Sap-Locked on Shurflo 4048 3/4 in Mainline

[zandstrafarms]

This is our first year running lines, much less hobby vac.

We have a fully automatied shurflo 4048 set-up running solar with auto temp shut-off AND lightbulb heater during cold temps with two batteries as backup. All our eletronics are functioning perfectly, but the lines not so much.

Things were smooth until we got a heavy flow this week, and suddenly our pump seems to not know how to handle it. Sap locked up in the mainline and eventhough pump was runing, it wouldn't pull the sap. Unscrewing the line filter a bit allowed enough change to re-charge the system (then screwed it back in) and it began sucking all the loaded sap out. We have a VERY gradual slope to the pump, PLUS from other tips we made sure the last 2 feet of the mainline were hard plastic 1/2 in tubing going into the pump (they said it helped keep pressure). Filter is not clogged, but soon as the line empties it re-loads with sap and stops pullingit agaain.

We are runing the shurflo 4048 with 600 feet of mainline 3/4" and 100 taps on about 15 lateral lines using 5/16 tubing. Vac was so good when flow was low that it sucked it right uphill on areas I hadn't finished adjusting gradient on. Our mainline drops a full 5ft from end to start, our land is very lightly sloped.

We JUST bought a vac gauage today (hard to get locally), but I don't have fast moving bubles, not leak sounds. All latterals seem to move VERY slowly, or little to none.

Am I corfrect that an air-leak will ALWAYS cause fast running bubbles?

One thing Id like to add is we also had several hard freezes and the taps all began leaking at the taphole (just read that they may need to be tapped back in a bit thanks to the freeze), if I had several taps slightly unseat would that cause vac to be low without any fast air-bubbles?

*****PLEASE NOTE: ****** the 4048 has a BUILT IN re-circulator line to keep the dia[hram wet. It IS adjustable, is this my issue? Maybe it needs adjusting? Do I want more liquid coming back or less?

Thanks!

Suzanne

[foursapsyrup1]

I have a very similar setup with a shurflo 4048. The mainline backs up a bit then the shurflo kicks in. Drawing 27 lbs - sounds good to me.

[Super Sapper]

If the sap is not running from the trees your sap will just sit there even with good vac.

[zandstrafarms]

"your sap will just sit there" that does answer another aspect we were pondering, especially in the evening when temps drop. Didn't know if sap was suppossed to get fully sucked out at night before pump turned off.

However, when the sap is flowing "well" and backs up, it backs up all the way to the taps. We are just really concerned we are losing potential sap. Am I correct in understanding if my vac is reading high that I shouldn't worry about it backing up?

"foursapsyrup1
I have a very similar setup with a shurflo 4048. The mainline backs up a bit then the shurflo kicks in. Drawing 27 lbs - sounds good to me." Did you have to adjust your internal bypass at all? I know that by adjusting that you can prevent the pump from "not engaging", although not sure which is a better way to turn it. clockwise increases pressure needed before it turns off and counterclockwise decreases it. least amount is like 10, factory set to 30, and max is like 65.

[Biz]

It is most likely an issue with slope or lack of slope on the mainline. If mainline is flat or there are any dips in the line at all that might gather sap, or rises that might create air pockets, the diaphragm pump will not work well, there will be air pockets and you can get surging. See if there is a way to modify the setup even temporarily to remove all sagging and flat spots, and see how it responds. Multiple 3/16" runs would immune to this effect even on flat ground when connected to a diaphragm pump so this might be an option to try another time if you can't fix the 3/4.

Dave

[mol1jb]

It is most likely an issue with slope or lack of slope on the mainline. If mainline is flat or there are any dips in the line at all that might gather sap, or rises that might create air pockets, the diaphragm pump will not work well, there will be air pockets and you can get surging. See if there is a way to modify the setup even temporarily to remove all sagging and flat spots, and see how it responds. Multiple 3/16" runs would immune to this effect even on flat ground when connected to a diaphragm pump so this might be an option to try another time if you can't fix the 3/4.

Dave

This was my thought as well. Check for sags in the main.

[zandstrafarms]

I'm wondering that too, the gradient seems to be very slight, but it IS a longer span between supports due to lack of trees. So maybe tying it off somehow to a far tree may help. I checked this morning and it was sending giant air bubbles backwards down the mainline from the pump, and backed up 6 feet. My laterals seems to be running, some faster than others.

But my boyfriend keeps insisting the issue isn't the line, but the pump and that the pump isn't 'releasing pressure and allowing air back into the line". he wants to add a pressure release or air intake section to the pump . . . am I correct to assume the pump already has this built in and that's why it's sending air backwards and that he's just beating a dead horse?

[Biz]

The pump won't send anything backward into the line. It only pumps forward, it's pretty simple, and you do not need any air inlet or venting. The only pressure control is at the outlet side, if it builds up pressure on the outlet side (not inlet vacuum) it will turn off at I think 60 psi.

If sap is running, you can get really good flow when all the lines are closed other than the taps into the trees. If the 3/4 mainline has a constant downward pitch then you won't have bubbles in it and I think you will have a lot better sap flow. Bubbles are a sign that there is a sag somewhere.

Dave

[zandstrafarms]

ok, that makes sense. We did get a vac gauge up and it read 17", and that was off a lateral line 100 feet down. However, I did notice yesterday an area of line maybe 250 feet down that looked like it had a slight dip, would this affect the pump and be causing the issue, even this far back? I plan to fix it this morning anyway, but I'm really hoping this is the issue because the approach to the pump seems pretty solid.


On a side note, despite my pointing out that many people run their discharge line verticle to a tank, my boyfriend decided the issue with the pump MUST be the discharge end not being gradiented (eventhough I'm telling him everyone on here says it's the mainline). So he went through last night and strung a wire on the discharge line (400 feet long). I supposse it's just as well considering the hard freeze we are about to have, and the last one popped our connections apart on the discharge end. Guess I'll hve to sneak out get it adjusted when he's not looking

[mol1jb]

Is there a freeze in the discharge line? 400 ft is long and if it would freeze it would cause issues as well