WVO Fine Filter / Storage Tank 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, WVO is fine filtered into this
and stored. Unless a barrel
is stored in a
location
where
the
temperature
never varies,
condensation is going to occur (more about
that later). This should 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. 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, but it's not strictly necessary.
The important things to remember when positioning your tap are
as follows:
- Never draw from the top - floating debris reside there
- Never draw from the bottom - heavy fats and water reside there
I would
recommend having the tap a couple of inches or so above the
base
of the barrel,
so any
water
or stray
fats
can
sink
safely below the
level of the tap. However, my arms couldn't reach that far
inside my barrel so I positioned it as low as I could... very
much a
case of do as I say, not as I do.
From the image above you'll see that I soldered a small length
of pipe on my tap, together with an elbow pointing downwards. As
I've said before, it's important not to draw your
WVO from the surface of the barrel, but ideally an inch or so below
the surface (because
some fats float, etc). The elbow fitting ensures that oil is never
taken from the surface. And as this is a fine filtering tank (as
opposed to the settling
tank) the oil near the bottom of the barrel
should be free of nasties down to 1 micron.
Sludge / Water Drain
Any stray fats or water should 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 15mm copper fittings. A tank connector was
drilled into the bottom of the barrel and to this was connected
to a 15mm 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 litre's of oil from the tap. As liquids need
air behind them to flow, you'll get a slower flow rate than you're
used to as a vacuum forms.
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