Re: Vacuum concentrators: Speedvac et. al.
Steve (Steve@atrbiotech.com)
Tue, 11 May 1999 09:11:11 -0400
The repair of the low temperature traps is an art of sorts. To achieve th=
e
specified end temperatures everything has to be just right. Compressor
burnout is not an uncommon problem with the Savant traps ( on a system th=
at
is heavily run a 4 year life cycle is about the norm ) and the repair co=
sts
are about in line with the average. In the estimate from your University
repair shop I'm surprised that the costs for the parts does not include t=
he
refrigerant. The age of your unit implies that the refrigerant is R13B1
which has been removed from the market as a high ozone depletion coolant =
so
the replacement cost for that gas alone is over $ 200.00, if you can find=
a
source. An alternative is to convert the system to the new refrigerants t=
hat
have lower capacities when retrofitted in the early generation traps. In
response to your statement that the system does not have access valves, t=
his
is a standard methodology to remove any components that have the potentia=
l
for leaking. The system, when operating normally, is working at pressures
around 250 psi and the standard schrader valve used in refrigeration is n=
ot
a reliable means to contain the refrigerant at these pressures. Enough ab=
out
refrigeration technology lets talk about the real problem with a dead or
marginally functioning cooling trap. We know the function of the trap is =
to
keep the solvents out of the vacuum pump. If your repaired trap does not
reach end temperatures to provide an effective barrier of solvents flow i=
nto
the pump then you are looking at a pump repair that may equal the repair
costs of the cooling trap. My suggestion is that you verify the end
temperature of the trap when it is returned to you. Put an alcohol
thermometer in the cryofluid and make sure that the trap is getting down
to -50=BA C. This will insure that the system will continue to provide
effective performance and reproducible drying for your samples.