PCC > How Changing Weather Conditions Influence Foam Quality and Performance.

How Changing Weather Conditions Influence Foam Quality and Performance.

We are currently in the so-called transition period between summer and fall. Working conditions are no longer stable and predictable,

now they change depending on the time of day – the temperature amplitudes are one of the highest in the year and reach as much as 20C.

During this period, working with spray systems presents contractors with additional challenges as they try to achieve the best possible result – related to performance, quality, and  time spent on insulating.
All this ultimately translates into economic efficiency.

During periods of changing weather conditions, we can see four areas where mistakes most often occur and where special attention should be paid.
These include:

Improper settings of the dosing machine causes a deterioration of foam quality and performance.

You should take into account the variability of conditions during the day and adapt the machine settings to the circumstances at any given moment and, if necessary, adjust the settings if the conditions change.
For example, in the morning temperature will be much lower than in the afternoon, when there is plenty of sunshine.
As the work progresses, the energy created by the reaction will also significantly raise the ambient temperature.
In the event of large temperature fluctuations during the day, we recommend that you adjust the machine settings accordingly.

Too low a temperature of the components in the barrel will lead to incorrect spraying of the mixture and a slower reaction.

Due to the much lower temperatures in the mornings, more attention should be paid to the temperature of components before spraying.
As time passes and temperature gets colder, the time needed to prepare the material will be longer.
If you are using a machine with relatively low-power heating blocks, consider using heating tape as an additional accessory to speed up the heating of raw materials.
Remember that the tape transfers heat locally and does not allow the temperature of the liquid to rise evenly throughout the entire volume of the barrel.
When using this type of device, bear in mind that you should not overdo it and always remember not to exceed the maximum recommended temperature of 40
OC. If the temperature in the barrels is not controlled and the polyol mixture is heated too intensively, the substance will age more quickly, delaminate more, or even become irreversibly spoiled. This is why proper preparation of the material before work is crucial if you want to achieve the best possible result.

The table below shows the optimal parameters for working with PCC Prodex open-cell systems – they have been developed and tested by the manufacturer. Adhere to them for the best end result

Heating temperature for components A and B[1] 50-60°C
Heating hoses 50-60°C
Component pressure 80-110 Bar (1160 – 1595 psi)
Temperature of the components in the barrels [2] 30-40°C

Inadequate working conditions cause a number of problems during processing.

Spraying in the right conditions is as important as the correct preparation of the material for processing and  selecting the optimal settings.
We have much less influence on these factors, but it is worth remembering the basic principles.

Unfavorable ambient conditions that most frequently occur during the execution of works include:

  • Temperature of the substrate below optimal values – causes worse adhesion, slower and incomplete foam expansion, and shrinkage
  • Ambient temperature below optimal values – causes slower and incomplete foam expansion
  • Air humidity exceeding optimal values – causes foam quality, adhesion to the substrate, and interlayer adhesion to deteriorate
  • Moisture content of porous substrate (wood) exceeding optimal values – causes adhesion to deteriorate and leads to detachment from the substrate

The table below shows the optimal ambient conditions for working with PCC Prodex open-cell systems – they have been developed and tested by the manufacturer. Adhere to them for the best end result

Ambient temperature 10-35°C
Recommended substrate temperature 15-50°C
Ambient relative humidity ≤ 70%
Moisture content of porous substrate Up to 15%
Moisture content of non-porous substrate 0%

In cool conditions at night it is difficult to ensure the minimum recommended substrate temperature.
The fact that the ambient temperature reaches the required values does not always mean that the substrate does so too.
If the temperature of the substrate on which the foam will be sprayed is too low, this may result in shrinkage and  deterioration of adhesion, even causing the foam to fall off sloping surfaces or ceilings.
This is why it is necessary to ensure that the substrate, membrane, formwork, and rafters have all reached the required temperature before works begin.
Using heaters or blowers at the spray site is an effective method of increasing substrate and ambient temperature while also reducing relative humidity.
If the ambient temperature and substrate temperature are too low, this will slow down reaction and prevent full expansion, which will in turn adversely affect the performance.
It is good to start insulating the roof from the end with a higher temperature (this can be checked with a pyrometer); this is usually the part of the roof that gets more sun at a given time.

It is important to measure the moisture content of wooden structures with a moisture meter each time.
Wood with moisture content above 15% will cause the adhesion of the sprayed foam to deteriorate.
It is also important to note that damp wood can shrink over time.
If  roof trusses have a moisture content that exceeds the optimum values, the only solution is to stop work until the wood dries naturally and reaches the level of maximum 15%.

Incorrect storage accelerates the aging of raw materials.

At the moment, temperatures in the mornings are much lower than even just a few weeks ago, so you need to pay more attention to the material storage conditions and the conditions in which the vehicle with the machine and barrels is kept.
It is worth remembering that the material is adversely affected by temperatures that are lower or higher than recommended.
We recommend that the kits be stored at  a temperature between 15-25°C and protected against direct sunlight and moisture.
Therefore, it is best to store the material and the dispensing device in a  heated garage/warehouse.
Cold has an adverse impact on the raw materials for the production of foam and the equipment used for spraying.
Low temperatures increase the viscosity and density not only of components, but also, among other things,
the oil in the compressor or the machine, thus creating much more work for both the transfer pumps and the entire equipment.

Radosław Szewczyk

Technical Support Manager

PCC Prodex

[1]  Heating temperature of components A and B – temperature during operation, high pressure side

[2]  Temperature of components in barrels – temperature of components, low pressure side