SDCHN636 Carbon, Hydrogen and Nitrogen Analyzer

The SDCHN636 Carbon, Hydrogen and Nitrogen Analyzer is a fully automatic elemental analyzer designed for the determination of carbon, hydrogen and nitrogen in a wide variety of solid and liquid samples, including coal, coke, biomass, petroleum products, chemicals, cement, soil, hazardous waste, food, animal feed, fertilizers and urea solutions.

The instrument combines non-dispersive infrared absorption technology for carbon and hydrogen determination with a high-sensitivity thermal conductivity detector for nitrogen analysis. During each analysis, the sample is automatically introduced into the combustion furnace and completely oxidized under an oxygen-rich atmosphere. Carbon and hydrogen are measured in the forms of CO₂ and H₂O, while nitrogen oxides are converted into N₂ and subsequently quantified by the thermal conductivity detector.

With a sample capacity of up to 36 positions on a single tray or 72 positions with a dual-tray configuration, the SDCHN636 supports continuous, unattended operation. Its optimized gas path, advanced combustion control, high-performance sensors and intelligent software provide reliable results while reducing routine workload and operating costs.

The analyzer is particularly suitable for laboratories requiring high-throughput CHN analysis, stable long-term performance and simplified daily operation.

Key Features

High-Throughput, Fully Automatic Operation

  • Accommodates up to 36 samples on a single tray or 72 samples with the dual-tray configuration.
  • Samples can be added or replaced while an analysis sequence is in progress.
  • Automatic sample introduction, combustion, detection, calculation and data storage minimize manual intervention.
  • Continuous batch analysis enables genuine unattended operation and significantly improves laboratory productivity.

Short and Reliable Gas Path

  • The integrated manifold-based gas circuit minimizes tubing and internal dead volume.
  • Reduced gas-path volume helps limit moisture retention and sample carryover.
  • Automatic and precise gas-flow control improves system stability and analytical consistency.
  • The simplified gas circuit enhances reliability and facilitates routine maintenance.

Accurate and Controlled Sample Combustion

  • The sample introduction assembly incorporates an air-barrier mechanism that reduces the entry of ambient air into the combustion furnace during sample dropping.
  • A gas-flow equalization structure promotes complete and uniform combustion.
  • The design helps prevent lightweight samples from scattering or splashing during introduction.
  • Real-time combustion monitoring enables the system to determine the combustion endpoint accurately, improving both analytical efficiency and result reliability.

High-Performance Infrared Detection for Carbon and Hydrogen

  • High-precision infrared sensors are used for the determination of carbon as CO₂ and hydrogen as H₂O.
  • Low-drift sensor technology provides stable baselines and reliable long-term performance.
  • Real-time signal monitoring helps identify complete combustion and optimize the analysis cycle.
  • The infrared detection system delivers excellent sensitivity across a wide concentration range.

Stable Thermal Conductivity Detection for Nitrogen

  • Nitrogen is measured using a high-sensitivity diffusion-type thermal conductivity detector.
  • Ultra-low temperature drift helps maintain a stable analytical baseline.
  • Independent precision temperature control minimizes the influence of ambient temperature variations.
  • The reduction and purification system converts nitrogen oxides into N₂ and removes interfering CO₂ and moisture before detection.

Low Helium Consumption

  • An integrated helium-saving function automatically adjusts the helium flow according to the operating stage.
  • The helium flow increases to approximately 0.7 L/min only during nitrogen analysis.
  • During standby and non-analysis periods, the helium flow can be reduced to approximately 0.05 L/min.
  • This intelligent flow-management strategy substantially lowers helium consumption and routine operating costs.

User-Friendly Operation and Maintenance

  • Automatic system leak testing can be completed directly through the operating software.
  • The crucible can be replaced from the top of the instrument for easier maintenance.
  • The furnace assembly is designed for convenient disassembly and reagent replacement.
  • The floor-standing structure eliminates the need for laboratory bench space.
  • High-quality casters and positioning devices allow the instrument to be moved and securely fixed when required.

Flexible Sample Compatibility

The straight-through sample introduction design is suitable for samples with low density or relatively large volume, including:

  • Coal and coke
  • Biomass and solid biofuels
  • Soil and geological samples
  • Food, cereals and animal feed
  • Fertilizers
  • Solid and hazardous waste
  • Liquid samples
  • Urea and urea solutions

Intelligent Software and Data Management

  • Automatic transfer of sample weights from an optional connected balance.
  • Configurable analytical methods for different sample types and combustion characteristics.
  • Automatic blank correction, calibration and drift correction.
  • Real-time display of analytical signals and operating status.
  • Result recalculation, relative standard deviation calculation and calibration-curve management.
  • Integrated database searching, reporting, printing and automatic data backup.
  • User-access management, operating logs and automatic diagnostic functions.
Applicable International Standards and Methods
Standard No.Standard TitleApplicable SamplesAnalytes
ISO 29541Coal and coke — Determination of total carbon, hydrogen and nitrogen — Instrumental methodCoal and cokeTotal carbon, hydrogen and nitrogen
ISO 609Coal and coke — Determination of carbon and hydrogen — High temperature combustion methodCoal and cokeCarbon and hydrogen
ISO 16948Solid biofuels — Determination of total content of carbon, hydrogen and nitrogenSolid biofuelsCarbon, hydrogen and nitrogen
ISO 22241-1Diesel engines — NOx reduction agent AUS 32 — Part 1: Quality requirementsAqueous urea solution (AUS 32)Urea
ISO 22241-2, Annex BDiesel engines — NOx reduction agent AUS 32 — Part 2: Test methodsAqueous urea solutionTotal nitrogen and urea
ISO 18611-2, Annex BShips and marine technology — Marine NOx reduction agent AUS 40 — Part 2: Test methodsAqueous urea solutionTotal nitrogen and urea
ISO 13878Soil quality — Determination of total nitrogen content by dry combustion (“elemental analysis”)SoilNitrogen
ASTM D5373Standard Test Methods for Determination of Carbon, Hydrogen and Nitrogen in Analysis Samples of Coal and Carbon in Analysis Samples of Coal and CokeCoal and cokeCarbon, hydrogen and nitrogen
AOAC 993.13Nitrogen (Total) in Fertilizers: Combustion MethodFertilizersNitrogen
Model Selection
ParameterSDCHN636SDCH636SDC636SDH636
Measurement RangeCarbon: 0.005%–100% Hydrogen: 0.01%–50% Nitrogen: 0.01%–100%Carbon: 0.005%–100% Hydrogen: 0.01%–50%Carbon: 0.005%–100%Hydrogen: 0.01%–50%
RepeatabilityCarbon: Cd ≤ 0.45%Hydrogen: Hd ≤ 0.10%Nitrogen: Nd ≤ 0.05%Carbon: Cd ≤ 0.45%Hydrogen: Hd ≤ 0.10%Carbon: Cd ≤ 0.45%Hydrogen: Hd ≤ 0.10%
Single-Sample Analysis TimeApprox. 6–8 min, depending on the sample type and analytes measuredApprox. 6–8 min, depending on the sample type and analytes measuredApprox. 6–8 min, depending on the sample type and analytes measuredApprox. 6–8 min, depending on the sample type and analytes measured
Sample Weight75–105 mg75–105 mg75–105 mg75–105 mg
Sample Capacity36/72 samples; continuous sample loading supported36/72 samples; continuous sample loading supported36/72 samples; continuous sample loading supported36/72 samples; continuous sample loading supported
Maximum Power≤4.5 kW≤4.5 kW≤4.5 kW≤4.5 kW
Gas RequirementsCombustion gas: Oxygen, purity ≥99.99%, pressure ≥1 MPa Pneumatic gas: Nitrogen, purity ≥99.5%, pressure ≥1 MPa Carrier gas: Helium, purity ≥99.999%, pressure ≥1 MPaCombustion gas: Oxygen, purity ≥99.99%, pressure ≥1 MPa Pneumatic gas: Nitrogen, purity ≥99.5%, pressure ≥1 MPa Carrier gas: Helium, purity ≥99.999%, pressure ≥1 MPaCombustion gas: Oxygen, purity ≥99.99%, pressure ≥1 MPa Pneumatic gas: Nitrogen, purity ≥99.5%, pressure ≥1 MPa Carrier gas: Helium, purity ≥99.999%, pressure ≥1 MPaCombustion gas: Oxygen, purity ≥99.99%, pressure ≥1 MPa Pneumatic gas: Nitrogen, purity ≥99.5%, pressure ≥1 MPa Carrier gas: Helium, purity ≥99.999%, pressure ≥1 MPa
Test TemperatureUp to 950°C3 h3 h3 h
Stabilization Time3 h3 h3 h3 h
Maximum Test IntervalIf the interval exceeds 1h, a blank or waste sample should be inserted as a transition sampleIf the interval exceeds 1h, a blank or waste sample should be inserted as a transition sampleIf the interval exceeds 1h, a blank or waste sample should be inserted as a transition sampleIf the interval exceeds 1h, a blank or waste sample should be inserted as a transition sample
Ambient Temperature15°C–28°C15°C–28°C15°C–28°C15°C–28°C
Crucible ReplacementManualManualManualManual
Dual-Control FunctionOptionalOptionalOptionalOptional
Mobile Remote-Control AppOptionalOptionalOptionalOptional
Software & Schematic Diagram
On-site Photos
Videos
Customer Testimonials
We have provided a complete set of Sundy testing solutions, including bomb calorimeter, sulfur analyzer, and thermogravimetric analyzer, to the fuel analysis laboratory of Kavçim Cement, a leading integrated cement plant on Turkey’s Black Sea coast. Sundy’s standardized instrument performance bring outstanding practical value to end users. The upgraded solution significantly simplifies daily operations, lowers manual intervention and maintenance costs, and unifies data consistency for routine fuel analysis. We are very satisfied with Sundy’s product quality and technical support, and will continue to promote and recommend Sundy analytical instruments for more industrial laboratory projects in Turkey.
Dr. Karahan, POTANTEK
After more than 10 years of continuous cooperation and market verification, we confirm that Sundy’s products, especially its automatic calorimeters and elemental analyzers, have high precise temperature control, accurate testing results, and ultra-low failure rate. All products are fully compliant with international ISO and ASTM standard, completely meeting the testing demands of coal laboratories, power plants, industrial enterprises, universities and scientific research institutions. We highly recognize Hunan Sundy Science and Technology’s strong production capacity, standardized quality management system, professional technical support team and excellent business credibility. In all our cooperation cases, Sundy has always demonstrated professionalism, reliability and a customer-oriented service attitude.
Dr. Kim, YEONJIN
FAQs
The SDCHN636 uses non-dispersive infrared absorption for carbon and hydrogen determination and thermal conductivity detection for nitrogen determination. Carbon is measured as CO₂, hydrogen as H₂O, and nitrogen as N₂ after reduction and gas purification.
The sample is combusted in an oxygen-rich atmosphere. The resulting gases undergo secondary combustion, desulfurization and filtration before being collected and mixed. CO₂ and H₂O are measured by infrared detectors, while nitrogen oxides are converted into N₂ in the reduction furnace and measured by the thermal conductivity detector.
The instrument is intended for carbon, hydrogen and nitrogen determination in solid and liquid samples, including coal, coke, biomass, petrochemical materials, cement, geological samples, environmental samples, solid waste, hazardous waste and urea-containing samples.

According to the operating manual, the measurement ranges are:

  • Carbon: 0.005% to 100%
  • Hydrogen: 0.01% to 50%
  • Nitrogen: 0.01% to 50%

The applicable range may also depend on the selected instrument configuration and analytical method.

A complete single-sample analysis normally takes approximately 6 to 8 minutes, depending on the sample type and the elements being measured.
The nominal sample weight is approximately 100 mg. The software allows an acceptable sample-weight range to be configured according to the analytical method and sample characteristics.
The single-tray configuration accommodates 36 samples, while the dual-tray configuration accommodates up to 72 samples. Samples may also be added or replaced during an ongoing analytical sequence.
Yes. After the samples, methods and relevant parameters have been entered, the system can automatically perform sample introduction, gas-path purging, combustion, gas collection, detection, calculation and result storage in sequence.
The straight-through sample-dropping structure facilitates reliable introduction of low-density or relatively bulky samples, such as biomass and certain liquid samples packed in tin capsules. It also reduces the possibility of samples becoming trapped in the feeding mechanism.

The instrument requires:

  • Oxygen as the combustion gas, purity ≥99.99%
  • Nitrogen as the pneumatic driving gas, purity ≥99.5%
  • Helium as the carrier gas, purity ≥99.999%

The supply pressure of each gas source should be at least 1 MPa.

The manual specifies the following typical pressure settings during commissioning:

  • Oxygen: approximately 0.26 MPa
  • Helium: approximately 0.18 MPa
  • Nitrogen: approximately 0.26 MPa before secondary pressure reduction, or approximately 0.18 MPa for systems without an additional secondary regulator

These values should be adjusted during installation and commissioning by qualified personnel.

During normal nitrogen analysis, the helium flow through the thermal conductivity system is approximately 700 mL/min. In standby mode, the helium-throttling function reduces the total helium flow to approximately 100 mL/min, thereby reducing helium consumption.

The throttling mode should normally be disabled approximately 30 minutes before starting nitrogen analysis.

After combustion, nitrogen may be present in the sample gas as nitrogen oxides. The reduction furnace removes residual oxygen and converts nitrogen oxides into N₂. The gas then passes through absorbents to remove CO₂ and moisture before entering the thermal conductivity detector.

Before the gas reaches the thermal conductivity detector, CO₂ and moisture are removed using absorbent and drying reagents. This purification step reduces interference and allows the detector to measure the N₂ concentration more accurately.

The operating manual recommends a warm-up period of at least 3 hours before routine analysis. If the instrument is maintained continuously at operating temperature, a separate warm-up period may not be required, although the sleep function is recommended when the system is idle.

Blank analyses are used to balance the system baseline, evaluate system stability and generate an effective blank correction value. At least four to five blank runs are recommended until the blank results are stable within approximately 0.1%.

Blank analyses should be performed daily before sample testing and repeated after replacing the oxygen supply.

Drift correction uses certified reference material results to compensate for small changes in the analytical system. According to the operating manual, drift correction should be performed approximately every four hours or whenever the result of a reference material fails to meet the accuracy requirement.

The reference material used for drift correction should be similar in composition to the routine samples.

Parameter adjustment is required during initial commissioning and may also be necessary after:

  • Loss of parameters following software replacement or upgrading
  • Replacement of tubing between the combustion furnace and gas collection chamber
  • Adjustment of oxygen pressure or combustion flow
  • Replacement or adjustment of the gas collection chamber

The instrument must be temperature-stable and pass the leak test before parameter adjustment is performed.

The control software provides automatic or guided functions for:

  • System leak testing
  • Oxygen-path leak testing
  • Helium-path leak testing
  • Combustion-furnace leak testing
  • Sensor leak testing
  • Gas-path purging
  • Moisture removal
  • Helium-cylinder pressure checking
  • Sample-dropping mechanism testing
  • Automatic system diagnosis

These functions help operators identify gas-path, pressure, temperature and communication abnormalities.

The manual provides the following typical maintenance intervals:

  • Replace the quartz wool in the dust filter every 50 analyses
  • Replace the crucible every 200 analyses
  • Replace the filter element every 300 analyses
  • Replace the combustion or furnace reagent every 600 analyses
  • Replace the reduction-furnace copper and nitrogen catalyst every 700 analyses
  • Replace the reagents in the drying tubes every 1,000 analyses
  • Replace the gas-collection filter after approximately 1,800 analyses
  • Replace the PTFE tubing between the combustion furnace and gas collection chamber approximately once per year

Actual maintenance frequency may vary according to sample type, ash content, operating conditions and laboratory workload.

Related Products

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