The HMKFlow 329 apparatus from Dandong HMKTest Instrument Co. Ltd is an angle of repose USP 1174 device that can be employed to quantify the angle of repose of pharmaceutical powders.
The angle of repose, which is the angle of the conical pile, is formed upon pouring a granular sample onto a horizontal surface (that is, test platform). Measuring the angle of repose of the powder forms part of the powder flow test.
Apart from complying with European Pharmacopoeia Chapter EP 2.9.36 and US Pharmacopoeia Chapter USP 1174, HMKFlow 329 conforms to ISO 4324 and agricultural fertilizers (ISO 8398) standards.
HMKFlow 329 Powder Flowability Angle of Repose Tester P/N 032998. Image Credit: Dandong HMKTest Instrument Co. Ltd.
HMKFlow 329 is equipped with free Windows software that helps obtain the test results within a second. The instrument includes a stand, test platform, funnel, stirrer, and a digital height gauge, with an accuracy of 0.05 mm and a range of 0–300 mm.
Users can pour the sample into the funnel and stir the sample if required. The powder forms a cone on the test platform, where a digital gage can be used to measure the height of the pile. The tangent of the angle of repose (in degrees) is calculated by measuring the powder cone height in millimeters from the height gage’s digital display and dividing it by 50.
Listed below are the flow properties and corresponding angles of repose as per European Pharmacopoeia Chapter EP 2.9.36-1:
- An angle of repose of 25°–30° represents excellent flow property
- A 31°–35° angle of repose denotes good flow property
- An angle of repose of 36°–40° corresponds to fair, aid-not-needed flow property
- A 41°–45° angle of repose denotes passable, may-hang-up flow property
- A 46°–55° angle of repose represents poor, must-agitate-and-vibrate flow property
- An angle of repose of 56°–65° corresponds to very poor flow property
- A >66° angle of repose represents very, very poor flow property