Venturi Meter: Theory, Operations & Working

Basic principle:

When a venture meter is placed in apipe carrying the fluid whose flow rate is to be measured, a pressure drop occurs between the entrance and throat of the venturimeter. This pressure drop is measured using a differential pressure sensor and when calibrated this pressure drop becomes a measure of flow rate.

Construction of Venturi meter

The following are the main parts and areas of venture meter:

The entry of the venture is cylindrical in shape to match the size of the pipe through which fluid flows. This enables the venture to be fitted to the pipe.
After the entry, there is a converging conical section with an included angle of 19’ to 23’.
Following the converging section, there is a cylindrical section with minimum area called as the throat.
After the throat, there is a diverging conical section with an included angle of 5’ to 15’.
Openings are provided at the entry and throat (at sections 1 and 2 in the diagram) of the venture meter for attaching a differential pressure sensor (u-tube manometer, differential pressure gauge, etc) as shown in diagram.


Operation of venturi meter:

The fluid whose flow rate is to be measured enters the entry section of the venturi meter with a pressure P1.
As the fluid from the entry section of venturi meter flows into the converging section, its pressure keeps on reducing and attains a minimum value P2 when it enters the throat. That is, in the throat, the fluid pressure P2 will be minimum.
The differential pressure sensor attached between the entry and throat section of the venturi meter records the pressure difference(P1-P2) which becomes an indication of the flow rate of the fluid through the pipe when calibrated.
The diverging section has been provided to enable the fluid to regain its pressure and hence its kinetic energy. Lesser the angle of the diverging section, greater is the recovery.


Applications:

• It is used where high pressure recovery is required.
• Can be used for measuring flow rates of water,gases,suspended solids, slurries and dirty liquids.
• Can be used to measure high flow rates in pipes having diameters in a few meters.

Advantages of venturi meters

• Less changes of getting clogged with sediments
• Coefficient of discharge is high.
• Its behaviour can be predicted perfectly.
• Can be installed vertically, horizontally or inclinded.

Limitations

• They are large in size and hence where space is limited, they cannot be used.
• Expensive initial cost, installation and maintenance.
• Require long laying length. That is, the veturimeter has ti be proceeded by a straight pipe which is free from fittings and misalignments to avoid turbulence in flow, for satisfactory operation. Therefore, straightening vanes are a must.
• Cannot be used in pipes below 7.5cm diameter.

Permanent Magnet Moving Coil Instruments

The permanent magnet moving coil instruments are most accurate type for direct current measurements. The action of these instruments is based on the motoring principle. When a current carrying coil is placed in the magnetic field produced by permanent magnet, the coil experiences a force and moves. As the coil is moving and the magnet is permanent, the instrument is called permanent magnet moving coil instrument. This basic principle is called D’Arsonval principle. The amount of force experienced by the coil is proportional to the current passing through the coil.

The PMMC instrument is shown in the below images.

The moving coil is either rectangular or circular in shape. It has number of turns of fine wire. The coil is suspended so that it is free to turn about its vertical axis. The coil is placed in uniform, horizontal and radial magnetic field of a permanent magnet in the shape of a horse-shoe. The iron core is spherical if coil is circular and is cylindrical if the coil is rectangular. Due to iron core, the deflecting torque increase, increasing the sensitivity of the instrument.

The controlling torque is provided by two phosphor bronze hair springs.

The damping torque is provided by eddy current damping. It is obtained by movement of aluminum former, moving in the magnetic field of the permanent magnet.

The pointer is carried by the spindle and it moves over a graduated scale. The pointer has light weight so that it deflects rapidly. The mirror is placed below the pointer to get the accurate reading by removing the parallax. The weight of the instrument is normally counter balanced by the weights situated diametrically opposite and rapidly connected to it. The scale markings of the basic d.c PMMC instruments are usually linearly spaced as the deflecting torque and hence the pointer deflections are directly proportional to the current passing through the coil.

The top view of PMMC instrument is shown in the below image.


Advantages of PMMC

The various advantages of PMMC instruments are,

• It has uniform scale.
• With a powerful magnet, its torque to weight ratio is very high. So operating current of PMMC is small.
• The sensitivity is high.
• The eddy currents induced in the metallic former over which coil is wound, provide effective damping.
• It consumes low power, of the order of 25 W to 200 mW.
• It has high accuracy.
• Instrument is free from hysteresis error.
• Extension of instrument range is possible.
• Not affected by external magnetic fields called stray magnetic fields.

Disadvantages of PMMC

The various disadvantages of PMMC instruments are ,

• PMMC is Suitable for direct current measurement only.
• Ageing of permanent magnet and the control springs introduces the errors.
• The cost is high due to delicate construction and accurate machining.
• The friction is due to jewel-pivot suspension.

Bourdon's Tube | Pressure Gauge: Principle, Diagram, Explanation

Basic Principle of Bourdon tube pressure gauge:

when an elastic transducer ( bourdon tube in this case ) is subjected to a pressure, it defects. This deflection is proportional to the applied pressure when calibrated.

Description of Bourdon tube Pressure Gauge:
The main parts of this instruments are as follows:

An elastic transducer, that is bourdon tube which is fixed and open at one end to receive the pressure which is to be measured. The other end of the bourdon tube is free and closed.
The cross-section of the bourdon tube is eliptical. The bourdon tube is in a bent form to look like a circular arc. To the free end of the bourdon tube is attached an adjustable link, which is inturn connected to a sector and pinion as shown in diagram. To the shaft of the pinion is connected a pointer which sweeps over a pressure calibrated scale.

Operation of Bourdon tube:

The pressure to be measured is connected to the fixed open end of the bourdon tube. The appilied pressure acts on the inner walls of the bourdon tube. Due to the appilied pressure, the bourdon tube tends to change in cross – section from ellipitcal to circular. This tends to straighten the bourdon tube causing a displacement of the free end of the bourdon tube.

This displacement of the free closed end of the bourdon tube is proportional to the applied pressure. As the free end of the bourdon tube is connected to a link – section – pinion arrangement, the displacement is amplified and converted to a rotary motion of the pinion.

As the pinion rotates, it makes the pointer to assume a new posistion on a pressure calibrated scale to indicate the appilied pressure directly. As the pressure in the case containing the bourdon tube is usually atmospheric, the pointer indicates gauge pressure.

Applications of Bourdon Tube pressure gauge:

They are used to measure medium to very high pressures.

Advantages of Bourdon tube pressure gauge:

• These Bourdon tube pressure gauges give accurate results.
• Bourdon tube cost low.
• Bourdon tube are simple in construction.
• They can be modified to give electrical outputs.
• They are safe even for high pressure measurement.
• Accuracy is high especially at high pressures.

Limitations of bourdon tube pressure gauge:

• They respond slowly to changs in pressure
• They are subjected to hysterisis.
• They are sensitive to shocks and vibrations.
• Ampilification is a must as the displacement of the free end of the bourdon tube is low.
• It cannot be used for precision measurement.

U- Tube Manomerter | Theory, Explanation, Diagram, & Working Equations

Construction of U-tube Manometer:

This manometer consists of a U shaped tube in which the manometeric liquid is filled. The manometer is used to measure the pressure which is unknown by the balancing gravity force and acceleration due to gravity, g = 9.81 m/sec2

The manometer consists of a steel, brass and aluminum material. It has a glass tube made up of pyralex glass. The graduations are made on the tube in terms of mm or in some condition it is graduated in kilo Pascal.

Working of U-tube Manometer:

The unknown pressure is applied in the one arm of the tube and the mercury in the tube or manometeric liquid filled in the tube moves in the tube or rises to the constant region and then the movement is stopped. The height of the liquid is measured and noted. The pressure is calculated by using the formula,

                                                                    P1-P2 = Pmhg

The above equation is arrived by 

P1 = Pthg = P2+Pmhg

P1-P2 = hg(Pt – Pm)

P1 = applied pressure

P2 = 0

Pt = specific gravity of the liquid or water

g = acceleration due to gravity.

P1 – P2 is approximately equal to Pmhg.

Advantages of U-tube Manometer:

Simple in construction

Low cost

Very accurate and sensitive

It can be used to measure other process variables.

Disadvantages of U-tube Manometer:

Fragile in construction.

Very sensitive to temperature changes.

Error can happen while measuring the h.

Characteristics of liquid used in U-tube Manometer:

Viscosity should be low.

Low surface tension is required.

The liquid should stick on the walls.

Should not get vaporized.

LVDT: Basic Principle, Theory, Working, Explanation & Diagram | Linear Variable Differential Transformer

A very basic transducer which is always useful in the field of instrumentation, I have studied about this in my college days. Now let me explain about the LVDT with its Principle of Operation and I will explain how it is constructed for its well known operation and you can understand the working of LVDT.

Principle of LVDT:

LVDT works under the principle of mutual induction, and the displacement which is a non-electrical energy is converted into an electrical energy. And the way how the energy is getting converted is described in working of LVDT in a detailed manner.

LVDT consists of a cylindrical former where it is surrounded by one primary winding in the centre of the former and the two secondary windings at the sides. The number of turns in both the secondary windings are equal, but they are opposite to each other, i.e., if the left secondary windings is in the clockwise direction, the right secondary windings will be in the anti-clockwise direction, hence the net output voltages will be the difference in voltages between the two secondary coil. The two secondary coil is represented as S1 and S2. Esteem iron core is placed in the centre of the cylindrical former which can move in to and fro motion as shown in the figure. The AC excitation voltage is 5 to 12V and the operating frequency is given by 50 to 400 HZ.

Working of LVDT:

Let's study the working of LVDT by splitting the cases into 3 based on the iron core position inside the insulated former.

Case 1:On applying an external force which is the displacement, if the core reminds in the null position itself without providing any movement then the voltage induced in both the secondary windings are equal which results in net output is equal to zero

i.e., Esec1-Esec2=0

Case 2:When an external force is appilied and if the steel iron core tends to move in the left hand side direction then the emf voltage induced in the secondary coil is greater when compared to the emf induced in the secondary coil 2. 

Therefore the net output will be Esec1-Esec2

Case 3:When an external force is applied and if the steel iron core moves in the right hand side direction then the emf induced in the secondary coil 2 is greater when compared to the emf voltage induced in the secondary coil 1. therefore the net output voltage will be Esec2-Esec1

Advantages of LVDT:

* Infinite resolution is present in LVDT* High output* LVDT gives High sensitivity* Very good linearity* Ruggedness* LVDT Provides Less friction* Low hysteresis* LVDT gives Low power consumption.

Disadvantages of LVDT:

* Very high displacement is required for generating high voltages.* Shielding is required since it is sensitive to magnetic field.* The performance of the transducer gets affected by vibrations* Its is greatly affected by temperature changes.

Applications of LVDT:

=> LVDT is used to measure displacement ranging from fraction millimeter to centimeter.=> Acting as a secondary transducer, LVDT can be used as a device to measure force, weight and pressure, etc..

Management Trainee @ Kerala Livestock Development Board Ltd

Management Trainee                                                                                       Date of posting:25 July

Eligibility: BE/B.Tech(Civil Engineering, Instrumentation & EIectronics)

MBA/PGDM

Location: Trivandrum

Job Category: Core Technical, Govt Sector, MBA

Last Date: 4 August 11

Job Type: Full Time

Hiring Process: Face to Face Interview.

Job Details

Kerala Livestock Development Board Ltd inviting application 
for the post of Management Trainee- On contract

How to apply

Post Name	Qualification, Exp and Pay Scale	No f post	Age
Management Trainee (Instrumentation)	B.Tech /BE in Instrumentation Technology from a Recognized University Approved by AICTE. 6 Months Experience from Central/State Government Institutions/PSUs. Rs.15,000/-	01	18 – 35 Years
Management Trainee (IT)	B.Tech Computer science/ Information Technology MCA/ Msc Computer Science from Recognized University Approved by AICTE. Minimum one year experience in the Central/State Government Institution/PSUs. Rs.15,000/-	01
Management Trainee - MBA	MBA (full time) from a recognized university Approved by AICTE 6 months experience from Central/State Government Institutions/PSUs. Rs.15,000/-	01
Executive Engineer (Civil)	B.Tech /BE in Civil or Equivalent from a Recognised University approved by AICTE 3 years experience in Civil engineering works in a reputed organization. Rs.25,000/-	01

Interested candidates may apply with bio data and copies of the certificates 

including experience records to the Managing Director, KLD Board Ltd.,
Gokulam, Pattom.P.O, Thiruvananthapuram – 695 004, so as to reach on or 

before 04.08.2011 along with Demand draft of Rs.500/- drawn in favour of KLD
Board towards application fees (for SC/ST candidates Rs. 150/-).
The candidates are requested to write their email address on the bio data.
Applications may also be sent through e-mail, the candidates who opt to
apply through email are requested to forward the Demand Draft along with
the hard copy. The e-mail ID is kldboard@kldb.kerala.gov.in or
kldboard8@gmail.com

Patent Analyst @ Sagacious Research

Patent AnalystDate of posting:30 July

Eligibility: BE/B.Tech(Computer Science Engineering, Electronics & Communication Engineering, Electrical Engineering, Instrumentation & EIectronics)
BSc(Computer Science, Electronics / Applied Electronics)
ME/M.Tech(Computer Science Engineering, Electrical & Electronics Engineering, Electrical Engineering, Electronics & Communication Engineering, Infrastructure Engineering)
Location: Gurgaon
Job Category: Core Technical, IT/Software
Last Date: 1 August 11

Job Type: Full Time
Hiring Process: Written-test.

Job Details

Eligibility :

• BE/ B.Tech/ ME/ M.Tech ( Electronics and communication/ Computer Science/ Electronics and Instrumentation/ Electrical Engineering)/ B.Sc (Electronics/ Compuers/ Instrumentation) from 2011 batches with aggregate 65% and above.

Job Description

Mandatory Skills :

• Good analytical skills
• Good Technical Knowledge

Preferred Knowledge/ Skills

• Patent Searching/Non-Patent Searching
• Patent Drafting
• Freedom to Operate
• Claim Chart Preparation

Role :

• The role of Patent Analyst (PA) will be to work on tasks involved in Patent Research projects (like screening/analysis, searching, chart preparation, deliverable preparation, etc) assigned to him/her and complete them with highest quality in the given timeframe.

For More details:

http://jobs.freshersworld.com/detail/2011/07/30/Sagacious-Research/Patent-Analyst

Engineer @ SAIL

MT (Technical/ Administration)Date of posting:20 July

Eligibility: BE/B.Tech(Ceramics Engineering, Chemical Engineering, Civil Engineering, Computer Science Engineering, Electrical & Electronics Engineering, Electronics & Communication Engineering, Information Science/Technology, Mechanical Engineering, Metallurgical /Materials Engineering, Electrical Engineering, Instrumentation & EIectronics)
CA
ICWA
MBA/PGDM
MCA
Location: Any where in India
Job Category: Core Technical, Govt Sector, MBA, Others
Last Date: 17 August 11

Job Type: Full Time
Hiring Process: Written-test.

Job Details

Steel Authority of India, invites applications for the posts of Management Trainees (Technical) and Management Trainees (Administration) in E-1 grade from young, energetic, result oriented and promising talent in the country.www.freshersworld.com

Post Name	Qualification	No. of Post
MT (Technical)	Degree in Engg. (full time)/MCA (3 years full time) with 65% marks (average of all semesters), in the disciplines of Mechanical, Electrical, Metallurgy, Civil, E&T, Instrumentation, Ceramics, Chemical, Computer Science and Mining Engineering	318
MT (Administration)	For HR and Marketing : Bachelors. degree in any discipline with 60% marks with at least two years full time MBA/PG Diploma in management with 60% marks in HR/PM&IR/Pers /MHROD for HR and Marketing for Marketing discipline. For MT -Finance : CA/ICWA	57

Note : For MT (Tech) : The SC/ST/PWD and Departmental Candidates having Engineering Degree in the required disciplines with 55% marks shall be eligible to apply . For MT (Admn.) : The SC/ST/PWD and Departmental Candidates having Bachelor's degree with 50% marks and MBA/PG Diploma in Management in the relevant discipline with 50% shall be eligible to apply against HR and Marketing disciplines. Age : 30 years as on 1.7.2011, i.e., not born earlier than 1.7.1981

For MT (Tech) post, candidates having degree in related disciplines as given below can apply against the respective discipline:

Main Disciplines	Eligible related Engineering disciplines
Mechanical	Mechanical / Production / Industrial Engg. / Production & Industrial Engg. /Thermal / Mechanical & Automation
Electrical	Electrical / Electrical & Electronics / Electrical, Instrumentation & Control /Power Systems & High Voltage / Power Electronics / Power Engineering
Electronics & Telecommunication	Electronics/Electronics & Telecomm./ Electronics & Communication
Instrumentation & Control	Electronics & Power / Electronics & Instrumentation / Instrumentation & Control/ Electrical, Instrumentation & Control
Computer Science	Computer Science/ Information Technology/MCA (three years)

Health : For MT (Tech) : Should be of sound physique, free from any physical defect. Medical standards stipulate minimum requirements of Weight 45 kg; Height 155 cm; Myopia and Hypermetropia, if any, not to exceed ± 4.00 in each eye and no squint or colour blindness, partial or full. Suitable relaxation in height and weight will be given to female candidates. For MT (Admn.) : Should be of sound physique, free from any physical defect. Medical standards stipulate minimum requirements of Weight 45 kg; Height 155 cm; Myopia and Hypermetropia, if any, not to exceed ± 6.00 in each eye. Suitable relaxation in height and weight will be given to female candidates.

Selection : Eligible candidates will be required to appear for a Written Examination, information for which will be provided in the Admit card. Candidates shortlisted on the basis of their performance in the Written Test will be intimated to appear for Group Discussion/Interview.
Written Test Centres : Eligible candidates will be required to appear for objective type written test in at any one of the centres at Agartala, Allahabad, Bangalore, Baroda, Bhilai, Bhopal, Bhubaneswar, Bokaro, Chandigarh, Chennai, Dehradun, Delhi, Durgapur, Guwahati, Hyderabad, Jaipur, Jammu, Kochi, Kolkata, Lucknow, Mumbai, Nagpur, Patna, Ranchi, Rourkela, Salem, Trichy, Vijaywada and Visakhapatnam.

Emoluments : Rs.20,600/- in the pay scale of Rs.20600-3%-46500 (E-1)

Application Fee : Pay in Slip for Rs.500/- as examination fee for General and OBC Candidates. Rs.100/- as processing fee for SC/ST/ PH/Departmental candidates. The Pay-in-Slip is to be download after filling in the required details.  Candidates should have latest passport size photograph as well as photograph of signatures in digital format (.jpg or jpeg file only, of less than 500 kb size) for uploading with the application form. Candidates applying for both MT (Tech.) and MT (Admn.) should register separately with separate application and processing fee. State Bank of India has been authorized to collect the registration fee (examination fee), in a specially opened account (No. 31836070568) at CAG Branch, New Delhi, on behalf of SAIL. Candidate has to approach the nearby SBI branch with a printout of the .pay-in-slip. which is available on the Application Registration Portal. The pay-in-slip printed from the Portal only should be used for depositing the fee for proper crediting of amount in the allocated account. On receipt of the money the concerned branch of SBI will issue a unique Journal Number and a Branch Code of the branch collecting the money. This Journal Number and the Branch Code are to be filled up by the candidate during online registration. In case the candidate deposits the fee in a wrong account, SAIL will not be responsible. There will not be any other mode of collection of registration fee. Also please note that an amount of Rs.20/- will be paid by the candidate as Bank Charges to the collection branch of SBI in addition to the applicable registration/processing fee. The SBI branches will accept the fee from 10.00 AM of the starting date to 5.00 PM of the closing date of submission of online application.

How to apply

Eligible and interested candidates would be required to apply online only.www.freshersworld.com
Important Dates :

1.	Starting date for submitting applications through website	27.07.2011
2.	Closing date for submitting applications through website	17.08.2011
3.	Starting date for downloading of Admit Card from SAIL website for written examination	05.09.2011
4.	Tentative Date of Written Test (will be confirmed in Admit Card)	25.09.2011

For More details:

http://jobs.freshersworld.com/detail/2011/07/20/SAIL/MT-Technical-Administration-

Project Engineer @ C-DAC Thiruvananthapuram

Project Engineer I, IIDate of posting:20 July

Eligibility: BE/B.Tech(Computer Science Engineering, Electronics & Communication Engineering, Instrumentation & Control Engineering)
ME/M.Tech(Computer Science Engineering, Electrical Engineering)
Location: Trivandrum
Job Category: Core Technical, Govt Sector, Others
Last Date: 3 August 11

Job Type: Full Time
Hiring Process: Written-test.

Job Details

Centre for Development of Advanced Computing (C-DAC), inviting application for the post of Project Engineer I, IIwww.freshersworld.com

Post Code	Post Name	Qualification	No. of Post	Salary
T-1	Project Engineer I	1st class (60%) BE / B.Tech in Electronics & Communications / Applied Electronics / Computer Science / Applied Electronics & Instrumentation / Electronics and Instrumentation.	80 (Electronics – 32 Computer Science - 45 Instrumentation – 03) (Gen: 41, OBC: 21, SC: 12 & ST: 6)	Rs.15000
T-2	Project Engineer II	1st Class (60%) ME / M.Tech in Electronics / VLSI / Computer Science / Electrical (Power Systems / Power Electronics).	17 (Electronics – 10 Computer Science - 03 Electrical - 04) (Gen: 10, OBC: 04, SC: 02 & ST: 01)	Rs.18000

Term: Fixed term of three years. Extendable as per requirement of the Centre.

Age Limit: Should not exceed 30 Years as on 03.08.2011.

Application fee :  Rs. 500/- (Rs. 50/- for SC/ST/PH) is payable by DD / Credit or Debit Card. In case you decide to pay the application fee by Demand Draft, please obtain a Demand Draft (obtained between 20.07.2011 and 30.07.11) of Rs. 500/- (Rs. 50/- for SC/ST/PH), favoring “CDAC Thiruvananthapuram”, from any nationalized bank, payable at Thiruvananthapuram. DD Option will not be available after 30.07.2011. You will have to enter the Demand Draft number in the On-line registration form. Therefore, you are required to take the Demand Draft before the final step of the online registration process. After completing the registration process, send the Demand Draft by post or courier super-scribing the envelope ‘Application fee  for PE I / PE II’ (as the case may be) to Administrative Officer (Recruitment), C-DAC, PB No 6520, Vellayambalam, Thiruvananthapuram – 695 033, so as to reach on or before 05.08.2011. Please mention name of the applicant, date of birth, registration ID and email id on the backside of the Demand Draft. Only the Demand Draft needs to be sent, the application forms need not to be sent. In case you decide to pay the application fee by Debit Card or Credit Card, please beready with the credit/debit card during Online Registration. At the payment step, the process will take you to the payment gateway, where you are required to give detailsregarding the Card. On successful completion of payment, you will be re-directed back to the registration process. Payment is towards administrative expenses for the selection process and fee once paid will not be refunded.

Mode of Selection: Candidates meeting the above eligibility criteria are required to appear for an online test on forenoon / afternoon / evening on 6th / 7th August 2011 at Thiruvananthapuram, Kochi and Kozhikode.


For More details:
http://jobs.freshersworld.com/detail/2011/07/20/C-DAC-Thiruvananthapuram/Project-Engineer-I-II

IITs in INDIA

The IITs are located in:

Name	Short Name	Established	City/Town	State/UT
Current IITs:
IIT Kharagpur	IITKGP	1951	Kharagpur	West Bengal
IIT Bombay	IITB	1958	Mumbai	Maharashtra
IIT Madras	IITM	1959	Chennai	Tamil Nadu
IIT Kanpur	IITK	1959	Kanpur	Uttar Pradesh
IIT Delhi	IITD	1963	New Delhi	New Delhi
IIT Guwahati	IITG	1994	Guwahati	Assam
IIT Roorkee	IITR	2001	Roorkee	Uttrakhand
New IITs:
IIT Ropar	IITRPR	2008	Rupnagar	Punjab
IIT Bhubaneswar	IITBBS	2008	Bhubaneswar	Orissa
IIT Hyderabad	IITH	2008	Hyderabad	Andhra Pradesh
IIT Gandhinagar	IITGN	2008	Gandhinagar	Gujarat
IIT Patna	IITP	2008	Patna	Bihar
IIT Rajasthan	IITJ	2008	Jodhpur	Rajasthan
IIT Mandi	IIT Mandi	2009	Mandi	Himachal Pradesh
IIT Indore	IITI	2009	Indore	Madhya Pradesh
IIT (BHU) Varanasi	IITBHU	1916	Varanasi	Uttar Pradesh