Course Title: Level 4
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Student name: AHMED ALHEFEITI 133270
Unit Name: Applications of Pneumatic and Hydraulics(J/601/1496) Unit No: 24
Assessment No: 1 Title: Circuit symbols, construction and operation
Hand out date: 18/4/16 Hand in date: 23/5/16
LO
Learning outcome
(LO) AC In this assessment you will have the opportunity to present evidence that shows you are able to: Task no.
Evidence
(Page no)
1 LO1 Be able to read and interpret pneumatic and hydraulic fluid power diagrams 1.1 recognise and describe given fluid power symbols that
conform to the latest ISO 1219 standards or their
national/international equivalent 1
1.2 From a given system diagram, read, interpret and explain the operation of either a pneumatic or hydraulic multi-actuator sequential system that uses a minimum of four actuators 2
1.3 produce a suitable circuit design drawing for either a
pneumatic or hydraulic reversible rotary actuation
system that includes speed control in both directions 3
2 LO2 Understand the construction, function and operation of
pneumatic and hydraulic
components, equipment and plant 2.1 Identify the features, describe the function and explain the operation of given items of pneumatic and hydraulic equipment. 4
2.2 analyse, compare and contrast the performance
characteristics for two given items of pneumatic and
two given items of hydraulic equipment 5
Learner declaration
I certify that the work submitted for this assignment is my own and research sources are fully acknowledged.
Student signature: Date:
Activity designed by Assessed by
Name: Rod Kirk Name: Rod Kirk 212/9/16
Date: 23/02/16 Date:
Internally Moderated by Internally Verified by
Name: Name:
Date: Date:
ASSIGNMENT DETAILS
Task 1:- LO 1.1
STANDARDS
Compile a list of the current fluid power standards (ISO and others) used in the design, construction, commissioning and operation for fluid power systems. For each state their purpose and application.
Using current standards study and explain the following statements:–
1/ How a Pneumatic and Hydraulic drawing should be laid out.
2/ Identification of symbols and numbering of symbols.
3/ what are the ISO standards for drawing size and the information that should be contained on the drawing.
Answer the following questions (use suitable illustrations if appropriate).
1/ How do you represent the junction of two lines.
2/ How would pilot lines be represented.
3/ How would pressure lines be represented.
As a marine engineer you have been given a range of Pneumatic & Hydraulic circuit diagrams, you have been tasked to identify all symbols and explain the operation of the circuit, use the current standards (ISO 1219).
Current Fluid Power Standards
a) Continuous Lines.
These lines represent a working fluid line which depicts a fluid originating from a prime mover channeled to the actuator.
b) Double lines.
A representation of the presence of a mechanical component between various components.
c) Pipe junction.
Shows the presence of a pipe connection at a junction.
d) Pressure take-off.
Power tapping point from a line.
e) Energy triangle.
In pneumatic systems, it shows direction of flow while in hydraulic systems shows the type of fluid.
f) Arrows.
Arrows can be used to represent the direction in which a fluid is flowing in a circuit. In addition to that, its shows the direction of rotation. A slanting arrow shows the ability of a device to be adjusted in a circuit.
g) Circles.
Indicate presence of a rotating device in a circuit diagram.
Statement 1
Block diagrams is the most essential initial step towards successfully designing a hydraulic or pneumatic circuit. The power circuit then comes in followed by a component to component analysis connection in the circuit.
Statement 2
Symbols and numbering are very essential when it comes to interpretation of the power circuit diagrams. It is important to note that in order to avoid confusion, both hydraulic and pneumatic circuits must have a proper numbering system due to the many components present in the circuit. Each component gets its own identity as a result of the numbering system (Anthony, 2011).
Statement 3
The circuit basics that must be present in the circuit diagram are: the power supply, pump and reservoir, control and the relief valve. Other components known as the auxiliary’s are added to the circuit to complete the whole design process depending on the parameters of the initial design. To improve the drawing’s aesthetics, the drawing should be centered.
Question 1
The most common way of representing a junction in a drawing is by intersecting two lines with a clearly visible dot at the point of contact. Another way of representing a junction is by drawing two lines intersecting each other. The image below explains further how to draw a junction (Beater, 2007).
Figure 1
Question 2
Dashed lines are a representation of pilot lines. When identifying them, one needs to look for dashed lines with smaller diameters and are longer in length. It is important to note that pilot lines are characterized by their ability to maintain the same pressure in them as other conducting lines. Below is a diagrammatic representation of a pilot line distinguishing it from other lines (Chanson, 2004).
Figure 2
Question 3
Pressure lines are characterized by the presence of a continuous thick dark line with no break. The pictorial representation of a pressure line is shown in the figure below.
Fig 1 – Speed control system.
Interpretation of the Circuit.
Symbols present in the circuit.
a. V1-cylinder with valves (operated using a push button)
b. Piston next to V6
c. V5-control component connection
d. V3 and V4 represent size to suit
e. V6-culinder with valves mounted on a roller.
f. V2-cylinder with valves.
g. FRL- filter regulator lubricator
Operation
The circuit utilizes different components which behave independently. Air gets into the circuit through the filter regulator lubricator whose main purpose is to act as a filter. A junction separates air and channels one section to V1 while the rest is channeled to V6. V1 is activated using a pushbutton controlled by V3 and V4 which is dependent on valves at V2. It is also important to note that V1 and V6 control V2 hence this entire operation is a well coordinated process which depends on all processes. V3 and V4 are responsible for directing uniform movement of fluid to the piston which acts as the output (Dancun, 2014).
Fig 2– Electro Pneumatic Double Bulkhead Lock
Interpretation of the Circuit
Circuit Symbols
a. Piston cylinders
b. Solenoid direct Control valves
c. Flow restriction valves
d. Fixed displacement unidirectional valve
Operation
The circuit incorporates the use of a ladder logicdiagram which aids in controlling pneumatic bulkhead lock. 24V supply is used to power the ladder logic diagram circuit. Coils 1 and 2 become energized upon closure of the switch hence activating prox 2 and 4. This makes pushes the fluid through the size to unit into the piston cylinder. As a result, the fluid is pushed downwards to the fixed displacement unidirectional valve. This process is recurrent and its main advantage is that it can be adjusted and controlled by simply altering the sequence at the logic diagram (Doddannavar & Barnard, 2005).
LO 1.2 Task 2
For the given system diagrams, read, interpret and explain the operation of both hydraulic multi-actuator sequential system that that are used on a vessel.
Fig 3– Hydraulic Rudder System
Components of the circuit
a) Piston cylinder
b) Pump
c) Rudder actuator
d) Control system
e) Flow restriction valves
The main components of a hydraulic rudder system are the rudder actuator and pump. The system’s rudder cables are responsible for pushing and pulling cables which aid in moving the valves of the hydraulic control as shown in the diagram below. Hydraulic valves on the other hand aid in the channeling of the hydraulic pressure to the actuator. This aids in moving the rudder. A constant frequency is produced which actuates the said valve (Galup-Montoro & Schneider, 2007).
It is conclusive to say that the whole operation of a hydraulic rudder control system can be summed as a connection between a cylinders hydraulically connected to a piston and valve. It is important to note that this system is characterized by a movable piston which is neither fixed nor aligned in a particular orientation. Presence of a linkage in the diagram shows a connection point between the pressure adjusting equipment and the piston. Lastly, the rudder actuator causes the necessary adjustments of the pump’s output at a constant pressure causing the rudder actuator to move to the desired position (Kishore, 2008).
Fig 4– Hydraulic ferry visor lock
Electro Hydraulic Sequence Circuit – ferry visor lock
Components of the circuit
a) Valve cylinders
b) Solenoid direct control valves
c) Control circuit
This circuit utilizes a control circuit diagram which aids in controlling the ferry lock circuit. It utilizes logics which can be altered based on the sequence of operations. This circuit is powered by a 24V source which consists of several coils and prox’s. Pressing the start button activates several coils in the circuit which energizes the prox’s hence activating the ferry visor lock pistons and actuators (Krivts & Krejnin, 2006). It is important to note that this process is sequential since prox 1, 2, 3 and 4 are activated differently depending on the sequence in the control circuit. The energized solenoid control valves determine the manner in which the fluid is channeled to either open or close the lock.
LO 1.3 Task 3
As an engineer on board ship you have been tasked produce a suitable circuit design and simulation for either a pneumatic or hydraulic reversible rotary actuation system that includes speed control in both directions, which operates the locking mechanism for the rudder position.
Two circuits were constructed with the aim of identifying the most suitable circuit. A closer look at the circuits indicate that the first circuit utilizes pneumatics. It is designed with the sole task of controlling the locking mechanism of the rudder system. Some of its components are the pressure regulators and the solenoid direct control valves. In addition to that, the circuit is fitted with an air motor that controls the locking and unlocking mechanism. An alternative design is shown in Figure b.
Figure a
Figure b
Task 4:- LO 2.1
Identify the features and describe the function and explain the operation of given items of pneumatic and hydraulic equipment, you should use technical data to validate your answer.
(A) Pneumatic equipment
Pneumatic Cylinder with cushioning and proximity sensors.
Solenoid operated 5 port 3 position NC Control valve.
Desiccant dryer
Shuttle valve
Sequence valve
(B) Hydraulic equipment
Hydraulic cylinder.
Gear pump
Pressure relief valve
Solenoid operated 4 Port 2 position spool valve
Pressure reducing valve.
(1) Pneumatic Equipment
Pneumatic Cylinder with cushioning and proximity sensors.
It consist of the following components: cushioning seal, cushioning piston, lip seal, cylinder barrel and the control valve. Air supply is used to return the piston back to its initial position by connecting it to the front port with the rear connected to the exhaust. In addition to that, air switching is done by the directional control valve.
Solenoid operated 5 port 3 position NC Control valve
This circuit can be activated either manually or via a solenoid. It has 5 way valves that can be programmed to act as either the normally closed of normally open and are powered by a 12V DC control voltage. An electric coil is incorporated in the circuit which upon being energized can control the plunger for either opening or closing the valve (Krivts & Krejnin, 2006).
Desiccant dryer
The main components are desiccant carousel, after cooler, process heater, regeneration air filter and the regeneration temperature control. It allows compressed air through pressure vessel fitted with alumina to aid in filtering out water. This is a repetitive process that ensures complete drying of air (Miller, 2011).
Shuttle valve
The main components of the valve are the piston, O-ring, nut, seals, core and cap. It is important to note that the valve allows fluid flow from at least one of the two sources and finds a major application in pneumatic systems. On the other hand, it is also used in hydraulic systems under special conditions.
Sequence valve
The valve consist of an inlet, drain, primary and secondary circuits. Its main use is to maintain a particular pressure level in the circuit before a shift to the next is realized.
(2) Hydraulic equipment
Hydraulic cylinder
The main components are a piston, O-ring, Rod wear ring and the piston wear ring. The hydraulic cylinder obtains its power from a pressurized hydraulic fluid. It has pistons which divides the cylinder allowing movement of fluid in a forwards and backwards motion (Recent design problems in safety functions of pneumatic systems, 2002).
Gear pump
The main function of the gear pump is to pump the hydraulic fluid being used in the entire circuit. Its main powering system comprises a motor with an embedded gear system which ensures a smooth flow of the hydraulic fluid.
Pressure relief valve
Consist of the following components: inlet nozzle, valve seat, and seal holder, valve body, set pressure, adjusting screw, cap, spring, bonnet and seal. Its main purpose is to control pressure depending on the operation. When the desired pressure is exceeded, it opens an auxiliary route hence maintaining the level at optimum.
Solenoid operated 4 Port 2 position spool valve
It is operated either manually or via a solenoid. Its four ports are either normally open or closed powered by a 12V DC. In addition to that, the solenoids are controlled by the control circuit which aids in a sequential opening and closing of the gates.
Pressure reducing valve.
The valve has the following components: spring, seat, disk, diaphragm, inlet and outlet. It has an adjustable orifice which can be varied to allow different volumes of flow. Its inlet pressure is usually higher than the controlled outlet pressure.
Task 5:- LO 2.2
Analyse compare and contrast the performance characteristics for two given items of pneumatic and two given items of hydraulic equipment.
(A) Pneumatic Screw compressor – Comp air L series Model L 15.
(B) Pneumatic Centrifugal compressor – Atlas copco ZH 7000
(C) Hydraulic Radial piston pump – Bosch radial piston pump Fixed displacement
Model EO55
(D) Hydraulic gear pump – Bosch fixed displacement gear pump model RE 10213
a. Pneumatic screw compressors operate at pressures below 10 bars while comp air L series Model L15 operate on pressures above 10 bars. In addition to that, pneumatic screw compressors operate by compressing air between the screw threads prior to release at a higher pressure while Comp air L series Model L 15 utilizes very complex control systems to compress air.
b. Pneumatic centrifugal compressors are applied in small gas turbine engines while Atlas copco ZH 7000 are utilized in large industrial gas turbine engines. In addition to that, pneumatic centrifugal compressors use the principle of compressing air in a circular manner. On the other hand Atlas copco ZH 7000 rely on the rotary motion produced by the internal combustion engines.
c. Hydraulic Radial piston pump are much reliant on eccentricity which is a very important determinant of the pump’s stroke. The main components towards the success of this operation are the pistons. Hand Bosch radial piston pump with fixed displacement on the other hand utilizes many pressure port connections which allows the assigning of different pistons different circuits.
d. Hydraulic gear pumps are used for the conversion of hydraulic energy. They pump by creating a vacuum which enables the fluid movement into and out of the pump at a higher pressure. On the other hand Bosch fixed displacement gear pump model RE 10213 have an optimized efficiency as compared to the hydraulic gear pumps. In addition to that, it is incorporated with an integrated controller which is responsible for its compact design.
References
Anthony, B. (2011). Hydraulics & Pneumatics. Hydraulicspneumatics.com. Retrieved 30 April
2016, from http://hydraulicspneumatics.com/
Beater, P. (2007). Pneumatic drives. Berlin: Springer.
Chanson, H. (2004). The hydraulics of open channel flow. Amsterdam: Elsevier Butterworth
Heinemann.
Dancun, I. (2014). ISO – ISO Standards – ISO/TC 131 – Fluid power systems. ISO. Retrieved 30
April 2016
Doddannavar, R. & Barnard, A. (2005). Practical hydraulic systems. Amsterdam: Elsevier.
Galup-Montoro, C. & Schneider, M. (2007). MOSFET modeling for circuit analysis and design.
Singapore: World Scientific.
Kishore, K. (2008). Electronic circuit analysis. Hyderabad: BS Publications.
Krivts, I. & Krejnin, G. (2006). Pneumatic actuating systems for automatic equipment. Boca
Raton: CRC/Taylor & Francis.
Miller, D. (2011). NFPA – What is Pneumatics? Nfpa.com. Retrieved 30 April 2016, from
http://www.nfpa.com/fluidpower/whatispneumatics.aspx
Recent design problems in safety functions of pneumatic systems. (2002). Washington, DC
In addition to the above PASS criteria, this assignment gives you the opportunity to submit evidence in order to achieve the following MERIT and DISTINCTION grades
Grade Descriptor
Indicative characteristic/s
Contextualisation
D1
Use critical reflection to evaluate own work and justify valid conclusions Effective judgements have been made.
An effective approach to study and research has been applied. To achieve D1 you must critically evaluate and justify the key parameters that an engineer would use in the selection of a compressor or pump.
Achievement Summary
Qualification HND in Mechanical Engineering
Assessor name
Rod Kirk
Unit Number and title Applications of Pneumatic and Hydraulics Unit 24
Student name AHMED ALHEFEITI
Criteria Reference To achieve the criteria the evidence must show that the student is able to: Achieved?
(tick)
LO 1
1.1 recognise and describe given fluid power symbols that
conform to the latest ISO 1219 standards or their
national/international equivalent Not achieved
1.2 from a given system diagram, read, interpret and explain
the operation of either a pneumatic or hydraulic multi-actuator sequential system that uses a minimum of four
actuators Not achieved
1.3 produce a suitable circuit design drawing for either a
pneumatic or hydraulic reversible rotary actuation
system that includes speed control in both directions Not achieved
LO 2
2.1 Identify the features, describe the function and explain
the operation of given items of pneumatic and hydraulic
equipment Not achieved
2.2 Analyse, compare and contrast the performance
characteristics for two given items of pneumatic and
two given items of hydraulic equipment Not achieved
Higher Grade achievements (where applicable)
Grade descriptor
Achieved?
(tick)
Grade descriptor
Achieved?
(tick)
D1
Use critical reflection to evaluate own work and justify valid conclusions
M1
Identify and apply strategies to find appropriate solutions
