CRH Testing

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Contents
Introduction to CRH ...............................................................................................................................................................1
1. Thermal Screening – Differential Scanning Calorimeter (DSC) .......................................................................................2
2. Thermal Screening - Carius Tube Testing .......................................................................................................................3
3. Reaction Calorimeter - Advanced Reactive System Screening Tool (ARSST)...................................................................4
4. Adiabatic Calorimeter – Accelerated Rate Calorimeter (ARC) ........................................................................................5
Introduction to CRH
Flow chart for selecting a CRH evaluation Test

1. Thermal Screening – Differential Scanning Calorimeter (DSC)
What is the Differential Scanning Calorimeter (DSC) test?
The Differential Scanning Calorimeter (DSC) test is usually the first step in
detecting the onset of an exotherm or thermal instability.
A sample of 10mg and a reference material are held in crucibles within a
temperature controlled oven. Both crucibles are heated at a constant rate,
typically 5 to 10°C /min and up to 400°C. The heating is carried out by a
control system that maintains the sample and the reference material at the
same temperature.
The variation in the heat that must be supplied to the sample to keep it at
the same temperature as the reference material, gives a quantitative
measure of any exotherm in the sample. The test result gives the heat flow
as a function of sample temperature. The baseline is then used to integrate
the heat flow and thus calculate the energy released by the reaction.
An inlet sample gas line is also present on the DSC, which allows tests to be
performed under air and nitrogen to identify whether a thermal instability
is due to oxidation or pure decomposition.
Advantages of DSC Testing:
 Easy setup for fast test turnaround as small amount of
sample needed (10mg)
 Quantified energy data
 Good for homogenous materials & mixtures
Why do you need DSC testing?
Typical outputs of a DSC test include the following:
 Onset temperatures, i.e. exothermic / endothermic
behaviours, phase transitions, decomposition, etc.
 Heat capacity and its change with time & temperature
 Reaction behaviour – if explosive
 Heat of decomposition Figure 3: Typical heat flow v temperature profile for
a DSC test
Figure 2: DSC test unit
-7
-6
-5
-4
-3
-2
-1
0
40 60 80 100 120 140 160 180 200 220 240 260 280 300
Sample Temperature (°C)
Heat
Flow
(mW)
Low onset
endothermic event
(melting)
Exothermic
Decomposition
Figure 1: DSC test setup

2. Thermal Screening - Carius Tube Testing
What is the Carius Tube Test?
The Carius tube test is used to detect the onset of an exotherm and
gas evolution.
A 10 g sample is held in a closed carius tube within an oven. The
temperature of this oven is then ramped upwards at a typical rate
of 2°C /min to up to 400°C or up to a set pressure cut-off. The glass
carius tube fitted with re-entrant thermocouple and pressure
transducer.
A differential temperature reading between the sample and
baseline of the oven can indicate energetic events, if they are
exothermic or endothermic. A plot of Ln(pressure) versus the
reciprocal of temperature can also indicate the onset of gas
generation.
Advantages of Carious Tube Testing:
 Easy to interoperate pressure data available
 Both pressure and temperature data
 Large sample size (more representative sample)
 Glass tube (no contamination)
 Agitation possible
 Semi-batch addition possible
 Study pressure effects and gas generation
 Allows for pure materials, liquids, solids or reaction
mixtures
Why do you need Carious Tube Testing?
Typical outputs from a test, include the following data:
 Onset temperatures, i.e. thermal instability or boiling
(tempering) temperature
 Rate of temperature & pressure rise
 Onset of gas generation potential
 Reaction behaviour - if it is explosive
 Further analysis can be undertaken with the residual gas
generated in a test using mass spectrometry
Figure 5: Oven assembly for the Carius Tube Test
Figure 4: Carius Tube test Setup
Figure 6: Typical Temperature & Pressure v time
profile for a Carius Tube test

3. Reaction Calorimeter - Advanced Reactive System Screening Tool (ARSST)
What is the Advanced Reactive System Screening Tool (ARSST) ?
The Advanced Reactive System Screening Tool (ARSST) is a batch reactor tool
used to identify potential safety hazards.
It consists of a well instrumented pressure vessel that holds a spherical glass
test cell, where it can heat a 10ml sample at a uniform rate of up to 400°C.
The reaction mixture and a magnetic stirrer are introduced into this cell as
well as a thermocouple. The pressure inside the vessel is measured by a
pressure transducer.
Due to the unique heating method by a wraparound heater, the sample is
kept in a quasi-adiabatic mode and no heat is lost to the surroundings occurs.
The ARSST determines the potential for runaway reactions and measures the
rate of temperature and pressure rise to allow determinations of the energy
and gas release rates.
Advantages of ARRST Testing:
 Easy setup for fast test turnaround
 Open or closed cell tests with small sample size
 Lightweight glass test cell with good mixing
 Low phi factor, thus more reliable for process scale up
 Used as a simplified method to asses vent requirements
 Flow regime detector distinguishes between foamy and non-
foamy behaviour
 Scanning and isothermal modes
Why do you need ARRST Testing?
The ARRST provides reliable energy and gas release rates, to
determine thermal hazards, runaway reaction evaluations and often
the proper sizing of pressure relief vents for a process. Typical
outputs from a test, include the following data:
 Rate of temperature & pressure rise
 Heat of reaction
 Heat of mixing
 Total adiabatic temperature rise
 Onset temperatures, i.e. boiling (tempering) temperature
and self-accelerating decomposition temperature
 Time to maximum rate (induction time profile)
Figure 7: ARSST Reactor Set-up
Figure 8: Vessel assembly for closed cell ARSST
Figure 9: Typical Temperature & Pressure v time profile
for an ARSST Test

4. Adiabatic Calorimeter – Accelerated Rate Calorimeter (ARC)
What is Accelerated Rate Calorimeter (ARC) Test?
The Accelerated Rate Calorimeter (ARC) test is used for determining potential
exothermic reaction of materials and provides a realistic worst case simulation
of runaway conditions.
Samples, up to 10g, are held in a titanium spherical cell known as a ‘sample
bomb’ and is heated under adiabatic conditions within a containment vessel.
Adiabaticity is achieved by heating the surroundings of the sample cell via
heaters, so that the temperature outside the cell matches the temperature
within the cell.
ARC testing can be undertaken in three main operating modes; ‘heat, wait and
search’ mode, an ‘isothermal aging’ mode for studying storage
conditions/auto-catalytic reactions and a ‘ramp’ mode for fast screening of
unknown samples.
The sample temperature is increased in steps, of 10°C increment and is then
held for a period at that temperature. The rate of any temperature increase is
observed to see if it exceeds a set value, typically about 0.02°C/min. If it does
not, the temperature is raised by the incremental amount and the procedure is
repeated until an exotherm is detected. Once detected, the heaters within the
vessel are then increased automatically to follow the sample temperature. This
outputs into an adiabatic temperature/pressure v time profile for an
exothermic reaction, all within a safe and controlled manner.
Stirring can also be undertaken in the ARC through the use of a thick-wall
sample cell equipped with an internally mounted magnetic stir bar.
Advantages of ARC Testing:
 Adiabatic pressure and temperature profile of
exothermic reaction. Thus useful as an initial starting
point for relief vent sizing and evaluation
 High precision in exotherm detection, thus beneficial
for storage conditions analysis i.e. self-accelerated
decomposition temperature (SADT)
 Low phi factor and fast tracking
 Gas collection for further analysis
 Sample addition, mixing and dosing possible
 Analysis of multiphase mixtures including gas/solid
phase reaction analysis i.e. decomposition under inert
conditions
Figure 12: Typical adiabatic temperature v time profile
for an ARC test
Figure 10: Accelerated Rate Calorimeter (ARC)
test setup
Figure 11: ARC test unit assembly

Why do you need ARC Testing?
The ARC studies reactions in an adiabatic environment, which is
more representative of plant and storage conditions than in other
isothermal or temperature-ramped instruments. Typical outputs
from an ARC test include the following data:
 Rate of adiabatic temperature & pressure rise during
exothermic reaction
 Heat of reaction
 Time to maximum rate (TMR)
 Measure of condensable and non-condensable gas
generated
80
100
120
140
160
180
200
220
240
260
280
300
320
340
360
700 800 900 1000 1100 1200
Time (minutes)
Temperature
(°C)
0
20
40
60
80
100
120
Pressure
(barg)
Figure 13: Typical adiabatic temperature and pressure v
time profile for an ARC test

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