Patent Application
20090000546
This invention relates to dispensing systems and methods of dispensing materials, such as polyurethane foams.
Polyurethane foams have a wide variety of applications, but are particular useful in the construction industry for filling, sealing, insulating, and providing sound attenuation. For this reason, relatively large quantities of polyurethane foam must be transported to, and dispensed at, remote construction sites. Most of the foam is transported as components in disposable or single use, pressurized DOT-39 compliant tanks. DOT-39 (49 CFR ยง178.65) provides specifications for relatively light weight, nonrefillable containers. These are desirable for this application because the containers can be made less expensively than refillable containers, and typically weigh less than refillable containers, which makes them easier to transport and handle. At the job site the tanks of the separate components are connected to a dispenser, and dispensed. After the materials are dispensed, the spent tanks are simply discarded.
However dispensing foam from the DOT-39 compliant containers is complicated by the fact that dispensing rates can diminish by as much as 50% or more as the contents of the tanks are used. Furthermore foam properties can vary as well, for example the density of the dispensed foam can vary by as much as 20% or more as the contents of the tank are used. Another difficulty with DOT-39 containers is their disposal. These containers can often only be filled to a maximum of about 60% due to the container volume required for propellant, thus a relatively large number of containers must be used for a given project, and once the foam has been dispensed the tanks must be disposed of. Disposal is further complicated by the fact that most of these tanks employ a dip tube system for extracting the contents of the tank. Because of manufacturing tolerances, the construction of these tanks and dip tube systems varies such that undispensed material is almost always left in the container. This is wasteful and it complicates recycling or other disposal methods of the spent containers. It is estimated that as much as 5% of the material is these containers may remain undispensed.
This disclosure relates to improved systems and methods for dispensing materials such as polyurethane foams from DOT-39 compliant containers.
According to one aspect, embodiments of the present invention provide a DOT-39 compliant system for dispensing material under pressure. The system preferably comprises a tank compliant with DOT-39 having at least two valves, and a charge of material to be dispensed. A pressure system is connected to at least one of the tank's valves for pressurizing or maintaining pressure in the tank. A dispenser is connected to another of the tank's valves for dispensing the material from the tank.
According to another aspect, embodiments of the present invention provide a DOT-39 compliant system for dispensing material formed from at least two components under pressure. The system comprises at least two tanks, each of which is compliant with DOT-39 and having at least two valves, and a charge of one of the components of the material to be dispensed. A pressure system is connected to at least one of each of the tank's valves for pressurizing or maintaining pressure in the tanks. A dispenser is connected to at least one of each of the tank's valves for mixing the components from the tank, and dispensing the material.
In the preferred embodiments of the systems of this invention, the tanks have at an upper valve adjacent the top of the tank, and a lower valve adjacent the bottom of the tank. The upper valve can be used for connection to a pressure system, the lower valve can be used for connection to dispensing system.
In still another aspect, embodiments of this invention provide a method for the pressure dispensing of a material at a remote location. This method can include transporting the material to be dispensed to the remote location in a tank compliant with DOT-39 and having at least two valves. A source of pressure is connected to at least one of valves of the tank. A dispenser is connected to at least one of the valves of the tank. In still another aspect, embodiments of this invention provide a DOT-39 compliant tank of a polyurethane foam component in which the component fills at least 70% of the volume of the tank, and more preferably at least 90% of the volume of the tank. The tank preferably has at least two valves, and more preferably one of the valves is located in the upper portion of the tank, and one of the valves is located in the lower portion of the tank.
In still another aspect, embodiments of the invention provide a method of dispensing foam from DOT-39 compliant tanks at multiple locations. The DOT-39 compliant tanks are connected to a source of pressure to dispense foam at the first site. The DOT-39 compliant tanks are disconnected from the pressure source and transported to a second site. At the second site the DOT-39 complaint tanks are connected to a source of pressure to dispense foam at the second site.
The various embodiments of the present invention provides systems and methods for dispensing materials, and particularly polyurethane foam, from DOT-39. The various systems and methods reduce or eliminate some or all of the difficulties encountered with conventional DOT-39 compliant dispensing systems. The various systems and methods also reduce some of the difficulties encountered in disposing of spent DOT-39 containers, by reducing the number of such containers, and reducing the amounts of undispensed material left in the spent containers. These and other possible features and advantages will be in part apparent and in part pointed out hereinafter.
A conventional foam dispensing system employing conventional DOT-39 compliant tanks is indicated generally as 20 in
A preferred embodiment of a system for dispensing material in accordance with the principles of the present invention is indicated generally as 100 in
Because containers 102 and 104 each have at least two valves, each can be connected to a source of pressure without interfering with the ability to access the material in the container. Thus, as shown, each of the containers 102 and 104 is connected to a source of pressure, such as a regulated gas cylinder 122, via hoses 124 and 126 connected to valves 106 and 114, respectively. Of course some other source of pressure could be used, such a compressor. Furthermore, while the source of pressure is preferably at a constant pressure, this is not critical. In the preferred embodiment, where the source of pressure is a source of constant pressure, the containers 102 and 104 will be maintained at a relatively constant pressure, which improves dispensing time, and the consistency of the foam being dispensed.
The connection to an external source of pressure also means that the containers 102 and 104 are not dependent solely upon their internal pressure to dispense their contents. This means that for a given size container, more of the volume can be used for the material to be dispensed, and less of the volume is used for propellant. Furthermore, a more consistent pressurization results in a more consistent dispensing rate, which also means more consistent properties (such as density) of the dispensed foam.
A dispenser 128 can be connected to the containers 102 and 104 via hoses 130 and 132 connected to valves 108 and 116, respectively. The connection to the containers 102 and 104 from valves at the bottom means that the material can be more completely drained from the containers. This means that more of the material loaded into the containers is available for use, and that there will be less remnants in the container to impair recycling of the containers.
The system of the invention can be used to dispense foams of any density, from 0.5 pounds per cubic foot to about 6 pounds per cubic foot.
While the preferred embodiment of the system is particularly adapted for use in transporting and dispensing two part urethane foams, the invention is not so limited and can be used in delivering other multipart substances, such as epoxies, polyurea, polyester styrene and silicones, and even single part substances such as paints/coatings, adhesives and sealants.
| Number | Date | Country | |
|---|---|---|---|
| 60946713 | Jun 2007 | US |
