Answer / 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.

Answer / afsar mumtaz

hi,
both are temperature measuring device ,
thermocouple is passive device and RTD is active device .
thermocouple generate milivolts and RTD generates resistance.
thermocouple are used for high temperature and RTD is used
to average temperature.
wire length is factor for RTD but in case of thermocouple no
mean.
thermocouple consist 2-3 wire but RTD 2-3-4 wire connection.

thermocouple range -260 to 2300 degree centigrade
RTD range -260 to 650 degree centigrade

in differential pressure transmitter,min&max pressure range for hp&lp

0 Answers  

---

what is the calibration standard for pressure and differential pressure transmitters?

1 Answers   Thermax,

---

Q- voltage source of 12v is driving the circuit.if circut draw the current of 0.5A them source voltage will became 11.8v.what is the power dilevered by source when circuit draw 5A current ?

4 Answers   Ecil,

---

what is temperature compensation?

1 Answers  

---

How a Flow Transmitter Works?

1 Answers  

---

Transducer Input 0 to 230 v ac Output-0 to 10vdc Receiver Input 0 to 10 vdc and Output 4 to 20 ma How?

1 Answers  

---

how to calibrate 0- 150 psi presure gauge by dead weght tester

0 Answers  

---

Can we use a 10000 Lph Flow Transmitter in 100 LPH flow line to get 20mA O/P by adjusting SPAN ?

1 Answers  

---

Identification of control valve parts.

0 Answers   CCIE, Oil and Gas Jobs,

---

If a control valve is hunting means means if we are giving 50% to the cv, the cv will open at 51% then slowly slwoly it will reaches 49% , so what to do for solve this problem. The cv is double acting and mounted for anti surge operation, it having 4 nos. volume booster, one sov, one positioner, etc..?

0 Answers   QAFCO,

---

Give me a simple formula to calculate the bore of orifice plate with datas avilable instead of BS 1040.I want to calculate the approximate bore size only.

0 Answers  

---

what is the electrical operation procedure for switching on 27.6MVA electric furnace.

0 Answers   Jindal,

---