1.0 Objective:
The
objective of this standard operating procedure is to lay down the procedure for
operation of Bomb Calorimeter
2.0 Scope:
This
SOP covers operating procedure of Bomb Calorimeter
3.0 Responsibility:
Jr. Research Officer, Research
Officer: Responsible for operation and maintenance of the instrument as per
procedure.
Head of Department: Responsible
for maintenance, timely as per schedule.
QA Officer/QA Manager: Review the records and governing the
document.
4.0 Procedure:
4.1 Clean the instrument free from dust.
4.2 Remove the inlet cover on the top of the
jacket by unfastening the screws and fill approximately 16-17 liters of water
in the jacket. Fill water up to 5-6 cm from the top of the jacket and close
cover.
4.3 Place the Bomb support (stand) in the
calorimeter vessel in a way that it is guarded against the “U” shaped bracket
and does not move. Notice on outer side of the calorimeter vessel at the
bottom, a small pin is attached. Now making sure that the pin is inserted in
the slot on the triangular support, place the vessel in the jacket.
4.4 Place the Bomb Lid on the stand provided on
the pressure gauge and attach ignition wire of approx 6 cm length across both
electrodes. The wire should be tight across the electrodes.
4.5 Make a pellet of sample, weigh it & place it in
crucible. Weigh of sample should be less than 1.10 gm or calorific value of
sample should be less than 10,000 cal/gm. For sample librating more than 10,000
calories, it is recommended to use ½ or 1/3 of the sample by weight.
4.6 Place the crucible in the crucible
holding ring.
4.7 Tie a knot of thread in the center of
ignition wire and make sure that the other end touches the pellets.
4.8 Place approximately 1-2 ml distilled water
from a pipette in the Bomb.
4.9 Close the Bomb with bare hands & charge
it with oxygen.
4.10 Place the Bomb in Bomb support inside
Calorimeter vessel using the hook provided and supporting the bomb from the
bottom.
4.11 Make electrical connections. Using the
smaller wire insert the plugs to the terminals on the water jacket. Using the
longer wire with “Y” clip insert the plug to the sockets provided at the back
of the firing Unit and attach the “Y” clips to the terminals on the jacket.
4.12 Add the measured quantity of water in the
Calorimeter Vessel.
4.13 Cover the water Jacket and vessel using the
combined lid. Notice a small pin on the jacket; it should be inserted in the
slot on the combined lid. A bigger slot is given for the wire.
4.14 Fix stir on the pole provided on the water
Jacket & dip it’s propeller in the water through the holes on the combined
lid.
4.15 Insert the sensor plug in the socket at the
back of the Firing Unit and dip the sensor in the water through the combined
lid.
4.16 Connect the Mains Cord of Digital Firing
Unit and switch “ON” the Mains Button.
4.17 Insert the stirrer’s plug to the socket at the back
of the firing unit and turn it “On”. (Do
not turn “off” the stir during the experiment until the final rise in
temperature is recorded).
4.18 After a period of 1-2 minutes, shift the
switch-indicating “Temp. Initial & Temp. Rise” on the firing unit to Temp.
Rise mode.
4.19 Now adjust the display to 0.00 by
simply rotating the knob indicating “zero adj.” in either direction.
Simultaneously press the “fire” button to ignite the sample. (Sample can also
be ignited even if the last digit on the display is fluctuating to ± 0.01).
4.19 The temperature will start to rise and will
gradually become constant; from this point the temperature will eventually
start to decrease. The peak in temperature must be recorded as the final rise
in temperature.
4.20 Turn “off” the stirrer and the Firing Unit.
Remove the stirrer and sensor from the water. Now remove the combined lid and
disconnect the lead from the Bomb. Using the hook, lift the Bomb from the
vessel and place it on a table.
4.21 Release the pressure from the Bomb using the
gas-releasing pin and dismantle the Bomb. Clean the Bomb interior including the
crucible and electrode with water and dry using a soft cloth or compressed air.
4.22 Enter the details of instrument usage
logbook as per given in Annexure –1.
5.0 Calibration:
5.1 Calibration of Calorimeter:
5.1.1 Bomb Calorimeter is standardized by igniting
a pellet of benzoic acid weighing one gram or less of known calorific value in
oxygen sealed Bomb.
5.1.2 By, igniting benzoic acid, water equivalent
(W) is evaluated which is the weight of water equivalent in effective heat
capacity to the entire system.
4.23 Insert the stirrer’s plug to the socket at the back
of the firing unit and turn it “On”. (Do
not turn “off” the stir during the experiment until the final rise in
temperature is recorded).
4.24 After a period of 1-2 minutes, shift the
switch-indicating “Temp. Initial & Temp. Rise” on the firing unit to Temp.
Rise mode.
4.19 Now adjust the display to 0.00 by
simply rotating the knob indicating “zero adj.”
In either direction.
Simultaneously press the “fire” button to ignite the sample. (Sample can also
be ignited even if the last digit on the display is fluctuating to ± 0.01).
4.25 The temperature will start to rise and will
gradually become constant; from this point the temperature will eventually
start to decrease. The peak in temperature must be recorded as the final rise
in temperature.
4.26 Turn “off” the stirrer and the Firing Unit.
Remove the stirrer and sensor from the water. Now remove the combined lid and
disconnect the lead from the Bomb. Using the hook, lift the Bomb from the
vessel and place it on a table.
4.27 Release the pressure from the Bomb using the
gas-releasing pin and dismantle the Bomb. Clean the Bomb interior including the
crucible and electrode with water and dry using a soft cloth or compressed air.
4.28 Enter the details of instrument usage
logbook as per given in Annexure –1.
5.2 Determining water equivalent:
5.2.1 The water equivalent of the system is
determined by igniting a pellet of supplied pure and dry benzoic acid of known
calorific value weighing not less than 0.8 and not more than 1.1 gram.
5.2.2 Record the corrected temperature rise (T),
calculate the calorific values of thread and wire (CVT & CVW)
using the data given below and evaluate water equivalent by
substitution in the equation.
Formula
for water Equivalent:
W = H x M + (CVT +
CVW)
T
Where,
T
= Final rise in temperature in
degree Celsius.
M
= Mass of sample in grams.
H
= Known calorific value of benzoic
acid in cal/gram.
W
= Water equivalent in calories per
degrees centigrade
CVT
= Calorific value if thread.
= 2.1/cm (when using thread 10 cm,
CV of thread = 2.1 x 10 = 21 cal)
CVW
= Calorific value of ignition
wire.
= 2.33/ cm (when using wire 6 cm, CV
of wire = 2.33 x 4 = 9.32 cal)
Now, calculated the
Calorific value of sample (CVs) =
M
5.3 Enter the details of calibration in
as per given in Annexure – 2.
6.0 Precaution:
6.1 Do not look right above the Bomb when
filling or releasing gas.
6.2 For safety precautions wear gloves
and safety goggles.
6.3
Do not allow the Bomb to shake once the
pressure has been increased and do not fire if Bomb has been dropped or tilted.
7.0 Routine maintenance:
7.1 Clean the instrument with dry cloth.
7.2 Clean the crucible and stirrer
with water and than dry cloth.
8.0 Documentation:
9.0 Annexure – 1 BOMB Calorimeter usage log book XXX/FRM/000
Annexure –2 BOMB
Calorimeter Calibration Record. XXX/FRM/000
8.0 History of Revision:
Revision No.
|
Effective
Date
|
Revision
details
|
Reason for
revision
|
Annexure – 1
|
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Date
|
A. R. No.
|
Name of Sample
|
B. No.
|
Used by
|
Remark
|
|
SOP No. :XXX/FRM/000-00 Format No. : XXX/FRM/000-00
|
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Annexure – 2
|
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CALIBRATION
DATA OF BOMB CALORIMETER
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Calibration Date : Next
Due date for Calibration :
|
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Model no. :
Make :
Benzoic
Acid :
Primary Standard No. :
B. No. :
Make :
Weight of Benzoic Acid (M) :
Calorific value of thread
(CVT) = 2.1/cm => 2.1 X
______ = __________cal
Calorific value of
ignition wire (CVW) = 2.33/cm => X
______ = __________ cal
Known
calorific value of benzoic acid in cal/gram (H) :
Rise Temperature
in Degree Celsius (T) :
Water Equivalent
(W) =
H X M + (CVT + CVW) =
T
Calorific value of
Benzoic acid (CVs): T X W - (CVT
+ CVW) =
M
Limit : ± 5 % of Stated value of Benzoic Acid
|
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Calculation status :
Satisfactory/Not satisfactory
|
||||||
Calibrated by :
Checked by :
|
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SOP No. :XXX/FRM/000-00 Format No. :
|
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