Perlite Problems

[BigWilley]

Well I finally got some Perlite and did some filter runs with it and so far the results have been lousy. First some details, Im using a small 2 meter horizontal leaf dosing filter. I filter between 10-30 Bbl per run. Normally I use Standard DE and Cellulose for a precoat and then Hyflo DE for body feed or Standard on the Lighter beers. The Perlite I aquired was grade 7 which I was told was very close to Standard Grade DE as far as micron rating and performance. I initially only used the perlite for dosing and didn't notice much difference. Then I tried a light beer with a Perlite and cellulose precoat and perlite body feed. The beer was nearly clear to start with and the filtration went smooth but I ended up with some haze. That beer had 25% corn and I had never used corn so I figured that might be it. Next I did another filter with all Perlite except for a bit of cellulose in the precoat, this beer had 25% wheat and after 1 BBl the outflow looked identical to the inflow and I had to break down the filter and set up again with DE. Today I filtered what is normally my easiest beer an I used equal parts DE and perlite in the precoat and perlite only in the body feed and the beer was clear but the pressure rose unusually fast. I noticed that when using Perlite only that the precoat never seemed to set as nice and never ran completely clear, also when I broke down the filter it seemed the edges of the plates had not been coated well. I have heard great things and some bad things about Perlite and I am now firmly in the not so good camp. Any ideas from successful perlite users?

[Valleybrew]

I made the switch to Perlite several months ago with no problems to date. I use a 2M horizontal leaf filter (Velo). I used to use DE grade called HiFlow and switched to the Perlite grade you are using. I use it on Ales and Lagers. I use around 1 pound perlite per barrel filtered, I only filter 7 BBL batches though so I haven't had any problems with pressure build up.
Steve

[brewsurfer]

The great thing about perlite is the way it slides off screens when you are done. Thus no need for cellulose.

After years of using DE on a 3 meter Velo Ero (used to filter up to 45bbls per run) I am now filtering 16-18bbl runs on a Velo Export 3. I use about 10lbs of perlite per run (5 for precoat and 5 for run). Grade 7 for precoat on a Light Lager or Kolsch with grade 3 for run. Straight grade 3 for Pale and Brown Ale. Pumpkin ale was a bit more problem than usual, but with all that spice and vegetable material...

As for breakthrough, check your O-rings and how your screens are seated. Had one brewer who rocked them so much we had to double up with a larger O-ring above to help block and seat screens.

[BigWilley]

I think my seals are alright because I have no problems with a DE filtration. I get crystal clear beer with DE but not with Perlite. The one thing I am not sure about is that the perlite i recieved is grade 7 I was told it was but there is no label on the bag that I can see. If they sent me grade 3 by mistake that could be the problem. I will have to check with the manufacturer and give them the code on the bag. Another thing I noticed w/ perlite is that it seems to create a larger cake on the plates than DE this could be a problem on longer runs. I will have to experiment a bit more. I hate the idea of breaking down the filter midrun again though.

[dick murton]

If you are not getting even coating across the plates, this suggests tubulence around the edge of the plate. This may be due to running the precoat and beer at too high speed, and or lack of baffles at the inlet in the bottom of the filter. Perlite is somewhat less dense than diatomaceous earth, and needs a slower flow rate to prevent scouring. We used to precoat our filters at 150 % of nominal flow rate with KG, to get even coating. When we introduced perlite, we had uneven precoats, with areas with absolutely nothing. We dropped the precoat flow down to nominal filter flow and precoat were then fine.

Typically looking for a precoat of 2 to 3 mm, requiring a dose rate of 500 to 600 g / square metre of coarse material, then a second coat of finer material, using the same material as the body feed. 2nd precoat recommended to be in region of 2 to 3mm thick also.

Normal filter flow rate with beer - 5 hl / square metre.

These figures are from a European supplier of large filters, somay differ slightly from the recommendations that came from your machines manufacturer

Cheers

[dick murton]

O yeah

Forgot to mention, no filter bed, and you will get hazes. I would sort out the filter bed first before worrying about seals. If your filter powder is too fine, then some of it will pass straight through - so it is well worth checking with your supplier.

Cheers

[MikeJordan]

I also have switched over from DE to Perlite. I was using standard and HiFlow grade DE and used the equivalent grades in Perlite. Your manufacturer of Perlite should be able to give you a chart that compares all grades of DE and Perlite. The changeover to Perlite caused no problems for me. One thing the manufacturer recommended was that you don't need as much Perlite in comparison to DE. They suggested a reduction of 30%. This worked wonders for me while saving money and materials. Good luck!

If you cannot obtain a chart let me know as I may be able to dig it up and fax it to you.

[beertje46]

I switched to perlite around a year ago. The best thing the supplier said was, "if you use a five gallon bucket of DE, use a five gallon bucket of Perlite." "Base your usage on the volometric of DE."