April 25, 2007

Part “A” Isocyanate and part “B” RES Polyol are moisture sensitive materials. Care should be taken to protect them from the even smallest amount of humidity, moisture in the air.

Isocyanate is one part of a plural component chemical that is often used as a catalyst. Isocyanate is sensitive to moisture, even the smallest amount in the air. Humidity will react with Isocyanate and create a hard film over the top of the material in the drum. This hard film can and will cause a variety of fluid handling and spray equipment problems. To prevent this hard film from developing, most chemical suppliers put a blanket of an inert gas (nitrogen) over the material at the time the drums are filled. This displaces the moist air in the drum and isolates the Isocyanate from humidity.

Polyol is the other part of a plural component chemical that is also sensitive to moisture, even the smallest amount humidity. Polyol is hydroscopic and will adsorb water from the air. This will react with the Isocyanate when mixed and will create CO2 gas which creates the small pin holes that you see in a cross section of cured material.

To prevent these problems from developing after you start spraying, there are three different types of systems to choose from:

1st: A Disposable Desiccant Cartridge has a manifold that dries displacement air entering the drums when you are spraying. It prevents condensation of water vapor and resulting contamination. The cartridge’s indicator window turns from blue to pink when the desiccant is exhausted. This type of cartridge provides an economical and versatile means for preventing moisture problems.

2nd: An Air Dryer Kit purges the air of moisture, oil and other contaminants. Individual regulators can be set at 5 lb. maximum pressure to provide container control. Quick disconnects and individual shut-off valves speed drum change-over. The air dryer is easily recharged or serviced for a long life. Note: This is a closed loop pressurized type of system and will keep 3-5 PSI of dry air in your “A” & “B” material drums.

3rd: A Nitrogen Regulator kit can be set at 3-5 pounds maximum pressure to provide control. This has a built-in relief valve to avoid excessive pressure buildup. It has a check valve which prevents blowing agents used in spray foam from backing up into the Isocyanate drum. This is a closed loop pressurized system and will keep 3-5 PSI of nitrogen in your A & B material drums.

To help keep material clean and dry, use one of these types of systems to vent drums or pressurize the drums when spraying.