Helix Bimetallic Thermometer

This article is a continuation of my previous post on Bimetallic Thermometer

Basic principle of Helix Bimetallic Thermometer:

When a bimetallic helix fixed at one end and free at the other end is subjected to a temperature change, the free end of the bimetallic helix deflects proportional to the change in temperature. This deflection becomes a measure of the change in temperature.

Description of Helix Bimetallic Thermometer:

  1. The main parts of a helix bimetallic thermometer are as follows:
  2. A bimetallic helix which is fixed at one end to the body of the instrument and free at its other end.
  3. To the free end of the bimetallic helix is attached a shaft.
  4. One end of the shaft is mounted in friction less arrangement and its other end is connected to a pointer which sweeps over a temperature calibrated circular dial graduated in degrees of temperature.

Operation of Helix Bimetallic Thermometer:

When temperature of a medium is to be measured, the bimetallic thermometer is introduced into the medium for a length “L”
The bimetallic helix senses the temperature and expands resulting in a deflection at its free end.
This deflection at the free end of the bimetallic helix rotates the shaft connected to it. When the shaft rotates , the pointer attached to the shaft moves to a new position on the temperature calibrated dial indicating the measured temperature.


Ultrasonics – Introduction.

Vibrations upto 20,000 cycles can be heard by human beings and so, the frequency range upto 20KHz is called sonic frequency. Sound waves do not belong to the electromagnetic wave family like heat and light. As such, study of sound waves is not exactly an electronic branch. However most of the ultrasonic sound waves find very valuable industrial applications as flaw direction, submarine communication, electronic soldering and welding.

Ultrasonics is today applied in medical diagnosis (echo-scanning) as an alternative to X-ray scanning. Production of ultrasonic sound waves involves use of electronic oscillators called transducers. Use of ultrasonic waves does not involve harmful wave radiation. Radiation is present in other methods for the applications mentioned above. Hence ultrasonics is a welcome substitute for electromagnetic waves in many industrial applications.

Properties of ultrasound.

The ultrasonic waves travel in different media with different velocities. In air it travels at 330m/sec. The velocities in liquids and solids range from 1200m/s to 4000m/s respectively. The property of a medium to conduct ultrasonic waves is represented in its acoustic impedance. When ultrasound travels through a homogeneous medium there is not change of velocity or wavelength and hence it essentially continues in a straight line. When the ultrasound beam reaches an interface between two different media, it undergoes reflection and refraction.

The reflected wave may be termed as the ultrasonic echo. The echoes produced by large objects with smooth surface are specular echoes. Much energy is returned by these specular echoes. Echoes from small objects with irregular shapes are called scattered echoes. When ultrasound gets reflected irregularly in multiple directions, only a small part of ultrasonic energy returns to the source. Through analysis of reflected waves leads to several useful applications in industry and medicine. The properties of ultrasound are summed up as follows:

  1. Can be directed into a beam.
  2. Obeys laws of reflection and refraction.
  3. Is reflected by small objects.
  4. Permits recording of clear echoes from interface that are approximately 1 mm part.


Instrumentation Engineer Sample Resume

Hello friends, a special post for Instrumentation engineers seeking a job.

Jimmy Freeney
56987 Calumet Ave, Apt#9
New York, NY 10040
Cell: 123-423-8999

Career Profile:

Seeking the position of an instrumentation design engineer with a view to utilize my professional experience in a renowned organization

Professional strengths:

  • Comprehensive knowledge of engineering techniques and instrumentation designing
  • Possess strong technical aptitude including applicable engineering tools and systems
  • In-depth knowledge of optics design, instrumentation and C++ programming
  • Familiar with Linux and UNIX working environment
  • Possess strong leadership and interpersonal skills
  • Effective communicator with outstanding management and organizational skills

Educational Qualifications:

Achieved Master's degree in Electrical Engineering
University of New York in the year 2007

Achieved Bachelor's degree in Electrical Engineering
Engineering College of New York in the year 2004

Work Experience:

Organization: GE Engineering Services, New York
Duration: May 2009 till date
Designation: Instrumentation Design Engineer

  1. Responsible for designing, analyzing and evaluating assigned projects by using engineering principles and by adhering to the business standards, practices, procedures and product / program requirements
  2. Handle the tasks of providing technical leadership to personnel supporting the assigned project
  3. Perform responsibilities of documenting technical data generated by the assigned project consistent with engineering policies and procedures
  4. Responsible for providing timely communications on significant issues or developments to the instrumentation manager
  5. Play active role in addressing organizational initiatives and generic issues
  6. Ensure proper documentation of technical data generated for the assigned projects by following the engineering policies and procedures

Organization: Almec Engineering, New York
Duration: March 2007 to April 2009
Designation: Junior Instrumentation Design Engineer

  1. Responsible for the process and mechanical design of oilfield equipment including water, gas separators and gas compressors
  2. Handle the tasks of preparing technical proposals and interpreting customer specifications
  3. Coordinate with vendors and sublets to specify and source instrumentation and accessories
  4. Perform responsibilities of evaluating and assisting instrumentation design engineer in the development of new technologies
  5. Work with customer to evaluate, test or assist in commissioning equipment

Personal Information:

Name: Jimmy Freeney
Date of Birth: 23/05/1982
Employment Status: Full time
Relationship status: Married


Will be pleased to provide upon request


Model Interview Questions for Instrumentation Engineers

Prepare yourself to get your job as your final sem is nearly.

1.) How much salary you’re Expecting?
Answer : I would expect a salary which reflects the experience and qualifications that I bring to the role.

Alternate Answer : Based on the information I have about the position, a salary in the range 15,000 - 18,000 would reflect the experience and expertise that I would bring to the role.

2)Why did you take Instrumentation as your branch in Engineering?

Answer:After having passed my class 12th examination,I actually didn’t have any idea about what was involved in Instrumentation.But I wanted to built my career around something from where we could control and monitor a whole industry.

3.) What kind of person would you refuse to work with?
Well, I am a person, who can work with all kinds of people. However, I feel bit uncomfortable to work with persons of selfish and ingratitude in nature.

4.) What have you done to improve your knowledge in the last year?
Every should learn from his mistake. I always try to consult my mistakes with my kith and kin especially with elderly and experienced person.

5.) What is more important to you: the money or the work?
Money and work both are like siblings. But I believe when you work hard; money will flow to you. So work is more important than money. Only hard work can help you put another feather in your success cap.

6.) Why do you want to join in industry?
industry is a place where the graduates have the opportunity to apply their skills n knowledge which they learn from their respective institutions. so feel industry is a best way for a person to applying their practical knowledge.

7.) Are you a team player?
while answering this question, try to keep yourself on both sides. For example, if the interviewer asks if you prefer to work alone or on a team, he may be trying to get you to say you are one way or the other. But you don't have to play this game. The reality is that most jobs require us to work both independently and in teams. Your response to this question should show that you have been successful in both situations or (In case you don’t find yourself comfy with team work say this) - I believe in individual work recognition [this would not put your weakness in front of others that strongly, Remember people who take interviews are super masters, do not fool them]

8)What is your greatest strength?
My greatest strength includes my analytical approach, my strong logics and my patience


A Complete Note on Difference between Lab View, PLC and DCS

Yesterday, i receive a question from one of my facebook fan asking " sir could u please say the difference between labview and plc and dcs "

As far as i know Lab View is completely different from DCS and PLC, Labview is a software.

LabVIEW is a graphical programming environment used by millions of engineers and scientists to develop sophisticated measurement, test, and control systems using intuitive graphical icons and wires that resemble a flowchart. It offers unrivaled integration with thousands of hardware devices and provides hundreds of built-in libraries for advanced analysis and data visualization – all for creating virtual instrumentation. The LabVIEW platform is scalable across multiple targets and OSs, and, since its introduction in 1986, it has become an industry leader.

A distributed control system (DCS) refers to a control system usually of a manufacturing system, process or any kind of dynamic system, in which the controller elements are not central in location (like the brain) but are distributed throughout the system with each component sub-system controlled by one or more controllers. The entire system of controllers is connected by networks for communication and monitoring.

A programmable logic controller (PLC) or Programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures. PLCs are used in many industries and machines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed-up or non-volatile memory. A PLC is an example of a hard real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will result.

The differences between DCS and PLC are: DCS (Distributed Control System) is a CONTROL SYSTEM that works using several controllers and coordinates the work of all these controllers. Each controller is handling a separate plant. This controller is referred to the PLC.

The PLC (Programmable Logic Controller) is a CONTROLLER which can be re-program back. If the PLC is only a stand-alone and not combined with other PLCs, it is called as DDC. It means PLC is a sub system of a large system called DCS.

What’s difference between PLC and DCS by its definition:
PLC is a controller or processor that can be programmed (programmable) whose function is to run (execute) logic functions. Logic means the discrete / sequence function is usually handled by the relay. From the beginning of the vendors who carry the name of the PLC is engaged in the business discrete / sequence control.

Regardless of the distributed control system (as opposed to the DDC = Direct Digital Control) is categorized as a DCS. In DDC all system controls are done in the central processor so that if it failed, the entire control plant will also failed. DDC is mostly used as a Regulatory Control. And from the beginning vendors that carry the name of DCS is to use the product as a regulatory control.

Different in functionality means that the DCS and PLC can not be implemented on the same application.
1. DCS is not a large PLC. Because system architecture of DCS and PLC are different.
2. DCS is not PLCs that integrated into one large system. "Controller" in the PLC is more intended as a "Logic Controller", while “Controller” in the DCS is more intended as a "Process Controller".
3. Both DCS and PLC is a configurable and reconfigurable.


About This Blog

Lorem Ipsum

  © Free Blogger Templates Columnus by Ourblogtemplates.com 2008

Back to TOP