What is the Bomb Calorimeter?

A bomb calorimeter, also known as an oxygen bomb calorimeter, consists of a combustion oxygen bomb, an inner and outer cylinder, a stirrer, a temperature sensor, a test ignition device, a temperature measurement and control system, and water. Typically, a sample is placed in a stainless steel oxygen bomb and ignited with oxygen. The entire bomb is then placed in an inner cylinder filled with water, where a temperature sensor records the temperature in real time for calorific value calculation. It is primarily used to measure the calorific value of organic or inorganic samples, such as solids like coal and liquids like fuels and chemicals.

A bomb calorimeter is an isothermal calorimetric system designed to measure the calorific value of organic or inorganic samples over a wide range of calorific values, such as solids like coal and liquids like fuels and chemicals. The BCA 500 oxygen bomb calorimeter can also be used to test energetic materials (propellants, pyrotechnics, explosives, etc.). It is used in product quality control and in research fields with demanding testing requirements. Its fully automatic control, simple operation, and intuitive user interface provide a comfortable user experience. The instrument requires minimal training and no special operator requirements.

Measurements can be performed in oxygen, air, or inert atmospheres, with initial pressures up to 50 bar and maximum pressures up to 2000 bar. An additional ignition head can be used to test the detonation heat of energetic materials. The instrument can operate under extremely harsh conditions and provides accurate test results for low calorific value samples.

Working Principle

Working Principle: The oxygen bomb calorimeter consists of a combustion oxygen bomb, an inner cylinder, an outer cylinder, a stirrer, a temperature sensor, a test ignition device, a temperature measurement and control system, and water. There are generally two types of oxygen bomb calorimeters: isothermal and adiabatic. Their calorimetric system is enclosed in a double-layered jacket (outer cylinder) filled with water. The only difference between the two types is the outer cylinder and its associated automatic temperature control device; the rest of the components are identical. In an anhydrous oxygen bomb calorimeter, the inner cylinder, stirrer, and water cup are replaced by a single metal block. The oxygen bomb is constructed of a double metal layer with an embedded temperature sensor, and the oxygen bomb itself constitutes the calorimetric system.

In addition to the water absorbing heat, the oxygen bomb, inner cylinder, thermometer, and stirrer also absorb heat in the calorimeter system, each with its own specific heat absorption rate. These factors are complex and cannot be determined through simple mathematical calculations. Instead, a reference substance with a known calorific value, such as benzoic acid, can be used to calibrate the heat absorbed per 1°C increase in the calorimetric system, effectively determining the heat capacity of the calorimeter.

The heat capacity calibration is valid for three months, but it should be recalibrated immediately in the following circumstances:

1. The calorimeter undergoes significant movement while in normal use;

2. Large parts of the calorimeter's oxygen bomb, such as the bomb cover or connecting ring, are replaced;

3. The calorimeter's thermometer is replaced;

4. When measuring calorific value, the actual inner cylinder water temperature differs by more than 5°C from the average inner cylinder water temperature during heat capacity calibration;

5. The calorimeter undergoes major repairs and a complete water change. The Calorimeter Network recommends that if the calorimeter's operating environment remains unchanged for an extended period, it should be calibrated annually in spring, summer, autumn, and winter, depending on the seasonal changes in the location.

Instrument Categories

Fully Automatic

Extra-large water tank, suitable for large-scale, continuous 24-hour experiments

Utilizing an advanced single-chip microcomputer system, operation is fully automated. All that's required is weighing, loading, and oxygenating the bomb. The instrument automatically completes quantitative water filling, stirring, ignition, results printing, and drainage.

The user-friendly interface features a large Chinese-character display showing time and test progress, allowing for immediate learning and immediate use. It also includes a function for converting high and low calorific values ​​after experiments.

Isothermal

Calorimeters are rapidly evolving, and a highly automated calorimeter has emerged, featuring automatic oxygen filling, automatic oxygen bomb raising and lowering, and automatic release of oxygen bomb exhaust gas after the experiment.

1. The user only needs to load the oxygen bomb. The remaining operations, including connecting an electronic balance to read the sample weight, oxygen filling, oxygen bomb raising and lowering, bomb identification, quantitative inner cylinder water volume, ignition, test completion, bomb release, and result statistics, are fully automated.

2. Automatically adjusts the temperature difference between the inner and outer chambers, ensuring that the inner chamber temperature is approximately 1K higher than the outer chamber temperature at the endpoint, fully complying with the requirements of GB 8.2.4 and ensuring long-term stable test results.

3. Capable of continuous testing for over 72 hours, this solves the technical problem of calorimeters without cooling devices requiring test pauses due to rising outer chamber water temperatures (overshoot).

4. Utilizes imported mechanical components for automatic oxygen filling, deflation, and oxygen bomb raising and lowering.

5. Utilizes compressor cooling and a dedicated heating device for automatic control of the outer chamber water temperature, achieving a temperature control accuracy that meets GB 7.1.4 requirements (±0.1K).

Touchscreen

1. Controlled by a single-chip microcomputer, it features a touchscreen Chinese LCD display, offering an elegant and easy-to-use interface.

2. Highly automated, with automatic water filling and outer chamber water temperature adjustment. The only manual operation required is weighing the sample and entering the weight. All other operations are automatically completed and the test results are printed, making it convenient and quick.

3. Stable and reliable test results are available for arbitration analysis.

4. Rational structure, reliable performance, low failure rate, and easy to learn and use.

5. Full-scale curve tracking of experimental data allows for easy viewing of temperature and time at any point in the curve.

6. Language function: The product provides prompts for operation and faults, and automatically announces the results at the end of the experiment.

7. Reliable fault self-tuning function and multiple protection features.

Maintenance method

After each test, the following inspections and maintenance should be carried out regularly to keep the instrument in good working condition and extend its service life.

1. Oxygen bomb: In addition to cleaning and drying the oxygen bomb after each test, the following points should also be noted and inspected:

(1) The oxygen bomb can only be twisted by hand. Stop when you feel resistance. Do not twist it hard with tools. Clean it after each test.

(2) The bomb cap and valve seat should be rinsed and wiped dry after use.

(3) Rinse the bomb cup, scrub the threads, and check whether there is any mechanical damage on the bomb cup. Be careful not to turn the bomb cup upside down.

(4) Check whether the sealing ring is worn or damaged during combustion. If the seal is not tight and there is air leakage, it should be replaced.

(5) Check whether the insulation pad and insulation sleeve are in good condition and whether there is any damage. Insulation performance can be checked regularly.

(6) Regularly conduct a 20.0 MPa water pressure test on the oxygen bomb. After each water pressure test, the oxygen bomb shall not be used for more than one year (or more than 5.000 tests).

2. Calorimeter: After the test, the water in the cylinder should be drained into the outer cylinder, wiped dry and kept clean.

3. Test water: It is best to use pure water and change it regularly to ensure the reliability and success rate of the test.

Common problems and solutions

1. Leakage at the orifice of the oxygen filling head vent valve: The sealing ring on the sealing block is contaminated or aging. Clean the dirt or replace the sealing ring.

2. Leakage at the white insulating sleeve of the oxygen bomb cover: The surface of the insulating sleeve is contaminated or damaged due to aging. Clean the dirt or replace the insulating sleeve.

3. Leakage at the oxygen bomb cover: The sealing ring of the bullet head is contaminated or aging. Clean the dirt or replace the sealing ring.

4. Gas cannot be released from the oxygen bomb: The ejector pin inside the bleed valve is too short to reach the bleed valve. Use a small iron rod to replace the bleed valve and push against it to release the gas.

5. The sealing ring on the oxygen bomb's sealing valve is dislodged: Reinstall the sealing ring.

6. Oxygen cannot be filled into the oxygen bomb: The sealing ring inside the oxygenator's sleeve is deteriorating. Apply silicone grease or replace the sealing ring.

7. The sealing valve is installed upside down: Reinstall the sealing valve.

8. The sealing ring on the sealing valve is contaminated or deteriorating: Remove the contaminant or replace the sealing ring.

In summary, the oxygen bomb calorimeter is a highly precise, versatile instrument essential for measuring the calorific value of a wide range of organic and inorganic samples. Its applications range from everyday materials like coal and fuel to specialized high-energy substances. Its advanced design, including fully automatic, isothermal, and touchscreen models, caters to diverse experimental needs, ensuring easy operation and accurate, reliable measurements. Regular maintenance, including a comprehensive inspection of the oxygen bomb and timely replacement of worn parts, is crucial to maintaining optimal instrument performance and extending its lifespan. By following proper maintenance procedures and promptly addressing common issues, users can maximize the efficiency and reliability of their oxygen bomb calorimeter, thereby promoting high-quality research and quality control across various industries.