Knowledge / Selection and temperature ranges
Planning CRT Shipping at +15 to +25 °C
Products requiring +15 to +25 °C also need protection from heat and cold during shipping. Insulated packaging slows heat transfer; water or suitable PCM can additionally absorb and release heat. The required configuration is tested with the intended payload and transport temperature profile.
Practical guidance
How do water or PCM protect goods from heat and cold when +15 to +25 °C must be maintained?
Rigid-shell cooling elements in different sizes. The medium and melting point are identified from the item labelling.
In this guide
- “CRT” alone does not define the permitted temperature range
- Insulation, water or PCM: which options are suitable?
- Compare water and PCM using the same quantities
- Worked example: warming water from +20 to +25 °C
- Check the definition and edition for international requirements
- Prepare PCM for warm and cold transport stages
- Gather this information before selecting a system
“CRT” alone does not define the permitted temperature range
CRT stands for Controlled Room Temperature. This article concerns the explicitly specified transport range of +15 to +25 °C. The abbreviation alone is insufficient for an enquiry because its definition can depend on the applicable framework. Take the precise limits from the product documentation.
Include time on the loading bay, in the delivery vehicle and in overnight storage. The description “does not require refrigeration” does not establish which temperatures the goods can tolerate there.
Insulation, water or PCM: which options are suitable?
| Option | Contribution to temperature control | Check before use |
|---|---|---|
| Insulation only | Slows heat transfer to and from the surroundings. | Whether the complete configuration is sufficient for the planned load, initial temperature and duration. |
| Temperature-conditioned water-based elements | Absorb heat as they warm and release it as they cool. Water remains liquid between +15 and +25 °C. | Mass, initial temperature and the usable temperature interval to each product limit. |
| PCM with a suitable melting range | Can absorb latent heat as it melts and release it as it solidifies. | Required solid or liquid starting state and suitability of the complete packaging. |
The article on using PCM in thermal packaging explains how to match the material and preparation.
Compare water and PCM using the same quantities
Compare how much heat the same mass or volume can absorb between the initial temperature and the permitted limit. Specific heat capacity describes heat absorption per unit mass and temperature change. Enthalpy of fusion describes heat absorbed during melting per unit mass. The two properties therefore cannot be directly compared.
For heat absorption through warming, approximately Q = m · c · ΔT, where Q is the quantity of heat, m the mass, c the specific heat capacity and ΔT the temperature change. With PCM, heat absorbed through melting is added, insofar as the required solid fraction is present.
Selecting a complete cooling element also involves the filling quantity, casing and heat transfer. A blanket statement such as “PCM is x times better than water” leaves these differences unresolved.
Worked example: warming water from +20 to +25 °C
One kilogram of water starts at +20 °C. It can warm by five degrees before reaching the upper limit of +25 °C. This temperature difference is 5 kelvin. The full ten degrees between +15 and +25 °C must therefore not be used in this calculation.
Using the simplifying assumption of a constant heat capacity c ≈ 4.18 kJ/(kg·K) gives Q ≈ 1 kg × 4.18 kJ/(kg·K) × 5 K = 20.9 kJ, equivalent to approximately 5.8 Wh. The rounded material property applies at +25 °C; it is treated as approximately constant over this short temperature span.
The calculation shows only the heat absorbed by the water up to +25 °C. It does not give the shipper’s duration. That would also require factors such as heat ingress over time, product mass and construction to be considered. Protection against cooling to +15 °C must be assessed separately.
Check the definition and edition for international requirements
Read temperature terms in product documents together with the named compendium or standard and its edition. A public briefing about a proposed revision does not establish that the revision is already effective. Confirm the applicable document before selecting the packaging.
If an enquiry states only “ambient” or “CRT”, ask for the permitted temperature range and the specific product requirements. This prevents the supplier and shipper from assuming different limits.
Prepare PCM for warm and cold transport stages
Solid PCM can absorb heat as it melts. If it is instead intended to release heat through solidification, a liquid fraction must be present. The packing instructions define the preparation appropriate to the intended sequence of warm and cold conditions. “Store at room temperature” is too imprecise without a temperature, duration and permitted stacking arrangement.
THERMOCON offers, among other options, PCMs with melting points of +18 and +22 °C. Testing the complete packaging establishes which variant is suitable.
A temperature-controlled vehicle also changes conditions around the shipper. The comparison of active and passive cooling explains how the two interact.
A similar surface temperature does not establish the same thermal state throughout the pack. The packing-process guide explains how to check preparation at the shipping site.
Source: THERMOCON: PCM cooling elements.
Gather this information before selecting a system
- Prescribed transport range and temperature of the goods at packing.
- Smallest and largest product quantity, with dimensions, mass and packaging type.
- Time until storage, including waiting times and possible delays.
- Expected hot, cold and changing ambient temperatures.
- Available equipment and space for preparing cooling elements.
The packaging selection guide shows how to compare this information with a quotation and test report. The glossary entry on thermal mass explains why product quantity influences temperature behaviour.
Sources
- NIST Chemistry WebBook: Water, liquid-phase heat capacity. Heat capacity of liquid water. The rounded value at +25 °C is treated as approximately constant in the example.
- USP: Proposed revision to Chapter 〈659〉 (2026). Public briefing on a proposed change; not an already effective revised edition.
- THERMOCON: PCM cooling elements. Available PCM melting points, sizes and formats.
Editorially updated on 5 November 2026.
Select PCM for your CRT shipment
Tell us the prescribed temperature range, the goods’ initial temperature and the expected hot and cold transport stages. This allows the appropriate PCM variant to be assessed.