Patent Application
20150144541
This invention relates to for water filters used in drip irrigation systems.
Water filters are commonly used in drip irrigation systems to filter water from wells, tanks, open reservoirs, recycled water, canals, rivers and lakes that may have suspended impurities such as silt, algae, and other organic particles. These water filters predominantly use sand as the medium to filter out these impurities. As water passes through the sand, the suspended impurities are retained above the sand in the filter unit, so that the water percolates through the sand as filtered water free from the impurities. This filtering process is essential to prevent clogging of drip pipes or conduits for drip irrigation systems.
The sand retains the impurities on top of the bed in the water filter, but it eventually may start clogging and thereby reduce the flow of water through the sand. This may be detected by measuring the water pressure differential between the inlet and outlet of the water filter. Once the pressure differential increases beyond a threshold, maintenance on the filter may be needed. The maintenance may include back-flushing the filter to remove the impurities settled on top of the sand bed. During back-flushing, the direction of water flow through the filter is reversed so that the water passes from the bottom of the sand bed and percolates in the upward direction to suspend the impurities settled on top of the bed. The suspended impurities then may be flushed out of the filter through the top inlet manifold of the filter, hence removing the impurities out of the filter.
However, during back flushing some of the sand in the filter may also get suspended and flushed out of the filter. The sand level may decrease below the level that is required for effective filtering operation. Without adequate sand, the filter may not effectively remove impurities which may block irrigation pipes.
In the past, the lid or cover of a water filter must be opened to check the sand level on a daily basis. This may be difficult due to high water pressure during operation, which also may persist during a non-operational state. The remaining water in the tank may need to be drained to release the pressure within the tank. Additionally, repeated opening of the tank may lead to damage to a seal between the tank and lid or cover. A water filter sand level sensor is needed to check the sand level without opening the filter. A water filter sand level sensor is needed that will notify the operator before the sand level becomes too low to effectively filter out impurities.
A water filter sand level sensor is positioned inside a water filter and detects if a sand level in the water filter is above or below a critical level. The sand level sensor is connected to an indicator light or warning alarm outside the water filter that provides a visual or audible signal regarding the sand level in the water filter. The sand level sensor may be a light dependent resistor detecting light from a light emitting diode and having a resistance that decreases with increasing incident light intensity. The sand level sensor also may be an ultrasonic transducer transmitting ultrasonic energy bursts vertically down through the water filter to the sand level and determining a time difference between a transmitted and a reflected signal.
The water filter sand level sensor does not require opening the water filter to check the sand level. The water filter sand level sensor will notify the operator before the sand level becomes too low to effectively filter out impurities.
In the first embodiment, sand level sensor 102 may include photoresistor or light dependent resistor (LDR) 110 and general purpose light emitting diode (LED) 112. The photoresistor or LDR may detect light from the LED, and has resistance that decreases with increasing incident light intensity. The resistance of the photoresistor or LDR may be used to turn on or off the indicator light.
In the first embodiment, both the photoresistor or LDR and the LED may be enclosed in transparent housing 114 which may be a clear glass or plastic tube or pipe. The photoresistor or LDR and LED preferably may be mounted less than about 1 mm apart from each other. The transparent housing may be vertically aligned so the photoresistor or LDR and the LED are fixed at a critical position of sand inside the water filter, and the transparent housing above and below the photoresistor or LDR and the LED may be provided with sealant 116.
In the first and second embodiments, unfiltered water may enter water filter 100 through inlet pipe 122 and may exit through outlet pipe 124. The sand 118 or other filtering media may retain impurities on top of the sand bed in the filter. This may be detected by measuring the water pressure differential between the inlet and outlet. Once the pressure differential is above a threshold, the filter may be back-flushed to remove impurities settled on top of the sand bed. To back-flush, the direction of water flow may be reversed so that water enters the filter through outlet pipe 124 near the bottom of the sand bed, and suspended impurities may be flushed out through inlet 122 near the top of the filter.
In the first and second embodiments, the sand level sensor may be electrically connected to a circuit having an indicator light 104 and/or warning alarm 106 located outside the water filter. The circuit also may include electrical power source 128 outside the water filter. The electrical power source may include a plurality of cells in series, such as four 1.5V lithium iodide button cells in series. The circuit also may include actuation switch 142 outside the water filter that an operator may use to turn on and off the sand level sensor to minimize power consumption. Electrical connections from the sand level sensor may include wires 130 extending upwardly inside the transparent housing of the first embodiment and through the lid or cover 126 sealing the top of the water filter.
Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.
