How many 7" plates?

[DoubleBrookMaple]

My filter press fabrication went well I think. Testing will reveal the truth.

I have made 6 plates (stages), but the pre-filter chamber is much smaller than the commercial presses. Mime are only 3/4" deep. I can double them up if necessary and get 1 1/2 deep with 3 stages instead of 6. I am a small time hobbyist, and don't expect to filter more than 5-10 gallons at a time.

What do you think? How many stages should I use, and should I double up the chamber plates to make the pre-filter side larger?

Thanks for your input.860786088609

[maple flats]

Don't make a pre-filter. It can be counter productive. The niter when mixed in with the filter aid (FA) actually aids in the filtering. I hope a plywood frame is OK for food contact. I'll let others address the chamber question.

[Thad Blaisdell]

By prefilter chamber you are referring to the hollow plates. But I will say that I am not so sure about the plywood...????

[DoubleBrookMaple]

By prefilter chamber you are referring to the hollow plates. But I will say that I am not so sure about the plywood...????

Not so sure...????

[DoubleBrookMaple]

Don't make a pre-filter. It can be counter productive. The niter when mixed in with the filter aid (FA) actually aids in the filtering. I hope a plywood frame is OK for food contact. I'll let others address the chamber question.

No pre-filter is being made. I only called the chamber plate a "pre-filter".
The plywood is Meranti marine grade, and pressure treated at 30 psi @ 200 deg with pharmaceutical grade mineral oil. I considered treating the inside edges of the plywood with Dow Corning 732, which is what the rear pressure plates have in them. This is the only silicone certified NSF 51 and NSF 61.
I considered the food safe issue. I am very concerned about this, and these are my thoughts on that.

Really, I think we have to be practical sometimes. The syrup is passed through the filter under pressure, and it seems highly unlikly that any of the glue would leach out and contaminate the syrup. Maybe the plywood could not technically stand up to the NSF standards, but like I said, we need to be practical. Having worked with engineers for years, and dealing with those who only leaned on text book knowledge, and those who had field experience, the practical engineer would sometimes authorize things a youngster would not.
This is how I feel about this. I will not expect plywood to stand up to certification, but feel reasonably confident that my syrup will not be unsafe. I would feed gallons of this to my children and grandchildren without missing any sleep.

Now that I have rambled, maybe someone will please respond to my question. How many plates, and how deep?

[CharlieVT]

Not so sure...????

I suspect folks are trying to kindly suggest that pumping hot syrup through your plywood frames will result in contamination of your syrup. That's certainly what I was thinking when I saw your project. Sorry to say but I think you need to come up with some other material for that component of your fabrication.

[CharlieVT]

......
Now that I have rambled, maybe someone will please respond to my question. How many plates, and how deep?

Try this:
http://www.uvm.edu/~pmrc/filter_press_brochure.pdf

[Scribner's Mountain Maple]

I suspect folks are trying to kindly suggest that pumping hot syrup through your plywood frames will result in contamination of your syrup. That's certainly what I was thinking when I saw your project. Sorry to say but I think you need to come up with some other material for that component of your fabrication.

I would have to agree. I have used nearly every kind of plywood available and wouldn't want to eat or drink anything that made contact with any of them. Maybe you could find something to coat it with to seal it from the syrup.

[CharlieVT]

The plywood is Meranti marine grade, and pressure treated at 30 psi @ 200 deg with pharmaceutical grade mineral oil. I considered treating the inside edges of the plywood with Dow Corning 732, which is what the rear pressure plates have in them. This is the only silicone certified NSF 51 and NSF 61.
I considered the food safe issue. I am very concerned about this, and these are my thoughts on that.

Really, I think we have to be practical sometimes. The syrup is passed through the filter under pressure, and it seems highly unlikly that any of the glue would leach out and contaminate the syrup. Maybe the plywood could not technically stand up to the NSF standards, but like I said, we need to be practical. Having worked with engineers for years, and dealing with those who only leaned on text book knowledge, and those who had field experience, the practical engineer would sometimes authorize things a youngster would not.
This is how I feel about this. I will not expect plywood to stand up to certification, but feel reasonably confident that my syrup will not be unsafe. I would feed gallons of this to my children and grandchildren without missing any sleep....

You have a nice looking project, I hate being one to rain on your parade. But I think the argumentation you use to be confident in the purity of syrup run through this press is highly speculative at best. The syrup is going in the press hot and pressure will force it into the plywood laminates. Those laminates are held together with adhesives of chemical composition unknown to you. When you shut down the press and the pressure is reduced, how do you know that the hot syrup hasn't solubilized some of the chemical components of the adhesive in the plywood? And how much of that material is going to weep out when the pressure is reduced and the press cools? You may be correct in stating that it won't, but you certainly don't know for sure.

If you are going to use the syrup run through this press for anything but your own consumption, you have to consider that your product reflects on the maple industry as a whole. We hope to maintain a system of voluntary certification.

[FDA]

No pre-filter is being made. I only called the chamber plate a "pre-filter".
The plywood is Meranti marine grade, and pressure treated at 30 psi @ 200 deg with pharmaceutical grade mineral oil. I considered treating the inside edges of the plywood with Dow Corning 732, which is what the rear pressure plates have in them. This is the only silicone certified NSF 51 and NSF 61.
I considered the food safe issue. I am very concerned about this, and these are my thoughts on that.

Really, I think we have to be practical sometimes. The syrup is passed through the filter under pressure, and it seems highly unlikly that any of the glue would leach out and contaminate the syrup. Maybe the plywood could not technically stand up to the NSF standards, but like I said, we need to be practical. Having worked with engineers for years, and dealing with those who only leaned on text book knowledge, and those who had field experience, the practical engineer would sometimes authorize things a youngster would not.
This is how I feel about this. I will not expect plywood to stand up to certification, but feel reasonably confident that my syrup will not be unsafe. I would feed gallons of this to my children and grandchildren without missing any sleep.

Now that I have rambled, maybe someone will please respond to my question. How many plates, and how deep?

Is the dow 732 food grade? Is that the silicone they use for implants?

[DoubleBrookMaple]

Is the dow 732 food grade? Is that the silicone they use for implants?

Like I said, it is the only RTV silicone certified NSF 51 and NSF 61

"Food Grade" or "FDA Approved" are something I am very careful about. The FDA does not approve these materials. They can claim to meet FDA standards, but you have no quarantee. To be sure, one must depend on NSF, as we use UL listed. Underwriters Laboratories tests products, as does NSF.

I DO NOT solely depend on manufacturers for my information.

Ref: NSF http://www.nsf.org/

You can do a search by product type, or manufacturer. THis is an amazing site. Dow Corning 732 is listed NSF 51 and NSF 61. The only RTV silicone NSF 61 certified that I found. This is for liquid submersion, and it is rated to nearly 400 F.

Here is the Dow Corning 732 information. Look at the charts, and you will see all the approvals you can verify on the NSF website. They also ref FDA 21.

http://www.dowcorning.com/content/publishedlit/80-3258.pdf

Hijacked my own thread.

Please read my original post and let me know how may plates and what depth I can use.

[gmcooper]

To answer your question on number of plates for what you have mentioned for total gallons to filter you appear to have enough capacity with what you have in the photo.

[DoubleBrookMaple]

Thanks...

I didn't know if the chambers were to small.

[maple flats]

A very likely scenario in you press use would be to pressurize it, by pumping a mixture at about 200 degrees and up to 30 or 40 PSI thru the filter. No problem yet as long as the plates hold the pressure and I doubt they'd fail yet. Then you shut the press off when done. While the press pressure falls to zero, a blend (however slight) of syrup and adhesive oozes into the filter press discharge hose. It either makes it out the end into your canner or whatever you are pumping to, or it may just set in the hose until next use. Next time you use the press, anything that was left in the hose is immediately deposited into your mixing tank as you run the press and begin passing the syrup thru the filter after blending in the FA. You now have a trace amount of an illegal added substance. By law syrup must be pure, with nothing added or blended in unless it is specified on the label. Food safe or not, it is illegal and very possibly could result in a very large fine if you were to sell the syrup and it was tested. I'm not familiar with Vermont's laws but I know in New York State we are randomly tested and with Vermont's proud tradition I'll bet they are very careful about what is sold as pure maple syrup.
My suggestion, if the purchase of a filter press is not in the cards for you, just use flat filters. Even some large producers only use flat filters and a few use FA with the flat filter for more clarity. The filter aid (FA) does not pass thru flat filters or the papers used in a press, so you are maintaining a pure product.
If you want to make a filter press, I suggest you build one out of a food grade super tough heat tolerant plastic like Leader has done.

[PerryFamily]

Well put Flats...
Its just not a good idea. Its things like this that will have the government knocking on the sugarbhouse door every year for Inspections!!

[NH Maplemaker]

esleighton, Now that you have done the hard work designing you press, Why not take one of the plywood piece to someone (metal shop) with a with a flame table. They could use your plywood piece as a pattern and cut you some from metal of your choice ! A lot of the newer ones are using aluminum.
Like everyone else, I do not think you should use plywood! If the plywood came from China who the Hell knows what"s in it !!!!

[CharlieVT]

A very likely scenario in you press use would be to pressurize it, by pumping a mixture at about 200 degrees and up to 30 or 40 PSI thru the filter. No problem yet as long as the plates hold the pressure and I doubt they'd fail yet. Then you shut the press off when done. While the press pressure falls to zero, a blend (however slight) of syrup and adhesive oozes into the filter press discharge hose. It either makes it out the end into your canner or whatever you are pumping to, or it may just set in the hose until next use. Next time you use the press, anything that was left in the hose is immediately deposited into your mixing tank as you run the press and begin passing the syrup thru the filter after blending in the FA. You now have a trace amount of an illegal added substance. By law syrup must be pure, with nothing added or blended in unless it is specified on the label. Food safe or not, it is illegal and very possibly could result in a very large fine if you were to sell the syrup and it was tested. I'm not familiar with Vermont's laws but I know in New York State we are randomly tested and with Vermont's proud tradition I'll bet they are very careful about what is sold as pure maple syrup.
My suggestion, if the purchase of a filter press is not in the cards for you, just use flat filters. Even some large producers only use flat filters and a few use FA with the flat filter for more clarity. The filter aid (FA) does not pass thru flat filters or the papers used in a press, so you are maintaining a pure product.
If you want to make a filter press, I suggest you build one out of a food grade super tough heat tolerant plastic like Leader has done.


Dave, thanks for your post. As I have said before, I have always been appreciative of the time you take to post on this site.

Eric, I am a "dyed in the wool" DIY'er (Do It Yourselfer), and I appreciate the effort and ingenuinty you have show in fabricating your filter press. Sometimes my DIY projects come to abandonment, and while discouraging, I accept the outcome. I suspect you originally posted in hopes that someone would appreciate your project; indeed I do. But our concerns for syrup quality remain. I suspect that if you were to ask the good folks at Vermont Sugarmakers Association who run the voluntary certification program about your filter press, they'd have some concerns as well. Check this site:
http://vermontmaple.org/sugarmakers/certification-program/

I suggest:
1) try your current setup with hot syrup and see how it works, but don't feed the syrup to anyone but yourself,
2) continue your fine efforts at a home-brew filter press, but look for a different material to fabricate the plates from,
3) "bite the bullet" and buy a filter press,
4) go with a gravity filter. This method has been used for generations and is still used by folks who make some mighty fine syrup. The syrup may not be as clear in a glass bottle as syrup that has been press filtered, but much quality syrup has been made using gravity filters and still is.

I'm not too far from Readsboro. I have an inventory of flat filters that I am not using, both the pre-filter and the synthetic flat filters that I would happily give you. I'd even deliver 'em to you for the priviledge of meeting you.

There is a learning curve in sugar making, as in all things. I have to laugh at myself when I considered washing 20 year old tubing for reuse (I bought the contents of a sugar operation) until I read about the consequences of bacteria in old tubing. Two steps forward, one step back....

Seriously, I'm retired.... send me a message on this site, we'll work out a time and I'll drive over with a bunch of gravity filter membranes for your coming season and we'll tell stories and share lies....:D

[TunbridgeDave]

A short stack 7" press has 3 frames and can easily handle up to 10 gallons of syrup. They are 1" thick though. Late season syrup will be harder to filter and you may get only 5 gal. You also have to add more filter aid. My concern other than the plywood issues is your pressure plates. How thick are they? I'd be willing to bet they will flex under pressure and you will get leakage at the top and bottom. I would beef up your angle iron somehow so it's not just squeezing across the middle.

[DoubleBrookMaple]

Thank You all for your valued input.
Sometimes we have to take a step back and take a new approach because we are determined to make something work. People hurt themselves doing dangerous things like standing on top of a step ladder to get the job done. I was blinded by my own determination.
I have spent hours of research on food safe products as one can imagine from my previous post. The materials I went through, and had to cross off my list was extensive. Plastics were not rated high enough in temperature (LEader's press is molded plastic, Aluminum raw stock thick sheet was expensive I thought, and not easy to machine for me. (by the way... many people have posted that they do not like to use aluminum and that is what the filter presses are made of).
How would coating the plywood with the NSF 51 and NSF 61 certified Dow Corning 732 sound? This way the syrup would never some in contact with the suspect material. The "waffle" plates already have the sealant, and I could fabricate new chamber plates and seal them with the DC 732 (New plates required because the ones I have are treated with mineral oil, and the sealant would not penetrate and stick) . Would that meet your approval? I have no intention yet, of throwing out the baby with the bath water. I can take what you have presented and improve on the idea.

[wiam]

Been watching this thread. How about HDPE. Specs here http://www.dynalabcorp.com/technical_info_hd_polyethylene.asp looks like it would take temps. Not overly expensive. Machinable with common power tools. My older cast iron 7" press has hollow plates that are about an inch thick. Not 2" like aluminum ones are.

[wiam]

http://www.professionalplastics.com/HDPESHEETSRODS cut to size for what I would say reasonable.

[maple flats]

HDPE is closer, but max. operating temperature is 180 and a filter press would need at least 200 and even better 215. However the melting temp. is 260. HDPE?
If the temp weren't an issue HDPE looks like it would work.

[DoubleBrookMaple]

HDPE is closer, but max. operating temperature is 180 and a filter press would need at least 200 and even better 215. However the melting temp. is 260. HDPE?
If the temp weren't an issue HDPE looks like it would work.

Yes, I considered just this option, but as I stated previously, the max operating temp would be exceeded and all bets would be off when you exceed the service limits of a product. The certification for food safe would not apply technically speaking, although there is certainly a safety factor built in. Usually at least 10%. Believe it or not, I was trying to stay safe. I still think that a layer of a certified safe sealant over the marine grade plywood is better. It is all about contact, and it does not matter what the underlying material is if it is isolated from the food product.

[wiam]

Look at the first link I posted. 110 Celsius. Plenty hot enough. Up to 120 for short time.

[DoubleBrookMaple]

Look at the first link I posted. 110 Celsius. Plenty hot enough. Up to 120 for short time.

Good option. I read the Data Sheet from the other link you sent. There they say 180 F.

Seems like a good way to go. Thanks.

[markct]

Why not Lexan, aka polycarbonate?

[noreast maple]

Thats what I was going to suggest also, Thanks mark. Im not sure about temp. thou.:?:

[noreast maple]

Also Im impressed and glad that you atleast gave it more than a passing thought. thast how things get done ,by trying and improving and try again. I think you have something great with this just dont get discouraged and give up. you can do it , just need to improve alittle. good luck!!!!!!!

[DoubleBrookMaple]

I like the polycarbonate. It is readily available in 1/2 inch sheets (thicker available in laminated sheets), and is not extremely expensive. I paid more for 2 half sheets of marine plywood ($140) than I will for polycarbonate. It can be easily cut, drilled, and most importantly I can use my existing template and router.
http://www.plasticsmachining.com/magazine/199609/polycarbonate.html
The Leader clear plastic filter press I saw up in Rutland may be a molded polycarbonate.

I'll get back on this after I finish my arch, which is nearing completion.

[DoubleBrookMaple]

Did I say thanks for all the feedback?