The case for foam process monitoring

A member of one of the largest foam manufacturers commented to me when we were discussing industry developments that he believes the biggest threat to the industry (and consumers) is the fact that installers can process foam off ratio (meaning that the two chemicals involved are not mixed in the proper proportion).

I would expand that general processing problem to include processing foam at the wrong temperatures, which often creates off-ratio material. While these problem projects rarely occur, my recommendation to the industry is mandating the use of monitoring equipment that would eliminate this equipment-based solution to the problem. I used this type of equipment in my business for twenty years, and it allowed me to work on high-need, high-profile projects like the Guggenheim Museum.

This type of QA monitoring equipment has been in use for many years by OEM foam molding companies throughout the industry. The equipment is easily adaptable to on-site spray foam processing equipment, which is very simple compared to automatic high production RIM molding equipment. The difference between factory processing and site processing is the lack of environmental control. In a factory, they can control material, ambient, and mold fixture temperatures within very narrow tolerances. Mix and ratio are closely controlled and monitored in repetitive operations, while on-site processing is seasonal and on a wide range of substrates.

Standard OEM QA Equipment

Temperature sensors and controllers are inexpensive, easy to implement, and reliable, even at the remote gun location. Flow meters are more expensive, but more than pay for themselves by avoiding off-ratio events. Shut-off switches and/or valves are also inexpensive, easy to implement, and reliable. Eighty percent of the real (not perceived) foam problems I see are caused by processing equipment related issues.

Restrictions in the hoses (upstream and down), improper daily machine setup, improper temperatures, and empty supply-side reservoirs cause most of the site processing problems. Basic temperature and flow ratio monitors would detect out-of-spec processing parameters and immediately shut down the processing equipment, thus preventing poor quality material from being installed.

Difficulties can still arise if the operator over-rides the lock-out functions built into these systems. However, most processing problems could be avoided by requiring reports generated by the monitors themselves as proof of quality. Web-based systems would eliminate inaccurate reporting, sending data directly to owners, auditors, architects, or commissioning agents. These reports would document out-of-spec. operations, allowing the specifier or consumer to identify improper processing quickly. This would discourage installers from over-riding the QA controls, and encourage proper maintenance. State-of-the-art monitoring systems have the computing power, data logging capabilities, and output interfaces necessary to generate reports for all of the processing parameters on a full-time basis.

Requiring this type of QA documentation will also serve to pre-qualify foam installers. A major qualifier to use when choosing an installer is whether he possesses the equipment capability of monitoring processing parameters. Those installers who do understand proper processing, or do not have the proper engineering control equipment, will not be able to meet the bid requirements.

The following information about process monitoring shows what it looks like, and provides an idea of what an installer needs to assure he is meeting the manufacturer’s requirements set forth in the SPFA Equipment Guidelines. Ideal process monitoring equipment would operate as indicated in this diagram:

What a temperature and ratio monitor looks like installed in a rig:

Pieces – parts
These are the two main components of a temperature and ratio monitoring system.

Miscellaneous accessories needed for a complete monitoring system include the following:

1. Thermistors and wire to locate at the gun, in the hoses, and right after the primary heaters.

2. In line air valve to shut off pump if electrical lock-out is not easily available

3. Electrical outlet with surge/overload protector at monitor plug in

4. Remote alarm or warning light if used in addition to built-in alarm

More up-to-date monitoring system would be web based, operating like home security systems with remote monitoring and reporting capabilities. Eliminating hard wired solutions, reduces the likelihood of equipment problems due to the harsh conditions at many job sites, and protects against lost data or out-of-spec. operation. The human interface of one of these wifi-based systems looks like this.

The incentive for the industry to use monitoring, in conjunction with other quality control methods, is to avoid problem foam installations. In the absence of ANSI standards, it is up to the industry to mandate this type of quality control equipment. Architects can specify this as a quality control method, and foam manufacturers, who are losing market share due to poor quality installations, should mandate that monitors be used by everyone who buys their material. This would have to be a universal mandate. If only one or two manufacturers require the use of monitors it would effectively raise the price of their products in what is already a very competitive marketplace.