This is a Water Aspirator Pump based on the Venturi principle. It is designed to create a moderate vacuum for chemistry laboratory applications, such as vacuum filtration (Buchner funnels), rotary evaporation, or pulling gases through a distillation setup. By running water through the internal nozzle at high velocity, it creates a low-pressure zone that pulls air or gas from the side-arm suction port.

Technical Specifications

• Operating Principle: Venturi Effect / Bernoulli’s Principle.

• Driving Nozzle:  3.0 mm orifice (optimized for standard house/lab water pressure).

• Water Inlet: Standard Male thread faucet connection (3/8") 

• Suction Port: 7-10 mm OD (serrated for standard vacuum tubing).

• Estimated Vacuum: Can reach approximately 20 - 30 mmHg (dependent on water temperature and flow rate).

Print Settings & Recommendations

To ensure the pump is watertight and maintains a high-velocity jet, follow these print guidelines:

• Material: * PETG or ASA/ABS: Recommended for better chemical resistance and durability.

  • Polypropylene (PP): Best for professional lab use (highest chemical resistance).

  • PLA: Use only for prototyping or water-only applications; it will degrade with chemical exposure and heat.

• Layer Height: 0.20 or smaller. Fine resolution is critical for smooth internal walls to reduce turbulence.

• Perimeters: 4 - 6 walls. This ensures the part is "air-tight" and can handle the water pressure without leaking through layer lines.

• Infill: 100% (solid). This prevents water from entering the internal cavities of the print and harboring mold or chemicals.

• Orientation: Print vertically (Water inlet facing down) to ensure the internal nozzle and throat remain perfectly circular without the need for internal supports.

• Supports: Add supports for the vacuum port and the section above the thread. 

• Lightly sand the vacuum connector after removing the supports.

How to Use & Safety

1. Assembly: Connect the top inlet to a high-pressure water source (faucet). Connect the side port to your vacuum flask using thick-walled vacuum tubing. A layer of vacuum grease over the inlet might reduce leaks.

2. The Vacuum Trap: Highly Recommended. Always use a vacuum trap (an empty overflow flask) between your distillation setup and this pump. If the water pressure drops suddenly, water can "suck back" into your experiment.

3. Chemical Handling: Because this pump mixes the sucked gases directly into the water stream, it acts as a scrubber. Ensure the discharge water is disposed of according to your local lab safety protocols if you are pulling acidic or toxic vapors.

Fusion 360 Model

The original Fusion 360 (.f3d) source file is included to allow for full customization. The model is designed parametrically, allowing you to adapt the geometry to your specific water pressure and laboratory requirements.

Below is a guide on how changing specific dimensions will affect the performance of your vacuum pump:

• Nozzle Diameter: 

  • Decrease (e.g., to 1.5 mm): Use this if your lab has low water pressure. A smaller nozzle increases the velocity of the water jet, which is necessary to "kickstart" the vacuum.

  • Increase (e.g., to 2.5 mm): Use this if you have high water pressure and need a higher pumping speed (evacuating a large flask quickly).

• Throat (Throttle) Diameter: This is the narrow section immediately following the nozzle. It should generally be 1.2 to 1.5 times the diameter of the nozzle.

  • Too wide: The water jet won't "fill" the throat, and air will leak back in, ruining the vacuum.

  • Too narrow: It will create back-pressure, causing water to spit out of your suction port.

• Diffuser (Outlet) Size & Angle: The long, tapering section at the bottom is the diffuser. A longer, shallower taper (roughly 5 to 7 degrees allows for better "pressure recovery."

  • Effect: A well-designed diffuser makes the pump significantly quieter and more efficient at maintaining a deep vacuum against atmospheric pressure.

• Hose Adapters: You can easily modify the inlet and suction port diameters to match your specific laboratory hosing or add threaded NPT/G-style fittings for a permanent faucet attachment. The NPT thread (7736N103) component was imported from McMaster-Carr.