 1) can be properly
filled gas to complete this operation. When the turbo-molecular
pump to rated speed should not always filled the air pressure is
atmospheric pressure. This life of the shaft at a disadvantage. The
current level pipe valve closed, you can turn off the mechanical
pump system, and the mechanical pump with release valve deflated
within. Turn off immediately after the shutdown cooling water to
prevent internal condensation. In normal operation, can be adjusted
to slightly above the dew point temperature to eliminate the
external pump may form the condensate. Start the system connected
to the cooling water must first open the valve before the stage
pipeline, and then also started mechanical pump and turbomolecular
pumps. The pump speed to the rated speed (typically 5 to 10min),
allows the filling liquid nitrogen cold trap. Since then the
festival can be described according to the steps of the vacuum chamber to
exhaust. 4, the following is not given a kind of high-vacuum
exhaust valve operation of the system than a valve exhaust system
much more convenient. Operation: open the cooling water and the
former first-class pipe valve, and simultaneously start the
mechanical pumps and turbo molecular pumps. Roughing pump selection
as appropriate to the rough vacuum chamber is equal to accelerate
time to time, then the vacuum system will not pump oil vapor reflux
in the case of a vacuum chamber pumped to the pressure of their
background. 5, no valves outgassing and shutdown the system: 1)
First-class pipe valve before the closure, such as pump speed is
reduced to 50% of the maximum speed of the pump and then filled the
top of drying gas. Atmospheric pressure when the system should be
sufficient to close the gas release valve, otherwise it will create
a vacuum chamber overpressure. 2) The method described
above and then turn off the mechanical pump and turning off the
cooling water. No single set Roughing pipeline turbo molecular pump
system operation: first open the molecular pump cooling system and
pre-pipeline valve, while pre-boot level (Roughing) Mechanical
pumps and turbo molecular pumps. If Roughing pump (before pump) the
right choices, to make rough time with the vacuum chamber is equal
to the acceleration of molecular pump (start) time, the vacuum
system will not pump oil vapor reflux in the case of the vacuum
chamber pumped their The base pressure. 3) The system shutdown
before the closure of the former first-class pipe valve, and then cut
off the power on and off molecular pump cooling water. And other
molecular pump rated speed down to half speed, and then filled in
the entrance of the pump drying gas into the atmosphere when the
system charge pressure, the gas valve should be closed up. Needed
after the closure of the first-class valve stopped at any time
before the pump system.
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