HFO 50 High-Density Closed-Cell Spray Foam | Rayston SPF for Compressive Loads
Contents
- What is HFO 50 spray polyurethane foam and when should you specify it?
- Cell gas and make-up of HFO 50 spray polyurethane foam
- Applied foam properties: density, closed cells, λ, compressive strength and fire
- HFO 50 spray foam aged thermal performance table (thickness / λ / R)
- Mix ratios and site application conditions
- Component properties and laboratory reactivity
- Safety, storage, equipment cleaning and empty containers
- HFO 50 spray polyurethane foam vs other Rayston grades: which one to choose?
- HFO 50 spray polyurethane foam: FAQ
- Engineering summary
- Related links
Rayston Spray Foam HFO 50 by Krypton Chemical: a high-density closed-cell spray foam (48–55 kg/m³ applied) with HCFO-1233zd(E) cell gas and closed cells > 90%, for applications requiring compressive strength greater than 200 kPa — figures from the technical datasheet.
- Product: Rayston Spray Foam HFO 50
- Grade: HFO 50 · high-density closed-cell
- Application: spray-applied thermal insulation
HFO 50 spray polyurethane foam (Rayston Spray Foam HFO 50) is a two-component rigid polyurethane system from Krypton Chemical, S.L. and the highest-density grade in the HFO family. It is sprayed directly onto the substrate at an applied density of 48–55 kg/m³ and is positioned for applications requiring compressive strength greater than 200 kPa. The cell gas is HCFO-1233zd(E), the formulation contains no HCFCs or HFCs, and closed-cell content is > 90%. The sheet lists λ = 0.021 W/m·K in the foam property table, while aged design values range from 0.028 to 0.025 depending on thickness, according to the official technical datasheet (last revised 02/06/2026).
This article covers a single grade of the Rayston Spray Foam range (the HFO family). For a full comparison of all seven grades, see the general guide: spray polyurethane foam. For a direct comparison, see the lighter HFO 40 spray foam and the high-density, water-blown 50W spray foam.
01
What is HFO 50 spray polyurethane foam and when should you specify it?
HFO 50 spray foam (Rayston Spray Foam HFO 50) is a formulated product containing the polyols and additives needed to produce a rigid polyurethane foam sprayed directly onto the substrate when reacted with polymeric isocyanate (PMDI) with a functionality of 2.6–2.8 and an NCO content of 30–32%. Applied density is between 48 and 55 kg/m³.
The datasheet describes the product as suitable for thermal insulation in construction and industry in applications requiring compressive strength greater than 200 kPa. In its application section, it gives the following use:
- Spray-applied thermal insulation on surfaces not subject to permanent loads, such as vertical walls and ceilings from the inside.
- On façades: repels water while still allowing the construction to breathe to some degree.
The sheet therefore combines a description aimed at compressive applications with application wording that limits use to surfaces not subject to permanent loads; any use under permanent load must be settled by an engineering decision and review with the manufacturer.
The product is for industrial and professional use only and not suitable for DIY.
Manufacturer: kryptonchemical.com.
Internal links: Knowledge base · Products · Documents.
02
Cell gas and make-up of HFO 50 spray polyurethane foam
The HFO 50 spray foam sheet states that the formulation contains no HCFCs or HFCs and that the gas trapped in the cells is 1-chloro-3,3,3-trifluoro-propene (HCFO-1233zd(E)). The product belongs to the HFO family of the Rayston line, alongside HFO 35 and HFO 40, as opposed to the water-blown grades (30W / 40W / 50W) and the 8W open-cell grade.
What sets HFO 50 apart within its family, according to its datasheet:
- Declared closed-cell content > 90%.
- The highest applied density in the family: 48–55 kg/m³.
- An explicit statement on applications requiring compressive strength greater than 200 kPa.
- Isocyanate component: PMDI with a functionality of 2.6–2.8.
Designation code according to the datasheet:
PU EN 14315-1-CCC4-CT3 (20)-TFT18(20)-FRB40(20)-W0,2-MU80
The code follows EN 14315-1:2013, the standard for sprayed rigid polyurethane foam systems before installation; it carries water absorption level W0,2 and water vapour resistance level MU80.
03
Applied foam properties: density, closed cells, λ, compressive strength and fire
Applied density
48–55 kg/m³
UNE-EN 1602
Closed-cell content
> 90%
— (row notes “does not allow water through”)
Reaction to fire
Euroclass E (all thicknesses)
UNE-EN 13823:2002
Compressive strength
greater than 200 kPa (product description text)
| Property | Value | Standard / TDS reference |
|---|---|---|
| Applied density | 48–55 kg/m³ | UNE-EN 1602 |
| Free-rise density (lab) | 38–44 g/L | EN 14315-1:2013 |
| Closed-cell content | > 90% | — (row notes “does not allow water through”) |
| Thermal conductivity (foam property table) | 0.021 W/m·K | UNE-EN 12667 |
| Reaction to fire | Euroclass E (all thicknesses) | UNE-EN 13823:2002 |
| Compressive strength | greater than 200 kPa (product description text) | — |
| Short-term water absorption | W0,2 (level in designation code) | EN 14315-1:2013 |
| Water vapour diffusion resistance | MU80 (level in designation code) | EN 14315-1:2013 |
Brief engineering notes:
- The λ = 0.021 listed in the foam property table must not be used in place of the aged performance table; the thermal calculation uses 0.028 / 0.026 / 0.025 depending on thickness.
- HFO 50 is the only grade in the HFO family whose sheet states compressive strength greater than 200 kPa, without a separate measured figure in the property table.
- The μ factor and water absorption appear in the HFO 50 sheet as levels in the designation code (MU80 and W0,2), not as separate rows in the table.
- Reaction to fire is Euroclass E for all thicknesses according to the datasheet.
04
HFO 50 spray foam aged thermal performance table (thickness / λ / R)
Base the thermal calculation on the target-thickness row of the aged performance table. The HFO 50 spray foam table starts at 25 mm: λ = 0.028 from 25 to 75 mm, then 0.026 from 80 to 115 mm and 0.025 from 120 to 200 mm, while thermal resistance R rises in proportion to thickness.
R (m²·K/W)
Aged λ (W/m·K) 0.028 · thickness 25–75 mm
25 mm
0.90
30 mm
1.10
35 mm
1.30
40 mm
1.40
45 mm
1.60
50 mm
1.80
55 mm
2.00
60 mm
2.10
65 mm
2.30
70 mm
2.50
75 mm
2.70
Aged λ (W/m·K) 0.026 · thickness 80–115 mm
80 mm
3.10
85 mm
3.30
90 mm
3.50
95 mm
3.70
100 mm
3.80
105 mm
4.00
110 mm
4.20
115 mm
4.40
Aged λ (W/m·K) 0.025 · thickness 120–200 mm
120 mm
4.80
125 mm
5.00
130 mm
5.20
135 mm
5.40
140 mm
5.60
145 mm
5.80
150 mm
6.00
155 mm
6.20
160 mm
6.40
165 mm
6.60
170 mm
6.80
175 mm
7.00
180 mm
7.20
185 mm
7.40
190 mm
7.60
195 mm
7.80
200 mm
8.00
Worked example: at 50 mm, R = 1.80 m²·K/W with λ = 0.028; at 100 mm, R = 3.80 with λ = 0.026; and at 200 mm, R = 8.00 with λ = 0.025 — the highest R at 200 mm in the Rayston range.
| Thickness (mm) | Aged λ (W/m·K) | R (m²·K/W) |
|---|---|---|
| 25 | 0.028 | 0.90 |
| 30 | 0.028 | 1.10 |
| 35 | 0.028 | 1.30 |
| 40 | 0.028 | 1.40 |
| 45 | 0.028 | 1.60 |
| 50 | 0.028 | 1.80 |
| 55 | 0.028 | 2.00 |
| 60 | 0.028 | 2.10 |
| 65 | 0.028 | 2.30 |
| 70 | 0.028 | 2.50 |
| 75 | 0.028 | 2.70 |
| 80 | 0.026 | 3.10 |
| 85 | 0.026 | 3.30 |
| 90 | 0.026 | 3.50 |
| 95 | 0.026 | 3.70 |
| 100 | 0.026 | 3.80 |
| 105 | 0.026 | 4.00 |
| 110 | 0.026 | 4.20 |
| 115 | 0.026 | 4.40 |
| 120 | 0.025 | 4.80 |
| 125 | 0.025 | 5.00 |
| 130 | 0.025 | 5.20 |
| 135 | 0.025 | 5.40 |
| 140 | 0.025 | 5.60 |
| 145 | 0.025 | 5.80 |
| 150 | 0.025 | 6.00 |
| 155 | 0.025 | 6.20 |
| 160 | 0.025 | 6.40 |
| 165 | 0.025 | 6.60 |
| 170 | 0.025 | 6.80 |
| 175 | 0.025 | 7.00 |
| 180 | 0.025 | 7.20 |
| 185 | 0.025 | 7.40 |
| 190 | 0.025 | 7.60 |
| 195 | 0.025 | 7.80 |
| 200 | 0.025 | 8.00 |
05
Mix ratios and site application conditions
Mix ratio by volume (polyol : isocyanate)
100:100
Mix ratio by weight
100:110
Component temperature
25–45 °C
Working pressure
60–120 bar
Ambient temperature
0 to 40 °C
Relative air humidity
< 90%
Wind speed
< 30 km/h
Substrate temperature
5–40 °C
Substrate moisture
No surface condensation
| Condition | Value in the HFO 50 datasheet |
|---|---|
| Mix ratio by volume (polyol : isocyanate) | 100:100 |
| Mix ratio by weight | 100:110 |
| Component temperature | 25–45 °C |
| Working pressure | 60–120 bar |
| Ambient temperature | 0 to 40 °C |
| Relative air humidity | < 90% |
| Wind speed | < 30 km/h |
| Substrate temperature | 5–40 °C |
| Substrate moisture | No surface condensation |
Apply the system with dedicated spray equipment at the mix ratios above. Note that the component temperature for HFO 50 is 25–45 °C, lower than the 30–60 °C range of the other rigid grades. The manufacturer’s recommendations do not relieve the applicator of reviewing the application method and running on-site trials whenever there is doubt about the system’s suitability for the project conditions.
06
Component properties and laboratory reactivity
The following values are given at 20 °C in the datasheet section on supplementary component information and reactivity:
Hydroxyl value
Polyol: 290–330 mg KOH
DIN-53240-2
Water content
Polyol: 1.2–1.4%
ISO 14897
Viscosity
Polyol: 300–400 mPa·s
Isocyanate: 180–250 mPa·s
INT-IT-17
NCO content
Isocyanate: 31%
UNE-92120-1
| Property | Polyol | Isocyanate | Standard |
|---|---|---|---|
| Hydroxyl value | 290–330 mg KOH | — | DIN-53240-2 |
| Water content | 1.2–1.4% | — | ISO 14897 |
| Viscosity | 300–400 mPa·s | 180–250 mPa·s | INT-IT-17 |
| NCO content | — | 31% | UNE-92120-1 |
| Cream time | 2–4 s | EN 14315-1:2013 | |
| Thread (string) time | 8–11 s | EN 14315-1:2013 | |
| Free-rise density | 38–44 g/L | EN 14315-1:2013 |
These are reference laboratory times; working times on site depend on component temperature, working pressure and ambient conditions within the declared ranges. The HFO 50 sheet does not give a drying time.
07
Safety, storage, equipment cleaning and empty containers
Occupational safety
Component B of HFO 50 spray foam contains isocyanates, so always follow the safety data sheet (MSDS): good ventilation and/or respiratory protection (combined organic vapour and particulate filters) together with protective clothing. Use the product only for the applications described in the datasheet; it is intended for industrial and professional use and is not suitable for DIY.
Storage
Store both components between 10 and 25 °C, always protected from moisture ingress. Under suitable storage conditions and in the original packaging, the maximum shelf life is 6 months from the date of manufacture.
Equipment cleaning
After application, clean the machine carefully to avoid contaminating the next system used on the same rig. Solvents are not recommended for cleaning machine parts; a plasticiser-based cleaning fluid such as Rayston Fluid is preferred. Remove component B completely from all parts exposed to air and replace it with cleaning fluid.
Empty containers and environment
Handle empty containers with the same precautions as full ones and hand them over as hazardous waste to a licensed waste manager. A and B can be mixed 1/1 to obtain an inert material, provided the quantity does not exceed 5 litres, to avoid a dangerous build-up of heat. Never mix residues with any other product without knowing the possible reactions.
08
HFO 50 spray polyurethane foam vs other Rayston grades: which one to choose?
Choosing a grade is a design decision governed by the application, density, λ and any declared compressive requirements — not by the trade name alone. Within the HFO 50 datasheet figures:
1
Closed cells > 90% with a stated compressive strength greater than 200 kPa and 48–55 kg/m³ density → HFO 50 is the direct candidate.
2
3
Water-blown with a numerically declared compressive strength (280, CS(10/Y)200) → compare 50W (48–56 kg/m³).
5
Declared sound insulation with lightweight open cells → 8W, not HFO 50.
This section does not replace the building’s thermal calculation or the technical datasheet of the selected grade. For a side-by-side comparison of all seven grades, see the spray polyurethane foam guide.
09
HFO 50 spray polyurethane foam: FAQ
What is HFO 50 spray foam, in short?
A two-component rigid polyurethane system (Rayston Spray Foam HFO 50) from Krypton Chemical, with an applied density of 48–55 kg/m³ and closed cells > 90%, for spray-applied thermal insulation in applications requiring compressive strength greater than 200 kPa.
What is the thermal conductivity of HFO 50 spray foam?
The datasheet gives λ = 0.021 W/m·K to UNE-EN 12667 in the foam property table, while the aged performance table gives 0.028 up to 75 mm, 0.026 from 80 to 115 mm and 0.025 from 120 to 200 mm; use the target-thickness row for design.
What is the compressive strength of HFO 50 spray foam?
The datasheet states that it is suitable for applications requiring compressive strength greater than 200 kPa, without a separate measured figure in the property table. The application wording still refers to surfaces not subject to permanent loads, so any permanent loading requires an engineering decision.
Is HFO 50 spray foam closed-cell?
Yes. Closed-cell content is declared as > 90%, and the designation code carries CCC4.
What is the correct mix ratio?
100:100 by volume and 100:110 by weight (polyol : isocyanate), with a working pressure of 60–120 bar.
What component temperature is recommended?
25–45 °C according to the HFO 50 sheet, a lower range than the 30–60 °C of the other rigid grades.
What is the reaction-to-fire classification?
Euroclass E for all thicknesses, tested to UNE-EN 13823:2002.
What is the shelf life and how should the components be stored?
Up to 6 months from the date of manufacture in the original packaging, with both components stored between 10 and 25 °C and fully protected from moisture.
10
Engineering summary
HFO 50 spray polyurethane foam (Rayston Spray Foam HFO 50) is the highest-density grade in Krypton Chemical’s HFO family: applied density 48–55 kg/m³, closed cells > 90%, HCFO-1233zd(E) cell gas with no HCFCs or HFCs, aged λ values of 0.028 / 0.026 / 0.025 depending on thickness with R = 8.00 at 200 mm, a stated compressive strength greater than 200 kPa and reaction to fire Euroclass E. Settle the final choice against the datasheet figures and the project thickness, and refer to the general guide to compare it with the other grades.
11
Related links
General guide
Grade articles
HFO 50
Rayston Spray Foam HFO 50
| Grade | Trade name | Article |
|---|---|---|
| 8W | Rayston Spray Foam 8W | 8W spray foam |
| 30W | Rayston Spray Foam 30W | 30W spray foam |
| 40W | Rayston Spray Foam 40W | 40W spray foam |
| 50W | Rayston Spray Foam 50W | 50W spray foam |
| HFO 35 | Rayston Spray Foam HFO 35 | HFO 35 spray foam |
| HFO 40 | Rayston Spray Foam HFO 40 | HFO 40 spray foam |
| HFO 50 | Rayston Spray Foam HFO 50 | This article |
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