ART-1 How to Use
Welcome to LFA’s video on how to use your Angle of Repose tester, the apparatus comes with:
- A test stand
- Powder flow funnel
- 3 different size nozzles
- A stirrer
- Test platform and a digital height gauge
To assemble the LFA ART 1 first take your base plate and attach the feet, there are 3 feet, the front attaches from the bottom, the other 2 are screwed in through the top, the rear 2 are adjustable. On top of the plate is a level so you’re able to adjust the feet to ensure the platform is level.
Once the platform is level, insert the funnel bar through the base, attach the nut underneath and tighten fully.
Next, we suggest fitting the nozzle needed, the most common nozzle use is the 10mm diameter.
Place the funnel flat on a surface upside down, remove the nozzle lock, place your nozzle on top and then replace the nozzle lock.
Place the funnel holder over the funnel bar and tighten the bolts but only finger tight as we will need to adjust the height of the funnel later.
Place in your hopper with nozzle fitted.
Place your test stand into the circle on the base plate and place your height gauge onto the base plate, turn on the gauge, move the gauge down onto the test stand and zero the gauge and then move the height gauge up to the 75mm mark.
Next, we need to adjust the nozzle height, the nozzle height needs to be at 75mm, so loosen the 2 bolts at the rear of the funnel holder and adjust, once complete these can be fully tightened using the Allen key that comes with your LFA ART 1.
Finally, place the stirrer into the funnel and tighten using the Allen key provided. Ensure the stirrer does not protrude out the bottom of the nozzle, it needs to be slightly raised from the nozzle not to interfere with the test.
Your LFA ART 1 is now ready for testing.
Take your height gauge and place it on the test platform and zero, leave it on, raise the height gauge so it’s out of the way and does not interfere with the test.
Take your powder, granules or formulation. This can be an excipient that you will be encapsulating or your final mix depending on what you are wanting to measure. Add it into the funnel. How much you add will depend on the bulk density of your powder. If necessary you can use the stirrer to assist your powder through the nozzle.
You want to add enough powder so it begins to fall off the edges of the test platform and the heap is at the highest point it will go.
In these examples, we used both microcrystalline cellulose and magnesium stearate.
Once the powder has formed a pile on the platform measure the height of the powder from the platform the highest point on its peak. (mm)
To calculate the angle of repose the calculation is:
tan-1(2h/d) - h is the height of the pile of powder and d is the diameter.
Below is a table of how the angle of repose might affect the ability of a powder to flow.
Angle of Repose (degrees)
|36-40||Fair - aid not needed|
|41-45||Passable - may hang up|
|46-55||Poor - must agitate or vibrate|
|>66||Very, Very Poor|