What concentration of oxygen, in percent by volume, is considered normal and safe to work in?

a. Less than 6
b. 6 to 16
c. 19.5 to 21.5
d. More than 23.5


c

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Technician A says that diamonds indicate a component that conditions fluid in the circuit, such as a filter or heat exchanger. Technician B says that  dashed lines indicate a return or exhaust circuit. Who is correct?

A. Technician A B. Technician B C. Both D. Neither

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Fill in the blank(s) with the appropriate word(s).

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The leading states in horse numbers are Texas, California, and:

A. Oklahoma B. Tennessee C. Colorado D. New Mexico

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You need to de-energize a circuit to work on a unit. To ensure your safety, you should:

A) Work quickly to reduce your exposure to the electricity. B) Leave a clearly written"Keep Off" message in 1" block letters. C) Lock out and tag out the circuit. D) Ask a friend to stand beside the disconnect switch to ensure nobody turns it on.

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