WVO Filter Design - My Filtering Setup
The internet is full of designs for WVO filtration. My design
is similar to many of these but it includes a few simple tweaks
which I believe make life easier.
The Barrel / Settling Tank
Starting with the barrel itself, where the WVO is allowed to settle,
my tank is airtight. Unless a barrel is stored in a location where
the
temperature
never varies,
condensation is going to occur (more about
that later). Pretty much this isn't a problem as this will sink
to the bottom of the
barrel,
but personally
I'd prefer discourage condensation as much as possible so I create
a vacuum within
my barrel - hence an airtight barrel is important to me.
My barrel was purchased from eBay.
I include the link in the hope that this guy is still selling these
barrels as they are excellent
value and top quality. They're actually recycled shipping containers,
so that adds to the green value of what we're doing.
Release Tap
My release tap is positioned approximated three-quarters
of the way down the barrel. This allows all the impurities to
settle below the level of the tap.
However, I decided to incorporate a float feed mechanism.
The float feed ensures that the oil is not taken from the top
of the tank but instead from approximately 1 inch below the surface.
A small section of pipe was consequently soldered on to the
tap to enable a hose to be attached between the float feed and
the
tap.
Thus all the oil that comes out from the tap is neither from the
surface or from the bottom of the tank.
Float Feed
I took a copper "T" fitting and drilled an 8mm hole
in the top. Through this I inserted an M8 bolt and secured this
in place with a nut. I then added a small length of 15mm copper
piping to the T and soldered everything together, including the
bolt.
The M8 bolt was the perfect size for a standard ball float (which
I bought at Wickes for approx £1), so this simply screwed
on the the bolt's thread giving it a secure fixing.
I connected a length of garden hose to the end of the float feed
with a hose clip and connected the other end of the hose to the
tap. This means that oil is removed from the settling tank from
approximately
1 inch below the surface level which is, theoretically at least,
where the cleanest oil resides. As the level of the oil drops,
the float remains in an upright position and feeds the tap until
the level of oil falls to the same level as the tap (approx three-quarters
down the barrel). As the oil below the tap is likely to contain
fats and impurities, this is ideal.
Sludge Drain
As mentioned before, the heavy impurities and water sink to the
bottom of the barrel and stay there, so it's nice to be able to
remove these. With that in mind I decided to add a drain facility.
I made this using 22mm copper fittings. A tank connector was drilled
into the bottom of the barrel and to this was connected to a
22mm pipe. At the end of this I placed a full bore release valve
(remembering to make sure it was in the closed position). For added
support I glued a block of wood and a pipe clip.
Vacuum Lid
Condensation is always an issue unless you're lucky enough to
store your barrel in a place where the temperature never varies.
Even
though condensation will sink to the bottom of the barrel, it
makes sense to me to introduce as little of it as possible. Consequently
I
decided
to incorporate a vacuum seal.
Luckily for me I sourced an airtight container. In its top I fitted
a 15mm tank connector and then a 15mm full bore release valve.
You'll also see a small circular wooded washer that's been glued
to the top of the valve.
Essentially there are two ways the create a vacuum in the tank:
- Place a vacuum cleaner nozzle on the end of the valve (hence
the wooden washer), suck out as much air as possible, then seal
the vacuum in by closing the valve, or
- More reliably, make sure the vacuum valve on the lid is closed
and draw out a few litres of oil from the tap. As liquids need
air behind them to flow, you'll a slower flow rate than you're
used to.
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