FDNY A-35 QUESTIONS AND
CORRECT ANSWERS
What happens in the compression chamber? ✅✅ANSW-There is a piston in a cylinder. The piston
moves up and down and when it moves down it draws in air through intake valve. Intake valve closes
when it is up and prevents air from escaping the cylinder which compresses the air.
What does the discharge valve do? ✅✅ANSW-Opens when pressure reaches a certain level and is
spring loaded. When it opens the compressed air is released into air receiver sometimes called air
tank.
Difference between single and multi stage compressors? ✅✅ANSW-Multi stage have levels of
pressure separated by an intercooler that cools the air as it travels.
Unloading valve safety component ✅✅ANSW-Allows air to escape from compression chamber
when there is a strain on the motor usually when first started. Usually operates automatically but
some old ones need to be manual and you should use instruction manual.
Check valve safety component ✅✅ANSW-Ensures air does not flow out when unloading valve
activates. Prevents backflow of air to the compressor head.
Where is the check valve installed? Why? ✅✅ANSW-Between compressor head air line and
unloading valve air line. Because air would escape as soon as compressor stopped and unloading
valve opened.
Pressure gauge ✅✅ANSW-Must not exceed manufacturer recommendations
Pressure relief valve ✅✅ANSW-Allows air to escape when pressure too great to avoid explosion.
Auto or can pull on ring.
Air intake valve ✅✅ANSW-Prevents dust from entering. Can cause fire in cylinder.
FMSA ✅✅ANSW-Filter and moisture. Between compressor and tank. Drain cock used to drain
water and dirt.
CORRECT ANSWERS
What happens in the compression chamber? ✅✅ANSW-There is a piston in a cylinder. The piston
moves up and down and when it moves down it draws in air through intake valve. Intake valve closes
when it is up and prevents air from escaping the cylinder which compresses the air.
What does the discharge valve do? ✅✅ANSW-Opens when pressure reaches a certain level and is
spring loaded. When it opens the compressed air is released into air receiver sometimes called air
tank.
Difference between single and multi stage compressors? ✅✅ANSW-Multi stage have levels of
pressure separated by an intercooler that cools the air as it travels.
Unloading valve safety component ✅✅ANSW-Allows air to escape from compression chamber
when there is a strain on the motor usually when first started. Usually operates automatically but
some old ones need to be manual and you should use instruction manual.
Check valve safety component ✅✅ANSW-Ensures air does not flow out when unloading valve
activates. Prevents backflow of air to the compressor head.
Where is the check valve installed? Why? ✅✅ANSW-Between compressor head air line and
unloading valve air line. Because air would escape as soon as compressor stopped and unloading
valve opened.
Pressure gauge ✅✅ANSW-Must not exceed manufacturer recommendations
Pressure relief valve ✅✅ANSW-Allows air to escape when pressure too great to avoid explosion.
Auto or can pull on ring.
Air intake valve ✅✅ANSW-Prevents dust from entering. Can cause fire in cylinder.
FMSA ✅✅ANSW-Filter and moisture. Between compressor and tank. Drain cock used to drain
water and dirt.
