What Is RTD RTD OutSide Parts RTD Part Inside View RTD Components RTD Works Why Platinum RTD Is Common in use

2. RTD:
•RTD stands for Resistance Temperature
Detector.
•Also Known As “Resistance thermometers”.
•The RTD wire is a pure material, typically
platinum, nickel, or copper.
•Resistance thermometer:
“a temperature-measuring device composed of
 A resistance thermometer element,
 Internal connecting wires,
 A protective shell with or without means
for mounting a connection head,
 Connecting wire or other fittings, or both.

3. RTD Parts Outside:

4. RTD Part Inside View:

5. RTD Components:
1. RTD Resistance element.
2. RTD Outside Diameter.
3. RTD Process Connection.
4 RTD Wire Configuration.
5. RTD Cold End Termination

6. RTD Components:
1. RTD Resistance Element:
This is the actual temperature
sensing portion of the RTD.
Elements range in length from
1/8" to 3“.
The standard temperature
coefficient for Pt sensing element,
α = 0.00385 &
standard resistance = 100 Ω at 0°C.

7. RTD Components:
2. RTD Outside Diameter:
The most common outside
diameter range from 0.063“ -
0.500"

8. RTD Components:
3. RTD Tubing Material:
SS316 is commonly used for assemblies up to
500°F.
Above 500°F it is advisable to use Inconel
600.

9. RTD Components:
4. RTD Wire Configuration:
RTDs are available in 2, 3 and 4 wire
configuration.
3 wire configurations are the most
common for industrial applications.
Teflon and fiber-glass are the
standard wire insulation materials.
Teflon is moisture resistant and can
be used up to 400°F.
Fiber-glass can be used up to 1000°F.
Fibre glass insulated
Teflon insulated

10. RTD Components:
5. RTD cold end termination:
RTDs can terminate on the cold end
with plugs, bare wires, terminal
heads and any of the reference
junctions common to thermocouples.

11. RTD Works:
•An RTD works by using a basic principle; as the temperature of a metal
increases, the resistance to the flow of electricity increases.
•An electrical current is passed through the sensor, the resistance element is
used to measure the resistance of the current being passed through it.
•As the temperature of the resistance element increases the electrical
resistance also increases.
•The electrical resistance is measured in Ohms.
•The resistance value can then be converted into temperature based on the
characteristics of the element.
•Response time for an RTD is between 0.5 and 5 seconds making them
suitable to applications.
•RTD elements are commonly specified according to their resistance in ohms
at zero degrees Celsius.
•The most common RTD specification is PT100, which means that at 0°C the
RTD element should demonstrate 100 Ω of resistance.
•Like Others are PT500 , PT1000
•Platinum is the most commonly used metal for RTD elements.

12. Why Platinum Is Common:
•Platinum is the most commonly used metal for RTD elements due
to a number of factors:
It is chemically inert,
 Linear temperature versus resistance relationship,
Temperature coefficient of resistance that is large enough to
give readily measurable resistance changes with temperature
Stability (in that its temperature resistance does not drastically
change with time).
• Other metals that are less frequently used as the resistor
elements in an RTD include nickel, copper and Balco.

13. RTD Configuration:
•RTD elements are typically in one of three
configurations:
•A platinum or metal glass slurry film deposited or
screened onto a small flat ceramic substrate known
as "thin film" RTD elements,
•Platinum or metal wire wound on a glass or
ceramic bobbin and sealed with a coating of
molten glass known as "wire wound" RTD
elements.
•A partially supported wound element which is a
small coil of wire inserted into a hole in a ceramic
insulator and attached along one side of that hole.
• The thin film is most rugged and has become
increasingly more accurate over time
Wire-wound PRT
Thin-film
Coil-element