Tinker & Rasor SR-2 User Manual

Web: www.tinker-rasor.com E-mail: [e-mail]

107-108

– 1 –

CORROSION MITIGATION INSTRUMENTATION

P. O. BOX 1667 SAN BERNARDINO, CA 92402 TEL: [phone] FAX: [phone]

PRODUCT INSTRUCTIONS

MODEL SR-2 SOIL RESISTIVITY METER

DESCRIPTION:

The Model SR-2 Soil Resistivity Meter is an electronic instrument useful in finding the resistance of soil at
various depths.

Uses:

• New Pipeline Surveys

• Direct Assessment Surveys

• U.S.T. Surveys

• Anode Bed Installations

• Geological Surveys

• Archeological Surveys

The instrument may be used with either two (2) or four (4) pins, which are set into soil in a straight line, at
equal distances. The Pins are named C1, P1, P2 and C2. Voltages are driven between C1 and C2, while
resistance drop is measured between P1 and P2 (4 pin method). In the two-pin method, the resistance drop
is measured between C1 and C2 only. The distance between the pins is equal to the depth of the soil
resistance.

The four (4) pin method has been standardized by ASTM (astm.org) as Standard G57-95(a), and this
method is also described in NACE Internationals, Peabody’s Control of Pipeline Corrosion, Second
Edition, pg. 84. (nace.org)

FEATURES: APPLICATIONS:
Simple Operation, Easy to Use Wenner 4 Pin Method
3 Megohm Range 3 Pin “Fall of Potential”
Data Logger connection 2 Pin Method
Internal rechargeable battery with Low Battery indicator Soilbox (Lab) tests
Common Pin Spacing multipliers and formula included on lid
Charging Indicator (LED)

CONTENTS:

(1) INSTRUMENT
(1) 9v BATTERY (replaceable)
(1) 12v BATTERY (rechargeable)
(1) BATTERY CHARGER (110v)

(1) INSTRUCTION MANUAL

OPTIONS AVAILABLE SEPARATELY:
Model DL-1 Data Logger cable
Test Cables and Reel
Earth Pins

DIMENSIONS:
10 ½” x 9 ⅝” x 4 ¾” (266.7mm x 244.48mm x 120.65mm)

WEIGHT:
6 ¾ lbs. (3.06 Kgs)
8 lbs with domestic packaging (3.63 Kgs)
9 lbs with international packaging (4.08 Kgs)

Web: www.tinker-rasor.com E-mail: [e-mail]

107-108

– 2 –

CORROSION MITIGATION INSTRUMENTATION

P. O. BOX 1667 SAN BERNARDINO, CA 92402 TEL: [phone] FAX: [phone]

PRODUCT INSTRUCTIONS

MODEL SR-2 SOIL RESISTIVITY METER

PRECAUTIONS:
The Model SR-2 can be used only in non-hazardous locations.
Do not measure across energized circuits. Damage to instrument may occur.

OPERATION:

Find a suitable location in the area where the survey is to be made.

Locate an area that will allow for the desired pin spacing (5’, 10’, 15’, 20’, etc) and also allow the operator

to make slight adjustments in location to avoid any subsurface impedances such as rocks or foreign
materials that do not allow the pins to be inserted into the soil. The soil should be of the same type along
the entire path of the pins C1, P1, P2 and C2. Any non-conductive bodies along the surface of the soil, such
as frozen soil, rocks and boulders, air pockets, etc, will affect results.

Place the pins in a straight line along the path of the survey. The distance between each pin should be
identical. The distance between each pin (Pin Separation) is equal to the depth of the soil resistance as
indicated by the Model SR-2. (Wenner 4-Pin Survey standard, ASTM G57-95a, www.astm.org)

Connect cables between each pin and the corresponding terminal on the Model SR-2 panel.
C1 and C2 are color coded on the Model SR-2 as BLACK. P1 and P2 are color coded RED. The terminals
allow for banana jacks or spade connectors.

WENNER 4 PIN METHOD:
Connect C1 on the SR-2 panel to the first pin, closest to the instrument. Connect C2 on the SR-2
panel to the last pin, farthest from the instrument.
P1 should be connected to the second pin from the instrument, and P2 to the third pin from the
instrument.
(Please see diagram 1, below)

2 PIN METHOD: Similar to the 4PIN method described above. Measures the impedance between
C1 and C2 only. This method is can be useful in troubleshooting the 4 PIN method. See
Troubleshooting guide later in this manual.

After making the connections from the pins to the terminals on the Model SR-2 panel, the instrument is
ready for use.

Locate the RANGE SELECTOR switch on the Model SR-2 panel. Ensure this switch is moved all the way
counter-clockwise (left), so that they white dot on the knob of the switch is pointing towards the arrow
labeled START HERE. (See picture 1)

NOTE: White dot may not line up exactly with the arrow.

Move the pin selection slide switch labeled 2 PIN 4 PIN METHOD to the appropriate position. This
switch is located just under the terminals area. (See picture 1). When in 4 PIN METHOD position, all four
connections will be read (C1, P1, P2, C2). When in 2 PIN METHOD position, P1 will be shorted to C1 and
P2 will be shorted to C2.

Push down on the circular area labeled PUSH TEST, and hold this button down during the test.

Web: www.tinker-rasor.com E-mail: [e-mail]

107-108

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CORROSION MITIGATION INSTRUMENTATION

P. O. BOX 1667 SAN BERNARDINO, CA 92402 TEL: [phone] FAX: [phone]

PRODUCT INSTRUCTIONS

MODEL SR-2 SOIL RESISTIVITY METER

The Test Indicator LED just above the PUSH TEST button will light during testing. If this LED is
blinking, the battery is low and will need to be charged within 24 hours. (See CHARGING below.)

If the LCD display shows “1_ _ _.”, move the RANGE SELECTOR switch one position clockwise (right),
and hold the PUSH TEST button down for 3 seconds. Repeat this procedure, moving the RANGE
SELECTOR switch one position clockwise each time, and holding the PUSH TEST button down for 3
seconds at each position.

When the LCD display shows an actual number, meaning the display changes from 1_ _ _. to something
like 3.9 or other, this is the result of the resistance of the soil. Do not move the RANGE SELECTOR
switch any further.

Make note of the number displayed on the LCD meter.

The Wenner 4-PIN Method describes a formula to be used to convert these results into Ohm-cm. This
formula is found in the ASTM G57-95(a) standard, as well as the Peabody’s Control of Pipeline
Corrosion,2nd Ed., pg. 87.

FORMULA:
The table below shows common distances and the multipliers to use for them.

COLUMN A

COLUMN B

PIN

SEPARATION (m)

MULTIPLIER

PIN

SEPARATION (m)

MULTIPLIER

RESULT

5 ft. (1.52m)

957.5

5.2 ft. (1.58m)

1000

(Range Selector) x (Display)

10 ft. (3.05m)

1915

10.4 ft. (3.17m)

2000

(Range Selector) x (Display)

15 ft. (4.57m)

2872.5

15.7 ft. (4.79m)

3000

(Range Selector) x (Display)

20 ft. (6.10m)

3830

20.9 ft. (6.37m)

4000

(Range Selector) x (Display)

25 ft. (7.62m)

4787.5

26.1 ft (7.96m)

5000

(Range Selector) x (Display)

NOTE: The middle column shows pin separations that are uncommon, but make the math much
easier, as the multipliers are round numbers.

SAMPLE EQUATIONS:

Example Formula COLUMN A:
Using 5 ft. Pin Separation

Meter shows 37.9

Range Selector Switch
is in Ohm range (x1)

(957.5) x (1) x (37.9) = 36,289.25 Ohm-cm
or 36.289 K ohm-cm

Example Formula COLUMN B:
Using 10.4 ft. Pin Separation

Meter shows 0.39

Range Selector Switch
is in KOhm range (x1,000)

(2000) x (1000) x (0.39) = 780,000 Ohm-cm
or 780K Ohm-cm

FORMULA:

ρ, Ω x cm = 2 π a R (a in cm) = 191.5 a R (a in ft)

R = average resistivity