FREEZE DRIER USER GUIDE
Your samples are:
- frozen (preferably in a freezer overnight)
- loosely covered (eg. kimwipes taped over samples) to prevent material from
entering the system while enabling the water to be sublimated
Preparation:
- leave your samples in the freezer, you have at least 30 minutes before you will
need them and you don’t want them to defrost
1. Check the seal of the refrigeration unit lid for loose particles – wipe with a
kimwipe and regrease with a small amount of vacuum grease if necessary. Put lid
on the refrigeration unit if it is not there already.
2. Check that the drain tube is plugged (the black hose at the lower left of the front
panel should have the black plug in it).
3. Check that the lids of the sample containers are free of loose particles – wipe with
a kimwipe and regrease with a small amount of vacuum grease if necessary.
4. Make sure the hose to the vacuum pump is connected to the back of the freeze
drier
5. If the freeze drier hasn’t been used in a while (check the log book), switch all the
ports (the black and white things sticking out the sides of the refrigeration unit) to
“vent” and close the secondary valves along the connection tubes (if there is a
leak somewhere, this will make it easier to find). If it has been used successfully
recently, the ports can be left in “vac” and the connections between the sample
chambers and the refrigeration unit can all be managed with the tube valves.
Start up:
1. Turn refrigeration switch to “on/man vac”. The green light above the switch will
turn on. The temperature indicator will flash amber for temperatures above -40C.
Below -40C the number will be steady green. If the temperature display goes
blank try flipping the refrigerator switch off and on once.
2. When the temperature is below -40C (after 15-25 minutes) turn the vacuum
switch to “on”. The vacuum pump will start and the light will turn on. Initially
the reading will say “HI” but it should start dropping shortly.
3. When pressure reads 133 or lower (i.e. 133 x10-3 mbar), add your samples to the
sample chambers. Systematically open ports (switch from “vent” to “vac” if they
are not already in “vac” position), and valves. If the unit has not been used in a
while, make sure the pressure drops after each opening to make sure there are no
leaks. The pressure may initially be somewhat high, but as water is sublimated
the pressure will drop.
4. Write your information in the log book.
Your samples are ready when the pressure has dropped to 5 to 15 x 10-3 mbar (this
number depends on the sample and how well the freeze drier is running-check log book
to see what other people were getting).
Shut down:
1. Record your final pressure in log book. If you are worried about your samples
blowing around, close the tube valves before proceeding.
2. Vent the system by slowly removing the plug from the drain tube. When the
pressure is “high” you may switch the vacuum pump off. NEVER turn the
vacuum pump off before venting, as this could suck pump oil into the condenser
and you’ll have a long cleaning job ahead of you.
3. Turn the refrigeration switch to off.
4. If you had the tube valves closed, slowly open the valves to gradually vent the
sample chambers.
Clean up (yes, you):
1. Remove lid from refrigeration unit to let ice melt. You may leave the drain tube
unplugged and let the meltwater run out that way, just make sure it is draining
into a pan or the sink.
2. Do not put sample chamber lids seal down on any surface, as they will pick up
material. If you do, clean them for the next person.
3. If you have accidentally sucked some sample material in the chamber, wipe it out
with a paper towel.
4. If freeze drier has been used for a while, use a rod to check if the vacuum pump
oil is dirty (it should be golden, not brown). The window showing the level of oil
in the pump is permanently dirty and doesn’t tell you anything except the level of
the oil. Record your observations in the log book.
Trouble-shooting:
If you have a leak in one of the sample ports, try gently twisting the entire port in
place to improve the seal. If that doesn’t work, you will need to clean and regrease
them. Remove the glass tubing first, then the port. You may need to remove the white
tube inside the port to make it easier. Gently work the black rubber part out (avoid using
sharp tools). Wipe seals and white tube with kimwipes and regrease with vacuum
grease. If the port is torn or otherwise damaged, replacements are in the cabinet under
the drying oven (the oven under the window). Replace by working the black rubber part
in first, then sliding in white tube.
If you have a leak in one of the sample chambers, try cleaning the seal of both the
lid and the base with a kimwipe and regreasing.
If the vacuum pump is not turning on, make sure that it is plugged into the power
cable to the right and down from where the vacuum hose connects to the freeze drier.
Changing pump oil:
Get a waste bottle from under the middle bench (northeast corner) and a funnel.
Remove the cap that says “OIL” from the top of the vacuum pump. While holding the
waste bottle under the pump, unscrew the black plastic screw at the bottom right of the
face with the oil level gauge on it and remove to allow the old oil to flow out. Tilt the
pump to encourage all the oil out. Replace screw and then add new oil until it is near yet
below the “MAX” on the gauge. Make sure that the vacuum hose connection has not
been jostled during this.