Pressure Sensor Operated Valve Established Microcontroller GENERALLY Engineering Essay

A pressure sensor measures pressure, typically of gases or liquids. Pressure sensor can be called as pressure transducers, pressure transmitters, pressure senders, pressure signals and piezometers. Pressure detectors are used for control and monitoring in a large number of every day applications.

Pressure Sensor Controlled Valve structured Microcontroller in General

A pressure sensor controlled valve founded microcontroller is a pressure sensing device that is with the capacity of managing a desired pressure up to the place point establish by the user. Besides, the pressure sensing device also allows the user to screen and control the complete process of the machine by interfacing a Microcontroller with a Computer Using RS232 and the Computer Serial Dock.

Pressure sensor and valve are required to design pressure sensing device regarding to their job Nowadays pressure sensors can vary in design, performance, application suitability and cost. Alternatively, pressure sensors can be grouped in term of pressure ranges they evaluate, temperature ranges of operation, & most importantly the type of pressure they measure.

Valves are used to regulate conditions such as circulation, pressure, temps, and liquid level. The opening or closing of the valve is depend on the impulses received from the controllers that compare a collection point to an activity variable where the value is obtain from the sensor that monitor the change of conditions. Besides, the opening and shutting of the control valve is done by electric powered, hydraulic or pneumatic system. A valve can also fluctuate in design, pressure range and heat range of the operation, software suitability and cost.

Project Objective

The main target of this job is to design and construct a prototype of pressure sensor controlled valve structured microcontroller. This prototype should have the following important features

Able to control the pressure through the "setpoint" arranged by an individual.

Able to activate the alarm if the pressure is above a setpoint.

Able to shutdown the complete process if the pressure is within critical pressure.

Able to screen the process of the control through Computer.

Upon successful implementation of these important features, enhancements are put into improve the safe practices of this pressure sensor manipulated valve centered microcontroller. The first improvement is adding manual control function to get this to control valve in a position to control by the user even the pressure sensor is fail to give a signal to the microcontroller. Besides, a backup electric battery is also added into the controller to provide power when there exists lack of main power supply. The backup battery pack will power the circuit only in the event of failure. On the other hand, a temps sensor will also be added into this pressure sensor managed valve centered microcontroller to maintain the optimum temperatures of the gas.

Project Overview

The pressure sensor handled valve centered microcontroller was created to control pressure either in gas or liquid medium in virtually any suitable request. The pressure sensor will senses the pressure from the across the tube or tube along the application. Underneath of the pressure sensor is linked with a T-Joint connection to the tube or tube and the analog control sign from the pressure sensor will be connected to the analog slot of microcontroller. The analog signal received by microcontroller will be examined by the microcontroller. The microcontroller will then control the control valve by with the sign received by the sensor.

Besides, a temperature sensor (LM35) will also be added in to the prototype to improve the performance of the prototype. The temperatures sensor will be installed at the surface of the tube or pipe. The temps sensor will sense the heat range of gas or fluids inside the tube or tube and send a control sign to microcontroller. The analog control sign from the temperatures sensor will be linked to the analog port of microcontroller. The microcontroller then will control the control valve according to the temps received by sensor.

Recently, serial interface of computer gradually phase right out of the market and to be substituted with USB. Nowadays, most builder will favor USB to serial converter to obtain virtual serial dock. So, to be able to for basic and convenient use, a USB to UART converter (UC00A) which offers USB plug and play, direct program with microcontroller will also be put into the prototype to create a monitoring system through Laptop or computer. The Transmit Sign (TX) from UC00A will be hook up to the microcontroller receiver pin (RX/RC7). As the Receive Transmission (RX) from UC00A will be hook up to the microcontroller transmitter pin (TX/RC6). Then, a GUI( Global User Interface) will be develop using Microsoft Visual Basic for user to monitor the process procedure of the prototype.

On the other hand, a backup electric battery of 24Vdc will also be connected parallel with the key power supply. That is to supply the prototype with a backup power supply when there is no electricity provided from main power. This is to prevent and protect the prototype from trip of circuit and critical shut down of the prototype that may cause damage to the hardware of the prototype.

Besides, a LCD display (2x16 heroes) can be used to display the pressure and heat assessed from the detectors and indicates the problem or position of the control valve and the environment compressor which ideal for calibration, monitoring, debugging and assessment.

A buzzer is embedded in the prototype is utilized as an security alarm when the pressure or heat is above the setpoint set by the user.

Project Range and Methodology

This task consisted both of the hardware and software implementation. According to the schedule, engineering of the final prototype was made certain to attain the project's objective. At exactly the same time, software also designed to meet all the fundamental requirements. If the prototype that found the primary goals was successfully produced, the remaining project's duration was allocated to improvements of the prototype to make it more durable and reliable.

In part one, project's objectives identification and planning have been done. After that, research on some the theoretical record of the task such as types of pressure sensor, temperatures sensor, type and size of accessories and tube, types of control valve and the basic electric element for the controller that necessary for this project.

Electronic components were carefully picked to construct the prototype based mostly of its features, dependability and cost. When hardware selection was finalized and chose, a layout for printed circuit table (PCB) was designed and fabricated. From then on, a simple program was written to check, calibrate and debug the prototype to make it worked well as detailed in the primary objective.

In part two, further enhancements to the prototype were prepared and executed. The mechanical pulling of the prototype have been designed. The mechanised area of the hardware such as pressure sensor, tubes, fitting, control valve is joint up together and the wiring is linked to the into the key board(Controller) of the prototype. Besides, monitoring system of the procedure is also embedded to the prototype to help ease an individual to keep an eye on the operation using a Laptop or computer in a control room. In the end features, were completed, testing was undertaking to ensure the reliability of the complete system. Troubleshooting and debugging period on software and hardware were essential to make all the system are more reliable and safe.

Structure of the Report

This statement is divided into six chapters. At the Chapter 1, Launch to the task which include Pressure Sensor Controlled Valve Established Microcontroller generally, Project objective, Project overview, Project range and Methodology had been discussed.

In Section 2, some theoretical background for this task will be explained and detailed in details.

While in Section 3, how hardware designed of this job as well as their functions will be elaborated. Besides, Technique used for design the hardware also will be discussed in this section.

Chapter 4 detailed the Methodology for the software development of the project. Flow graph for the program will be showed and described. Besides, equipment and tools used to create complete software also will be mentioned in this section.

In Chapter 5, results and discourse will be proven to explain how the pressure sensor control valves structured microcontroller carries out its procedure. On the other hands, the issues encountered while designing the prototype either in hardware or software and how these problems fixed will be also talked about in this chapter.

Chapter 6 will be the summary and finish of the statement whether all the fundamental requirements and targets achieved for Last Year Task. Then, you will see a short recommendation or suggestion to improve this project so that it can be used in various types of industry environment.

Chapter 2: Theoretical Background

2. 1 Intro to Pressure Sensor

A pressure sensor is the one that will measure the pressure either gasses or fluids. Pressure is an expression of the drive necessary to stop a liquid or gas from extending, and it can be express as the equation below. [1]



P is the pressure,

F is the normal power,

A is the region.

Pressure Devices can be expressed as the stand below

Table 1: Pressure Unit

2. 1. 1 Types of Pressure Measurement

Basically, stresses sensor can be categorized in term of pressure runs, temperature ranges & most significantly the pressure type. Pressure sensor can be categorised in 5 types of pressure dimension which can be

Absolute pressure sensor

-Whereby the sensor measure the pressure relative to perfect vacuum pressure (0 Psi or no pressure)

2) Gauge pressure sensor

-Whereby the sensor gauge the pressure in accordance with given atmospheric pressure. For instance when a wheel pressure gauge read 0 Psi so this means to say you can find 14. 7 Psi (atmospheric pressure) in the tire.

3) Vacuum pressure sensor

-The sensor is employed to evaluate pressure significantly less than the atmospheric pressure.

4) Differential pressure sensor

-The sensor actions the difference between several pressures created as inputs to the sensing product.

5) Sealed pressure sensor

- Whereby the sensor is utilized to gauge the pressure in accordance with sea level pressure.

2. 1. 2 Types of Control Indication from Pressure sensor

There are two types of Control signal from stresses sensor that happen to be current end result and voltage end result signal. Current output normally ranged from 4-20ma while the voltage result normally ranged from 1-5Vdc or 1-6Vdc (The voltage productivity range mainly is depend by the manufacturer or the kind of application). The existing outcome and voltage outcome always begin from 4ma and 1Vdc is to check whether the wiring of the pressure sensor is performed correctly also to check whether there may be faulty at the pressure sensor. For instance, if the pressure sensor productivity an up-to-date below 4ma or 1Vdc, we must check at the pressure sensor because they could be faulty at the pressure sensor.

The current productivity control sign is trusted in many kind of industry compared to voltage end result control signal. It is because there is no voltage drop when current end result control sign travel a very long distance compare to voltage productivity control indication. When visiting at a very long distance, voltage end result control signal will have disadvantage because of the level of resistance of the long cable may cause a voltage drop and might give an inaccurate lead to the controller. So, the current output control sign tends to give a more accurate effect compare to voltage end result control signal. Because of limitation at PIC microcontroller which only has Analog-to-Digital Converter, so a voltage outcome control signal could be more suited to the project.

Types of Software of Pressure sensor

A pressure sensor can be trusted in various kinds of application. For example: [2]

1) Pressure Sensing

-The pressure is measure directly using pressure receptors. This is very useful in oil and gas industry, cars, airplane, and other equipment which has a pressure functionality put in place.

2) Drip Testing

-A pressure sensor may be used to sense the decay of pressure anticipated to a system leak. This is done by either evaluation to a known leak using differential pressure, or by means of utilizing the pressure sensor to solution pressure change over time.

3) Level Sensing

- A pressure sensor can be used to calculate the level of a fluid. This system is commonly used to gauge the level of items in a fish tank (such as in a normal water tower). For some practical purposes, fluid level is immediately proportional to pressure. Regarding fresh water where in fact the articles are under atmospheric pressure, 1psi = 27. 7 inH20 / 1Pa = 9. 81 mmH20. The basic equation for such a way of measuring is

P = p * g * h

Where P = Pressure, p = Density of the Substance, g = Standard Gravity, h = Level of smooth column above pressure sensor

Introduction to Valve

A valve is device that is utilized to regulate the flow of any liquid or gasses by starting and shutting or partially obstructing various passageways. A valve can be functioning either in manual operation or automatic operation powered by change in pressure, temperature or move. For manual operation, the opening and final of the valve is control by using hands steering wheel, lever or pedal using individuals force. In the mean time for the programmed operation, the opening and shutting of the valve is control using an actuator. An actuator will stroke the valve depending on its input and set-up, allowing the valve to be located accurately, and allowing control over a variety of requirements. Nowadays, Actuators are widely used for the purposes of computerized control such as in washer cycles, handy remote control including the use of any centralised control room, or because manual control is too difficult such as when the valve is large. [3]

2. 2. 1 Types of Actuator in the Valve

Valve can be categorized on how they may be actuated. Included in this are: [3]






For a hydraulic system actuator valve is normally used to control a high pressure while Pneumatic system actuator valve is normally used to control a medium pressure in request. In the mean time low pressure, solenoid or motorized system actuator valve can be utilized.

2. 2. 2 Software of Valve

Valve can vary generally in form and program. The size of the valve is normally range from 0. 1mm to 60cm. Some special valve can have a diameter exceeding 5 metres. The cost for a valve is depending on types of the design, material build, range of temp and pressure and supplier. When a custom made, engineer, or customer decides to employ a valve for an application, he/she should ensure the ranked maximum heat and pressure should never be exceeded and that the wetted materials are compatible with the smooth the valve interior is subjected to. [3]

The industries in which the majority of valves are used are coal and oil, power generation, drinking water reticulation, sewerage and chemical manufacturing. [3]

2. 3 Benefits to Tubing

Tubing is pipe or a hollow cylinder for the transmitting of liquid (liquid or gas). The term of "pipe" and "tubing" can be interchangeable although there are minimal distinctions can be found- fundamentally, "tubing" imply tighter executive requirements than "pipe". Both "pipe" and "tubing" can be varies in various rigidity and permanence. For samples, a "hose" is generally portable and versatile. Besides, tubing and pipe can be specified by standard pipe size designation. Types of tubes are given by the genuine inside diameter, outside diameter and the wall membrane thickness. [4]

2. 3. 1 Types of Tubing

Basically, there are few types of tubing can be utilized in industry. Included in this are

Copper Tubing

Stainless Steel or Aluminium Tubing

Plastic Tubing

For copper tubes, there are two basic types of copper tubing, delicate copper and rigid copper. Copper tubes can be signed up with using flare connection, compression connection, or sweat (solder). Soft copper tubes can be bent easily to visit around road blocks in the road of the tubes while a rigid copper cannot be bent and must use elbow fittings to bypass corners or about road blocks. Soft copper is typically the most popular choice for refrigerant lines in split-system ac units and heat pushes while rigid copper is most popular choice for normal water line. [5]

For Aluminium Tubing, it is sometimes used in industry because it is resistance to corrosion and solvents, and because of its ductility. Besides, aluminium cannot create sparks when there's a transmitting of flammable solvent and the weight for aluminium is lighter compare to steel and iron which make it ideal to use in many types of industry. [5] Aluminium tubing can be joined up with using flare connection, compression connection, or sweating (solder). Aluminium tubing can be used for heat copy tubing such as with refrigerant systems. [6]

For Plastic Tubing, there are few types of plastic material tubing that are PVC(polyvinyl chloride) and CPVC, Polyethylene, Rigid Polypropylene, Ab muscles (acrylonitrile butadiene styrene) and Nylon tubing. The most popular for plastic tubes is PVC. It really is rigid, and uses thread or glue associations. Besides, it comes in many of pressure range. [5] Plastic tubing is trusted for its light weight, chemical amount of resistance, non-corrosive properties, and ease of making relationships. [6]

2. 3. 2 Types of Tube Fittings

There are various kinds of connection options for tubing program in industry. The four most typical types of tube fttings connections are

Compression Tube Fittings

Flare Fittings

Bite-Type Pipe Fittings

Mechanical Grip-Type Pipe Fittings

The Compression Tube Fitting was the first pipe fitted to be introduced, which consist of three components: nut, body and gasket band or ferrule. The disadvantages of compression tube fittings was it can endure only minimal pressure and the remake is very hard due to the contrustion of the sealing ring. [7]

CompressionTube Fitting

The Flare Installing was the another variant in pipe fittings designs. The fittings is made up from a nut, sleeve and body with a flare or coned end. During installation of a tubing, a special flaring tools are usually required. The negatives of flare fittings is that flaring of the tubing may cause stress riser at the bottom of the flare or cause the axial splits on thin tubing. [7]

Flare Fitting

For Bite-Type Pipe Fitting, it can be used to support higher pressure request within the compression tube fitting design. The fittings is typically made-up with a nut, body and ferrule(s) getting a sharp industry leading, which give bites into the skin area of the tubes to accomplish griping and possessing ability. You will find two types of design for bite-type tube fittings which are the one ferrule and twin ferrule design. In one ferrule bite, the nose area of the ferrule performs two functions. The first function is to bite in to the tube to carry it and second function is to provide a sealing aspect for the coupling body. In twin ferrule bite, the back ferrule is used to bite and offer gripping into pipe and leading ferrule is used for sealing element for the coupling body. [7]

Single-Ferrule Bite-Type

Two-Ferrule Bite Type

Meanwhile for Mechanical Grip-Type Pipe Fittings are usually two-ferrule in design. Leading ferrule can be used to seals by coining the top of tubing and coupling body. As the back ferrule is utilized holding action. The trunk ferrule grasp the tube for a distance just out-board from tube possessing point of the ferrule nasal to improve vibration resistance. The primary advantanges of this design compare to the bite-type fittings is the fact that break in the action and remake of the fitted after assembly can become more successfully accomplished without harm to either the appropriate components or the tubing. [7]

Mechanical- Hold Type

2. 4 Advantages to Tube Thread

Basically, there are two types of standard for tube thread which can be

British Standard Pipe- BSP

American Country wide Pipe-NPT/NPS

Both of English Standard pipe and American Country wide Pipe is specified by trade size somewhat than actual diameter.

Under BSP, there are two basic types of BSP threads which will be the BSPT (British Standard Pipe Taper) - which is also know as R threads and BSPP (Uk Standard Tube Parallel) - which is also known as G threads. Both of the BSPT and BSPP have the same thread viewpoint, shapre and pitch ( threads per in. ). The sole difference for BSPT and BSPP is BSPT threads are tapered and BSPP threads are right ( parallel). BSP thread have a 55o include perspective and have curved peaks and valleys.

On the other hands, for NPT, there are also two basic types of national pipe threads which can be NPT ( Country wide Tube Taper) abd NPS ( Country wide Pipe Straight). Both NPT and NPS have the same thread perspective, shape, and pitch (threads per in. ). However, NPT threads are tapered and NPS threads are straight (parallel). Both threads have a 60 covered angle and have flat peaks and valley

2. 4. 1 NPT vs BSP Pipe

NPT thread are trusted in United Talk about but, BSP thread tend to be widely used in many other countries. You see, the specified outside diameters of American National Pipe is slightly different from Uk Standard Pipe, . NPT/NPS and BSP thread aren't appropriate for each another. This is because of the distinctions in their thread forms and pitch. NPT/NPS threads have a 60 covered angle and have flattened peaks and valleys while a BSP threads have a 55 covered angle and also have round peaks and valleys As conclusion, never ever make an effort to partner a BSP fittings with an NPT or NPS fittings if the pressure holding capability is at all critical.



In this chapter, the hardware components used to create the hardware would be elaborated and discussed. Each component's features and its operation were studied before check out the hardware design. These components were examined on breadboard individually with simple program. The main reason for this is wanted to determine components and algorithms used are work and function properly. Based on these algorithms, an entire program could be made to make all the components work in the right manners. The details about software methodology will be discussed at next chapter.

After all the hardware components handed down the testing, an effective design of Printed Circuit Layout (PCB) was needed. A good and cool design of the PCB would ensure all the components work balance and properly to achieve the project primary objectives. During this stage, Electromagnetic Disturbance (EMI) theory possessed studied to avoid undesired manners such as noises or crosstalk occurred in the PCB board. Besides, the look attracting of hardware prototype is also have been studied before assembling the hardware prototype.

At the last stage, the tubes, fittings, valve, pressures sensor and pressure gauge is assemble carefully to be able to avoid gasses leakage from prototype.

3. 1 Microcontroller Device (MCU)

A microcontroller is your computer system that operates about the same built in circuit. It usually contains Central Processing Unit (CPU), memory product and Suggestions/Output (I/O) modules. Apart from these, a MCU also contains timers, counters and interrupt scheduling circuitry. Microcontrollers are extensively applied in the robotics and inlayed system controllers. Different microcontroller models may offer extra peripherals and registers for some applications (eg. UART, SPI, I2C and etc. ). They usually run in a set oscillating occurrence.

There are advanced microcontrollers which are 32-bits microcontroller developed nowadays. But, 8-tad microcontrollers are usually sufficient to create a tiny embedded controller. Within this job, Microchip microcontroller have been chosen because of its extra features. For instance, PIC had built-in ADC module to help ease the analog to digital signal converting and General Synchronous Asynchronous Recipient Transmitter (USART) component to communicate with PC.

3. 2 Microchip PIC Microcontroller

PIC are a symbol of Peripheral Software Controller. Until now, Microchip had developed and manufactured multiple families of PIC microcontroller in various packages. They may be several young families in a certain category such as PIC10, PIC12, PIC16, and PIC18 in 8-little bit PIC microcontrollers, PIC24F, PIC24H, dsPIC30 and dsPIC33 in 16-little PIC microcontrollers and PIC32 in 32-bit PIC microcontroller.

The PIC microcontroller that is employed in this task is PIC16F877A. One of the reason this PIC microcontroller was choosen because it is at 40-pin DIP bundle. It had been also chosen because it is powerful yet easy to program CMOS Adobe flash with only 25 solo word instructions established 8-bit microcontroller. Using the 20MHz operating rate of recurrence, the PIC only need only 200 nanoseconds to perform and education.

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