Basic Control System unit3

E3145/3/1PIPING AND INSTRUMENTATION DRAWING (PNID)

PIPING AND INSTRUMENTATION DRAWING (PNID)

OBJECTIVES

General Objective : To understand and to apply the concept of piping and instrumentation drawing (PNID).

Specific Objectives : At the end of the unit you will be able to :

State the definition of PNID.

Discuss the comparison between pneumatic control system and hydraulic control system.

Draw the instruments symbols.

Name the symbols of pneumatic system components and hydraulic system components.

UNIT3


3.0 Explanation of PNID

Piping and instrumentation drawing (PNID) includes the components of pneumatic control system and hydraulic control system. Pneumatic control system uses compressible fluid meanwhile the hydraulic control system uses incompressible fluid.

The basic components of pneumatic system are : compressor , air tank, air dryer, regulator, directional control valve and actuator. For hydraulic system the components are : pump, motor or cylinder, oil tank and valve.

Basically, pneumatic system is widely used in the electronic, food, and automotive industry. Below are the uses of pneumatic system :

Transferring of materials Drilling system Material handling (clamping, shifting, positioning, orienting) Stamping Packaging Automation

Meanwhile, hydraulic system is normally used to operate :

INPUTINPUT

Piping and instrumentation drawing (PNID) includes the components of pneumatic control system and hydraulic control system.


Back hoe Bull dozer CNC machine Load loader Die casting machine

The advantages of using pneumatic system and hydraulic system are shown in Table 3.1 :

Pneumatic System Hydraulic System

1. Air – easy to get (unlimited). 1. Flexible – In power transmission , hydraulic power is more flexible compared to pneumatic power.

2. Transmission – air is easy to transfer for a long distance through pipe line.

2. Force gain – a small force can be used to control the large force.

3. Storage – compressed air can be stored in air storage tank and can be released if not needed.

3. Component – Does not need a lot of moving mechanism.

4. Temperature – compressed air is not sensitive to temperature reactions that can cause burning.

4. Compact – hydraulic motor size is smaller compared to electric motor.

5. Clean – air leakage does not cause environmental pollution.

5. Economy – hydraulic system is better and more profit.

6. Component – pneumatic system is easier to maintain and cheaper.

7. Speed – it can work faster than hydraulic system.

8. It responses very fast to the start and stop commands from the controller.

9. Air does not need a back flow.

Table 3.1 : Advantages between pneumatic system and hydraulic system(Source : Jubaidi Bin Razali, Pneumatik & Hidraulik)


3.1 IDENTIFYING INSTRUMENTS SYMBOLS

3.1.1 Symbols of pneumatic componentThe symbols of pneumatic components found in a pneumatic system are shown below :

(Source : Jubaidi Bin Razali, Pneumatik & Hidraulik)










3.1.2 Symbols of hydraulic componentThe symbols of hydraulic components found in a hydraulic system are shown below :













Activity 3

TEST YOUR UNDERSTANDING BEFORE YOU CONTINUE WITH THE NEXT INPUT…!

3.1 Explain what is meant by Piping and Instrumentation Drawing (PNID)

3.2State the basic components of pneumatic system and hydraulic system.

3.3 State 5 components of pneumatic system and hydraulic system.

3.4 Give 3 industries that use pneumatic system.


Feedback To Activity 3

3.1 Piping and instrumentation drawing (PNID) includes the components of pneumatic control system and hydraulic control system. Pneumatic control system uses a compressible fluid while the hydraulic control system uses incompressible fluid.

3.2The basic components of pneumatic system are : compressor , air tank, air dryer, regulator, directional control valve and actuator. The basic components of hydraulic system are : tank, filter, pump, valve, motor and cylinder.

3.3 Pneumatic system componentsa. Pneumatic compressorb. Pneumatic cylinder (single acting)c. Pneumatic cylinder (double acting)d. Valve 2/2e. Flow controller valve

Hydraulic system componentsa. Fixed displacement hydraulic pumpb. Double acting cylinderc. Differential cylinderd. Pneumatic motore. Direction controller valve 2/2 type

3.4 a. Food industryb. Automotive industryc. Electronic industry


KEY FACTS

1. Piping and instrumentation drawing (PNID) includes : components of pneumatic control system components of hydraulic control system

2. The basic components of pneumatic system are : compressor air tank air dryer regulator directional control valve actuator

3. The basic components of hydraulic system are : pump motor or cylinder oil tank valve.


SELF-ASSESSMENT

You are approaching success. Try all the questions in this self-assessment section and check your answers with those given in the Feedback on Self-Assessment given on the next page. If you face any problems, discuss it with your lecturer. Good luck.

Q3-1 Define the word ‘PNEUMATIC’ and explain how this system functions.

Q3-2 State the advantages between pneumatic system and hydraulic system.

Q3-3 State 5 advantages of pneumatic system.

Q3-4 Draw the symbols of the pneumatic components given below in the space provided.

COMPONENT DESCRIPTION SYMBOLS

Pneumatic compressor

Fixed displacement

Pneumatic cylinder (single acting)

Non-return spring

Spring return

One rod


Pneumatic cylinder (double acting)

Two rod

2/2 valveClosed loop double port

Open loop double port


Feedback To Self-Assessment

Have you tried the questions????? If “YES”, check your answers now.

Q3-1 The word ‘Pneu’ is from Greece which means wind, ‘matic’ refers to power. Therefore pneumatic system means a system which is operated by wind. The pneumatic system uses compressed air as a power transfer medium. The compressed air is obtained from the environment. Then it is compressed using electric motor.

Q3-2

Pneumatic System Hydraulic System

1. Air – easy to get (unlimited). 1. Flexible – In power transmission , hydraulic power is more flexible compared to pneumatic power.


2. Force gain – a small force can be used to control the large force.


3. Component – Does not need a lot of moving mechanism.


4. Compact – hydraulic motor size is smaller compared to electric motor.



5. Economy – hydraulic system is better and more profit.


7. Speed – it can work faster than hydraulic system.



Q3-3 (Any five answers from this list are accepted)

1. Air – easy to get unlimited.






7. Speed – it can work faster than hydraulic system




Q3-4


Education

Basic Control System unit3