问题 问答题 简答题

阀门检修应注意哪些事项?

答案

参考答案:

⑴阀门检修当天不能完成时,应采用防止杂物掉入的安全措施⑵更换阀门时,在管道焊接中,要把阀门开启23圈,以防阀头因温度过高而胀死、卡住或把阀杆顶弯

⑶阀门在研磨过程中,要经常检查密封面是否被磨偏,以便随时纠正或调整研磨角度

⑷用专用卡子进行阀门水压试验时,试验人员应注意防止卡子脱落伤人,要躲开卡子飞出的方向

⑸在阀门组装前对合金螺栓要逐条进行光谱和硬度检查,以防错用材质

⑹更换新合金阀门时,对新阀门各部件均应打光谱鉴定,防止发生错用材质,造成运行事故。

单项选择题
单项选择题

Scientists around the world are racing to learn how to rapidly diagnose, treat and stop the spread of a new, deadly disease. SARS — Severe Acute Respiratory Syndrome — was (1) for the first time in February 2003 in Hanoi, (2) since then has infected more than 1,600 people in 15 countries, killing 63. At this (3) , there are more questions than answers surrounding the disease.

Symptoms start (4) a fever over 100.4 degrees F, chills, headache or body (5) . Within a week, the patient has a dry cough, which might (6) to shortness of breath. In 10% to 200% of cases, patients require (7) ventilation to breathe. About 3.5% die from the disease. Symptoms (8) begin in two to seven days, but some reports suggest it (9) take as long as 10 days. Scientists are close to (10) a lab test to diagnose SARS. In the meantime, it is diagnosed by its symptoms. There is no evidence (11) antibiotics or anti-viral medicines help, (12) doctors can offer only supportive care. Patients with SARS are kept in isolation to reduce the risk of (13) . Scientists aren’t sure yet, but some researchers think it’s a (14) discovered coronavirus, the family of viruses that cause some common colds.

Most cases appear to have been passed (15) droplets expelled when infected patients cough or sneeze. Family members of infected people and medical workers who care for them have been most likely to (16) the illness. But recent developments in Hong Kong suggest that the (17) might spread through air, or that the virus might (18) for two to three hours on doorknobs or other (19) Health experts say it is (20) , though, that sharing an elevator briefly with an infected person would be enough to pass the virus.

19()

A.exteriors

B.outside

C.surfaces

D.coverings