DESIGN IV MECHINERY SYSTEM
DEPARTMENT OF MARINE ENGINEERING
Calculation and Specification of
Compressed Air System
Doc. No. 09 - 42 20 AK015 - CA
Prepared by Approved by
Rev. Date Remark
Raka Adhwa Ardhya M Dr. I Made Ariana S.T.,M.T.
Doc. No. 09 - 42 20 MA015 - CA
Calculation and Specification of
Rev. No. 0
Compressed Air System Page 1 of 5
I. INTRODUCTION
Compressed Air system are used to start the engine, to provide actuating energy for
safety and control devices and other system in the ship, such as quick closig valve,
hydrophore tank, and equipment that requier the compressed air, but in the system
focus in starting engine.
II. OBJECTIVES
The object of Compressed Air System is:
a) Knowing the components and function of the Compressed Air System
b) Knowing the specification of pumps ad equipment used.
III. REFERENCES
a) ABS Rules 2017 Part 4, Chapter 6, Section 5 Piping System For Internal
Combustions Engine.
b) Engine Guide for Wartsila 9L26
IV. LIST OF ABBREVIATIONS
a) Q = Capacity
b) V = Volume
V. SYSTEM DESCRIPTION
Compressed Air system are used to start the engine, to provide actuating energy for
safety and control devices and other system in the ship, such as quick closig valve,
hydrophore tank, and equipment that requier the compressed air, but in the system
focus in starting engine. Compressed Air System is divided into two path : direct and
indirect. Direct system works by inserting pressurized air directly into the
combustion chamber, pressurized air incorporated during the process, while
indirect piston system works by inserting pressurized air to rotate the flywheel that
drives the crankshaft.
in wartsila 9L26 is started with pneumatic starting motor operating at a nominal
pressure of 3 Mpa. The Starting motor drives a pinion that turns the gear mouted on
the flywheel.
Compressed Air System Component :
1) Air Compressor Unit
Function : Compressor used to supply air pressurized in to air receiver.
2) Air Receiver
Function : Air Receiver used to save the air pressurized.
3) Non Return valve, straight, screw down
Function : valves are used at high pressure and direction of flow in one
direction.
4) Globe Valve
Function : Globe Valve are used to open and close the flow at relatively high
pressures due to be passed by the high-pressure air.
5) Safety Valve
Function : Safety Valve are used maintain the pressure at the nominal and as
safety device if the air receiver over pressure
6) Filter
Function : Filter are used to separate the air from the moisture before engine
Doc. No. 09 - 42 20 MA015 - CA
Calculation and Specification of
Compressed Air System Rev. No. 00
Page 1 of 1
VI. DESIGN REQUIREMENTS
Key
NO Reference Parameter Design
Equipment
1
Cooling water pumps of propulsion gas turbine and
ABS Rules,
associated reduction gear and cooling water pumps of
Part 4, Chapter
propulsion diesel engines with bores greater than 300
6, Section 5 mm and associated reduction gears are to be certified
(9.3.1) in accordance with 4-6-1/7.3. Pumps supplying
cooling media other than water are to be subjected to
Air
the same requirements.
Compresso
Water jackets or casing of air compressors and
r ABS Rules,
coolers which may be subjected to dangerous
Part 4, Chapter
overpressure due to leakage into them from air
6, Section 5
pressure parts are to be provided with suitable
(9.3.2)
pressure relief arrangements.
ABS Rules,
They may be accepted based on satisfactory
Part 4, Chapter
performance and verification of capacity stated in 4-6-
6, Section 5
5/9.3.1 after installation on board.
(9.3.3)
ABS Rules, Vessels having internal combustion engines
Part 4, Chapter arranged for air starting are to be provided with at
6, Section 5 least two starting air reservoirs of approximately
(9.5.1) equal size.
2 Air Receiver
Starting air reservoirs having a design pressure
ABS Rules, greater than 6.9 bar (7 kgf/cm2, 100 psi) or with a
Part 4, Chapter design pressure greater than 1.0 bar (1.0 kgf/cm2,
6, Section 5 15 psi) and design temperature greater than
(9.5.2) 149°C (300°F) are to be certified by ABS.
Pipe fittings and joints are to meet the
requirements for certification in 4-6-1/7.1;
Pipe and ABS Rules,
3 materials in 4-6-2/3
Fittings Part 4, Chapter
6, Section 5
(9.7.1)
Doc. No. 09 - 42 20 MA015 - CA
Calculation and Specification of
Compressed Air System Rev. No. 00
Page 1 of 1
All discharge pipes from starting air compressors
are to be led directly to the starting air reservoirs,
ABS Rules,
and all starting air pipes from the air reservoirs to
Part 4, Chapter
propulsion or auxiliary engines are to be entirely
6, Section 5
separated from the compressor discharge piping
(9.7.2)
system.
Where engine starting is by direct injection of air
into engine cylinders, and in order to protect
starting air mains against explosions arising from
3 Air Receiver improper functioning of starting valves, an isolation
non-return valve or equivalent is to be installed at
ABS Rules, the starting air supply connection of each engine.
Part 4, Chapter Where engine bore exceeds 230 mm (91/16 in.), a
6, Section 5 bursting disc or flame arrester is to be fitted in way
(9.7.3) of the starting valve of each cylinder for direct
reversing engines having a main starting manifold
or at the supply inlet to the starting air manifold for
non-reversing engines.
Where a propulsion engine can be started from a
remote propulsion control station, low starting air
ABS Rules, pressure is to be alarmed at that station.
Part 4, Chapter Propulsion machinery spaces intended for
4 Air Receiver
6, Section 5 centralized or unattended operations (ACC/ACCU
(9.7.3) notation) are also to be provided with alarms for
low starting air pressures in the centralized control
station.
Doc. No. 09 - 42 20 MA015 - CA
Calculation and Specification of
Compressed Air System Rev. No. 00
Page 1 of 1
DESIGN IV MECHINERY SYSTEM
DEPARTMENT OF MARINE ENGINEERING
ATTACHMENT
Calculation and Specification of
Compressed Air System
Attachment of Doc. No. 09 - 42 20 AK015 - CA
Doc. No. 09 – 42 20 MA015 - CA
Calculation and Specification of
Rev. No.
Compressed Air System Page
In Wartsila 26 (9L26), the cooling system is explained by this statement :
Compressed air is used to start engines and to provide actuating energy for safety and control devices. The use of
starting air for other purposes is limited by the classification regulations. To ensure the functionality of the
components in the compressed air system, the compressed air has to be free from solid particles and oil.
1 VOLUME OF STARTING AIR VESSEL (AIR RECIEVER)
- The starting air vessels should be dimensioned for a nominal pressure of 3 Mpa
- It is recommended to use a minimum air pressure of 1.8 MPa, when calculating the required volume of the
vessels.
- The starting air vessels are to be equipped with at least a manual valve for condensate drain
Wartsila 26 Project Guide page 8-5
The starting air consumption stated in technical data is for a successful start. The
required total starting air vessel volume can be calculated using the formula:
PE = Normal Barometric Pressure = 0,1 MPa
VE = Air Consumption per starts = 1,4 Nm3
n = required number of starts = 6 [non-reversible]
according to the class
PRmax = maximum starting pressure = 3 MPa
PRmin = minimum starting pressure = 1,8 MPa
So :
VR = (PE x VE x n)/(PRmax-PRmin)
= (0.1 x 1,4 x 6)/(30-18)
3
= 0,700 [m ]
= 700 [Liter]
2 DIMENSION AND SPECIFICATION OF STARTING AIR VESSEL (AIR RECIEVER)
Dimension of Starting Air Vessel ( Air Receiver ) :
Size = 700 liter
L1 = 2740 mm
L2 = 255 mm
L3 = 133 mm
D= 650 mm
Weight = 625 kg
Spesification of Starting Air Vessel ( Air Receiver ) :
Merk = MELLCON
Doc. No. 09 – 42 20 MA015 - CA
Calculation and Specification of
Rev. No.
Compressed Air System Page
Type = SL.NO.3
Volume = 750 liter
Height = 1450 mm
Dia = 750 mm
Pressure = 30 bar
3 CALCULATION OF STARTING AIR COMPRESSOR
At least two starting air compressors must be installed. It is recommended that the compressors are
capable of filling the starting air vessel from minimum (1.8 MPa) to maximum pressure in 15...30 minutes.
For exact determination of the minimum capacity , the rules of the classification societies must be followed.
Wartsila 9L 26 Project Guide page 8-4
Q = VR/t Where :
= 0.5 / 0.25 Q = Capacity of the starting air compressor
3 3
= 3,0 m /h VR = Volume of starting air vessel = 0,75 m
t = time for filling the starting air vessel = 15 minutes
= 0,25 hour
4 SPECIFICATION OF STARTING AIR COMPRESSOR
Spesification of Starting Air Compressor
Merk = HATLAPA
Type = L9
Capacity = 6,6 m³/h
RPM = 1150
Power = 1,7 kW
5 SPECIFICATION OF WATER & OIL SEPARATOR (doesn't need power )
An oil and water separator should always be installed in the pipe between the compressor and the air
vessel. Depending on the operation conditions of the installation, an oil and water separator may be needed
Doc. No. 09 – 42 20 MA015 - CA
Calculation and Specification of
Rev. No.
Compressed Air System Page
vessel. Depending on the operation conditions of the installation, an oil and water separator may be needed
in the pipe between the air vessel and the engine.
Merk : Spirax Sarco
Type : Spirax Monnier Separator
Sizes : 3/4" and 1"
Connection : Screwed BSP (BS21-Rp)
Max Temp. : 70ᵒC
Work Press : 17 bar
Height : 275 mm
Width : 96 mm
Length : 96 mm
