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Better Polyurethane Foams for hot water tanks insulation

30 Jul 2019

New energy-conscious regulations are raising the bar for the insulation performances of any thermal apparatus, and water boilers play an important role in this category of devices, more and more demanded domestic uses, but in particular for the storage of hot media produced with solar panels and heat pumps.

For these applications conventional water-blown low-density rigid foams are not providing a sufficient degree of insulation: alternative blowing agents must be used to raise their lambda value without increasing the thickness of the insulating media. A specific polyurethane foam mixing head designed by Cannon provides the right solution, even to the owners of existing foaming machine.

New Polyurethane Foams solutions for boilers insulation

The manufacturers of water boilers and hot water tanks have chosen Cannon PU foaming machines and equipment to insulate their products for the past 50 years.

They have gone through the whole development curve of the foam industry: from low-pressure metering to high-pressure, from water-blown formulations to more performing CFC – and HCFC – blown ones, to gain polyurethane foam quality and insulation characteristics.

Now that international regulations call for higher thermal efficiency from their products and for lower environmental impact from their production cycles, they must face a new challenge: increase the thermal efficiency of their boilers, or hot water tanks in general, without increasing the thickness of the insulating foams.

New polyurethane formulations are available to raise the insulation factor of the rigid foams, by using a flammable blowing agent like Cyclopentane or a liquid HydroFluoroOlefine.

Both solutions have a specific market:

  • Cyclopentane can be used by mass-producers of standard models, that can afford the one-time cost of a plant conversion to provide all the required safeties against a potential fire, using a flammable blowing agent.
    The cost of this HydroCarbon is affordable and the insulation effect meets the desired values.
  • HydroFluoroOlefines are more expensive than Cyclopentane, but do not demand explosion-proof foaming equipment. This allows the manufacturers of small series of large tanks to avoid important investments in new or refurbished foaming production plants. A separate metering line feeding this blowing agent directly into the mixing chamber of the head is desirable when using HydroFluoroOlefines. Cannon provides high-pressure mixing heads models, in both explosion-proof or conventional versions, able to efficiently meter the two mentioned blowing agents.

What is Lambda Value?
Lambda value λ(w/mK) = the value of the insulating capacity of product designed for thermal performance. The lower the value, the better the insulating capacity of the product (for a given thickness).

The new Cannon polyurethane foam mixing head

A new mixing head, the FPL SR series, in the QCC and /3 versions, has proven to be the winning tool for the users of HydroFluoroOlefines: the third stream available on these two models allows for a direct injection of the blowing agent stream into the mixing head, providing optimum foam quality without blending the HFO with the polyol stored in the tanks.

This solution is obviously available for the supply of new foaming equipment, but can also be provided for existing foaming plants, implementing the necessary adjustments to the machine’s circuits and control panel.

A new third component high-pressure dosing module and a new Cannon FPL SR mixing head can retrofit an existing Cannon or competitor’s high-pressure dosing unit for the polyurethane foam production.

This flexibility in solving new problems through the development of innovative solutions has won for Cannon the confidence of major players in this vast market niche. In the past ten years nearly 200 dosing machines for this specific application, 90% of them high-pressure models, have been supplied to Haier, Electrolux, Ariston, Viessmann, BRD Termea, OSO, and more than 100 other leading manufact.

Discover the full range of Cannon mixing heads for reactive polymer processing.