Patent Application
20250188956
A siphon moves liquid upward above the surface of a reservoir without using a pump. A bell siphon automatically starts and stops the siphoning action as the liquid level in the reservoir rises and falls. Bell siphons are used in a variety of fluid flow applications including wastewater discharge, restroom fixtures, and water flow in hydroponic and aquaponic systems.
Historically, the bell siphon has had two parts. The first is the upright, inner standpipe through which a liquid will drain out of the surrounding reservoir. The second part is the bell, which is typically a PVC pipe or a metal tube with a cap on the top, through which no liquid can escape. It also has one or more openings cut into the perimeter on the bottom so that liquid and air can flow through as it stands on the reservoir bed. When the liquid level reaches the height of the standpipe, the liquid and air flow into the standpipe creating a lower pressure inside of the bell. This causes liquid to be siphoned out of the reservoir and into the standpipe. The level drops until the liquid level reaches the level of the opening(s) at the bottom of the bell. At this point, air flows into the bell, breaking the siphon effect. The reservoir can now fill with liquid again.
Ideally, the bell siphon breaks its siphon effect every time the liquid level drops to the level of holes on the bottom. However, the air flowing into the bell may be carried by the moving liquid out the standpipe. If this occurs, the liquid level will remain at the low level in the reservoir and the siphon will never stop.
The bell siphon is a traditional way of automatically regulating liquid reservoir levels to keep a fill-drain cycle running repeatedly. For example, U.S. Pat. No. 649,170A, “Automatic Siphon,” discloses an early automatic siphon design that was used for the flushing of sewers; it consists of the traditional bell and standpipe. US20220356691A1, “Underground Stormwater Storage System,” discloses a similar use of a bell siphon in a stormwater storage system. US20130047508A1, “Aquaponics System” discloses a bell siphon for regulating water level in the plant bed of an aquaponics system.
However, there are disadvantages to this conventional bell siphon design in all these applications. First, if the liquid flow rate into the reservoir is too low then the bell siphon will fail to start the siphon effect. Second, if the flow of liquid is too high, the bell siphon will never stop. This range of flow rates where the siphon will both start and stop is limited.
Other attempts to provide reliable siphoning include U.S. Pat. No. 9,565,811B2, “External Cultivation liquid siphon,” which implemented a U-tube shaped bell siphon in an aquaponics system. Another common addition is a small straw, also referred to as a snorkel, that runs up the side of the bell siphon external to the bell and allows an alternate path for air to enter. A cup around the snorkel provides some additional benefits, as seen in “Construction of Automatic Bell Siphons for Backyard Aquaponic Systems” by Bradley K. Fox, Robert Howerton, and Clyde S. Tamaru, University of Hawai'i at Mānoa, Department of Molecular Biosciences and Bioengineering, 2010 (https://www.ctahr.hawaii.edu/oc/freepubs/pdf/BIO-10.pdf). However, a snorkel allows only a limited amount of air to enter. A small-diameter snorkel is also susceptible to clogging.
Our dual-bell siphon replaces the snorkel with a second outer bell that wraps around the entirety of the inner bell (360 degrees), providing better air intake and less chance of clogging, while also allowing a smaller overall diameter of the device. The optional surrounding cup further enhances the airflow to stop the siphon.
the stopping of the siphon. The snorkel tip is at the level of or higher than the highest opening in the bell.
The purpose of the optional cup 9 is to separate a select volume of water from the rest of the tank. As the water level drops below the lip of this cup, the water inside the cup separates from the entire liquid reservoir. This creates a set volume of water that once siphoned through the outer bell cannot be replaced by water from the reservoir. This means that the siphon will more reliably stop.
PVC plastic is the recommended material for the bells. Although any engineer or designer with proper resources could create a bell siphon in another plastic, such as CPVC or acrylic, or metal, we built the bells with Schedule 40 PVC. The spacer 7 and the cup 9 may be 3D-printed out of PLA, ABS, or other plastic.
