Siphon Selection
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The Siphon Selection page appears when your system uses a siphon instead of a pump to deliver effluent to the absorption area. Siphons use gravity and hydraulic pressure — no electricity required — making them suitable when the absorption area is significantly downhill from the dosing tank.
How Siphon Selection Works
The siphon list is displayed as a list organized by manufacturer. Each siphon model is evaluated against your system’s calculated hydraulic requirements:
- Enabled (selectable) — the siphon can deliver adequate flow with sufficient terminal head
- Disabled (grayed out with hint text) — the siphon does not meet requirements
Evaluation Criteria
A siphon must satisfy all of the following to be enabled:
- Terminal head — the calculated head at the end of the delivery run must be at least 3 ft plus the persona’s surplus head requirement
- Minimum discharge — the system’s flow rate must meet the siphon’s minimum discharge specification
- Flow rate range — the system’s flow rate must be within 80% to 120% of the siphon’s average discharge rating
If a siphon is disabled, the hint text explains why (e.g., “insufficient head”, “flow rate too low”, “flow rate too high”).
Siphon Types
There are two categories of siphons:
- Fixed drawdown siphons (e.g., Fluid Dynamics) — these have a set drawdown depth determined by the siphon design. The dosing tank must have sufficient cross-sectional area to accommodate this drawdown. A trap fitting (270-degree elbow) is required.
- Adjustable drawdown siphons (e.g., Flout) — these allow the drawdown to be adjusted within a range. The dosing tank must fit within the siphon’s adjustable drawdown range. An in-tank vent is required instead of a trap.
Tips
- Siphons are a good choice when the site has significant natural grade — they eliminate the need for electricity and pump maintenance.
- The dosing tank must have adequate cross-sectional area for the siphon’s drawdown. If no dosing tanks qualify on the Tank Selection page, the siphon may require a wider tank.
- Flout siphons offer installation flexibility with adjustable drawdown.