Answer / nupur

A null type instrument as compared to deflection type
instrument has...which of the following.?
.(1)a higher accuracy(2)a lower reliability(3)a faster
response(4)all of the above?

Answer / nupur

A null type instruments are more accurate than deflection types.

Answer / sandy

The accuracy of these two instruments depends on different
things. For the Null type ins it depends on the linearity
and calibration of the spring, while 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.

Answer / 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.

Answer / ramesh.a

the null ins is gives the different between two
voltage/current......
the deflecting instrument is gives the value of the
measurand like voltage/current.....

I saw one P&ID 6" control valve has been connected with 8" process line, and 2" valve also connected in parallel with 6" valve. why the 2" valve connected in parallel, Is there any technical reason. please clarify. With Regards-Kittu

5 Answers   GNFC,

What is the difference between PLC-HMI and DCS as each function of DCS based system is possible in PLC ?

2 Answers   Lucky Cement,

How to convert Differential pressure to flow in TPH

0 Answers   Chettinad, ELCO,

Please explain the difference between instrument range and calibration range in terms of pressure transmitter? line design pressure: 93 bar operating pressure : 82 bar press Transmitter Range? calibration range ?

3 Answers   L&T,

Why mmwc unit is used?

0 Answers  

can you provide me full detail about instrumentation in ONGC??

0 Answers   BRML, ONGC,

why pneumatic control signal output is use 0.2 to 1 kg/cm2

3 Answers   Jindal,

How to convert gpm into inches of eater.I nerd formula with example so pls help me.

1 Answers  

if differential pressure created by orifice falls below vapour pressure of liquid flowing through it what will happen

1 Answers   BARC,

In control valves (like feed water control valve) we will give 3 kg pressure and how it controls 110 kg of water pressure?

4 Answers   SSL,

flow transmitter formula?

0 Answers   BEMCO, Siemens, Yokogawa,

What is meant by GAP VOLTAGE, in vibration measurement. Normally how much GAP VOLTAGE is set and state the reason.

3 Answers   ADMA OPCO,