Expand one of the blocks below for more information.
Test methods
For thermal conductivity testing, the selection of test method is dependent on the sample type.
If you are not sure of the test method to be used, please contact us with your sample information or read the Samples section below.
Steady state method with heat flow meter
The steady state method is mainly applicable to thick insulation materials with two parallel flat surfaces, e.g. mineral wool board.
ASTM C518-17 Standard test method for steady-state thermal transmission properties by means of the heat flow meter apparatus
This method is SAC-SINGLAS accredited
Transient method with hot wire thermal conductivity meter
The transient method is mainly applicable to general solid (e.g. plastics), powder (e.g. sand), paste (e.g. silicone grease) and liquid materials (e.g. lubricating oil).
Depending on the material type, one of the methods below will be used:
ASTM C1113/C1113M-09 Standard test method for thermal conductivity of refractories by hot wire (platinum resistance thermometer technique)
ASTM D5930-17 Standard test method for thermal conductivity of plastics by means of a transient line-source technique
ASTM D5334-14 Standard test method for determination of thermal conductivity of soil and soft rock by thermal needle probe procedure
ASTM D7896-19 Standard test method for thermal conductivity, thermal diffusivity, and volumetric heat capacity of engine coolants and related fluids by transient hot wire liquid thermal conductivity method
Instruments
There are two instruments available at OTM for thermal conductivity testing.
Heat flow meter (for steady state method)
OTM uses Thermtest HFM-100 heat flow meter for the steady state method. The NIST standard reference material (SRM) 1450d Fibrous Glass Board is used in the lab for heat flow meter calibration.
Heat flow meter
Hot wire thermal conductivity meter (for transient method)
Transient hot wire meter
Hot wire sensor
Samples
There are different sample requirements depending on the test method.
Steady state method based on ASTM C518
Typical sample types:
Insulation materials, e.g. mineral wool, polystyrene foam, polyurethane foam
Bulk solid materials, e.g. concrete block, fiberglass reinforced board
Thermal conductivity range: up to 2.5 W/(m K)
External thermocouple kit will be used for non-insulation materials
Temperature range: -15 to 65 °C
Sample size:
Preferred size: 300 mm x 300 mm
Maximum size: 300 mm x 300 mm
Minimum size: 200 mm x 200 mm
Maximum thickness: 100 mm
Sample requirements:
Parallel and flat top & bottom surfaces
Non-parallel and non-flat surfaces result in smaller results, due to contact resistance
Transient method based on ASTM C1113/D5930 (solid)
Typical sample types
General solid materials, e.g. concrete, brick, plastics, ceramics
For homogeneous materials only
Thermal conductivity range: up to 10 W/(m K)
Temperature range: room temperature only
Sample size:
minimum size: 30 mm x 30 mm x 1 mm
Size requirement is dependent on material type
Sample requirements:
Two samples are required, to sandwich the thin film probe in-between
The surface touching the probe shall be flat and smooth
Customer may machine or sand the surfaces to flat
OTM can only do sanding, but not machining
Non-flat surfaces result in smaller results, due to contact resistance
Transient method based on ASTM D5334 (soil)
Typical sample types:
soil and soft rock in tube form
Thermal conductivity range: up to 5 W/(m K)
Temperature range: room temperature only
Sample size:
Preferred soil tube size: 200 mm long and 100 mm in diameter
Sample requirements:
In soil tube form
In the intact form, i.e. with moisture level and density as close to the original state as possible
Transient method based on ASTM D7896 (liquid)
Typical sample types:
Liquid, e.g. lubricating oil, coolant, water
Thermal conductivity range: up to 10 W/(m K)
Temperature range: room temperature only
Sample volume:
Minimum volume: 100 mL
Sample requirements:
The liquid shall be non-toxic and safe to handle in general laboratory environment without special protection
Extended results
More than thermal conductivity
On request, the following extended results can be calculated and reported:
Thermal resistivity
Thermal resistance (R-value)
Thermal conductance
Thermal transmittance (U-value)
The calculations are based on:
ASTM C1045-19 Standard practice for calculating thermal transmission properties under steady-state conditions
Our sales personnel will guide you through the necessary procedures.
Upon your request, the following three documents will be emailed to you:
Official quotation
Standard terms & conditions
Test request form
The client needs to return us the following documents:
Official purchase order (PO) or signed quotation
Completed test request form
The client needs to submit the test samples to our laboratory. The test will commerce as soon as possible after the test samples are received.
FAQs
Frequently Asked Questions (FAQs):
Q1. Can you test thermal conductivity of metals, e.g. aluminium?
No. The thermal conductivities of metal materials are too large to be measured by our instruments.
Q2. Can you test thermal conductivity of paint
No. As paint is typically a very thin layer, the thicknesses of typical paint layers are insufficient for our lab testing.
Q3. How accurate are your results?
The measurement uncertainties are stated in the test reports. They are typically ±5% with the steady-state method and ±8% with the transient method. However, as mentioned in the Samples section, the accuracy is also dependent on the samples. Non-parallel and non-flat samples result in smaller results, due to contact resistance.
Q4. Can you test thermal resistance or U-value
Yes. For the steady-state method with heat flow meter, the thermal resistance (R-value) can be directly measured. For other cases the thermal resistance cannot be directly, we can do calculations based on the thermal conductivity measured and the thickness declared by you, according to ASTM C1045. For U-value, it cannot be directly tested and the calculation method based on ASTM C1045 is always used. We can use the boundary conditions specified in this BCA code or declared by you. We can calculate a range of extended results on your request.
You will receive the results within 5 working days, after sample submission.
Q6. What are the procedures?
Please contact us with your sample size and quantity. We will provide you the relevant documents and the sample submission instructions accordingly.
Q7. Can I visit your lab?
Sure, we welcome you to visit our lab to understand our testing procedures and assess our quality system. Please contact us if you wish to visit our lab.
