Interested to Buy Any Domain ? << Click Here >> for more details...
difference between null and deflecting instrument.
- 5 Answers
- 58452 Views
- ONGC, I also Faced
- E-Mail Answers
Answer Posted / jasmine
The pressure gauge is a good example of a deflection-type instrument, where the value of the quantity being measured is displayed in terms of the amount of movement of a pointer. An alternative type of pressure gauge is the dead-weight gauge which is a null-type instrument. Here, weights are put on top of the piston until the downward force balances the fluid pressure. Weights are added until the piston reaches a datum level, known as the null point. Pressure measurement is made in terms of the value of the weights needed to reach this null position.
The accuracy of these two instruments depends on different things. For the first one it depends on the linearity and calibration of the spring, whilst for the second it relies on the calibration of the weights. As calibration of weights is much easier than careful choice and calibration of a linear-characteristic spring, this means that the second type of instrument will normally be the more accurate. This is in accordance with the general rule that null-type instruments are more accurate than deflection types.
In terms of usage, the deflection-type instrument is clearly more convenient. It is far simpler to read the position of a pointer against a scale than to add and subtract weights until a null point is reached. A deflection-type instrument is therefore the one that would normally be used in the workplace. However, for calibration duties, the null-type instrument is preferable because of its superior accuracy. The extra effort required to use such an instrument is perfectly acceptable in this case because of the infrequent nature of calibration operations.
| Is This Answer Correct ? | 20 Yes | 14 No |
Post New Answer View All Answers
what effects a surging can produce in the compressor
what is easiest way to read STL language in PLC?
Hi Friends , i need one urgent help , i am preparing for M.tech entrance examination , i need some obejective questions related to instrumentation field. where can i get those ? can anyone help me pls ?
Can combine control system for Emergency control system (ESD)and Fire & Gas System ( F & G) is possble to built and offer to client? Can such system is as per Norms in India?
What is the difference between mmwc and mmwg?
How do you identify between actual alarm and false alarm in a Temperature Transmitter in SCADA based Control System
What is offset in a control system.
How can we test a bently nevda 3500/42M accelerometer monitor card by simulating it with test equipment?. what king od of signal (milli volts or volts or or resistance ) we should feed in the terminals of the card?
how to calibrate load cell
What is hp & mp seperator .& what is its working principle ?
Calibration procedure for electro magnetic flow meter
Which is your favourite subject & explain any one topic of it.
How you calibrate absolute pressure with the calibration range of 0 to 1000 0C Absolute. Please explain the procedure for calibration.
The company where I am working, their is rosemount 5400 series radar type level transmitter, it is meant to show level of filled tank, but along with the level it is showing temperature also, so my question is how a onon-contact type radar type level transmitter can show temperature even if it does not have any contact with the fluid?
installation process of orifice,a question asked for confusion creation in interview by BARC 1.if orifice is tightly fitted with pipe ,it will act like venturi 2.if orifice is left hanging in between liquid it will not create the pressure difference exactly,
