Fluid sprinkling – spraying – and diffusing – Processes
Reexamination Certificate
2000-02-03
2001-09-11
Scherbel, David A. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Processes
C239S067000, C239S070000, C239S099000, C239S200000, C239S203000, C239S204000, C239S207000, C239SDIG001, C137S624200
Reexamination Certificate
active
06286765
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to turf landscape irrigation systems and, more particularly, to underground, automatically timed irrigation systems which utilize pop-up fixed spray heads to distribute water.
Installed sprinkler irrigation systems generally fall into two broad categories, spray head sprinklers and rotary sprinklers. Spray head sprinklers, once turned on with water flowing through a piping system, pop-up to a height (2-6 inches typically) and become fixed, spraying out water in a pattern of a full circle, half circle, quarter circle or any required arc segment of a full circle with a range radius of 0 to 17 feet. Rotary sprinklers, on the other hand, once turned on with water flowing through a piping system, pop-up to a height (2-6 inches typically) and throw a relatively thin stream out to a determined radius (typically 20 to 50 feet) while rotating through a circle or partial circle to be irrigated. The rotation of a rotary head is typically accomplished by utilizing the energy of the pressurized water stream moving through the rotary head and out the nozzle in the stream. The water moves a series of vanes which drive a gear train to produce the desired rotational motion. Variations of rotary sprinkler heads exist with different mechanisms to extract the energy of the flowing stream to cause rotation, i.e. a ball striking a plate within a swirling stream, a spring-loaded arm entering a high energy stream, etc.
Rotary sprinklers are found to have certain advantages over pop-up spray head sprinklers. First, they have a lighter precipitation rate, or rate of water application, which is better suited to the intake rate of most soils and turf combinations. This lighter precipitation rate means less water running off of the turf and smaller pipes per equivalent irrigated area. The lighter precipitation rate also is less taxing to municipal water systems, which must design water treatment and pumping facilities to handle the maximum load of irrigation systems which are turned on, almost simultaneously, in the summer months. The second observed advantage or rotary irrigation systems is more uniform water distribution to the irrigated turf area.
One test which is conducted to determine the uniformity of an irrigation sprinkler head is termed a “catch can” test. In this test, a series of cans are spaced about the head while it is running, catching the water at the different locations about the head. Through measurement of the amount of water caught, the uniformity of the particular head can be determined.
One measure of this testing is termed the “scheduling coefficient” of the head, which is basically a multiplier times the required water application for the plant material to ensure that all areas serviced by the sprinkler head receive the required water. For instance, if a particular sprinkler head had a measured scheduling coefficient of 1.8, then 1.8 times the required water would have to be put out to ensure that all areas would receive the required amount. Obviously, at 1.8 times the required water, if some areas are just receiving the required amount, others are being greatly over watered. Using the scheduling coefficient as a uniformity measure, a coefficient of 1.0 would be a perfectly uniform sprinkler and any amount over 1.0 would represent the non-uniformity of the system. Most rotary heads have scheduling coefficience in the range of 1.2 to 1.5. The relatively efficient application of water of the rotary heads can be attributed to the fact that the single water stream is rotated through the arc slowly, and it is much easier to obtain an even fallout of a single stream as opposed to a fanned-out spray head pattern.
Pop-up spray heads have advantages over rotary heads and are predominantly utilized in residential and light commercial applications because of their small wetted radius (0 to 17 feet) which is easy to fit into small irregularly shaped lawns typical of these type of installations. The disadvantages that spray heads have against rotors are a higher precipitation rate (typically 1.2 to 1.5 inches per hour which is a much higher application of water than can be absorbed by the turf, leading to excessive runoff and waste of water) and a less uniform wetting pattern with a scheduling coefficient that typically ranges from 1.5 up to 3.0.
The primary reason for the non-uniformity of pop-up spray heads can be found in the spray pattern itself. A spray head must take a fixed flow of water and attempt to evenly distribute the water around the head in a certain arc and radius through a series of water droplets. All of the water starts from the same source within the head at the same pressure. In order to get the water droplets to distribute uniformly around the head, they must be of different mass and size. For a droplet to have enough kinetic energy to make it to the outer limits of the wetting pattern, it must have considerable mass. On the opposite end of the spectrum, for a droplet to fall close to the spray head, it must have kinetic energy and small mass. The problem is that small droplets with small kinetic energy and small mass that will drop out close to the head in perfect conditions will drift great distances with any minimal wind condition. Very rarely do perfect conditions exist when the spray head is operating and the effect of the head itself creates wind conditions. The non-uniformity and high precipitation rate have led to a widespread search for a more efficient means to irrigate turf areas associated with residential and light commercial areas.
Attempts to solve the problem with fixed pop-up sprinkler heads have included utilizing a secondary orifice to throw water close to the head. Larger droplets are “thrown” from the secondary nozzle to a close-in position via trajectory independent of kinetic energy of the droplets. This and other methods help improve the distribution uniformity but are expensive to implement. There exists no method to reduce the precipitation rate. No one method of improving the distribution uniformity and reducing the precipitation rate has been developed which is both effective and economical.
SUMMARY OF THE INVENTION
It is, therefore, a general object of the invention to overcome the above-described limitations and other problems associated with sprinkler pop-up spray head devices installed in an automatic irrigation system.
The method and apparatus of the invention is installed to provide a controlled, continuous up-and-down motion of the pop-up spray head device which approximates a modified sine wave output from the pop-up sprinkler device. In the first form of the invention, a control circuit cycles power to associated solenoid valves in an on/off repeating cycle, which can be selected to a range of on-and-off times. The valves, in response to the on/off signals from the control circuit, turns on and off. The flow of water through the valve to the pop-up spray head has little rise time at turn on and small drop-off at the turn off time. The flow within the line, therefore, turns on to full zone flow for the configuration of pop-up spray heads attached to the zone and then turns off to zero flow in a cycling pattern. When the valve is turned on at the initiation of the cycle, the pop-up sprinkler heads must extend through the full stroke of the spring-loaded piston length. During the upward stroke following energizing of the solenoid valve, the motion is slowed by the resistance of the retraction spring associated with the pop-up spray head and a pattern of water is sprayed out of the nozzle from 0 feet around the head to the fully developed spray pattern accomplished at full extension and pressure. The water that is sprayed during the upward stroke consists of large droplets which are distributed around the head, providing fill-in to the final, fully developed and extended pattern.
Following full extension and development of the full radius spray pattern, the control circuit turns the solenoid valves off, stopping the flow to the circuit of spray heads. As the solenoid valve closes the zone
Evans Robin O.
Nibco Inc.
Price Heneveld Cooper DeWitt & Litton
Scherbel David A.
LandOfFree
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