Ro-tap Particle Separator

(clicking)

- [Voiceover] The Ro-Tap Particle Separator uses a dried sample that is placed on a series of stacked sieves and shaken horizontally while simultaneously a metal arm repeatedly taps the top of the sieve stack to incorporate a vertical shaking element.

Doctor Dave Mertens used the Ro-Tap Separator to develop the concept and methods for physically effective NDF.

And today it's used for research and by commercial forage testing labs.

Because the Ro-Tap uses vertical shaking and dried samples, it's results are often very different from techniques like the Penn State and ASABE separators that use horizontal shaking and as-fed samples.

In this video, Doctor Jud Heinrichs will tell you more about the Ro-Tap method and explain how it differs from the other methods.

- Okay, this is a Ro-Tap separator.

It's a very classical way of doing particle science on dry feed samples.

It's a system that was originally used to develop the equations that we use for a physical effective fiber evaluation of feeds and forages.

This is a piece of equipment that actually has a bar that you'll see that actually uses for tapping the sample.

We have a series of sieves.

One dimensional sieves going from the largest on top to the smallest on the bottom.

We put this in, we put our forage sample in here.

Again it's a dry sample we put on here.

Put the top together.

And we turn it on and you'll see why it's called a Ro-Tap separator.

(machine rattling)

'Kay, what this is doing is it's separating in a circular manner here but now it's also tapping it on top which is where it gets a Ro-Tap from.

Which actually then gives you a three dimensional separation because it's moving those dry feed particles up and down through the sieve.

Now what I'm gonna demonstrate for you here is using some coffee straws that I've cut up in various different sizes.

And I'm gonna put them in the Ro-Tap separator.

They're all the same diameter but different lengths.

(machine rattling)

Okay, so I'm gonna take these off to show you what's happened here.

And I had various different sizes, some of them being quite long but because of that three dimensional manner, something even that long passes through there.

It's two or three times the size of that sieve opening.

What you see is a lot of these really long pieces will end up on a particular screen.

It does some sorting but it actually allows various different particles to get all the way down through to where the diameter of this straw is not allowing it to pass through any further.

So it's effectively sorting on a three dimensional manner.

It's putting all different sizes together.

I can show, let me put these.

If I do it long enough they'll all pretty much come up on the same.

It puts all these different particle sizes together because it has sorted on the smallest dimension which is the diameter or that coffee straw.

So it's a completely different type of system, again using dry samples and a three dimensional type of separation.