Will Buries Vacuum and Sap Pipelines Freeze

[Tmeeeh]

We are contemplating burying both vacuum and sap pump back pipes.

We would be using 2" Vacuum line going 2,000 ft. to a releaser with 1,400 taps on it. 1,000ft of that 2" pipe would have to be buried, going through a culvert under one road and buried under a driveway. The minimum slope of the buried part will be 3%. The pump back pipe would be 1" and buried with the vacuum line and drain back to the a tank when the pump is not running.

The buried section will be no less than 3 feet deep.

We would be sure there are minimal sags in the installed pipes.

Given that the pipes will be in a forzen environment in some places (under the driveway where the frost goes deeper, inside the culvert, and where the pipes enter and leave the ground) What is the risk of the pipes filling with ice?

If there is significant risk of the pipes plugging with ice we will go to plan B

Would love to hear from those of you who have experience with this.

[wiam]

I have about 1600' buried. 1.25" for vac and 1" for pump line. This is for 1000 taps. Most is about 4' deep. There is a sag in the middle part. The only place it has ever froze is where it is not underground. I have had releaser and moisture trap failures so I know there is liquid in the vac line. I think this is a problem for vac transfer. I am going to set up a double moisture trap at the releaser end before next year. Mine goes over a hill. The sap tank is actually higher than my sugarhouse and will siphon after I get it going with a pump.

[Tmeeeh]

I forgot to mention that the vacuum pump will be 60 feet higher than the the releaser. Would a moisture trap still be needed? Vacuum can't suck sap that high. I definitely wouldn't want sap getting in the new vacuum pump I'm planning.

[maple flats]

Observe the action in a sap ladder when air is leaked into the tubing. A vacuum can't draw a column of liquid up 60' but with air which the pump is always drawing and it can lift a long ways. It would just be a mist, but a a slug is possible and a pump will not like it. I'd have a moisture trap, the trap is far cheaper than the damage that could happen to the pump if liquid hit it.

[Randy Brutkoski]

oil cooled or liquid? You might have already said , but if liquid, it will be pointless having a trap. But highly recomended for an oil cooled.

[Tmeeeh]

We are planning to replace the Bosworth diaphragm pump and the water cooled liquid ring pump with a single Airtech oil cooled or a Bush air cooled pump. Definitely don't want water or sap to go into the pump! The pump will be 60 feet above and 1,000 feet away from one releaser and 2,000 feet and 160 feet above the other. Both dry vacuum lines slope continuously down to the releasers..no sags.

[Amber Gold]

I'd put two moisture traps in, one at the releaser to keep a slug of sap going into your vac. line, then second at the vac. pump to catch any moisture which settles out of the vac. line.

I've got a vac. line which has gotten sap most of the way to the releaser....probably 60' in elevation difference. I've had to drain it a few times because of frozen sap in the line.

[batsofbedlam]

I have a 1 1/2' wet line/ dry line system running through a street culvert. I was concerned about freeze ups so I have a third line installed as a backup. It turns out that I never had a freeze and and the wet line flowed all season long. My secret is to make sure there is some slope towards the releaser and I kept the pump running 24/7. I use a Busch vacuum pump set to 20 hz., and it used very little electricity.

[wiam]

oil cooled or liquid? You might have already said , but if liquid, it will be pointless having a trap. But highly recomended for an oil cooled.

This is true for the pump protection. But not to keep liquid out of the vac line.

[gmcooper]

Where your lines run under the driveway or any other spot you feel it might be in danger of freezing put a layer of 1" foam insulation over the top of the pipes. We use this frequently in construction. The water line to my barn is only 18-24" deep because of ledge and it runs 100' under the driveway. No freeze ups and we have been down to -30 more than once.
Mark

[Mark]

With buried main lines I would be worried about a leak and sucking in ground water.
In my neck of the woods a water well has to have the check valve at the well to keep the line to the house under pressure when the pump is off.