Technical and ordering guidance
Frequently Asked Questions
Precision coil-wound platinum resistance temperature detectors
Thermal Developments International manufactures precision coil-wound platinum resistance temperature detectors, including wire-wound Pt100 elements and high-specification RTDs.
These detectors form the temperature-sensing heart of many reference thermometers, industrial probes and calibration instruments.
Component supply only: TDI supplies the core sensing elements from which thermometer manufacturers build complete devices. We do not manufacture finished thermometers, probe assemblies or complete temperature-measurement systems.
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Products and supply scope
What TDI manufactures and how the detectors are supplied.
What does TDI manufacture?
TDI manufactures precision coil-wound platinum resistance temperature detectors.
Our products include wire-wound Pt100 detectors and other high-specification resistance temperature detectors designed for use in precision temperature-measurement applications.
They are supplied as sensing elements for incorporation into a finished thermometer, probe or sensor assembly.
Does TDI supply complete thermometers or probe assemblies?
No. TDI supplies the platinum resistance detector itself rather than the completed thermometer.
We do not manufacture:
- Finished thermometers
- Temperature probe assemblies
- Thermometer sheaths
Our detectors are intended for use by specialist thermometer and sensor manufacturers that have the expertise and equipment required to assemble, protect, connect and calibrate the finished device.
Can TDI attach lead wires to the detector?
No. TDI cannot attach external lead wires to the detector.
The detector is supplied as a component only. The customer or thermometer manufacturer is responsible for making the electrical connections and incorporating the detector into the completed assembly.
These operations require appropriate materials, processes and controls to avoid introducing mechanical strain, contamination, thermal conduction errors or changes in resistance.
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Performance and application
Detector tolerances, finished-thermometer accuracy and assembly responsibilities.
What accuracy can be achieved?
The accuracy of a completed thermometer cannot be determined from the detector alone.
TDI offers detectors in a range of resistance tolerances. The specified tolerance is guaranteed at 0 °C. As the temperature moves further away from 0 °C, the permissible deviation associated with the applicable resistance-temperature characteristic generally increases.
The performance of the finished thermometer will also depend on factors including:
- The detector tolerance and resistance-temperature characteristic
- The mechanical construction of the probe
- The method used to support and connect the detector
- Lead-wire resistance and wiring configuration
- Insulation resistance
- Thermal contact and immersion
- Mechanical strain and vibration
- Self-heating
- The calibration method and measurement equipment
When correctly selected and assembled, TDI detectors can be used in thermometers designed to perform in accordance with relevant international standards. The manufacturer of the completed thermometer is responsible for determining, testing and stating the accuracy of the finished product.
Is the detector tolerance guaranteed across the range for complete thermometers?
No. The detector tolerance is guaranteed at 0 °C.
Performance at other temperatures depends on the detector’s resistance-temperature relationship and the specification under which it is supplied. The uncertainty and allowable deviation of the completed thermometer must be assessed by the thermometer manufacturer across the temperature range in which it will be used.
Does a high-accuracy detector automatically produce a high-accuracy thermometer?
No. A high-quality detector is an essential starting point, but it is only one part of the complete thermometer.
Assembly methods, materials, mechanical stress, wiring, thermal design and calibration can all affect the completed thermometer’s performance. A detector with a close resistance tolerance can still produce unsatisfactory results if it is assembled incorrectly.
Similarly, a carefully designed and calibrated thermometer can achieve excellent performance by combining an appropriate detector with well-controlled manufacturing processes.
Can TDI recommend how the detector should be assembled?
No, the detailed design and manufacture of the finished thermometer remains the responsibility of the customer. Assembly methods will vary according to the intended temperature range, response time, environment, accuracy requirement and mechanical construction.
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Orders and customers
Quantities, delivery planning and the organisations TDI supports.
Is there a minimum order quantity?
TDI does not have a general minimum order quantity.
We work with a wide range of customers, from researchers and engineers requiring only a small number of detectors to leading international sensor manufacturers placing scheduled orders for tens of thousands of components.
Several of our largest customers began by ordering small quantities for evaluation and product development.
What are the delivery times?
Delivery times are determined individually for each order.
There is no single standard lead time because requirements can vary considerably. An order might involve a few specialist detectors for a research project, a development quantity for product evaluation, or a scheduled production order involving tens of thousands of components.
Lead time may be influenced by:
- Detector type and specification
- Order quantity
- Existing production schedules
- Whether the order is a one-off requirement or part of a scheduled programme
Please contact TDI with the required detector type, quantity and preferred delivery date. We will review the requirement and provide an appropriate quotation and estimated delivery schedule.
Can TDI support prototype and development orders?
Yes. TDI welcomes enquiries for prototypes, evaluation quantities and development projects.
Small initial orders allow manufacturers and researchers to assess detector performance, refine their assembly methods and validate a design before moving into larger-scale production.
Can TDI supply scheduled production quantities?
Yes. TDI supplies established sensor and thermometer manufacturers requiring regular production quantities.
Scheduled orders can help customers plan future demand and allow production and delivery arrangements to be agreed in advance. Requirements are considered individually according to detector type, volume and delivery frequency.
Who typically uses TDI detectors?
TDI detectors are used by organisations involved in precision temperature measurement, including:
- Reference thermometer manufacturers
- Industrial temperature-sensor manufacturers
- Calibration-equipment manufacturers
- Research laboratories
- Universities and scientific institutions
- Process instrumentation companies
- Specialist engineering organisations
Still Have a Question?
Contact TDI to discuss your detector requirement. Whether you need a small quantity for research and evaluation or an ongoing production supply, each enquiry is considered individually.
Contact TDI