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I have the 4CFM Commercial pump.
Very nice and so quiet.
I have a few questions about optimizing my recipes.
I get that it would work with the regular recipes, but wondering if it has some tweaks available.
What is the impact from lowering the mtorr setting?
If I lower it, can or should I lower the temp setting as well?
Is there an advantage to going slower on water extraction for pump life?
Thanks,
Nathan
Jim,
If Brent says anything different, listen to him :)
I run 1/3 but do 2 runs on the oil before replacing it.
I am thinking of filtering it before that second run or maybe seeing about getting a third run after.
Either way that strategy has a lot to do with the amount of oil and the ballast.
Since I am not running for a long time on the oil, I default to just leave it closed.
What its doing is limiting the amount of water being collected in the oil. Closed default is better because if you forget and leave it open you will increase your final vacuum on the run. After a few, oh, I forgot, I just leave it closed now.
I figure other than replacing every time I am pretty close to max on protect the pump, but all in would be leaving ballast open until the pressure drops below, say 2000 mtorr. Thats about a 10 min wait and I just dont have the patience :)
The NAVAC manual is for general use and pulling the amount of water from freeze drying is NOT the optimal operation of the pump. I am also using the blue oil. You get some feedback on the amount of water you are pulling from looking at the condition of the oil after use. Water is the enemy for RV pumps. If your replacement cycle doesnt look too bad on the sludge then to me you are optimizing the life of the pump.
Similarly I am thinking that reducing the mtorr slows down the amount of released water vapor (because of the temp ramp) which gives the existing cold trap less of a burden, so more water on the walls and less in your pump.
I didnt do any outgassing of the mats, I didnt smell anything or get any taste that seemed strange. But... DONT EVER put onions on the mats and if you do bake them in an oven for as long as it takes. I had a full load of Onions that hit an earlier bug in the firmware so they just cooked at 117 with no vacuum. It took about 48 hours in the oven at 250 to outgass that. I didnt think about putting them into the vaccum chamber instead with nothing on them.
Thank you so much, Nathaniel. My wife is out getting some fruit (cherries, blue berries, etc) and she asked me that 'nearly' the same question "will the onions cause a cross flavoring of the fruit"? I'm thinking 'yes' with your explaination. So, no onions on the mats!
Just updated the firmware to 17.4, painless operation. The board obviously gets power through the USB 'C' - I was wondering if the unit needed to be energized. Nope, the laptop powered the board. I now have the 'bread run' in the menu, and the mTorr default is now 600 - I think Blue Alpine stepped up and made the decision to help us lengthen the lives of our pumps in V 17.4.
We are dumping the oil after she gets home with some replacement oil. It has one run on it (pseudo bread run) and we are considering it the 'break-in oil'. I'm wondering... what is the 'blue oil'? Blue Alpine suggests using an oil with detergent to minimize the affects of sugars in the evacuated air so we've some dairyland on order but purchased 2 quarts from harbor freight of JOHNSEN'S Vacuum Pump Oil to get us through a few cycles.
Do you filter your used oil after allowing it to separate? I read that you can do this up to three times, then discard the oil.
On fruit, Apples, Bananas, STRAWBERRIES (I add a little bit of Stevia), do really well. If it has a skin like blueberries, cherries, etc. you should poke them to let the water out. Dont do onions or even pickles in the same load as fruit. The blue oil is the dairyland pump oil from the Blue Alpine video. There are some more recent videos about dont use that oil but I think thats for the HF pumps that purge the oil. Yes I let the oil separate by gravity in a jar where it gets drained. Then I will throw it into a HF filter. You want it to be clear. The how many times is just how picky you want to be about pump life. So below Brent has answered keep it OPEN which means it would always be venting water vapor, CLOSED means the water vapor goes into the oil. I would think that having it CLOSED would result in more vapor released at the max run temp giving deeper drying but at the cost of more water in your oil. So my approach is I want a hot rod but a well taken care of hot rod. If you want max pump protection then OPEN is best. I am thinking that I will also use the filtered oil to push out the old stuff on the bottom of the drain. I am getting tired of lifting the pump to get the last bit. On the 1/3 vs 2/3 its really not that much more oil once you get into the site glass. I was going off their old video so will move to 2/3.
Thank you so much, Nathaniel. Not that it's important, but wondering what 17.3 and 17.4 incorporated? Peggy picked up bananas, blue berries, and Ranier cherries. We'll take your suggestions (yea, we are total nubes). The gas ballast valve I had backwards until checking this out:
https://www.leybold.com/en-us/knowledge/vacuum-fundamentals/vacuum-generation/how-does-a-gas-ballast-work#:~:text=2)%20the%20gas%20ballast%20valve,the%20gas%20ballast%20valve%20open).
I'm off to do the first oil change. Glad you mentioned tipping the pump to get the dregs out. Tossing this 1st oil change, I think it may potentially have fine metal particles from manufacturing (although the pump had the remenants of oil in it, maybe for post assembly testing purposes?)
Hey Nathan,
Dropping the mtorrs on the recipes will make them take longer but will make them more delicate. If you are on 2.17.x software then the delicate recipes is about as delicate as you would ever need to get (unless you are doing some medicines or chemicals or something).
The freeze dryer will only heat the shelves as much as it thinks it needs to heat them in order to reach the set pressure. So if you drop the pressure too low, or the vacuum pump cannot pull deep enough, then the heat rack will never turn on.
At the end of the cycle when the food is done, some foods just dont pull below 400-500 mtorr, while others will pull to 200 all day long. So if you drop your pressure too low on the recipe it will never turn on the heat rack. You can drop the pressure to 500 for most recipes, but you would need to do some testing and see if the specific food can go lower if you wanted to drop the pressure lower than 500.
You dont really have to lower the temp setting necessarily, unless the food is turning out shriveled or such. Similar to what I said earlier, lowering the pressure has the effect of slowing the temperature ramp on the tray rack. If the tray rack only has to be at 38F to sublimate off enough water reach 500mtorr in pressure, then it is going to stay at 38F. The lower the set pressure the slower that ramp will be because it will not need to heat as fast to reach the lower set pressure.
Yes, if you go slower on the freeze drying process the pump will last longer. Candy is about the worst it comes for pump life. If you kept all recipes at 500-700 then you would have no problem with pump life. We have actually been thinking about dropping our stock recipes to that rage so that everyone's pumps last longer, then for the people that really need it to be faster for production then they can up their pressures to be faster still.
Thanks
Brent
BA70LFD S/N 000873 Firmware V 2.16.9 - I've lowered the default pressure to 675mTorr, left the default temp at 120 F. I'd like to extend the pump life (NAVAC NRD 4) using the suggested 500-700 mTorr. The manual cites doing a BREAD RUN OVERRIDES to off gas the silicon mats, but that function doesn't exist in the current firmware. Several questions...
Will updating the firmware make the bread run overide available?
I did one 'quick start' run with bread on all mats, it ran for nearly twenty hours before I interupted the dry cycle (9 hours remaining). Will that 'quick start' run suffice well enough to off gas the mats?
The NAVAC OEM manual suggests the sight glass be 2/3 full, the video suggests 1/3 to 1/2. Stick with the OEM manual figure 6 suggestion of 2/3?
The NAVAC manual also cites opening the gas ballast valve for the first half hour, closing the valve once system pressure is reduced to a 'certain level'. Is this the pressure the recipe cites? Is the ambient atmosphere considered a 'condensable gas"? The pump that came with the Blue Alpine has only one open position, there isn't a position 1 and 2. Should I even be concerned about the gas ballast valve, just leaving it closed?
Hey Jim,
Yes updating the software to 2.17.4 will add the bread run button.
The quick start will likley not be good enough for the bread run, unless you change the settings. The bread run operates at 165F from what i remember. The default quick start is only 110F.
Yes for the Navac pump it would be good to keep it at 2/3, we will have to update the video.
For the gas ballast valve, just keep it open all the time for the Navac pump.
The atmosphere is not combustible with food. That would only be the case if you are freeze drying alcoholic beverages for some reason, or something similar.
And yeah like I said, just leave the gas ballast valve open.
Thanks
Brent
Thanks, Brent - I wasn't expecting an answer so quickly. I'll leave the Gas Ballast Valve open, by your direction. I'm not really sure HOW this would make the pump last longer, or get to the vacuum needed for candy. I need to do some studying on these vacuum pumps. Love this unit! I need more ventilation in the well shed, so I'm putting another window on the opposite wall and will run a fan with a 2x2 filter bringing outside air in, exhausting through the window the Blu Alpine is backed up against (it's open, but the fan circulating air in the shed isn't enough - it gets warm but not hot (up to maybe 80 F max). Thanks again!
My room gets pulled up to 77F-80F. As long as the internal chamber temp is getting down then its doing its job. Oh yeah, if you have a fan running but have it blowing over your pump that should help with pump reliability also. Heat is bad and those pumps are working hard for almost continuous runs. But they were designed for it. Candy is easy peasy for this machine.
