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矿用本质型安全电气设备的特点是什么?

答案

参考答案:本安电路是指在正常工作或规定的故障状态下产生的电火花和热效应均不能点燃规定的爆炸性混合物的电路。其设备特点是:1)一般不用隔爆外壳,而是通过合理设计电路和选择电气元件,使可能产生的电火花能量小于最小点燃能量。目前国内、外公认的在常温常压下的最小点燃能量是:瓦斯与空气的混合气体为0.28ml;煤尘与空气的混合物为0.4mj。2)为了限制电路中的火花能量,电呼中的工作电压必须限制在安全电压以下,即应小于36V,一般采用直流9V或12V。3)本安电路中应尽量不用电感、电容等储能元件,否则应采取限压、限流等保护措施,为了可靠,多采用双保护。4)在非本安电路的接口处一定要加设安全栅。

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If you see someone drowning, speed is very important. Once you get him out of the water, if he isn't breathing, you have four minutes before his brain is completely destroyed. Support his neck, move his head back and press his chin upwards. This stops the tongue blocking the airway in the throat and is sometimes enough to get him breathing again. If that doesn't work, start mouth-to-mouth breathing. Press his nostrils (the two holes at the end of your nose, through which you breathe and smell things) together with your fingers. Open your mouth and take a deep breath. Blow into his lungs until his chest rises, then remove your mouth and watch his chest fall. Repeat twelve times a minute. Keep doing until professional help arrives.

To bring a child back to life, keep your lips around his mouth and gently blow into his mouth. Give the first four breaths as quickly as possible to fill the blood with oxygen. If, in spite of your efforts, he starts turning a blue-grey colour, and you can feel no pulse(脉搏), then pressing is the last chance of saving his life.

With arms straight, rock forwards, pressing down on the lower half of the breastbone. Don't be too hard or you may break a rib. Check how effective you are by seeing if his colour improves or his pulse becomes independent to your chest pressing. If this happens, stop the pressing. Otherwise continue until rescue arrives.

小题1:If you want to save someone drowning, you __________.

A.have to pull off his clothes first .

B.should try to get him out of water as quickly as possible.

C.should first make out who he is.

D.ought to throw a life coat to him first .小题2:Once a person stops breathing, it means ___________.

A.you have no more than 4 minutes to bring him to life again .

B.his brain is completely damaged .

C.he has passed away.

D.there is no way to save his life .小题3:To press his chin upwards is a way to _____________.

A.keep the tongue from blocking the airway in the throat .

B.prevent the tongue from stopping the airway in the throat .

C.wipe the tongue out of the throat .

D.see if he can possibly be saved .小题4:If the drowning boy has no pulse,_____________.

A.press his chin upwards is enough to get him breathing .

B.blow air into his mouth is sure to save his life .

C.press his nostrils together with your fingers can work .

D.press is the last chance of saving his life .小题5:Which of the following statement is true?

A.Don’t stop pressing his chest, if the drowning man starts breathing again.

B.If you see someone drowning, you must give him mouth-to-mouth breathing.

C.If a man does not breathe for four minutes, his brain will be completely destroyed.

D.When pressing, you can do it as hard as you can.