Bladder press

That wasn't stupid! I promise that you'll throw rocks at your old ratchet press after your first use.

Nonexistent. Don't leave grape shears in it though!

If you can find some, a coarse stainless steel screen lining the _inside_ is a good idea. Without that, every once in awhile a geyser of must will come shooting out the side - especially if you apply pressure too rapidly.

The short answer: Use the plastic bag!

BTW, once you reach full pressure (~3 bar) you can leave it under pressure _overnight_! You'll be surprised how much more juice you'll get out of your fruit, and this is the stuff with the most extract ("goodies"). You might want to keep the heavy press fraction separate, but FWIW I never do. The next day the pomace will be very dry - even without breaking it down and re-mixing before re-pressing.

Tom S

Well, no, I want it to look nice when I sell it. ;-)

Are you using your house water supply to inflate the bag? Do you start out at a lower pressure and build up as the skins are pressed? How do you control this, just shut the tap off and let it sit until the pressure drops? The guy I'm buying it from just opens the tap and lets the relief valve drain off water when it gets to 3 atm, but that seems very wasteful of water.

Brian

Brian, I know you are asking Tom S, but here is my experience:

I do.

Yes. I try to keep a constant juice flow.

I regulate it by the water tap, starting off slowly, then gradually increase it. I turn the water off when I get to 3 atm and wait about

Just turn off the water when the relief valve engages at 3 atm. Also, to reiterate what Tom S said...definitely use the bag. I tried it once without a bag and got a 360 degree juice spray.

-David

Yes. Yes. And yes - sort of. I shut the valve on the press off until the flow from the press slows to a trickle.

If the pressure regulator is set properly the relief valve never opens at all. Sounds like he has the regulator set _above_ the relief valve set point.

Tom S

I have adapted my bladder press to work on compressed air no leaking water and if the bladder brakes I will not lose my must. I use a small compressor with a valve in the line to shut of the compressor at

There's a pressure regulator on the press itself, or am I misunderstanding?

Where is it, and how do you set it?

Brian

Yes but compressed air is far, far, far, far more dangerous. Compressed gas blows out it throws things. Compressed liquid blows out and it spits. That is why hydraulic systems always use liquid rather than gas. This probably will not change your mind but just to let others know -- this is not a good idea.

Ray

"Ray" wrote:

Ray, I don't know what you mean by "blows out", "throws things" or "spits", but the primary reason that "hydraulic systems" use liquid rather than gas is that the word "hydraulic" means "operated by liquid". If they used gas, they would be called "pneumatic".

The preference for hydraulic systems over pneumatic is that liquids don't compress under pressure like gas does. Thus, the hydraulic brakes on your car becoming "spongy" and less effective when there is air in the lines. Pneumatic systems also require large storage tanks, and heavy compressors, which are impractical for smaller applications.

Household water pressure is more than sufficient to operate the press. An air compressor must be regulated down to ~30 psi or you run the serious risk of rupturing the bladder. However, if you have such a regulator, it seems that compressed air would be preferable. Water hoses often leak, and sometimes burst. Unless you press outdoors (where there are more insects and bacteria to worry about), this could be a problem.

Umm, the grapes you are pressing were grown outdoors. Why would you worry about it? That's what SO2 is for.

Brian

Negodki,

Jim has it right, I'm afraid. What Jim was getting at, is that gases, _because_ they are compressible, store a great deal of energy to get them under pressure.

Think of how long an air compressor must run in order to build up 30 psi in a bladder. All that time represents energy being stored up, just as if one were compressing a spring. If a failure occurs, that energy isn't released in the same gradual way it was stored, it comes out immediately & explosively. Water, of course, doesn't compress and reaches a pressure soon after filling its container. If a hydraulic failure occurs, the only energy being released comes from the elasticity of the container, not the medium. It's really an astounding difference between the two. It's also somewhat counterintuitive, so convincing people is difficult.

A while back, someone here wrote that he once arrived at a winery just after an air-filled bladder press ruptured, presumably under normal pressures. It shattered the thick, 3" wide oak staves of the press and hurled pieces & must for about 50 feet, as I recall. It was remarked that a person in the way would have been killed. This jives with what I know about compressed gas: it's amazingly dangerous.

Please don't take these comments as criticism. It's just that a lot of people were never taught how different the two are, and learn too late.

Besides, we need to keep all the good winemakers on this group alive & posting. ;)

Luck, Mike MTM

"Brian Lundeen" wrote:

Umm, I don't want insects or bacteria in my wine, sulphited or not. Furthermore, I don't wish to add the levels of sulphite necessary to kill the swarm of fruit flies that might find my lees an attractive place to nest and lay their eggs. Nor is it desirable to add sulphite to the wine at the time of the press, when fermentation is still occurring.

Vegetables are also grown outdoors. Yet most people wash the dirt and insects from them before serving them to guests.

Thank you for the explanation, Mike. I'm convinced. :)

misunderstanding?

Well, _mine_ has one anyway. It's just before the gauge. I've never fiddled with it.

Tom S

Tom S

Absolutely right, Ray.

There is considerable potential energy in compressing that much air, which turns into a _lot_ of kinetic energy if that bladder bursts. Someone could be seriously maimed or killed if that happens.

Use water pressure.

Tom S

As I said earlier the pressure relief valve is in the line from the compressor and set at 25psi. When that pressure is reached the compressor shuts down until the pressure drops and then it starts to pump again. Commercial wineries use large horizontal bladder presses which are filled with air to 25psi. and to my knowledge no one has bin injured by one.

That's not the same thing as a wood-slatted basket press. Tank presses are made from stainless steel, and are surrounded by a second layer of steel shrouding. They're _designed_ to run on compressed air. Basket presses are not.

Tom S

wow, as I sit here constantly sipping my own wine, watching this growing thread about your new acquisition, I'm starting to feel my own kind of bladder press...

gotta go before IIIIIIIIIIIII explode!!!!

Rick

Thank you Rick for that vote of confidance.

Beg to differ Negodki. Compressed Gas is dangerous and you are advocating dangerous practices. Liquid is used in hydraulics because it is safe. It does not compress. Or at least very little. If there is a breakage only a few drops of liquid are thrown out as that is all the compression you get. Gas can be used in hydraulic systems just as well as liquid as is being advocated here. The difference is that "when" there is a failure, not "if", then the compressed gas will throw anything it comes in contact with. This can have maiming if not deadly effect. The system he is using was designed to by liquid driven. Using air may work but it certainly does not have the shielding necessary.

Don't intend to get in an argument over this. I have said my peace.

Ray