Auxiliary Machinery. Test 28 – Online Maritime Tests

When an air compressor is going to be started it is important that the compressor is started with the 'blow off' valves open. Why?

To be sure that all pressure valves in the HP line to the starting bottle are open.
To ensure that the electric motor will not have a too low torque during start.
To ensure that we do not have any water assembly in the cylinders when the compressor start.
To ensure that the compressor does not have any back pressure due to a leak suction valve in stage one.

What is meant by a two stage compressor ?

The compressed air goes back from stage two and into stage one to get extra pressure before it goes into the starting air bottles.
Air from stage one goes through discharge valves in stage one and through suction valves into stage two. In stage two it will be compressed to high pressure air.
The two stage air compressor takes some air from the surroundings to stage one and compress and some air from the surroundings to stage two and compress.
Two stage air compressors have the capability to compress air in stage one and dry the air in stage two.

You have checked the oil viscosity in an auxiliary engine with the viscosity test kit. The result shows that the viscosity is low. What will You do?

Start to purify the oil.
Decrease the oil temperature.
Clean the system and change the oil.
Increase the oil temperature.

What symptom would you think shows that the freon filter drier has become blocked?

A hammering noise from the drier.
A large temperature drop across the drier.
A hammering noise from the compressors.
Pressure rise before the drier.

In a two stage compressor you will find pistons with different diameters (one is bigger than the other).Which one of the following statements is correct ?

The biggest diameter piston is the stage two piston.
The smallest diameter piston is the stage two piston
A big piston will deliver dryer air into stage one.
A big piston will give less oil content in the air.

After starting a freon compressor, how long should you wait before opening the oil separator return valve?

One minute.
Open the valve immediately.
Carefully open the valve.
After the separator shell has warmed up.

What do we have to do if the lube oil becomes yellow/white (mixed with water) ?

Drain the water.
Clean the lube oil filter with very short intervals.
Change the lube oil.
Fill more lube oil to dilute the water contained in the oil.

What do you think would be the most likely cause of too low suction pressure in a freon compressor?

Blocked condenser.
Blocked condenser tubes.
Too little gas in the system.
Broken suction valve plate.

Review Answers