Model UC - Electrochemical Devices, Inc.

Model UC
Underground Cathodic Protection Coupon
Featuring

Patented 10 sq. cm. concentric coupon removes nearly all soil IR drop error in current-on
measurements

Optional 1 sq. cm. coupon for AC current density measurements

Easily fitted to the base of a test station riser or used in a stand-alone configuration when
fitted with the optional internal zinc reference electrode

Potential measurements are made through the riser tube with either portable or
permanent reference electrodes
Style A (on left) is installed at the base of a
test station riser as shown in drawing UC-9. A
zinc reference electrode can be installed in the
housing as an option.
Style B (on right) can be installed remote from
a test station. It is only available with the
optional internal zinc reference electrode.
Model UC2 (shown) has an optional AC
coupon.
Model UC1 (see drawing UC-7) does not have
an AC coupon.
Specifications:
 10 sq. cm. concentric coupon for IR Drop
free potential measurements
 1 sq. cm. coupon for AC current density
measurements (Model UC2 only)
 2 inch (nom.) PVC pipe construction
 Size - 2 1/2 inches dia. x 10 inches long
(6.4 cm x 28 cm long)
 Shipping weight - 6 lb (2.8 kg) plus wire
The Model UC Underground Cathodic Protection Coupon is fitted to the base of a test station riser. It is
designed to allow essentially IR-Drop free measurements with CP current on. The amount of IR-Drop
error included in a current-on measurement is negligible and can therefore be ignored in routine
measurements. Refer to NACE paper 05039, available on our web site, for quantitative performance data.
Many factors contribute to the magnitude of IR-Drop error at any particular site; therefore it is
recommended that each installation be calibrated separately.
U.S. Patent 6,060,877 – Produced under license.
electrochemical devices, inc.
Web: www.edi-cp.com Email: info@edi-cp.com
Tel: 617-484-9085
Fax: 617-484-3923
Address: PO Box 789; Middlefield, OH 44062
U Series
Underground
Reference
Electrodes
UC4c.doc – 05/15 © EDI 2015
Model UC1
Refer to drawing UC-8 UC2ASY
for version with AC coupon
Style A - Test Station Foot
Style B - Self contained
Use Style A when the coupon is affixed to the
base of a test station. This style may be ordered
with or without the optional zinc reference.
Use Style B when coupon is to be located
remote from a test station. Style B is only
available with a zinc reference electrode.
Endcap to hold factory installed
backfill in place during shipping.
Remove during installation.
10 sq. cm. steel concentric
CP coupon with two 1/8Ø
sensing ports.
2 in. (nom.) PVC end cap
All coupons are internally connected to a
4-conductor 18 ga. cable. The red and
black wires are connected to the DC
coupon, the blue wire is connected to the
optional zinc reference electrode, the
orange wire is not connected on Model UC1.
Specify as EDI Model UC1z-xxx-LWnnn where
z = A for Style A test station foot
z = B for Style B self contained
xxx = BDG for no internal reference electrode (only on Style A)
xxx = ZIN for an internal packaged zinc reference electrode
nnn = lead wire length in feet.
Note: If no lead wire length is specified,
10 feet (3 meters) will be supplied (LW010).
Model UC1 Concentric Coupon Assembly
electrochemical devices, inc.
PO Box 789, Middlefield, OH 44062 440-632-5616
www.edi-cp.com
info@edi-cp.com
© EDI
2015
SCALE
HALF
DRAWN
BY
FJA
DATE
04 FEB 2015
DRAWING
NUMBER
UC - 7 UC1ASY
Model UC2
Refer to drawing UC-7 UC1ASY
for version without an AC coupon
Style A - Test Station Foot
Style B - Self contained
Use Style A when the coupon is affixed to the
base of a test station. This style may be ordered
with or without the optional zinc reference.
Use Style B when coupon is to be located
remote from a test station. Style B is only
available with a zinc reference electrode.
Endcap to hold factory installed
backfill in place during shipping.
Remove during installation.
1 sq. cm. steel coupon for
measuring AC current
10 sq. cm. steel concentric
CP coupon with two 1/8Ø
sensing ports.
2 in. (nom.) PVC end cap
All coupons are internally connected to a
4-conductor 18 ga. cable. The red and
black wires are connected to the DC
coupon, the orange wire is connected to the
AC coupon, the blue wire is connected to
the optional zinc reference electrode.
Specify as EDI Model UC2z-xxx-LWnnn where
z = A for Style A test station foot
z = B for Style B self contained
xxx = BDG for no internal reference electrode (only on Style A)
xxx = ZIN for an internal packaged zinc reference electrode
nnn = lead wire length in feet.
Note: If no lead wire length is specified,
10 feet (3 meters) will be supplied (LW010).
Model UC2 Concentric Coupon Assembly
electrochemical devices, inc.
PO Box 789, Middlefield, OH 44062 440-632-5616
www.edi-cp.com
info@edi-cp.com
© EDI
2015
SCALE
HALF
DRAWN
BY
FJA
DATE
04 FEB 2015
DRAWING
NUMBER
UC - 8 UC2ASY
For PVC Risers:
Cement a PVC reducer
coupling and riser tube to
coupon housing assembly.
For all other riser materials:
Cement a socket x male PVC fitting to
coupon housing assembly as shown
below. This fitting can be threaded into
any appropriate transition piece.
moisture retaining
backfill: 75% sand,
25% bentonite
3 in. (nom.) pipe
EDI SlimLine
reference electrode
(Model US)
3 in. to 2 in. (nom.)
PVC reducer
structure wire
concentric coupon
assembly, style A
Installation
Transfer structure wires to inside the riser
tube by passing them through strain reliefs
on the transition fitting. The riser tube is to
be filled with a moisture retaining backfill.
A suitable reduced diameter reference
electrode may be placed in the riser tube
as shown.
Measurements
Measurements may be made with either a
permanent reference electrode installed in
the riser tube, a portable reference
electrode placed on the backfill in the riser
tube or the optional internal zinc electrode.
Installing a Permanent Reference in a Test Station Riser
electrochemical devices, inc.
PO Box 789, Middlefield, OH 44062 440-632-5616
www.edi-cp.com
info@edi-cp.com
© EDI
2015
SCALE
1/4 & 1/2
DRAWN
BY
FJA
DATE
04 FEB 2015
DRAWING
NUMBER
UC - 9 Riser
structure wire
structure wire
not used
AC current
measurements
made between
these terminals
AC coupon wire
reference wire
Potential
measurements
made between
these terminals
Potential
measurements
made between
these terminals
reference wire
DC coupon
wires
Wiring - Connect a structure wire and one
of the DC coupon wires to a terminal pair
that can be shunted through a switch or
shorting bar. For convenience, a magnetic
switch such as EDI Model UI-MS may be
used. Connect the other DC coupon wire,
the second structure wire, the AC coupon
wire and the reference wire each to their
own terminals.
DC coupon
wires
structure wire
Calibrating - Measure the potential when
the switch is closed and the instantdisconnect potential as the switch is
opened. The difference between the two is
the offset potential which should be
recorded. This offset potential will usually
be less than 10 millivolts.
structure wire
UC2
UC1
Measurements - Measurements can be
made with the switch or shorting bar closed.
In most cases, the offset potential will be
sufficiently small that it can be neglected.
cable
cable
electrochemical devices, inc.
PO Box 789, Middlefield, OH 44062 440-632-5616
© EDI 2015
www.edi-cp.com
info@edi-cp.com
Wiring Connections for Concentric CP Coupon
SCALE
DRAWN
BY
FJA
DATE
09 JAN 2015
DRAWING
NUMBER
UC - 10 WIRING
electrochemical devices, inc.
PO Box 789, Middlefield, Ohio 44062
Tel: 440-632-5616
info@edi-cp.com
Fax: 440-632-3033
www.edi-cp.com
Installation
Instructions
Model UC Underground CP Coupon
The Model UC Underground Cathodic Protection Coupon is designed to minimize IR-Drop error in
measurements made with CP current on. With this unit the amount of IR-Drop error included in a
current-on measurement is negligible and, therefore, can be ignored in routine measurements.
Since many factors contribute to the magnitude of IR-Drop error at any particular site, it is
recommended that each installation site be calibrated separately.
Installation – Style A
1. Remove the yellow protective label covering the steel coupons and place the coupon assembly in a
position reasonably close to the structure being monitored. Be sure to orient the coupon assembly
vertically with the protective plastic cap at the top. Experience and testing indicate that it is best to face
the CP coupon directly toward the structure. Place local soil around the coupon as backfill; make sure
no rocks larger than a centimeter in diameter are within a centimeter of the metal plates. Tamp the
backfill to ensure it is in good contact with the coupons.
2. Remove the protective plastic cap from the top of the coupon assembly; do not remove the cotton cloth
backfill retainer. Cement a PVC coupling or reducer to the top of the assembly using PVC cement.
Cement riser pipe to the coupling.
3. Fill the riser with either screened local soil or a slurry consisting of 25% bentonite and 75% sand or fine
fill. A reduced diameter reference electrode, such as an EDI Model US, can be placed in the riser pipe
prior to filling. If this is done, then the riser fill must consist of the bentonite slurry.
4. Complete the installation by capping the top of the riser pipe as desired. One of the two wires from the
DC coupon is to be connected to the structure through an interruptible shunt, such as EDI Model UIMSC or equivalent. The other DC coupon wire is connected to a meter when making potential
measurements. See wiring diagram overside.
Installation – Style B
Style B coupons have a self-contained zinc reference. They can be placed at any orientation and located
remote from test stations. After removing the yellow protective label, follow the backfill instructions in Step
1 above.
Measurements
In order to minimize IR-Drop error in potential measurements, all such measurements on Style A coupons
must be made with either a permanent reference electrode contained in the riser pipe or a portable
reference electrode contacting the riser fill. In some areas, it may be necessary to moisten the fill to
increase its conductivity to an acceptable level. Measurements on Style B coupons are made using the
self-contained zinc reference. To determine the amount of IR-Drop error, first measure the potential of the
coupon with the shunt wire connected to the structure. Then determine the IR-Drop error by disconnecting
the shunt from the structure and note the instantaneous voltage drop. In most installations the
instantaneous voltage drop (IR-Drop error) will be sufficiently small that it can be neglected in future
measurements.
UCinstall2015.docx-5/7/2015