BREATHING AIR COMPRESSOR

 BREATHING AIR COMPRESSOR

Breathing air compressors are used to fill up SCBA and EEBD cylinders. Having the compressor on board determines the minimum number of SCBA cylinders on board as follows:

• If the ship has a BA Compressor, there must be at least 1 charged spare cylinder for each SCBA set for Fire Fighterer Equipment and Safety Equipment. 

Ex: Total SCBA Set on board: 9

       Spare Required: 9

•  If the ship does not have a BA Compressor, there must be at least 2 charged spare cylinder for each SCBA set for Fire Fighterer Equipment and Safety Equipment.

Ex: Total SCBA Set on board: 9

       Spare Required: 18

Please note that these cylinders shall be interchangeable.

For passanger ships carrying  more than 36 passangers or constructed on after 1 July 2010 ;

• The source of emnergecy can be from main and energency switchboard or independently driven.
• 60 l/min < BA Compressor filling capacity < 420 l/min or  
• self-contained high-pressure storage systems of suitable pressure to recharge the breathing apparatus used on board, with a capacity of at least 1,200 l per required breathing apparatus, not to exceed 50,000 l of free air.'' (50,000 l / 1200 l = 41.7 ≈ 42 max  BA cylinders on board if this storage system is being used).

-SOLAS II-2/10

WORKING DIAGRAM OF BA COMPRESSOR

We will see below the working diagram of a BA Compressor. This is just a sample. Please see BA Compressor Manual on board your ship for the correct procedure. Every BA Compressor's system may slightly differ from each other.

Air flow diagram
Source: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/http://www.erpbrandbev.nl/uploads/kcfinder/files/JuniorII-InstructionManual.pdf

• Air is taken from air intake (1).
• Air is compressed in three stages (3,4,5).
• Between cylinders, there are two intercoolers, one after cooler and one seperator (6,7,8). The intercoolers and after cooler take the heat from the compressed air and let the temperature of the air drops which will increase the compression ratio of the next cylinder. The seperator extracts oil & water.
• The cartridge (filter system) purifies the air compressed air (Hazmat gases such as CO & CO2 are filtered).
• The purified compressed air comes at pressure maintaining valve. There are two options: 300 bar or 200 bar. One of them would be operational by user choice, which a valve is given. If you turn it clockwise, 300 bar in operation. When you turn it counter-clockwise, 200 bar is operational. The pressure switch over valve should be adjusted only when the compressor is not running and there is no pressure in the system.

BA Compressor Procedure

Please note that, the procedure of filling cylinders changes from one compressor to other. So check your compressor's manual before use. The sample above is just an example.

Parts of BA Compressor

Source: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/http://www.erpbrandbev.nl/uploads/kcfinder/files/JuniorII-InstructionManual.pdf

Filter Assembly

Filter assembly consists of a cartridge, seperator chamber and timer (optional).

In the seperator chamber surrounding the cartridge, the oil and water is removed. During operation, this area has to be drained together with cartridge before and after operation and once every 15 minutes during operation by the  drain valves (1,2,3 in the photo left) .

The cartridge removes oil, water and hazmat gases (such as CO, CO2). Without the cartridge, the compressor is designed not to work such that the cartridge also provides a gas tight seal at the outlet of the filter system which allow the pressure built up. Without cartridge, the air will escape into the atmosphere and the pressure will not build up.

Filter lifespan is 4,000 loads at 330 bar or 35,000 loads at 225 bar working pressure difference or  1,000 for 330 bar units, and 8,750 for 225 bar units.. So that the maintenance records are vital. Fortunately, there is a timer on some of the cartridge.

The timer counts working time of compressor, cartridge pressure, temperature and air delivery rate of compressor.  It also displays operating hours, cartridge lifetime, and all maintenance due for the compressor. The timer may differ in property depending on the compressor if fitter. So that, please check the properties of timer of your compressor, if fitted, before use.

• It is better to keep 50-80 bar pressure in the system after use to prevent moisture.
• Always keep maintence records up dated.
• Before any maintenace, depressurise the system.

Pressure Maintaining Valve

Pressure maintaining valve is used to build up pressure. It is adjusted in factory. However, if it mulfunctions, you can adjust it as below:

• Loose the nut (2)
• Set screw (1)
• Adjust screw by a screw driver (1)

Source: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/http://www.erpbrandbev.nl/uploads/kcfinder/files/JuniorII-InstructionManual.pdf

Clockwise: Increase pressure

Counter Clockwise: Decrease pressure

Safety Valves

There are three safety valves at all three compression stages. However, what we are interested is the safety valve for third stage or final safety valve because it is mounted above the filer assembly (the other two ones are not visible) and it allows us to adjust final pressure. Actually, that safety valve is intented to be used to blow off pressure the exceesive pressure in case of mulfanctioning but in reality, I have observed that the engineers responsible for BA Compressor maintenace were adjusting final pressure simply by turning the knob at the top of the final safety valve.

Please note that some BA Compressor's final safety valves are factory sealed. So that only Maker's personnels are allowed to adjust.

Also, the final safety valves are two; one for 200 bar pressure outlet, and the other one is for 300 bar pressure outlet.

BA Compressor referenced: Bauer Junior II.