The deposition efficiency is typically low for alloy powders, and the window of process parameters and suitable powder sizes is narrow. To accelerate powders to higher velocity, finer powders (<20 micrometers) are used. It is possible to accelerate powder particles to much higher velocity using a processing gas having high speed of sound (helium instead of nitrogen). However, helium is costly and its flow rate, and thus consumption, is higher. To improve acceleration capability, nitrogen gas is heated up to about 900 °C. As a result, deposition efficiency and tensile strength of deposits increase. Spray Coating
Since our founding in 1973, Dal-Bac Manufacturing Co., Inc. has grown and expanded to become one of the premier providers of coating services to customers in a diverse range of industries. We are capable of applying both solvent and water-borne coatings to a wide variety of substrates, including fabrics, films, foams, and papers. Our capabilities include both knife-over-roll and Meyer rod coating methods for roll goods up to 61” in width. With our custom built equipment, we process materials accurately and cost-effectively. Coating Services
During the 1980s, a class of thermal spray processes called high velocity oxy-fuel spraying was developed. A mixture of gaseous or liquid fuel and oxygen is fed into a combustion chamber, where they are ignited and combusted continuously. The resultant hot gas at a pressure close to 1 MPa emanates through a converging–diverging nozzle and travels through a straight section. The fuels can be gases (hydrogen, methane, propane, propylene, acetylene, natural gas, etc.) or liquids (kerosene, etc.). The jet velocity at the exit of the barrel (>1000 m/s) exceeds the speed of sound. A powder feed stock is injected into the gas stream, which accelerates the powder up to 800 m/s. The stream of hot gas and powder is directed towards the surface to be coated. The powder partially melts in the stream, and deposits upon the substrate. The resulting coating has low porosity and high bond strength.
As stated earlier, ignition barriers are a less stringent form of fire prevention compared to thermal barriers. If you are using the spray foamfor an attic or crawl space, then an ignition barrier can be used instead of a thermal barrier if the space meets certain conditions. If the crawl space or attic has no floors, is not used for storage, has no easy access, and is only accessed in order to make repairs and conduct maintenance, then an ignition barrier can be used.
Spray foam insulation is a great product. Homes insulated with it can be some of the most efficient and comfortable homes built. I've been in plenty of these homes and can tell you that when spray foam is installed properly, they outperform 99% of fiberglass batt-insulated, stick-built homes. (I can also tell you that 73% of all statistics are made up on the spot, so please don't ask for documentation of that statistic.)
There have been a few mentions of intumescent coatingsabove, and it would be helpful to elaborate on them. Intumescent coating is a type of paint that will bubble when it is exposed to heat or flames. The bubbles act as a barrier that is relatively flame resistant. The bubbled coating delays the ignition of the spray foaminsulation. Because of this, intumescent coatings have become more common in building and construction. Insulation Spray Coating
FIRESHELL® (F10E) is a proprietary non-flammable, intumescing (expands up to 2000%) interior coating that provides oxygen starvation to fire. It is a non-toxic, water based, drain safe, no fuming GREEN product. FIRESHELL® passes full scale room corner over foam, NFPA 286 and E84 class A certified. Meets requirements for 15 minute thermal barrier. It is a water-based one part coating system that comes white but can be tinted different colors. This coating can be top-coated with either latex or oil based coating. Insulation Spray Coating
In the case you have above the installer wasn't reading his foam. They must be trained to do that as they spray. Temps and conditions are constantly changing thru out the day. Either he wasn't properly trained or if he was,he wasn't doing his job! This is a serious problem with people jumping in to the foam business. A lot of homeowners and builders are looking the best price and end up with someone who doesn't know what they are doing. Hope this info helps. Foam insulation is a great product. It just has to be done right by someone who knows what they are doing.
I am building a house in Central Texas (Caldwell). Several builders are cautious about using foam insulation and/or a closed attic. I would like to use both. Here in Texas, heat and humidity (except for the past few years of drought) are a continuing problem. Which type of foam would be the best to use in our home, where should the vapor barrier be or should be use one at all, if we are using fans in the exterior walls to supply fresh air to the house, do we need a vented attic or will it cause more problems than it solve? I have printed out your article and the blogs to give to my contractors and architect, but I would really appreciate your comments on the products being used in my part of the US.
Health monitoring: In order to avoid development of illnesses associated with exposure to isocyanates, health authorities recommend that people who use spray paint products that contain the substance provide a urine sample after a work shift at least once a year, with high frequencies in first few months on the job. A urine sample with ascertain levels of exposure, not the presence of disease associated with harmful chemicals. Spray Coating Services
The problem was that the installer was doing his first spray foam job ever, and the thickness of the insulation varied from zero (visible roof deck) to about 9". Unfortunately, good average thickness doesn't cut it. The coverage needs to be uniform because a lot of heat will go through the under-insulated areas. (See my article on flat or lumpy insulation performance.)
I employed a company to insulate my three story house in 2011. They started Insulating it in August of 2011...They said it would be a 3-4 day job. They installed it in 0.5"-8" lifts all in the same cavity, this left burned insulation and voids. They removed what they told me was the bad insulation and in the process cut many electrical wires. They fixed this. They then reinstalled too thick again in some spots and removed again. They then installed it for a 3rd time. The areas that I thought were good are now separating from the structural members leaving voids. As of October 2012, 1 year and 2 months of dealing with the contractor I told them I want proof that what has been installed carries a warranty or I want my money back and I will fix the problems myself. They have yet to provide me with this warranty. I have spent many hours in the house looking at what is bad and they need to fix. I am frustrated, 14 months of additional rent due to their negligence. I would like to know how I can get proof that the product carries the manufacturers lifetime warranty, or has it been installed improperly throughout the entire house. Desperately awaiting your response. Spray Coating Services
OK, Peter, I finally went back and read Alex Wilson's article on what he perceives as a serious problem. I haven't seen the full report, but based on the summary he wrote on the Green Building Advisor website, I question the science. It seems to me that he's chosen the wrong metric and he's basing his conclusion on too many assumptions because he doesn't have enough data. You can see my comments at the end of his article. Coating Services
While building codes may not require it or enforce it, spray foam should have some form of fire protection. Unprotected spray foam insulation can be a fire hazard. If spray foam is exposed to fire, it can result in a flash fire. Because of this, steps should be taken to protect against fires. Builders who do not use ignition barriers are taking on liability should a house they worked on ever burn down.
The process typically operates at 39–120 °C to avoid thermal damage. It can induce non-thermally activated surface reactions, causing surface changes which cannot occur with molecular chemistries at atmospheric pressure. Plasma processing is done in a controlled environment inside a sealed chamber at a medium vacuum, around 13–65 Pa. The gas or mixture of gases is energized by an electrical field from DC to microwave frequencies, typically 1–500 W at 50 V. The treated components are usually electrically isolated. The volatile plasma by-products are evacuated from the chamber by the vacuum pump, and if necessary can be neutralized in an exhaust scrubber. Spray Coating