pressure gauge reads 2 psi ??

[Maplesapper]

Why would our pressure gauge read 2 psi for a 3/16 gravity vacuum ?
We put on one of those engine gauges, the face reads HG one side, psi the other.
We tested the gauge before installing it.

We have 3 separated and identical gravity lines with equal numbers of taps.
Only one of the laterals has a gauge on it as a test.
The first four trees at the top of the hill on this lateral seem frozen maybe, but the rest trees on this lateral are draining down the hill.
As a comparison, all of the trees on the other two lines are dripping.

Even if we had a leak, the gauge would read 0 hg or atmospheric pressure wouldn't it ?
Cannot understand why it reads 2 psi... that would imply back pressure no ?

Thanks;

[GeneralStark]

Assuming your lines all have good slope, where do they drain to? Are they all separate or do you have them connected to each other?

[psparr]

Maybe you have the positive and negative tubing hooked up backwards😄
Or I'm stealing all your vac!http://tapatalk.imageshack.com/v2/15/03/14/ff8fc3e78e126df759f89e4d03571131.jpg Sorry couldn't help it.

[Maplesapper]

Assuming your lines all have good slope, where do they drain to? Are they all separate or do you have them connected to each other?

All three laterals are separate runs, slope over 60' from the last drop.
Each dumps into a 55 gallon drum at the base.
Think trees on the plateau and collection at the bottom of cliff.
PSI just moved to 1 from 2, so I am thinking maybe this is related to thawing of the first few trees in the run.
Will wait for the first major run, and then move the gauge to one of the other laterals.

[Russell Lampron]

When a trees thaws and starts running it builds a pressure that pushes the sap out of the tap hole. That is what you are seeing on your gauge. I wouldn't worry about it until all of the trees are thawed out and running. It should pull a vacuum then.

[Flatlander]

Maple sapper

I am curious. Did you buy a Bosch vacuum/fuel pressure gauge? My local auto parts store had that so I bought it. Had a nice brass hose barb fitting already installed. Fit my 3/16 tubing just fine, but one of the first days, it was reading a couple lbs of pressure as well. then it went the other way to read vacuum. I thought it was because I placed my gauge (uphill) of the highest taps where I tied off the tubing with end of line hook (about 4 ft from the first maple).

[mellondome]

If you have line downhill of your Guage that hasn't thawed out for the day, but trees above the frozen line have, you could show a lot of pressure .

[Maplesapper]

Maple sapper

I am curious. Did you buy a Bosch vacuum/fuel pressure gauge? My local auto parts store had that so I bought it. Had a nice brass hose barb fitting already installed. Fit my 3/16 tubing just fine, but one of the first days, it was reading a couple lbs of pressure as well. then it went the other way to read vacuum. I thought it was because I placed my gauge (uphill) of the highest taps where I tied off the tubing with end of line hook (about 4 ft from the first maple).

Yes, same tool Flatlander-
I suspect the frozen trees are the culprit.
Today is the first sun, so hopefully, we get a good run and thaw to check everything out.

[Locust Farms]

Last year I had several drops disconnect. Suspect foul play at first. Came a snow and no tracks, lines still came off. A few days later hooked up another lateral with several drops and taps,ran out of taps ,went home for lunch, came back cut into line to install drop tee and got sprayed with sap under pressure. Decided trees thawed before the laterals in shade was causing drops to disconnect. Was using make shift 3/16 connections to tap into 5/16 laterals.

Dwight

[DrTimPerkins]

Why would our pressure gauge read 2 psi for a 3/16 gravity vacuum ?

1. Bad gauge.
2. Serious leaks.
3. Error in the way you are measuring it.
4. The reading is right and you have pressure....probably due to the line being frozen somewhere along the way.

If you're sure the gauge is good, and you're pretty sure that you don't have any serious leaks, then describe how and where you are making the measurements? Is the gauge at the TOP of the hill? Is it permanently installed, or are you putting it on the line only intermittently?

[Maplesapper]

Thank you for your response-

I will try to post a picture.
The Automotive gauge reads HG to the left and psi to the right. Maple store was out of stock of gauges.
Before installing, I tested the gauge under vacuum and pressure and it functioned correctly.
The gauge is placed at the top of the hill, permanently installed.
The gauge has a 3/16 nipple with 5 barb fitting; and it is attached against the first tree at the very beginning of the 3/16 lateral.
Then 12" inches downhill of this connection is the first drop and spile into the 3/16 lateral.
There are 15 drops on this lateral with an overall length of 350'.
Think plateau and cliff. The 15 drops are connected over a run of 200', with an elevation drop of 25'.
The remaining 150' is one piece, and has an elevation drop greater than 60'.

We have three completely separate but similar gravity setups on this hill as a comparison.
The other two laterals, are both flowing well, with only infrequent bubbles and long columns of continuous sap.
The lateral with the gauge on it, seems to be flowing more slowly than the other two; with more air bubbles than the other two.

Today we had +5 temps and sun after 12pm.
Sap is flowing out of the spiles, down the drops, and flowing downhill to the collection tank.
All except the first four trees...Upon further review, the first four drops don't seem to be flowing.

The tree with the gauge and the next three trees have sap in the drops; but it isn't flowing downhill thru the lateral.
Last night the gauge was reading 2 psi- unchanged from our original post.
In the bright sun today, the gauge was now reading 9 psi, and the spile at the first tree was leaking sap . I suspect back pressure.
When I pulled out the first spile; you could hear the hiss, and the gauge zeroed out immediately.
Once I re-installed the spile back into the tree, the psi slowly started to build again.
The first three trees still seemed unchanged. The sap seems trapped in the drops.
There does seem to be air bubbles entering the lateral from the "T" where the drop enters the lateral from the fourth tree.

Any suggestions Dr. Tim; as to how best ,methodically start replacing fittings trying to find the culprit.
Thank you for your help.

[Super Sapper]

I would suspect a piece of wood or something is blocking your line at the Tee just past where you do not see flow from the taps.

[BreezyHill]

Sounds to me you have a faulty section of line or a bad fitting.

Since the issue starts at the top check the last of the top four for a blockage at the T and then the line after that point for blockage.

Since the drops are filling and it is not making it to the lateral line then it is possible that the T is faulty and not an open port. Find the appropriate drill size to enter the T and see if is clear all the way thru.

Good Luck!

Ben

[Maplesapper]

Ok thanks Lads-
Off to replace the " T ", as soon as the lines start moving again

[Maplesapper]

Thanks for all the help.

After replacing many of the fittings as I traced the PSI condition.
It turns out, I had mashed the tubing against one side of one of the `` T```s
Thereby, blocking the uphill side, and creating the back pressure.
Was hard to find, since the drop was behaving properly, and the sap was able to exit the other side of the T and resume downhill.

Note to self-
Buy the 3/16 fitting tool instead of trying to fashion a solution using the 5/16 tubing tool.

[BreezyHill]

Glad you found the issue. Sucks having to spend so much $$$ on tools but they usually do pay for them selves in the long run.

Goood Luck!