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Temperature Calibration Information
Temperature Calibration Questions
- How accurately can I measure temperature using a Labfacility sensor?
- I use many thermocouples in testing and experiments, can I make my own thermocouple junctions?
- Does Labfacility offer any publications to help technicians and students understand the choice and use of thermocouples and PRTs.
- What is the minimum immersion depth for a PRT probe?
- What do the thermocouple terms ‘cold junction compensation’ and ‘linearisation’ mean?
- There are several different types of extension cable construction; is the choice important?
- I need to use "fail-safe" alarms on my process. Can my controller and alarms share the same thermocouple?
- What is the longest thermocouple I can have without losing accuracy?
- What accuracy will I get at a certain temperature using a Pt100 detector; if a better grade detector is used what effect will this have to the accuracy?
- As most instrumentation only takes 2 or 3 wire Pt100s, if I took the correction made on the 3 wire system and incorporated that on to the single leg could I achieve a 4 wire system?
- If copper can be used at the same point on each leg of a thermocouple can I use Copper connectors on thermocouples?
- What is Automatic Cold Junction Compensation?
- How can I keep abreast of new developments, products and services from Labfacility?
Calibration Information
Q How accurately can I measure temperature using a Labfacility sensor?
A To published, internationally specified tolerances as standard, typically ( 2.5°C for popular thermocouples, (0.5°C for PRT. Higher accuracy sensors can be supplied to order, e.g. (0.5°C for type T thermocouple, (0.2°C for PRT. All of these values are temperature dependent. A close tolerance, 4-wire PRT will give best absolute accuracy and stability.
Q I use many thermocouples in testing and experiments, can I make my own thermocouple junctions?
A Yes, Labfacility can supply a benchtop welder and fine thermocouple wires - it is easy and inexpensive to make unsheathed thermocouples.
L60+ Fine Wire Welder product details
Q Does Labfacility offer any publications to help technicians and students understand the choice and use of thermocouples and PRTs?
A Yes, please see the Labfacility Temperature Handbook.
Q What is the minimum immersion depth for a PRT probe?
A Usually 150mm or more; increase the immersion until the reading is unchanged.
Q What do the thermocouple terms "cold junction compensation" and "linearisation" mean?
A Refer to the Labfacility Temperature Handbook for a full explanation. With most types of measuring instrument, these functions are automatically applied and do not require user consideration.
Q There are several different types of extension cable construction; is the choice important?
A Yes; some are waterproof, some mechanically stronger, some suitable for high or low temperature.
Send you enquiry and let us help you choose the right cable.
Q I need to use "fail-safe" alarms on my process. Can my controller and alarms share the same thermocouple?
A Use duplex sensors, one connected to the controller and the other to the alarm. Your controller may have alarms incorporated in which case you are relying on your control sensor.
Q What is the longest thermocouple I can have without losing accuracy?
A It could be; try to ensure a maximum sensor loop resistance of 100 Ohms for thermocouples and 4-wire PRT's. Exceeding 100 Ohms could result in a measurement error. Note By using a 4-20mA transmitter near the sensor, cable runs can be much longer and need only cheaper copper wire. The instrument must be suitable for a 4-20mA input though.
Q What accuracy will I get at a certain temperature using a Pt100 detector; if a better grade detector is used what effect will this have to the accuracy?
A Refer to the Labfacility Temperature Handbook for Pt100 tolerance information.
Q As most instrumentation only takes 2 or 3 wire Pt100's, if I took the correction made on the 3 wire system and incorporated that on to the single leg could I achieve a 4 wire system?
A No; cable length and ambient temperature variations come into play.
Q What is the maximum number of calibration points I can have programmed in to a Tempmaster-100.
A Ten
Q If copper can be used at the same point on each leg of a thermocouple can I use Copper connectors on thermocouples?
A Yes but only if both legs are maintained at exactly the same temperature. Not recommended.
Q What is Automatic Cold Junction Compensation?
A This is a feature of most measuring instruments which allows for the fact that the thermocouple input termination is at a varying temperature other than stable at 0°C.
PVC Insulated Cables
Glass Fibre Insulated Cables
PRA & PTFE Insulated Cables
PRT Sensor Cables
