Introduction

The determination of gross calorific value in animal feeding stuffs, animal products, and faeces or urine is fundamental to feed energy evaluation systems. Gross energy serves as the essential starting point for estimating digestible, metabolizable, and net energy, while the calorific values of faeces or urine provide a critical basis for calculating energy utilization efficiency and determining the energy available to the animal. Accurate gross calorific value data not only support science-based diet formulation, the assessment of the energy potential of unconventional feed resources, and product quality control, but also provide a reference for evaluating the energy content of animal products. Therefore, establishing accurate and efficient methods for determining gross calorific value is essential for the precision feeding and sustainable development of the feed industry.

Method Reference

ISO 9831 Animal feeding stuffs, animal products, and faeces or urine — Determination of gross calorific value — Bomb calorimeter method

Principle

Combustion of a weighed portion of the test sample in oxygen in a bomb calorimeter under specified conditions. Calculation of the gross calorific value from the temperature rise of the water in the calorimeter vessel and the mean effective heat capacity of the calorimeter. Allowances are made for the heat released by the ignition fuse, for thermochemical corrections and, where appropriate, for heat losses from the calorimeter to the water jacket.

Sample Preparation

Prepare the test sample in accordance with ISO 6498.

Accessories

Oxygen: ≥99.99% (V/V), free from combustible matter, at a pressure sufficient to fill the bomb to 3 MPa.

Firing wire: nickel-chromium wire (approximately 0.1 mm in diameter).

Combustion aid: polyethylene bags.

Calibration Standard

Benzoic acid: thermochemical standard, certified by a nationally recognized authority.

Testing Parameters

Water: 5 mL, Grade 3 or higher in accordance with ISO 3696

Ignition heat: 50 J

Oxygen pressure: 3.0 MPa

Oxygen filling time: 15 s

Ambient temperature: 22 °C

Jacket temperature: 28 °C

Bucket temperature: 26 °C

Water tank temperature: 24 °C

Procedure

Instrument Preparation

Prepare the instrument and bomb as outlined in the instruction manual.

Determination of effective heat capacity of the calorimeter

a. Select “Heat capacity” test mode in the instrument software.

b. Weigh (1.0 ± 0.1) g benzoic acid and perform heat capacity test. (Refer to the operator’s manual for the detailed test procedure.)

c. Repeat the heat capacity test five times.

d. The software automatically calculates the effective heat capacity.

Determination of Gross Calorific Value

Select “Calorific value” test mode in the instrument software.

Weigh approximately 1 g of the sample into a polyethylene bag of known mass and calorific value, and then place the bag in a crucible for analysis. Enter the mass and calorific value of the polyethylene bag into the software so that its heat contribution can be automatically corrected for.

Refer to the operator’s manual for detailed test procedures.

Typical Results

Summary

For the determination of gross calorific value in animal feeding stuffs, animal products, and faeces or urine, the Sundy SDAC1200 calorimeter fully complies with ISO 9831. Based on the bomb calorimeter method, it delivers accurate, reliable results that meet the standard’s precision requirements. The SDAC1200 also automates the entire testing process, completing a single sample analysis in approximately 10 minutes. Easy to use and highly consistent, it offers a compliant, efficient, and reliable solution for routine gross calorific value determination in these matrices.

For more information about the Sundy SDAC1200 Bomb Calorimeter, please contact us by phone or email.

Phone: +86-731-88112150

Email: sales@sundytech.com