Guns and Chemical in Cold Weather

Today I want to talk about working with spray guns and chemical in cold weather, what happens to them and how to work with them.

SPRAY GUN

All spray foam guns are basically the same; and as big hunks of metal, they lose heat quickly and are generally cold in cold weather.

O-rings get brittle, lubricating oil and grease get thick, like honey or cement paste, and gun grease hardens. These are all used to lubricate and protect moveable parts, if they get cold and stiffen, they may fail. If you pull the trigger under these conditions and failure occurs, you may end up with a cross-over – or a total foam blockage in the head of the gun.

This is expensive – parts, labor, and downtime.

Solution: Keep your equipment warm during the cold weather. If you don’t have a heated rig, make sure to travel with the foam gun in the cab of your heated truck.

ISO

Like any liquid, when iso gets cold it gets thicker, not as quickly as the resin, but it does get thicker, and it can freeze, sort of – as iso approaches freezing, the molecules get really close together and can attach to each other, resulting in dimers, sometimes referred to as crystals.

Around freezing temperatures, iso will not solidify like water but will be more like a frozen slushie. These crystals can ruin the iso material and damage your equipment. If you use this material, you could plug up and clog your entire system from the drum to the gun. This can be expensive – equipment, downtime, and lost revenue.

In some cases, you can salvage the material by increasing the drum temperature and straining the crystals. To do this you need a clean barrel, a funnel, and a screen. Then you can transfer the liquid by hand, pouring it over the screen, filtering the crystals out and draining the liquid into the new drum. Note, you have to be careful about using a pump because of the crystals.

Solution: Be proactive, keep your chemical warm during cold weather and do not let it get close to freezing.

RESIN

Resin will generally be more affected by cold weather than iso; it will get thicker, faster as the material gets colder. Additionally, the resin for water blown foam can freeze into a solid mass, due to the water content. The good news, at least with some water blown foam, is you may be able to thaw out the material, mix it up and it can still be used – make sure to check with the manufacturer for their recommendations.

However, in general, it is important for your inlet resin temperatures to be in the 60 to 80F range for optimum performance. As the resin drops in temperature the viscosity increases exponentially, not linearly.

Several tests of a material with a documented viscosity of 700 to 1100 cps at 77F, have a viscosity of about 2000 cps at 62F and a viscosity of 7800 cps at 47F. For reference this would be like changing from thick motor oil (~1000cps) to honey (2000 to 3000 cps) to molasses, as the temperature of the material drops.

This increased material thickness makes it more difficult to pump and move the material through the proportioning system.

To keep your material warm, drum blankets work great, and band heaters can work if placed at the very bottom of the drum and they are thermostatically controlled, but the best solutions are climate-controlled storage and a climate-controlled rig. Also, something to remember when using a band heater is if the heater goes wild and overheats it can blister the drum liner and this debris can break off into the resin, showing up in the screen filters or getting caught somewhere in the spray hose.

Solution: Keep your chemical warm during cold weather. Hopefully by now you are noticing the theme – protect your stuff and keep it warm during cold weather.

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