DYNAMICS OF SAP AND VACUUM FLOW
Timothy D. Perkins, Director
Timothy
D. Perkins, Director
University of Vermont
Copyright Timothy Perkins, UVM Proctor Proctor Maple Research Center
Maple Res Ctr, May 2010
30
Sap
p Productio
on in 2004 S
Season
(ga
allons - dia
ameter adju
usted)
Effects of Vacuum
25
r2 = 0.969
20
15
10
Microspout
5
0
0
3
6
9
12
15
Vacuum Level (inches Hg)
18
21
24
Vacuum increases sap yield. 50‐200% increase in sap yield using vacuum. Strong linear relationship between vacuum level and sap yield (more vacuum
relationship between vacuum level and sap yield (more vacuum = more sap). Does NOT greatly affect sap chemistry, sap sugar content, or wounding. Copyright Timothy Perkins, UVM Proctor Vacuum level? The higher the better! Detection and repair of leaks is critical.
Maple Res Ctr, May 2010
Fewer taps on a lateral line results in higher production. Vacuum is not propagated well through liquid. When lines are full of liquid, vacuum level at the tree is reduced, resulting liquid When lines are full of liquid vacuum level at the tree is reduced resulting
in lower production. Copyright Timothy Perkins, UVM Proctor “Strive for five, no more than ten” OR
Every extra 5 taps loses ~10% of sap yield
Maple Res Ctr, May 2010
University of Vermont
Proctor Maple Research Center
Underhill Center, Vermont
Control ‐ 5 Taps/Lateral
Martin Block
(High Yield
(High Yield Study)
Chamber Spout Base
One Tap/Lateral
Mainline / No Laterals
Sap
Shed • Initial thinning
• Treatment plots laid out
(12 Plots, Total 775 taps
Avg 65 trees/plot, Avg 14.2” dbh)
• Mainline/tubing installed
Sap shed expanded
• Sap shed expanded
• Vacuum pump installed
• Custom releasers
Red
Series
(Strategies Study)
*
Sugarhouse
*
PMRC Lab *
Main Bush
Main
Bush
(Tubing Comparison
Study)
0
Property Boundary
Tapping Boundary
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
500
1,000
2,000
Feet
Funded By: NAMSC & USDA Grants
High Sap Yields
Treatment 1
Treatment 1. Treatment 2
Treatment 2. Control – Standard Layout
Chamber Spout Base
3/4” Mainline
5/16” Lateral Line
3’ long, 5/16” Droplines, 3‐5 taps per lateral
3/4” Mainline
5/16” Lateral Line
3’ long, 5/16” Droplines, modified chamber spout base
Treatment 3. Treatment 4. One Tap per Lateral
No Lateral Lines
3/4” Mainline
5/16” Lateral Line
3’ long, 5/16” Droplines, 1 tap per lateral
3/4” Mainline
3’ long, 5/16” Droplines, 1 tap per lateral
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
All single‐pipe systems
Very long mainlines
Average of 65 trees/plot
Average of 65 trees/plot
25‐26” Hg
Tapped at the same time
Standard Leader Spouts
& Stubbys (NOT CV)
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
35
31.5
32.1
30.7
29.1
30
Sap Yield (ggal/tap)
25
20
15
10
5
0
5 Taps Per Lateral
1 Tap Per Lateral
Mainline Only
Treatment
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Chamber Spout Base
Mainline Systems have been Optimized
Both single‐pipe and dual‐pipe systems, if sized and installed
properly are able to transfer vacuum to the far reaches of the
mainline system. Research and practical experience have resulted
in systems that function Copyright Timothy Perkins, UVM Proctor very well. Little more can be done here.
Maple Res Ctr, May 2010
Why No Differences in Sap Yield?
Chamber Spout Base results are likely NOT representative due to large number of leaks from both the spout/tree and
from both the spout/tree and
spout/spout base interface. We will repeat this study in 2011 using an improved Chamber Spout Base design or
p
p
g
(more likely) something else.
1. Vacuum is being equally well transferred through all the mainline systems.
2. Sap flow in 2010 was low‐moderate for most of the season and never truly “challenged” any of the systems.
3 Mainline is NOT the major restriction in 3.
Mainline is NOT the major restriction in
tubing systems. Something else is.
4. Other?
So is the system we have now So
is the system we have now
the best possible?
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
What about Lateral Lines and Drop Lines ?
Plastic tubing was originally
adapted from medical and
industrial tubing sources
and tended to be ¼” inside
diameter.
Fittings were necessarily
sized to fit the tubing.
Early
l on, most tubing
b was on gravity. When
h run downhill,
d
h ll having
h
a
number of taps on small diameter tubing served to develop
“natural vacuum”, which increased sap yields.
In current systems, vacuum pumps replace “natural vacuum”,
however this creates a problem of having to transfer gases (from
the tree and from leaks) through the tubing system along with sap.
sap
Copyright Timothy Perkins, UVM Proctor Vacuum is not propagated
well through liquid.
Maple Res Ctr, May 2010
Factors that Restrict the Flow of p
g y
Sap and Vacuum in Current Tubing Systems
Δh = λ (l / dh) (v2 / g 2)
Major Losses
• Type of fluid (capillarity)
yp
( p
y)
• Flow rate (number of taps on a lateral line)
• Pipe length (length of laterals and drops)
• Pipe roughness (dirt/debris/biofilms)
• Pipe diameter
Minor Losses
• Tubing fittings (restrictions, number of fittings on lateral line changes in direction/bends
on lateral line, changes in direction/bends,
merging of sap streams at tees)
• Turbulence
• Gas from tree (gas moves faster than liquid)
Copyright Timothy Perkins, UVM Proctor • Change in flow direction (backflow)
Maple Res Ctr, May 2010
Fitting ID
2.0
Tubing ID
100' 5/16” Lateral line
10 taps
Mod‐High Flow Rate
18
1.8
0.2" 1.6
1.4” Hg
Heaad Loss (ft)
1.4
1.2
1.0
0.9” Hg
1/4 "
1/4 "
0.8
0.6
0.4
5/16"
3/8 "
0.2
7/16"
5/8 "
1/2 "
0.0
0.15
Δh = λ (l / dh) (v2 / g 2)
0.25
0.35
0.45
0.55
0.65
Tubing Diameter (inches)
A loss of pressure that results from friction sustained by a fluid passing through a line,
line
valve, fitting, or other device. Head loss that occurs in pipes is dependent on the
flow velocity, pipe length and diameter, and a friction factor based on the roughness
Copyright Timothy Perkins, UVM Proctor of the pipe and the Reynolds number
of the flow.
Maple Res Ctr, May 2010
2.0
10 taps
Mod‐High Flow Rate
1.8
1.6
Head Loss (ft)
1.4
1.2
0.9” Hg
1.0
0.8
0.6
04
0.4
0.2
1/2” line + fittings
0.0
50
Δh = λ (l / dh) (v2 / g 2)
100
150
200
250
300
Lateral Line Length (ft)
A loss of pressure that results from friction sustained by a fluid passing through a line,
line
valve, fitting, or other device. Head loss that occurs in pipes is dependent on the
flow velocity, pipe length and diameter, and a friction factor based on the roughness
Copyright Timothy Perkins, UVM Proctor of the pipe and the Reynolds number
of the flow.
Maple Res Ctr, May 2010
2.0
100 ft
Mod‐High Flow Rate
g
1.8
1.6
Head Loss (ft)
1.4
1.2
1.0
0.9” Hg
0.8
0.6
0.4
0.2
1/2” line + fittings
0.0
0
2
Δh = λ (l / dh) (v2 / g 2)
4
6
8
10
12
14
16
18
20
Number of Taps per Lateral Line
A loss of pressure that results from friction sustained by a fluid passing through a line,
line
valve, fitting, or other device. Head loss that occurs in pipes is dependent on the
flow velocity, pipe length and diameter, and a friction factor based on the roughness
Copyright Timothy Perkins, UVM Proctor of the pipe and the Reynolds number
of the flow.
Maple Res Ctr, May 2010
14.0
12.25
Mathematical Modeling of
Pressure Loss in Lateral Lines
Peak Flow
10 50
10.50
(many taps, long lines)
10.0
8.75
8.0
7.00
Moderate Flow
6.0
5.25
4.0
3.50
Slow Flow
(few taps, short lines)
1 75
1.75
2.0
1/2” line + fittings
0.0
0 00
0.00
0 05
0.05
Δh = λ (l / dh) (v2 / g 2)
0 10
0.10
Pressure Losss (“ Hg)
Heaad Loss (ft)
12 0
12.0
0 15
0.15
0 20
0.20
0 25
0.25
0.00
0 30
0.30
0 35
0.35
0 40
0.40
Sap Flow Rate (gal/hr)
A loss of pressure that results from friction sustained by a fluid passing through a line,
line
valve, fitting, or other device. Head loss that occurs in pipes is dependent on the
flow velocity, pipe length and diameter, and a friction factor based on the roughness of
Copyright Timothy Perkins, UVM Proctor the pipe and the Reynolds number Maple Res Ctr, May 2010
of the flow.
Fewer taps on a lateral line results in higher production. Vacuum is not propagated well through liquid. When lines are full of liquid, vacuum level at the tree
liquid When lines are full of liquid vacuum level at the tree
is reduced, resulting in lower production. Copyright Timothy Perkins, UVM Proctor “Strive for five, no more than ten” OR
Every extra 5 taps loses ~10% of sap yield
Maple Res Ctr, May 2010
Measurement of Sap Flow Under Vacuum
Two trees (25” and 11” or 16” dbh)
5/16” spout and tubing
Connected to vacuum chamber
22” Hg
Each line runs through an individual Each
line runs through an individual
tipping bucket rain gage
Bucket tips are 7.6 ml (0.002 gal)
Time of each tip recorded with datalogger.
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Tipping
Bucket Bucket
Rain
Gage
Inside
Vacuum
Ch b
Chamber
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Vacuum Measurements
Recording Gages Error limits + 0.1% FS (0.09
Error limits +
0 1% FS (0 09” Hg)
Hg)
Measured at 1 sec intervals
6 locations in dual‐pipeline system
Pump (before moisture trap)
• Releaser (upper stage)
• Mainline (25’ after manifold)
• Mainline end (~300’ from manifold)
• Dropline (4
Dropline (4th tap –
tap – normal spout
normal spout
• Dropline (4th tap – CV Adapter)
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Sap in lines
Pump
Turned On
Natural
vacuum
Vacuum in dual
Vacuum
in dual‐line
line system
system
closely tracks pump
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Vacuum level at the taphole p
slowly decreases during sap run
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Approaches to Reducing Losses Due to Lateral/Drop Line Restrictions
Due to Lateral/Drop Line Restrictions
Dual Lateral & Drop Lines
Chamber Spout Base
(Modified Stubby)
Oversized Lateral Lines
Fall 2008
Spring 2009, Spring 2010
Spring 2010
Spring 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Dual‐Line
Dual‐Line Spout Video
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
30
2009 ‐ Single versus Dual‐Lateral/Dropline
25
Sap
p Yield (gallo
ons/tap)
18.9%
20
15
10
5
Single
Dual
0
2/26
3/5
3/12
3/19
3/26
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
4/2
4/9
4/16
Chamber Spout Base
Chamber Spout Base
½” PVC Fittings
Bushing to mate to a Clear‐Straight‐Through
g
g
(CST) Spout
5/16 Drop & Lateral
5/16”
Drop & Lateral
Line
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
45
2010 ‐ Over‐Sized Lateral Lines & Fittings
with modified Spout Base
ih
difi d S
B
40
18.4%
35
Saap Yield (gal/tap)
30
25
20
15
10
5/16" line
5
1/2" line
0
2/24
3/3
3/10
3/17
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
3/24
3/31
4/7
Summary
Calculations indicate that we are frequently losing up to 2‐4” Hg of vacuum due to lateral and d li
droplines (diameter, length, fittings, etc.) at (di
t l th fitti
t ) t
moderate‐high flow rates, and transiently losing up to 10” Hg at peak flow rates.
p
g p
This represents a 10‐20+% loss in potential sap y
yield during good runs, and up to 50% loss during gg
,
p
%
g
brief peak flow periods.
Does this loss actually occur in the field?
Does this loss actually occur in the field?
Is this an acceptable loss?
Can we do something about it?
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010
Copyright Timothy Perkins, UVM Proctor Maple Res Ctr, May 2010