FIELD OF INVENTION
The invention relates to a protective device of Resistance Thermometer to enhance
longer life adaptable to direct temperature measurement in highly corrosive chrome
plating electrolyte media.
BACKGROUND OF THE INVENTION
Hard Chrome plating bath (electrolyte) is facilitated with the PP/FRP tanks provided
with a direct heating set up with a temperature controller. The Temperature controller
fits with resistance thermometer to measure the temperature of the bath. The
resistance thermometer is directly in contact with the bath for accurate reading of bath
temperature. This device is among the most precise temperature sensors available with
resolution and measurement uncertainties of ±0.1°C. This type of resistance
thermometer is employed for temperature sensing and measurement with an external
indicator, controller or transmitter.
The resistance thermometer is used in the prior art having an Inconel sheath as the
outer covering. It is experienced that when this resistance thermometer is used for
direct temperature measurement, the Inconel sheath is unable to withstand the
corrosive nature of the Chrome Plating bath. Fig.1 shows the typical resistance
thermometer used for direct measurement. Due to long usage, the Inconel sheath of
the resistance thermometer starts decay by dissolving in the Bath and the resistance
thermometer gets spoiled and frequent replacement of thermometer is needed. The
production of hard chrome plating is being interrupted. In view of the above, the new
bath is required to be put into operation at any cost even though it is not economical.
There is no suitable resistance thermometer available in the market to compensate this
requirement.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose a protective device of
resistance thermometer to enhance longer life adaptable to direct temperature
measurement in highly corrosive chromium electrolyte media which eliminates the
problem of the existing state of art.
Another object of the present invention is to propose a protective device of resistance
thermometer to enhance longer life adaptable to direct temperature measurement in
highly corrosive chromium electrolyte media which increases the production.
A further object of the present invention is to propose a protective device of resistance
thermometer to enhance longer life adaptable to direct temperature measurement in
highly corrosive chromium electrolyte media which reduces the break down time.
A still further object of the present invention is to propose a protective device of
resistance thermometer to enhance longer life adaptable to direct temperature
measurement in highly corrosive chromium electrolyte media which increases the life of
resistance thermocouple.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1 shows a schematic diagram of resistance thermometer having an Inconel Sheath
as the outer covering and depletion of the Inconel sheath occur due to corrosive
electrolyte is also shown.
Fig.2 shows the schematic diagram of the newly invented protective device of
resistance thermometer covered with a borosilicate tube for enhancement of longer life
in direct temperature measurement in highly corrosive chrome plating electrolyte
media.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
In the present invention, tube (1) having an OD 10 mm and ID 8 mm and of length 200
mm is employed in which the resistance thermometer (2) can be inserted to protect it
from getting corroded during usage in chrome plating bath. The tube (1) is made of
high quality glass (Borosilicate) that can easily withstand up to 100°C and does not
dissolve in Chromic acid (3). Therefore, the resistance thermometer (2) is inserted in
the tube (1) so that there is no contact between the probe and chromic acid (3).
To improve the accuracy of temperature measurement of the bath (3) a thermal
conductive material like Tin powder (4) is filled in the gap between the tube and
resistance thermometer.
The tube (1) is provided a circular flange support (5) near the open end of the tube (1)
for holding Resistance Thermometer with protective tube.
As a trial this probe was put into operation for 36 hours and no problem was faced
during the trial run. The accuracy of the probe is found to be ±0.15°C which is within
the limits specified by the standards.
WE CLAIM
1. A protective device of Resistance Thermometer to enhance longer life adaptable
to direct temperature measurement in highly corrosive chrome plating electrolyte
medium comprising:
- one close end and one open end tube having 10 mm outer diameter and 8
mm internal diameter and of 200 mm long, provided with a flange support
near open end;
- one resistance thermometer is placed through the open end of the tube
up to full length of the tube;
- a thermal conductive powder is filled in the gap between tube and
resistance thermometer;
2. The protective device as claimed in claim 1, wherein the tube (1) is made of high
quality glass (Borosilicate).
3. The protective device as claimed in claim 1, wherein the tube (1) is filled with tin
powder to increase the thermal conductivity.
4. The protective device as claimed in claim 2, wherein tube can withstand a
temperature from 80°C-100°C.
5. The protective device as claimed in claim 1, wherein the tube is non-corrosive in
chrome plating electrolyte medium.

The present invention relates to protective device of Resistance Thermometer to
enhance longer life adaptable to direct temperature measurement in highly corrosive
chrome plating electrolyte medium comprising one close end and one open end tube
having 10 mm outer diameter and 8 mm internal diameter and of 200 mm long,
provided with a flange support near open end and one resistance thermometer is
placed through the open end of the tube up to full length of the tube and a thermal
conductive powder is filled in the gap between tube and resistance thermometer.