Pentair HAFFMANS RPU-352 Instruction Manual page 98

2
Temperature Probe position
It is generally accepted that a slow circulation takes place in the beverage
container, driven by the temperature difference between the hot container wall
and the cooler body of liquid inside. This implies that the product will not be well
mixed in the container during pasteurisation and so we must assume that there
will be variations in the treatment received between individual contaminant cells
and micro-organisms. We might try to measure the value of PU achieved for the
average contaminant cell but we cannot tell which place in the container will
receive the average treatment. Neither can we guarantee that some portion of
the product will not receive considerably less treatment than the average,
resulting in the survival of a significant number of the micro-organisms we are
intending to remove.
We recommend that the tip of the temperature probe, which is its most sensitive
part, should be positioned at the cold spot of the container. This is approximately
10 mm to 20 mm up from bottom of the container and exactly on the central axis.
Choosing the cold spot gives the minimum result for PU achieved; in fact every
contaminant cell may have been warmer than the cold spot at some time during
the process, so that we can be certain that we are measuring a safe,
conservative value. The recorded PU total varies very little with probe height just
at the cold spot and so this position also gives the best repeatability of PU
measurement.
Choosing probe length
As a starting point, for bottles, choose a standard length temperature probe that
is between 5 mm shorter and 15 mm longer than the outside height of the bottle.
For cans choose one that is between 5 mm shorter and 5 mm longer than the
outside height. For situations where a standard length is unsuitable, special
lengths can be supplied.
Temperature probes fit into the container in a way that allows some adjustment
by way of a threaded insert in the seal. This allows the tip to be positioned at the
correct height above the bottom of the container and on the central axis. The
adjustment is 40 mm for bottle probes and 10 mm for can probes.
For cans and small bottles the tip of the probe should be 10 mm to 15 mm from
the bottom of the container. For larger bottles (over 250 mm high) the tip of the
probe should be 15 mm to 20 mm from the bottom of the bottle.
Page 98 of 112
HAFFMANS RPU 352, RPU 353, RPC 80 RPC 50
RPU 352, RPU 353, RPC 80, RPC 50