OfiTE 152-95 User manual

Calcimeter
Gauge-Read Model #152-95
Recording Model #152-96
Instruction Manual
Updated 1/27/2011
Ver. 2.2
OFI Testing Equipment, Inc.
11302 Steeplecrest Dr. · Houston, Texas · 77065 · U.S.A.
Tele: 832.320.7300 · Fax: [phone] · www.ofite.com
©Copyright OFITE 2011

Table of
Contents
Intro.......................................................................................................2
Description ...........................................................................................2
Components.........................................................................................3
Safety ....................................................................................................4
Setup.....................................................................................................5
Recording Calcimeter ......................................................................5
Gauge-Read Calcimeter ..................................................................6
Test Procedure....................................................................................7
Creating a Calibration Curve..............................................................9
Chart Recorder...................................................................................11
Maintenance.......................................................................................13
OFITE, 11302 Steeplecrest Dr., Houston, TX 77065 USA / Tel: [phone] / Fax: [phone] / www.ofite.com 1

The OFITE Gauge-Read Calcimeter and the OFITE Recording Calcimeter
are used to determine the amount of Calcium Carbonate (CaCO3) and
Magnesium Carbonate (Dolomite) in a sample of alkaline earth carbonates
such as oil well cores or drilled cuttings. Calcite build up in drilling fluids
and in water treatment processes causes scaling problems. Data from the
OFITE Calcimeters can help determine the proper chemical treatment.
These instruments comply with the ASTM D 4373 - 84 (Reapproved 1990)
Standard Test Method for Calcium Carbonate Content in Soils. This test
method is under the jurisdiction of ASTM Committee D-18 on Soil and Rock
and is the direct responsibility of Subcommittee D -18.13 on Marine
Geotechnics, published July 1984.
In the OFITE Calcimeter, calcium carbonate and magnesium carbonate are
reacted with 10 percent hydrochloric acid in a sealed reaction cell to form
CO2. As the CO2is released, the pressure build up is measured using
either a pressure gauge or a pressure recorder. During the calibration
process, a calibration curve is created by reacting HCl with pure, reagent-
grade CaCO3. By using a known weight of CaCO3reagent, you can deter-
mine the relationship between the amount of pressure released and the
weight of CaCO3in the sample. Since all reaction cells are slightly differ-
ent, this relationship will be different for each cell. Therefore a calibration
curve is required to obtain accurate results.
The calcium carbonate content of soil (ASTM Procedure D 4373) is deter-
mined by treating a 1 g dried soil specimen with HCl in the reactor cell.
The resulting pressure increase is then measured and compared to the cal-
ibration curve to determine the total weight of CaCO3in the test sample.
The OFITE Gauge-Read Calcimeter (152-95) features a pressure gauge on
top of the reaction cell. With this model, the pressure within the reaction
must be manually read from this gauge.
The OFITE Recording Calcimeter (152-96) includes a transducer and a
chart recorder that automatically records the pressure readings without
user intervention. This model was designed to make the test procedure
easier by enabling you to run it virtually unattended.
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Description
Intro

Components Gauge-Read Calcimeter (152-95):
#142-54 O-ring
#152-95-1 Gauge with Cover, 30 PSI, 4" Diameter
#152-95-2 Bleed-Off Screw
#152-95-3 Cell Cap
#152-95-4 Reaction Cell
#152-95-5 O-ring, 13⁄8" × 1⁄16"
#152-95-6 Sample Cup
Recording Calcimeter (152-96):
#152-95 Calcimeter
#142-54 O-ring
#152-95-2 Bleed-Off Screw
#152-95-3 Cell Cap
#152-95-4 Reaction Cell
#152-95-5 O-ring, 13⁄8" × 1⁄16"
#152-95-6 Sample Cup
#141-17 Clip for Graduated Cylinder
#152-37 AC Power Cord, 3-Conductor
#152-95 Calcimeter
#152-96-2 Minigraph Recorder
#152-96-3 Stainless Steel Case
#152-96-4 Chart Paper for Minigraph
#152-96-5 Pressure Transducer
#152-96-6 Porcelain Mortar, 65 mL
#152-96-7 Porcelain Pestle
#152-96-8 #30 Gear Train
#152-96-10 Power Supply
#152-96-11 Female Cable Jack
#152-96-12 Male Cable Plug
#152-96-13 Insulated Banana Plug, Black
#152-96-14 Insulated Banana Plug, Red
#153-02 Brush; Graduate; 11⁄2" × 103⁄4"
#153-18 Glass Graduated Cylinder 10 mL × 2⁄10 mL
#153-55 Silicone Stopcock Grease, 150 g Tube (Dow Corning)
#166-03 Hand-held Balance, 0 - 320 g (0.1g)
#275-03 *Hydrochloric Acid; 10%; 8 oz (UN #1789)
#280-00 Wetting Agent; 1 oz
#285-00-1 Calcium Carbonate; 100 g
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The Calcimeter test relies on the reaction of CaCO3with hydrochloric acid.
Hydrochloric acid is corrosive and may cause chemical burns. Use care in
handling the acid. Avoid contact with skin, eyes, and clothing. In the event
of exposure to skin or eyes, immediately flush with large quantities of water
for at least 15 minutes. Do not inhale vapors. Process hydrochloric acid
beneath a laboratory hood or in a well ventilated area to reduce the risk of
inhalation. Wear appropriate safety equipment at all times.
Do not take internally. In the event of accidental exposure, get med-
ical attention immediately.
Refer to the Material Safety Data Sheet (MSDS) for more information
on Hydrochloric Acid.
The OFITE Recording Calcimeter uses an electrically powered transducer
and recorder to record the pressure in the reaction cell. Observe the fol-
lowing safety considerations at all times:
1. Make sure the power switch is off before connecting the power cable to
an electrical outlet.
2. Make sure you are using a three-wire grounding type power cable and
outlet.
3. Always unplug the power cable before opening the recorder to replace
chart paper or any other maintenance or repair work.
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Safety

Important
!

Setup
Recording Calcimeter
1. Begin by carefully unpacking the equipment. Inspect each piece to
ensure everything is clean and in good operating condition. Inspect the
cell cap o-ring for cracks or wear.
2. Verify that the chart recorder has enough paper and that it is loaded
properly. For more information, see the “Chart Recorder” section on
page 2.
3. Plug the power supply into the back of the chart recorder. Make sure
the red cord goes into the red plug and the black cord goes into the
black plug.
4. Connect the transducer to the power supply. The cable connectors are
keyed to prevent an incorrect connection. Be sure to tighten the cable
lock to keep the connection secure.
5. Plug the chart recorder and power supply into an appropriate AC power
outlet.
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Power Supply Chart Recorder
To Power Supply
To Transducer
To AC Power Outlet
To Chart Recorder
Transducer
Cell Cap
Bleed Valve
Transducer
(Male)
O-ring
To Power Supply Power Supply
(Female)

Setup
Gauge-Read
Calcimeter
1. Begin by carefully unpacking the equipment. Inspect each piece to
ensure everything is clean and in good operating condition. Inspect the
cell cap o-ring for cracks or wear.
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Gauge
Bleed Valve
Cell Cap
O-ring

Test
Procedure
Before starting the test procedure, make sure the equipment is clean and in
good operating condition. Verify that a calibration curve is available for the
particular equipment to be used. If a calibration curve is not available, see
the “Creating a Calibration Curve” section on page 8 to construct one.
1. Obtain a sample of core, drilled cuttings, or other solids that are to be
analyzed. The sample should be dry and free of contaminants. Grind
the sample to 100 mesh or finer, using a mortar and pestle and a 100-
mesh sieve. If you do not know whether the sample has been dried,
heat it in an oven at 220°F (105°C) for 12 to 24 hours.
2. Weigh approximately 1.0 - 1.4 g of the sample to the nearest .001 g.
3. Load the test sample in the reactor cell.
a. Unscrew and remove the cell cap. Remove the acid cup from the
reaction cell.
b. Inspect the reaction cell and top. Make sure both are clean and dry.
c. Make sure the reaction cell o-ring on the top and the o-ring on the
bleed valve are in good condition. Use a light coating of vacuum
grease on the o-ring seals. Make sure all pipes or tubing connec-
tions are tight and do not leak.
d. Hold the reaction cell in a horizontal position and slide one piece of
paper and its sample to the bottom. Brush the paper with a small
brush to remove traces of the sample, then remove the paper.
e. Fill the acid cup with 20 mL 10% hydrochloric acid. Carefully place
the cup into the cell. Be careful not to spill the HCl or get any on
the bottom of the cup.
f. Hand tighten the cell cap. Be careful not to splash any acid onto
the sample.
g. Open the bleed valve until the pressure reading is zero. Then close
the bleed valve tightly.
4. Turn the reaction cell back to vertical and start timing the test. This will
start the reaction between the HCl and the CaCO3.
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5. At 30 seconds, record the pressure as “CaCO3Pressure”. If the test
sample contains any dolomite, there will be a pause, then a slow, sec-
ond rise in pressure. Swirl the reaction cell and allow sufficient time for
the reaction to finish. The reaction is complete when the pressure
stops increasing. This should happen in 30 to 45 minutes. The final
pressure value is the total CaCO3pressure plus the dolomite pressure.
To calculate the dolomite pressure, subtract the CaCO3pressure (30
second reading) from the total pressure (30 - 45 minute reading).
6. Refer to the graph below to interpret the pressure readings.
7. Use the equations below to calculate the percentages of CaCO3and
dolomite. For values of “Slope” refer to the “Creating a Calibration
Curve” section below.
%CaCO3=
%Dolomite =
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(Pressure Reading, PSI) (100)
(Sample Weight) (Average Slope)
(Total Pressure - CaCO3Pressure) (100) (.92)
(Sample Weight) (Average Slope)

Creating a
Calibration
Curve
The volume of a calcimeter reaction cell determines the relationship
between the pressure increase and the amount of CO2released. This rela-
tionship is constant for a given reaction cell. The calibration curve and cal-
culated calibration factor are used to convert the amount of pressure
released into a percentage of calcium carbonate. All points on the calibra-
tion curve represent 100% CaCO3(for that sample weight). Any number of
samples can be used to construct the calibration curve. The following are
recommended for accuracy.
1. Prepare five sets of duplicate specimens with the following masses of
CaCO3:
0.2 ± 0.01 g
0.4 ± 0.01 g
0.6 ± 0.01 g
0.8 ± 0.01 g
1.0 ± 0.01 g
2. Load a calibration sample.
Perform the procedure outlined in the “Test Procedure”, step 3.
3. Tip the cell and allow acid to run out of the cup onto the sample. Swirl
the cell gently and continuously until a constant pressure is obtained.
This will take at least 10 minutes. Keep the reactants in the lower part
of the cell to avoid getting acid into the pressure gauge or pressure
transducer. As soon as the reaction has started, observe the rapidly
rising pressure. Record the peak pressure to the nearest 0.1 PSI (0.5
kPa) as the CaCO3pressure for the sample weight used.
If a mechanical shaker is available, it may be used to agitate the cell
rather than swirling the reactants. Agitate the sample for 10 minutes.
4. Repeat steps 2 and 3 for each of the remaining samples you prepared
in step 1.
5. For each sample create a plot on linear graph paper. On the x-axis plot
grams of CaCO3and on the y-axis plot the final pressure in PSI. Draw
a straight line through the average of the points. The graph on page 9
shows a sample calibration curve.
6. Because the relationship between pressure and sample size is linear,
you may assume the curve to be a straight line with a constant slope.
As the graph on page 9 illustrates, the slope of the curve is 2 PSI / .1 g
CaCO3, or 20 PSI / 1.0 g CaCO3, resulting in a slope of 20. Therefore,
the calibration factor is .05 × 100 = 5. This number is the slope or aver-
age slope for the equipment. It is a function of the volume of the reac-
tion cell.
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
Tip

As shown by the equations below, the slope can be written as a “Cell
Factor” to multiply the pressure reading by to directly obtain percent-
ages of Calcium Carbonate and Dolomite.
As described above Slope = 20 PSI for a 1g sample therefore
% CaCO3= = 5 × Pressure
% Dolomite =
or
% Dolomite = 4.6 × (Total Pressure - CaCO3Pressure)
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(Total Pressure - CaCO3Pressure)(.92)(100)
(1 g × 20)
Sample Calibration Curve
(Pressure) (100)
(1 g) (20)

Chart
Recorder
The OFITE Recording Calcimeter differs from the pressure gauge model
only in that a pressure transducer and small strip chart recorder are provid-
ed to replace the pressure gauge. It is highly recommended that you care-
fully read the instruction manual for the chart recorder before attempting to
use the equipment.
The unit is a Love Controls 1200 series Minigraph Recorder. It uses an
“inkless writing system”, which uses a metal stylus to tap a dotted line on
pressure sensitive chart paper. It has been adapted for use with the
Calcimeter by adding a pressure transducer and power supply. The unit
will record the pressure changes within the reactor cell as they occur. The
percentage of calcium carbonate and dolomite can be calculated by apply-
ing the calibration factor to the chart reading.
The transducer in the chart recorder has a range from 0 to 15 PSI.
However, the chart readings represent milliamperes, not pressure. In order
to convert the reading to PSI, figure the percentage of full scale that is
being displayed. Then multiply that percentage by 15. This will give you
the PSI reading.
The chart paper included with the recorder shows 10 large divisions. If the
chart paper shows a value on the third division (30% of full scale), the pres-
sure reading is 4.5 PSI (15 PSI × .3 = 4.5).
There are two methods for installing chart paper. The Reroll method routes
the chart onto a roller for storage and review at a later time. The Feed
Through method routes the chart upwards through the top of the door so
that it may be viewed easily during recording. OFITE recommends using
the Feed Through method.
1. Remove all signal and power inputs to the instrument before chang-
ing the chart paper.
2. Press down on the door release latch and carefully swing the door
downward.
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Door Release Latch

3. Flip the chassis latch outward.
4. Roll the o-rings from the center of the feed through the roller to fit
into the groove on each side of the roller.
5. Flip up the roller retaining lock clips.
6. Remove the supply roller from the instrument. Slide the supply
roller into the perforated end of a roll of chart paper.
7. Hold the loose end of the chart paper in your left hand and the sup-
ply roll in your right hand so that the blank side of the chart paper is
facing upward between your left hand and the roller. Slip the chart
paper under the right hand side plate. Carefully maneuver the chart
paper so that the perforations fit into the sprocket and drive rollers.
8. Press the supply roll tension arm toward the left side plate. Set the
supply roller pins into the notches of the side plates and snap the
roller retaining lock clips down into the lock position.
9. Pull the chart paper out from the supply roll until it extends out
beyond the top of the door.
10. Press down on the right-hand side plate. Flip the chassis latch up
(press the latch against the side plate until it snaps into place).
Close the door. Reconnect the signal and power cables. Rotate
the thumbwheel on the outside of the door to advance the chart
paper as desired.
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Roller Retaining
Lock Clip
Reroll Roller
Chassis Latch
Right-Hand Side Plate
Supply Roll
Supply Roller

Maintenance After each test, thoroughly clean the cell and acid cup with water and a
mild soap. Use only alcohol-free cleaners. Alcohol can damage the plexi-
glass cell.
Testing For Leaks
Leaks in the pressure system are the most common case of inaccurate
readings.
1. Periodically inspect the reaction cell and replace the o-rings if they
are dry, cracked, or worn.
2. Clean the pipe-thread connection between the reaction cell top and
the pressure gauge or transducer with a brush and soap suds. If
repairs are necessary, disassemble the pipe-threaded connection
between the reaction cell and the gauge or transducer. Use teflon
tape to re-seal the connection.
3. Check for plugging in the connection between the reaction cell and
the gauge or transducer. Also check the gauge entrance or the
transducer barrel and diaphragm for build-up of calcium deposit
over long periods of time. A warm Chlorox wash should clean these
parts.
4. To check for leaks, pressurize the instrument as described in
“Creating a Calibration Curve” above using a .6 g sample. Let the
unit stand for at least one hour. The pressure within the reaction
cell should remain stable unless leaks are present.
Calibration Data Does Not Give a Straight-Line
If there are no leaks in the system, but results are not giving a straight-
line calibration curve or data is otherwise questionable, check the fol-
lowing:
1. Make sure the scale or balance is clean. Shield the balance from
air currents and vibration as much as possible when weighing sam-
ples or CaCO3for calibration.
2. Check the reaction cell for contaminants. Be sure the cell is clean
and dry.
3. Check for impurities in reagents. Moisture in CaCO3will result in
low-pressure readings.
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Recorder Not Responding To Pressure Changes In Reaction Cell.
1. Make sure the power cable is plugged into the electrical outlet and
that power is available at the outlet.
2. Verify the power switch on the recorder is ON.
3. Check the plug and receptacle going into the recorder to make sure
they are making a good connection.
4. Check the plug and receptacle connecting the transducer to the
recorder. Make sure this plug and receptacle are making a good
connection.
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