Too much vacuum?

[jrmaple]

I am considering purchasing a used vacuum pump, it is rated at 50 cfm and will pull 27-28", the only issue is I would only have 350-450 taps on it this year, but by next season I will have 2,000 to POSSIBLY 3,000 taps on it with two of three sap ladders and a booster or two and it is pretty level ground… Whats the opinions? Can damage be done to the lines or to the trees with too much vacuum? Or will it be fine and just overcome the leaks easier and pull a constant high vacuum? The previous owner used it on 1,000 taps for one season and he said it pulled 27" all season long, but when he went to almost 3k taps it hovered at 25 on one of his lines because he couldn't track all the leaks.

[Maplewalnut]

No damage will happen. You can not go higher than the atmospheric vacuum level allowed for your elevation, regardless of how many taps/tubing you have. Tubing is rated for high vaccum. After that it depends on how high vacuum you want to maintain? Are you happry with 24-25 or do you wantt 27+. As you allude to though will 50cfm be enough for 3000 taps, probably if you leak patrol everyday, probably not is you leak patrol once or twice a season.

Good Luck

[GeneralStark]

I am considering purchasing a used vacuum pump, it is rated at 50 cfm and will pull 27-28", the only issue is I would only have 350-450 taps on it this year, but by next season I will have 2,000 to POSSIBLY 3,000 taps on it with two of three sap ladders and a booster or two and it is pretty level ground… Whats the opinions? Can damage be done to the lines or to the trees with too much vacuum? Or will it be fine and just overcome the leaks easier and pull a constant high vacuum? The previous owner used it on 1,000 taps for one season and he said it pulled 27" all season long, but when he went to almost 3k taps it hovered at 25 on one of his lines because he couldn't track all the leaks.

If it has a 3 phase motor you can run it with a VFD and control the speed of the motor for lower cfms and less power consumption. As you add taps, just speed up the pump.

[jrmaple]

It is a gas motor, so I can idle it down or run it high, that's what I was assuming but I didn't want to jump the gun and shoot myself in the foot… Most likely it will be 2k taps, I probably won't reach 3k on this system until 5 years down the road once I let some more trees mature and finish thinning the rest of the woods.

[BreezyHill]

No, damage will not happen on the tubing system or on trees. Upon reaching max vac that's it, nothing more to suck out.
Now on say a Zero tank, after the company filed chapter 13...YES you can collapse those cheaper tanks...several failed while under normal milking use at 15-17" of vac.

9991

This is a pic of my CFM Tester. It will test up to 149 cfm. Rotate the orfice closures to reduce the vacuum reading to find the pumps cfm rating. I use it after rebuilding a pump or to test a pump to see how it is standing up to wear.
The orifice for every 10 cfm is nearly the size of our sap tubing. Your pump would be open to 5 on the tens dial and 0 on the ones dial. The Ones has a much smaller orifice.

On your 50 cfm the lower dial can be open with 4 holes showing and 9 holes on the top dial before the needle will waver. Upon opening the large dial to 5 the needle will drop and you slowly close the smaller dial until the needle holds the desire vac level.

There is a very district possibility that the previous owner was not having a leak issue but had meet the pumps capacity. I have yet to test a pump that did the amount it was claimed to do on the tag. They are either not broke in yet or are already showing wear.

Trees produce gas and sap. Both affect vacuum. a leaky system will have a dramatic affect on lowering your vac readings but if the pump was actually 50 cfm and his system was prone to leaks for one or several reasons he could have easily reached the pump capacity. On my system I design for 100 taps per cfm; but I use an electric releaser that uses no cfms and I am a leak finder. I want as much vac to the last tape as I can get for maximum production.

I would ask the owner if the line that gave him the issues was the furthest from the pump. If so then he exceeded the pumps capacity by sheer number of taps most likely.

I also have limited slope and use several ladders, and my terrain is some sloped to the sugar house but most is not and feeds the ladders.

Booster tanks are really just a balance tank. They don't increase your vacuum just even the highs and lows of surges. If you put in 3 3 gallon "booster tanks that is another .5 cfm of space that will need to be evacuated every day by your pump and a source of potential leaks. BUT if you are using these in a ladder design then it is a managed risk.

I will not expound further unless you wish.

Keep chasing those dreams!

Ben

[maple flats]

If you use blue maple tubing you can't get too much vacuum. If you use black tubing for mains, if a section gets direct sun enough to warm it to the point of getting soft, you can collapse it, but that is only remotely likely without a warm day with lots of sun hitting the black piping.

[BreezyHill]

If you use black tubing for mains, if a section gets direct sun enough to warm it to the point of getting soft, you can collapse it, but that is only remotely likely without a warm day with lots of sun hitting the black piping.

Dave what kind of tubing was this you had fail?

I run 28+" Last season the gauge was running just under 30 and the temp was 70 with the strong April sun beating down and none of the tubing even drooped.

[maple flats]

I didn't personally, but someone (Their name escapes me) I was talking to at one of the winter conferences at VVS school said it had happened to them.

[nymapleguy607]

I heard of it happening to a couple Vermont producers the year that we had 70 degree temps and lots of sun. I have never seen it before.