KB Slurry Testing Methods

Specific Gravity (Density)

Quick Calcium (Qualitative)

Marsh Funnel Viscosity

pH

Sand Content

Specific Gravity (Density)

Equipment Needed:
Mud Balance with base and cap per API Spec. 13B-1, Sec. 1

Procedure

1. Set the balance and its fulcrum base on a flat, level surface. Make sure that the balance is clean, dry and free of any caked-on mud or residue.
2. Fill the clean, dry cup on the end of the balance with the slurry to be tested. The slurry sample should be freshly agitated to resuspend the sand and silt captured with the sample, but should not be aerated or contain visible air bubbles. Fill the cup until it overflows.
3. Put the cap on the filled mud cup and rotate until it is firmly seated. Make sure that some slurry is expelled through the hole in the cap in order to free any trapped air or gas.
4. Holding the cap firmly on the mud cup (with the cap hole covered with a finger), wash or wipe outside of the cup and the entire balance clean and dry.
5. Place the beam on the fulcrum base and balance it by sliding the rider along the graduated scale. Balance is achieved when the bubble is under the center line.
6. Read slurry weight at the edge of the rider toward the mud cup. The balance has four scales: two each on the side of the beam. Select the appropriate scale to report slurry weight in specific gravity (grams per cm3), pounds per cubic foot, or pounds per gallon. (The 4th scale, psi per 1,000 feet depth, is not normally used in construction, although it can be readliy adapted to give psi per foot of depth.)

Quick Calcium

Equipment Needed:
Calcium Indicator Solution, 2 oz. dropper bottle
Small glass test tube w/rubber stopper

Procedure

1. Fill the glass test tube about 80% full with water, polymer slurry, or slurry filtrate to be tested for calcium. Sample must be clear or almost clear.
2. Add 10 drops of calcium indicator solution to liquid in test tube.
3. Plug mouth of tube with rubber stopper, or cover with fingertip. Invert the tube several times, to gently mix the indicator solution into the sample.
4. Observe liquid in tube to see if cloudy white precipitate forms. This indicates the presence of calcium in the sample. Test interpretation (all calium concentrations expressed in calcium ion)
       Clear to slightly perceptible haze: less than 50 mg/L (low)
       Slightly cloudy: 50 to 100 mg/L (moderate)
       Translucent milky white ("skim milk"): 100 to 200 mg/L (high)
       Heavy opaque white: greater than 200 mg/l (very high)

Marsh Funnel Viscosity

Equipment Needed:
Marsh Funnel
Graduated cup: one quart
Stopwatch or wristwatch with a second hand

Procedure

1. For polymer slurry, capture a sample at least two quarts (1.9L) in volume. If the fluid is "dirty" (laden with silt or sand), allow to stand undisturbed for two minutes to let sand and silt to settle to the bottom of the sampler container.
2. Check Marsh funnel to be sure it is clean and that the outlet at the bottom of the funnel is clean throughout and free of obstructions. Hold funnel upright and cover the bottom opening with a finger. Pour the slurry sample slowly through the screen. (If the polymer slurry plugs the screen due to high viscosity or presence of 'gel pearls', the slurry may be poured into the funnel through the open side, bypassing the screen.)
3. Hold the filled funnel over the empty graduated cup resting on a level surface. Remove finger and start timing. Measure the time required for the slurry flowing from the funnel into the cup up to the one quart mark. This mark is shown as a scribed line around the inside circumference of the cup.
4. Report the time to the nearest second as the Marsh Funnel Viscosity, expressed as seconds per quart.

pH

Equipment Needed:
pH Indicator Strips: non-bleeding, multi-color type. (ColorHast by EM Science Co. or equivalent) Range 0-14, resolution 1.0 pH unit
For salt water and other contaminated waters: Electronic pH meter - Consult KB International for this equipment and procedure when required.  Colormetric pH indicator strips are not reliable in salt water or in some very dark-colored contaminated waters.

Procedure

Dip pH indicator strip into sample of water or polymer slurry to be tested. For mineral slurries use filtrate instead of whole slurry. Immerse indicator strip in the liquid for at least 10 seconds. Withdraw the indicator strip from the liquid sample. Determine the pH value by  comparing its color with the reference colors on the box in which the strips are packaged.  Estimate the pH value to the nearest 0.5 pH unit by interpolating colors.

Sand Content

Equipment Needed:
200-mesh sieve, 2.5 inches in diameter
Funnel to fit the sieve
Glass measuring tube marked for the volume of the slurry to be added (The tube is graduated from 0 to 20 precent in order to read directly the volumetric percent of sand in the sample.)
Wash bottle or other source of water spray
Household bleach should also be available

Procedure

1. Use a freshly agitated sample of slurry. For polymer slurries, the sample must be shaken or agitated to assure that all sand captured in the sample is in suspension when a portion of the sample is poured into the sand content tube.
2. Fill the glass measuring tube with freshly agitated slurry to the 'mud to here' mark. Add bleach to the 'water to here' mark. Cover or stopper the mouth of the tube and shake vigorously to mix the slurry and bleach. Inverting the tube several times is helpful.
3. Pour the mixture onto the clean screen. Discard the liquid passing through the screen. Add more bleach to the tube, shake, and again pour onto the screen. Repeat until the tube is clean. Use a bleach solution to wash the retained sand on the screen to free it of any remaining silt or mud. Tapping the screen barrel helps the fluid to pass through the screen.
4. Put the funnel upside down over the top of the sieve. Slowly invert the assembly and insert the tip of the funnel into the mouth of the glass tube. Wash the sand into the tube by playing a fine spray of water through the screen. (Be careful not to overflow the glass tube.) Allow the sand to settle. From the gradations on the tube, read the volume percent of sand.
5. Report the sand content of the slurry in the volume percent. Report the source of the slurry sample, i.e., bottom of excavation, mid-excavation, etc.

Modified Procedure for Dealing with Silt Floc
When the polymer slurry contains silt, the silt flocculates spontaneously when water or bleach is added to the slurry sample in the glass tube to dilute the sample (see step 2 above). This occurs because dilution reduces the polymer concentration to a low level which causes the polymer to behave as a flocculant, or agglomerator, for fine silt particles. These flocculated particles  are as large as sand particles, and will be retained in the 200-mesh sieve in the sand test, showing up as false sand. This "false sand" can cause indicated sand content to exceed specifications. In order to avoid this, it is often helpful to substitute dilute acid for bleach in the sand test for diluting the sample and washing the sand through the screen. The acid breaks down the polymer as it is diluted to prevent the polymer from acting as a flocculant.

Preparation of the Acid Wash Solution:
In a clean container, mix one part commercial-strength sodium muriatic acid and four parts water. Substitute this mixture for the bleach in the dilution and sand-washing steps of the sand content procedure. After diluting the slurry sample in the glass tube, shake the mixture vigorously and wait at least two minutes to allow time for the acid to break down the polymer's viscosity. Proceed with the sand test, vigorously washing the sample on the screen.

Equipment Cleanup after use of Bleach and Acid Solution:
Bleach and Acid are corrosive to many materials, and will damage the brass screen of the sand content kit if not rinsed in clean water after use. Immediately after running a test, wash all the test equipment, including the screen, funnel, glass tube and wash bottle in fresh clean water. Dry everything thoroughly. Failure to take these precautions will necessitate replacement of the sand content test equipment. Never store bleach or acid solution in the wash bottle or inside the slurry test kit.

RETURN TO TOP OF PAGE