Does mainline size affect vacuum ?

[TerryEspo]

I was reading an old post, cant find it now. It confused me so now need to ask.

What I was reading made me think that using a larger mainline created a higher vacuum level. Maybe that was for large operations with mucho taps, maybe for real vacuum / releaser pumps and not a Shurflo pump.

So, I ask,,,,Does a larger mainline help create better vacuum ? I was thinking 3/4" mainline this year but maybe 1" is better for my 75-85 taps on Shurflow ??

Thanks.

Terry

[BreezyHill]

Large line transfers more cfm Cubic feet per minute, but on a sure flow that has limited cfm ability there is a theory that a small system to be evacuated is easier for that style of pump to maintain.

Think of it like this:
If you have 500' of 3/4" =11.47 gallons and the same distance of 1" is 20.37 gallons. It will take nearly twice as long to evacuate the tubing. For many years it was said 1/2" can handle 100 and 1" was 500. Now we know that there is a distance and slope factor to these equations and friction is a limiting factor.

But on a relatively small length of tubing and a pump of limited capacity I would think that you would want to keep the area of the vessel(the tubing system)as small as possible to allow the pump to have a smaller area to evacuate to get the highest amount of vacuum as quickly as possible.

Ben

[brookledge]

You can't ever get more vacuum then you have at the pump but what does happen is the ability to transfer the vacuum efficiently through out the main line. The air moves faster than the sap does and if the main line is not big enough it ends up creating turbulents that get the sap stirred up so the air can't move efficiently. That is why many go with a dry line also so that you can separate the gasses from the sap
Keith

[BreezyHill]

I agree your point on a large system of multiply lateral mains and tap counts that near capacity of a mainline.

50 taps on a 500' main under high vac will produce a maximum of 110 gallons of sap at peak flow. 3/4" main on 2% slope has 195 g capacity and 395 at 6% slope.

So after the addition of the last tap the main will be a most half full. Since the distance the sap has been flowing its flow rate has increased and so will capacity of the system at gallons per hour. Since the addition of less sap to a main will have less affect on speed, less turbulence than in past case studies.

Also factor in this is a surflow pump and not a vein or piston pump...low cfm pump. These pumps move the fluid of the system more efficiently than they move air; so mixture of air and sap is a benefit to the efficiency of this pump.

Ben