DIY Laboratory Vacuum Filter : 4 Steps

A vacuum filter is a piece of laboratory equipment used to separate a solid precipitate from a solution. I have built one from objects found in my home and simple parts from eBay. The total cost of this vacuum filter including the filtration papers was £10.70 whereas a laboratory vacuum filter would range from hundreds to thousands of pounds.

Some of these parts are interchangeable with different things you can find around your home.

Supplies

Materials

1. Base container- 70cl whiskey bottle

2. Funnel top – I cut the top off a screw cap wine bottle *KEEP THE LID*

3. 6mm dia. vinyl tubing

4. 60ml syringe https://www.ebay.co.uk/itm/2-x-50ML-DISPOSABLE-SYR...

5. 2x one way valve 5mm https://www.ebay.co.uk/itm/Non-Return-Valve-Fuel-N...

6. Lab general purpose filtration papers https://www.ebay.co.uk/itm/90mm-Filter-paper-9cm-G...

7 Circular screen the same diameter as the wine bottle – I cut a piece of plastic from an old takeaway container and drilled holes to create a screen

8 Glue

9 6mm glass drill bit

10 Hand drill

Step 1: Creating the Funnel

1. Using large drill bit, drill a hole in the top of the wine lid leaving about a 4mm wide edge. Glue the lid to the top of the whiskey bottle with the opening facing up to allow the ½ wine bottle to be screwed on top. Ensure the lid is attached with a tight seal, no gaps between the lid and the bottom bottle.

2. Using a glass drill bit the same size as the vinyl tube, drill a clean hole in the whiskey bottle close to the edge of where the bottle starts to narrow into the neck. Make sure there is a constant flow of water on the drill bit as you drill through the glass.

3. Glue the screen inside the wine bottle funnel so stays in place during use. It should sit as far down as possible, where the bottle begins to narrow into the neck. The filter paper will sit on top of this.

4. Screw the funnel onto the cap on the base container.

Step 2: Creating the Vacuum

5. cut one piece of vinyl tube about 40mm and one about 10mm

6. in the 40mm piece cut a hole in the side 6mm in diameter, glue the 10mm piece of tube over the opening, make sure you create an airtight seal

7. insert a one way valve into the end of the 10mm tube ensuring the air flow is directed out of the tube. There will be arrows embossed on the valves to show the air flow direction. This arrow should point away from the tube.

8. in the 40mm tube, insert the nozzle of the syringe into one end and the 2nd one way valve into the opposite end. The arrow on the one way valve should point into the tube towards the syringe. (see images)

9. Attach a longer piece of tubing (around 250mm) to the open end of the valve

When you pull the end of the syringe out you should feel/hear a sucking from the open end of the long tube piece and nothing from the open end of the 1st valve. When you push the syringe end back in, you should feel/hear the air flow out the open end of the 1st valve and nothing out tube.

Step 3: Attach Both Together

10. The final assembly step is to glue the open end of the long tube into the hole you drilled in the base container. Make sure you have an airtight seal.

Now you are ready to filter! When you add the filter paper to the funnel, wet the paper first and make sure the edges are sealed to the sides of the funnel to create the vacuum. Once you have filtered the solution, the filter paper will hold the solid particulates and you can unscrew the funnel and pour the liquid out of the base container.