French Press Prepare the following:

French Press
Prepare the following:
Small or large French press cell with cover: put in cold room the night before use
Output valve
Output hose
Samples, 3 ml (small) or 30 ml (large) or less in volume in ice bucket
Centrifuge tubes to receive extracts
Beaker with ice
P1000 pipetteman and tips
Kimwipes
Operation of Press
1. Setup
Turn pump on
Set pressure gauge at correct ratio for desired pressure inside the cell with pressure
adjust knob
Note: There is a table on the front of the machine that relates ratio to pressure.
small cell can ONLY be used
be used on either
setting do not completely overlap.
The large cell can
but note that the ranges for each
2. Assemble cell
Carefully insert piston into cell; hold piston in place while completing assembly
Screw in output valve to be snug but not tight
Screw in adaptor with output hose, again snug not tight
3. Operation of Press
Add sample to cell chamber.
Adjust piston so that top of sample is far enough below top of chamber to leave room
for stub on cell cover.
Place cover on cell. (Cover pushes into place)
While continuing to hold the cell in an inverted position, open output valve slightly
and push piston up until sample is visible in output hose; then pull piston back out
slightly and close output valve. This adjustment is made to remove air bubbles, which
2
interfere with the efficiency of the procedure. If your arm strength is insufficient, there
is a black stand with 3 posts that holds the large cell during this step.
Invert the assembly so that piston is on top and place cell in the press. If you are using
the large cell, place it directly on the French Press against the three limiting pins. If you
are using the small cell, put it on top of the stainless steel cylindrical adapter that
compensates for the height of the shorter cell. Secure cell in place with nuts.
Make sure the piston arm is turned 90o with respect to the securing nuts. This is
so that the arm will not contact and break the securing nuts when the cell
reaches the top.
and cell will move up slowly until it touches
the metal frame of the press. Open the output valve slowly and direct flow into sample
tube in beaker of ice. You want the flow to be dropwise. Broken cells get darker in
color. (Watch for color change.). As piston moves to final stop position, output valve
will need to be gradually opened for best sample flow.
When piston comes to rest on the top of the cell
the
platform will come down. Remove output tubing from pressure cell to release
remaining sample. Remove cell from apparatus and take cover off of cell. Remove
remaining sample from chamber with P1000.
Rinse chamber and output tube thoroughly before applying a new sample.
Typically, for bacteria, a sample is passed through the French press 3 times.
4. Shutdown
Upon completion of sample runs, turn off the pump and return the pressure gauge to
zero. Then disassemble cell and rinse appropriate parts thoroughly. Flush water
through openings for output valve and output hose. Dry and wipe chamber with
mineral oil by pushing kimwipe with small amount of oil through chamber. Also apply
mineral oil to threads on output valve and hose and screw valve into cell to oil threads.
Periodically change teflon ball of output valve and O-rings on all parts. Make sure the
the cell where it is nearly impossible to dislodge.
For more on the French Press: http://en.wikipedia.org/wiki/French_pressure_cell_press