OHAUS HB1AL Manual De Instrucciones página 15

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UNIFORMITY TESTING
1. The manufacturer has performed uniformity tests on Dry Block Heaters to
ensure even heating across the entire heater plate. For the one block heaters,
the manufacturer used a specially designed Modular Heating Block with five (5)
temperature holes. Five independent calibrated temperature measuring devices
were used during the test. For multiple block units, Modular Heating Blocks were
placed in all positions to cover the entire heating plate and then an independent
calibrated temperature measuring device was used in the thermometer well of
each block. For all tests, the tip of the temperature measuring device was an exact
fit for the temperature well in the Modular Heating Block with no air gaps. The
temperature was set and the units were allowed to heat up and stabilize for twenty
(20) minutes or more. Readings were then taken at regular intervals to monitor the
temperature uniformity for four (4) hours. These tests were repeated after rotating
the temperature measuring devices to different thermometer well positions to confirm
the temperature uniformity of the units.
2. The recommended procedure for testing the unit's temperature uniformity is as
follows:
a. Set-up the unit in a stable environment.
b. Set-up the unit with the proper number of Modular Heating Blocks to cover the
entire heating plate. Then set up the blocks with the proper fitting tubes or vials.
Place liquid samples in tubes or vials where the liquid level is lower than the
height of the top surface of the Modular Heating Block.
c. Select multiple calibrated temperature measuring devices that are designed
for immersion in liquids. Use these temperature measuring devices at the
same time across various positions in the Modular Heating Block(s). Place the
temperature probes in the bottom of several of the filled tubes or vials. Ensure
the liquid levels in the tubes or vials with the temperature probes does not rise
above the height of the top surface of the Modular Heating Block.
d. Set the temperature of the unit. Allow the unit to reach temperature and stabilize
for twenty (20) minutes or more and then take temperature readings from all the
temperature devices to test for temperature uniformity
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e. Please note the characteristics of the liquid used for the test and the fit of the
tube or vial in the Modular Heating Block can affect the results of the uniformity
test for the Dry Block Heaters. Tubes and vials must be the proper size for the
Modular Heating Block so there is a secure fit with no air gaps to ensure good
thermal contact.
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