Abstract: A positive displacement flushable flow meter has sensing elements that are rotated by and at a rate in accordance with a flow of fluid through the flow meter. The flow meter is particularly adapted for measuring the volume flow rate of coating material supplied to spray coating apparatus, and to permit the flow meter to be quickly flushed by means of alternate bursts of relatively high velocity air and solvent, without overdriving the sensing elements and damaging the flow meter, a bypass valve is provided. During a spray coating operation, the bypass valve is closed and all of the coating material flows past and rotates the sensing elements. During a flushing operation, the bypass valve is opened to divert some of the relatively high velocity flow of air and solvent around the sensing elements, while allowing a controlled and limited amount of air and solvent to move past and rotate the elements to clean them without causing them to be overdriven.

Abstract: To measure the flow rate of a fluid in a pipe, a heat pulse is injected into the fluid by a heat pulse generator, and the time of flight of the pulse between the generator and a sensor is measured. Arrival of the pulse at the sensor is determined by detecting a selected temperature level of the ascending flank of the pulse, and a predetermined temperature level of the descending flank is then detected to initiate generation of the next subsequent pulse. Since the temperature of the descending flank generally represents the temperature of the fluid between the heat pulse generator and sensor, the technique ensures that the accuracy of each successive flow rate measurement is not affected by residual heat from the preceding measurement, and yet enables measurements to be obtained at maximum frequencies. In one embodiment the measurements are used to control the flow rate of the measured fluid, and in another the flow rate of fluid in one or more additional pipes.

Abstract: Flushable rotary gear pumps for delivering fluidic material, such as liquid coating material, may quickly and thoroughly be flushed of material of one type in preparation for delivering material of another type. In one embodiment, a valve selectively establishes a bypass channel between an inlet to and an outlet from a pump, thereby to accommodate a relatively large volume flow of flushing media through the pump and supply and delivery lines therefor. In another embodiment, the valve is structured to monitor fluid pressure developed by the pump and to automatically control and limit the pressure to a maximum value should an overpressure condition develop. In yet other embodiments passages are provided internally of the pump for conveying flushing media to all exposed surfaces of the gears, gear shafts and pump body to flush the same of coating material, whereby the entirety of the pump may readily be cleansed. If desired, the various features may be combined in a single pump.

Abstract: A color change system for spray coating apparatus is characterized by two pumps, each of which is connectable with a selected color of coating material for providing the same to spray coating apparatus. The arrangement is such that the pumps alternately supply different colors of coating material to the coating apparatus, and when one of the pumps is supplying material the other is being cleansed of previously supplied material. In this manner, one pump is always clean and ready for supplying a newly selected color of material, so that any number of different colors of coating material may be provided to the coating apparatus with minimum numbers of pumps, e.g., two pumps. In one embodiment the color change system is used with automatic spray coating apparatus, and in another with manual or hand held coating apparatus.

Abstract: A color change system for spray coating apparatus is characterized by two pumps, each of which is connectable with a selected color of coating material for providing the same to spray coating apparatus. The arrangement is such that the pumps alternately supply different colors of coating material to the coating apparatus, and when one of the pumps is supplying material the other is being cleansed of previously supplied material. In this manner, one pump is always clean and ready for supplying a newly selected color of material, so that any number of different colors of coating material may be provided to the coating apparatus with minimum numbers of pumps, e.g., two pumps. In one embodiment the color change system is used with automatic spray coating apparatus, and in another with manual or hand held coating apparatus.