问题 问答题 简答题

使用减压器应注意那些问题?

答案

参考答案:

使用减压器应按下述规则执行:

(1)、氧气瓶放气或开启减压器时动作必须缓慢。如果阀门开启速度过快,减压器工作部分的气体因受绝热压缩而温度大大提高,这样有可能使有机材料制成的零件如橡胶填料、橡胶薄膜纤维质衬垫着火烧坏,并可使减压器完全烧坏。另外,由于放气过快产生的静电火花以及减压器有油污等,也会引起着火燃烧烧坏减压器零件。

(2)、减压器安装前及开启气瓶阀时的注意事项:安装减压器之前,要略打开氧气瓶阀门,吹除污物,以防灰尘和水分带入减压器。在开启气瓶阀时,瓶阀出气口不得对准操作者或他人,以防高压气体突然冲出伤人。减压器出气口与气体橡胶管接头处必须用退过火的铁丝或卡箍拧紧,防止送气后脱开发生危险。

(3)、减压器装卸及工作时的注意事项:装卸减压器时必须注意防止管接头丝扣滑牙,以免旋装不牢而射出。在工作过程中必须注意观察工作压力表的压力数值。停止工作时应先松开减压器的调压螺钉,再关闭氧气瓶阀,并把减压器内的气体慢慢放尽,这样,可以保护弹簧和减压活门免受损坏。工作结束后,应从气瓶上取下减压器,加以妥善保存。

(4)、减压器必须定期校修,压力表必须定期检验。这样做是为了确保调压的可靠性和压力表读数的准确性。在使用中如发现减压器有漏气现象、压力表针动作不灵等,应及时维修。

(5)、减压器冻结的处理。减压器在使用过程中如发现冻结,应用热水或蒸气解冻,决不能用火焰或红铁烘烤。减压器加热后,必须吹掉其中残留的水分。

(6)、加压器必须保持清洁。减压器上不得沾染油脂、污物,如有油脂,必须在擦拭干净后才能使用。

(7)、各种气体的减压器及压力表不得调换使用,如用于氧气的减压器不能用于乙炔、石油气等系统中。

多项选择题
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Now, there is a growing movement to pay the students in American schools---in some cases, even just for coming to class.

Students at one school in New Mexico can earn up to three hundred dollars a year for good attendance. In Baltimore, Maryland, high scores in state graduation tests can be worth more than one hundred dollars. And a New Jersey school system plans to pay students fifty dollars a week to attend after---school tutoring programs.

Schools that pay students can be found in more than one---fourth of the fifty states. Other schools pay students with food or other rewards.

Robert Schaefer is a public education director. He says paying students may improve performance in the short term, but students develop false expectations for the future. He sees a lack of long term planning in these programs because of the pressure on schools to raise test scores.

Public schools need to show improvement under the education reform law. Low---performing schools may lose their federal money; teachers and administrators(行政人员) may lose their jobs. Often these schools are in poor neighborhoods where getting students to go to school can be a continual problem.

Critics(评论家) say paying students sends a message that money is the only valuable reward. But some students say it makes school more exciting. And some teachers have reported getting more requests for extra help.

In two thousand four, the city schools in Coshocton, Ohio, launched a program. They wanted to see if paying elementary school students as much as one hundred dollars would help in passing the state exams.

Now, Eric Bettinger of Case Western Reserve University (EUCWRU) has reported mixed results. Math scores increased, but only white students were able to get paid. And there was no evidence of higher scores in reading, social studies and science. Official will decide later this year whether to continue the program.

小题1:Paying students who show improvement in tests __________.

A.has been done in most American schools

B.is becoming a growing practice in the USA

C.is not very popular with teachers

D.only aims at high scores at school小题2:According to the text, Robert Schaefer _____________.

A.is a very excellent teacher

B.thinks highly of paying students

C.thinks students will show improvement in study in the future

D.thinks people should make a careful plan for the paying program小题3:From the last paragraph we can see __________.

A.EBCWRU has got great success in its paying program

B.not all the students in EUCWRU have made progress in all subjects

C.only students who study math can get paid

D.EBCWRU will go on with the paying program小题4:The text is mainly written to _____________.

A.persuade teachers to give students more prizes

B.tell people how to become an excellent student

C.introduce something about American paying students program

D.explain the advantages of American paying students program