1. What determines the amount of hydrogen sulfide produced in a sewer?
a. BOD concentration
b. D.O. concentration
d. SS concentration
2. Four conditions are necessary to create an explosion. Three of these conditions are: combustible gas, adequate oxygen and sufficient heat. The fourth is _.
a. constant supply of combustible gas
b. enclosed area that will hold the gases
c. proper mixing of gas and oxygen
d. none of the above
3. The lack of an unpleasant odor in a manhole, lift station or other structure does not meant that no dangerous gases are present because _.
a. some dangerous gases have no odor
b. oxygen may still be lacking
c. some gasses deaden the sense of smell
d. all the above
4. As the impeller wears on a pump, the pump efficiency will _.
d. not change
5. How closely an instrument measures the actual value of the process variable being measured is called its _.