FDNY A-35 STUDY GUIDE 2025/2026 QUESTIONS WITH
SOLUTIONS GRADED A+
✔✔Compression Chamber operation - ✔✔Air is compressed in compression chamber
which consists of a PISTON inside a CYLINDER. Piston moves up and down.
When piston moves down -->draws air into cylinder, through INTAKE VALVE (valve
automatically opens when piston moves down).
When piston moves up-->air is compressed (intake vale automatically closes to avoid
air escaping from cylinder).
✔✔Air Reciever Operation - ✔✔When air pressure reaches a certain level, it forces
open a DISCHARGE VALVE (which is spring loaded). This releases compressed air
into air reciever (aka air tank), which is what supplies compressed air when needed.
✔✔Single Stage Air Compressor - ✔✔with one cylinder and one piston
✔✔Multi Stage Air Compressor - ✔✔with more than one piston and cylinder.
Each cylinder will increase the pressure of the air by taking air from the discharge side
of the previous cylinder and increasing the pressure to a new level. Once it reaches the
last level, the pressurized air is discharged into the reciever.
✔✔As air is compressed it becomes - ✔✔heated.
This is why in a multi stage air compressor there is an intercooler between stages of
compressor.
✔✔Exception to single stage/multi stage distinction - ✔✔CAVEAT: there are air
compressors with multiple pistons and cylinders that are single stage but these are only
the ones where each cylinder discharges directly into air receiver (unlike a true multi
stage air compressor).
✔✔Storage containers - ✔✔some systems force the compressed air from the receiver
into storage containers allowing it to be used later as needed.
✔✔System of Connected Air Compressors - ✔✔Air forced from one compressor into
another several time to increase pressure each time and ultimately forced into a hose
line or storage container.
Used when there is a need for air under very high pressure.
✔✔Unloading Valve - ✔✔safety component.
, allows air to escape compression chamber when there is a strain on the electrical
motor. This usually occurs in the first few cycles when the compressor is first started.
Automatic in most systems but it may be manual in older compressors. Follow
instruction manual for old compressor.
✔✔Pressure Gauge - ✔✔safety component.
Indicates pressure inside receiver. CF holder should pay close attention to reading.
Must NEVER exceed manufacturer's recommendations. If greater than recommended
level there could be explosion. Pressure in the receiver is controlled by a switch; turn
switch in the desired direction to adjust pressure.
✔✔Pressure Relief Valve - ✔✔safety component.
Allows air to escape from the system when pressure is too great. Operate automatically.
May operate manually by pulling on the ring attached to the pressure relief valve
✔✔Air intake valve - ✔✔safety component.
Fitted w/ an air filter which prevents dust from being drawn into compression cylinder.
Dust in the compressor could result in fire in the cylinder b/c of heat in the cylinder. Fire
could case damage to air compressor.
This is why its important to make sure filter is always clean and securely connected to
the compressor.
✔✔Filter & Moisture Separator Assembly (FMSA) - ✔✔safety component.
Moisture can be a problem; this filter removes moisture from compressed air.
Installed between compressor and receiver.
Drain cock attached to FMSA to drain water and dirt.
✔✔Automatic Control Device - ✔✔Attached to receiver.
Shuts down compressor when pressure in receiver is adequate and restarts when more
pressure needed.
✔✔Safety Relief Valves - ✔✔safety component.
keep compressor tank from bursting if pressures witch stops working
✔✔Constant Speed Control Switch - ✔✔safety component.
SOLUTIONS GRADED A+
✔✔Compression Chamber operation - ✔✔Air is compressed in compression chamber
which consists of a PISTON inside a CYLINDER. Piston moves up and down.
When piston moves down -->draws air into cylinder, through INTAKE VALVE (valve
automatically opens when piston moves down).
When piston moves up-->air is compressed (intake vale automatically closes to avoid
air escaping from cylinder).
✔✔Air Reciever Operation - ✔✔When air pressure reaches a certain level, it forces
open a DISCHARGE VALVE (which is spring loaded). This releases compressed air
into air reciever (aka air tank), which is what supplies compressed air when needed.
✔✔Single Stage Air Compressor - ✔✔with one cylinder and one piston
✔✔Multi Stage Air Compressor - ✔✔with more than one piston and cylinder.
Each cylinder will increase the pressure of the air by taking air from the discharge side
of the previous cylinder and increasing the pressure to a new level. Once it reaches the
last level, the pressurized air is discharged into the reciever.
✔✔As air is compressed it becomes - ✔✔heated.
This is why in a multi stage air compressor there is an intercooler between stages of
compressor.
✔✔Exception to single stage/multi stage distinction - ✔✔CAVEAT: there are air
compressors with multiple pistons and cylinders that are single stage but these are only
the ones where each cylinder discharges directly into air receiver (unlike a true multi
stage air compressor).
✔✔Storage containers - ✔✔some systems force the compressed air from the receiver
into storage containers allowing it to be used later as needed.
✔✔System of Connected Air Compressors - ✔✔Air forced from one compressor into
another several time to increase pressure each time and ultimately forced into a hose
line or storage container.
Used when there is a need for air under very high pressure.
✔✔Unloading Valve - ✔✔safety component.
, allows air to escape compression chamber when there is a strain on the electrical
motor. This usually occurs in the first few cycles when the compressor is first started.
Automatic in most systems but it may be manual in older compressors. Follow
instruction manual for old compressor.
✔✔Pressure Gauge - ✔✔safety component.
Indicates pressure inside receiver. CF holder should pay close attention to reading.
Must NEVER exceed manufacturer's recommendations. If greater than recommended
level there could be explosion. Pressure in the receiver is controlled by a switch; turn
switch in the desired direction to adjust pressure.
✔✔Pressure Relief Valve - ✔✔safety component.
Allows air to escape from the system when pressure is too great. Operate automatically.
May operate manually by pulling on the ring attached to the pressure relief valve
✔✔Air intake valve - ✔✔safety component.
Fitted w/ an air filter which prevents dust from being drawn into compression cylinder.
Dust in the compressor could result in fire in the cylinder b/c of heat in the cylinder. Fire
could case damage to air compressor.
This is why its important to make sure filter is always clean and securely connected to
the compressor.
✔✔Filter & Moisture Separator Assembly (FMSA) - ✔✔safety component.
Moisture can be a problem; this filter removes moisture from compressed air.
Installed between compressor and receiver.
Drain cock attached to FMSA to drain water and dirt.
✔✔Automatic Control Device - ✔✔Attached to receiver.
Shuts down compressor when pressure in receiver is adequate and restarts when more
pressure needed.
✔✔Safety Relief Valves - ✔✔safety component.
keep compressor tank from bursting if pressures witch stops working
✔✔Constant Speed Control Switch - ✔✔safety component.
