Tag Archives: filtering oil

Homemade vacuum pump oil filter

Homemade vacuum pump oil filter

It is once again time to change the filter material in our homemade vacuum pump oil filter for our Harvest Right home freeze dryer. The oil filtering system is a simple one comprised of a Brita water filter. Their filter is removed from the pitcher and a new one is made by rolling up a large potion of a roll of toilet paper. That plug of toilet paper is made to be a little large in diameter than the hole where the Brita filter is intended to go.

Remove the old filter material

The old toilet paper filter will need to be removed and the pitcher cleaned. The old filter is going to be full of oil and food particles from the food that has been run through the freeze dryer. Gloves such as nitrile or Food handlers glove for handling the the old filter and cleaning up the pitcher are a good idea. You can grab the filter from the top and pull it out of the pitcher, or remove the part that holds the filter so you can push it out from the bottom.

A finger will work for most people to push the filter out from the bottom. For those with large diameter fingers an improvised tool such a pencil or screw driver will push the old used toilet paper filter from the pitcher housing. Having a rag or paper towel on hand to wipe the oil from your tool would be a good idea.

Clean out the Brita pitcher

After the old toilet paper filter is removed there will be a lot of gunk that is comprised of food particles that needs to be cleaned. We use paper towels for this task.  Here is what the inside of our homemade filter looks like before cleaning.

Homemade vacuum pump oil filter
This toilet paper filter needs replaced and the container cleaned

To prevent the mess from getting into the pitcher one should consider cleaning the mess out as much as possible before removing the filter material.  After we have wiped out the mess it is simple to push the toilet paper filter out from the bottom.  Here is what our filter looks like at the time we replaced it.  It is gross, but you can see all the food particles that this removes from the oil.

Homemade vacuum pump oil filter
Homemade vacuum pump oil filter after replacing filter material

Replace the filter material

Once the pitcher clean and the old toilet paper filter material is removed it is time to add the new filter. To replace the dirty filter material you see above just take a roll of your toilet paper and start rolling it.

You will want to make the diameter of the filter slightly larger than the hole in the pitcher.  When the toilet paper filter is pushed into the pitcher it should fit snugly but not require a lot of force to get into place.  If the filter fits loosely the oil will flow past it and not get filtered.  If it is too tight the oil may not pass through the  roll.

Here is our homemade vacuum pump oil filter cleaned, a new toilet paper filter is in place.

New toilet paper filter installed
Homemade vacuum pump oil filter

Which Brita pitcher to use

I prefer the larger pitcher that can handle a couple quarts of oil at a time.  We bought the 10 cup Brita filter and are very happy with it.  These are often available used at 2nd hand stores for a few dollars.  You can expect to spend 20 to 30 dollars if you buy one new

Why filter vacuum pump oil 

Why filter vacuum pump oil

In another blog post I discuss the process of filtering vacuum pump oil. But why filter vacuum pump oil?  Cleaning and removing water from your oil allows you to reuse the expensive vacuum pump oil several times.  Refilling the vacuum pump with clean oil that is free of water helps ensure the pump has a long life.  Continually operating the vacuum pump with dirty oil that contains moisture will lead to early pump failure.

In the picture below you will see vacuum pump oil in a quart jar.  This oil ran one complete freeze dry cycle before being drained into the jar,  It sat for around 24 hours to allow the water to collect at the bottom.  The cloudy mess in that jar is food particles from the food.  It is drawn out of the freeze dryer as the vacuum pump pulls a vacuum on the chamber and makes it into the oil.  You will be able to see what the oil should look like below after I discuss removing the water from the oil.

Why filter vacuum pump oil 
Why filter vacuum pump oil

Remove the water from the oil

To remove the water from the used vacuum pump oil we start by draining the used oil into a quart mason jar.  Secure a lid and ring on the jar and place it into the freezer and allow the water to freeze solid.

You can see the water under the oil in our mason jar in this picture.  This was a significant amount of water and is not typical.  This was a result of a long freeze dry cycle with a full load of very high moisture content food.

Why filter vacuum pump oil 
remove water from used vacuum pump oil

Once the water is frozen solid pour off the oil into your filter and allow the very viscous oil to drain into the toilet paper filter.  (You can see my Brita TP filter in the picture at the bottom of this page.)

After the majority of the oil is out of the mason jar and before the water begins to melt, I transfer the jar to the filter that came with the Freeze Dryer unit.  There the remainder of the oil drains from the jar along with the water as it melts.  Once there is a fair amount of oil in the Harvest Right filter it too will go into the freezer to remove the water.

Here is what it looks like after filtering

This is the exact same oil as shown in the first picture after it went through our toilet paper filtering system.  The difference is remarkable. One can see how much particulate matter was in that oil before filtering.  Clean and filtered vacuum pump oil generally should look like this amber color.  Some vacuum pump oil will be a different color, but this is what our Black Gold oil looks like.

Why filter vacuum pump oil 
Clean vacuum pump oil after filtering

So why filter vacuum pump oil?  doing so will reduce operating cost and help reduce expensive repairs to the vacuum pump.