Answer Posted / rhaman
RTD's employ the property that the electrical resistance of metals varies with temperature. They are positive temperature coefficient (PTC) sensors whose resistance increases with temperature. The main metals in use are platinum and nickel. The most widely used sensor is the 100 ohm or 1000 ohm RTD or platinum resistance thermometer.
RTD�s are the most accurate sensors for industrial applications and also offer the best long-term stability. A representative value for the accuracy of a platinum resistance is +0.5 percent of the measured temperature. After one year there may be a shift of +0.05�C through aging. Platinum resistance thermometers can cover temperature ranges from -200 to 800�C
Thermocouples are based on the effect that the junction between two different metals produces a voltage which increases with temperature. Compared with resistance thermometers they offer the clear advantage of a higher upper temperature limit, up to several thousand degrees Celsius. Their long-term stability is somewhat worse (a few degrees after one year), the measuring accuracy is slightly poorer (on the average +0.75% of the measurement range). They are frequently used in ovens, furnaces, flue gas measurements and other areas with temperatures above about 250�C.
| Is This Answer Correct ? | 16 Yes | 0 No |
Post New Answer View All Answers
what are the steps I have to deal with?
SOME OF YOUR QUESTIONS ARE NOT MAKING ANY SENSE SO TRY AND PUT IN A LITTLE BIT MORE EFFORT BEFORE YOU POST A QUESTION. WE WILL ONLY HELP THOSE WHO WE CAN SEE ARE TRYING TO HELP THEMSELVES.
I want to know the questions asked in ONGC interview(after being selected in the written exam) for Instrumentation branch.Kindly help.
how the arrangement of equipments done in control room
why use 50% lel methane gas concentration for gas detector calibration instead of 60% lel gas concentration whereas the hi alarm set at 60% lel.
How to calibrate the flow transmitter
I want to apply for the universities in US,but i got the GRE score of (650+300=950)TOEFL 69/120.Is this score sufficient for applying universities please i am married i need to go to US because my husband didn't get H1 yet.please send me suggestion
all types of liquid analyzer principle with drawing?
1.what is the power consumption of three element drum level control in sugar industries? 2.how to reduce that?
what is the input of digital counter during the the calibration time?
1.can you use SCADA instead of DCS,DCS instead SCADA 2.Difference between DCS and PLC,can their role be reversed i.e. role interchange 3.Difference between RTU and PLC
why we are using drum level control valve air to close?
What is instrumentation measurement?
POSSITIVE PULSE IS APPLIED TO AN INVERTER INPUT.THE TIME FROM THE LEADING EDGE OF THE INPUT TO THE LEADING EDGE OF THE OUTPUT IS 10 ns. THE TIME FROM THE TRAILING EDGE OF THE INPUT TO THE TRYLING EDGE OF THE OUTPUT IS 8 ns. WHAT ARE THE VALUES OF tPLH and tPHL?
How RAL(Rotary air lock)works in cement industry?