15 Jan 2019

Panel World is Successfully Using VAI (Vacuum Assisted Injection) for Refrigerated Truck Panels

UNIDO, the United Nations Industrial Development Organization, funded a Demonstration Project to assess the technical and economic advantages of the Vacuum Assisted Injection (VAI) in discontinuous panel’s plant production.

An existing foaming plant was retrofitted with dedicated equipment to allow to switch blowing agent, from 141b to Pentane, with the help of vacuum during the foam injection and polymerization phases. The execution of the tests at Panel World, Frankfort, Free State, South Africa, demonstrated the success of VAI technology. The results of this Project offer a new opportunity for the conversion of the production process in order to phase out the use of HCFC-141b (as determined by the Montreal Protocol in 2007) in the manufacturing of sandwich panels.

Company Profile

Panel World Products is a family owned business, originally founded by the three Muller brothers in 2000 and famous for quality and delivery time, on which Panel World became a benchmark.

With over 2,500 m² of manufacturing space, located in Frankfort (South Africa), and employing more than 50 staff members, Panel World Group’ production includes Polystyrene & Polyurethane panels, made using Polyurethane foam blended with HCFC-141b & Polystyrene foam blocks from a local suppliers.

A production process mainly manual.

Project Objective

  • Demonstrate benefits from the application of the vacuum assisted injection in replacement of HCFC-141b with Pentane in term of insulation properties in the panel’s sector.
  • Demonstrate the easy applicability of the technology and, consequently, the replicability of the results.
  • Demonstrate that lower cost structure can be obtained by means of shorter foaming time, lower foam density, lower thermal conductivity.
  • Demonstrate the advantages in terms of safety against explosion and environmental and health sustainability for the operators.
  • Objectively analyse, if the incremental capital cost could be reduced overall in similar future projects by means of using VAI applied in the foaming process automatically used also for suction of flammable and harmful gaseous substances.

Thus, providing means of reducing the cost of exhaust ventilation system in the hydrocarbon based plant conversions.

Testing Organization

In order to demonstrate technical and financial advantages of VAI, baseline equipment had to be fitted and existing technology to be modified. Cyclopentane was the preferred blowing agent, since it is a natural substance and represents environment and human health friendly and sustainable technology.

The parameters to be tested and verified were:

  • k-Value
  • Density
  • Shot weight
  • Adhesion
  • Dimensional stability
  • Visual Aspects
  • Demoulding Time

The Demonstration Project was split into three steps:

  • Step-1: Benchmarking to be done based on 141b panels. From existing samples and tests results.
  • Step-2: Trials with Supplier 1 by using Pentane (without and with Vacuum) getting test results.
  • Step-3: Trials with Supplier 2 (if needed to achieve further improvements) and main focus in fine tuning of the process to achieve the objectives of UNIDO project.

Testing Procedure

Panel World uses Pentane as a blowing agent which is dosed via a Cannon Penta EasyFroth 20 to the foam dosing unit, a Cannon A 100 Compact Penta high pressure machine.

Foaming press is a Manni press set up for Pentane, 8.5m long, with 2+2 polymerization cavities system, equipped with additional Vacuum Assisted Injection hardware. The VAI production method applies into the press a depression surrounding the metal-faced insulation panel.

Prior to the foaming operation, a controlled degree of vacuum is applied between the press platen where the pre-assembled panel is positioned.

The reduced pressure applied during the injection and the expansion of the foam, facilitates the filling of the panel, providing substantial benefits.

Two panels were sampled using Resichem Polyurethane system containing 9% of Pentane and one panel was tested with a Dow Chemical system using 7% Pentane.

Each panel was divided into three equal segments (Left-, Centre & Right) along the length of the panel. The test samples were then cut from the middle of each segment. This method allowed to assess the consistency of the results along the chemical flow path or panel length.

The tests done on the resulting foamed panels were: density distribution, compressive strength, thermal conductivity and foam stability.

Results and Observations on the VAI Technology

Foam Density & Distribution

In all the panels the overall density was below the target by 1 g/l. The overall density was evenly distributed in all the panels. The density differentials were all below 4 g/l (typical for this application).

The compression strength results are within the following ranges:

  • Panel 1 ( at 41.5 g/l foam density)160 +15 kPa, (Resichem System Pentane 9%)
  • Panel 2 ( at 37 g/l foam density)135 +15 kPa, (Resichem System Pentane 9%)
  • Panel 3 ( at 37.2 g/l foam density)165 +20 kPa. (Dow System Pentane 7%

Advantages, in brief

  • 40% less demoulding time, 25% higher plant efficiency, 25% less energy used for production
  • Up to 10% lower applied foam density
  • Improvement on Thermal Insulation: up to 5% compared to a Pentane expanded foam without Vacuum; up to 14% compared to a Methyl Formate expanded foam; same as a 141b expanded foam.
  • Much better foam quality, aspect and dimensional stability
  • Eliminated the fumes ventilation system
  • Much cleaner and healthier working environment
  • Replaced HCFC blowing agent with a more environmentally friendly one


REAC Chemicals, the Cannon agents for South Africa, have been fundamental for the success of this project: their technical and commercial support has allowed to install efficiently this equipment and to apply on site all the necessary adjustments and fine tuning during different sets of trials.
All data shown in this article has been extracted from their final report to Unido.
The project objectives have been met. An entire techno-economic replicability is confirmed: the VAI technology is globally applicable for any new installations as well as for retrofitting/upgrades.
If you want to deepen the Cannon solutions for insulations panels, VAI technology or existing plants retrofitting, contact us.