CENTRIFUGE TUBES
Each centrifuge tube shall be an 8-inch, 203-millilitre cone-shaped tube with dimensions, scale divisions and scale
numbering as shown in API Manual of Petroleum Measurement Standards, Chapter 10.3, “Determination of Water
and Sediment in Crude Oil by the Centrifuge Method (Laboratory Procedure)” (ASTM D4007).
Each tube shall be certified that it meets the calibration tolerances set forth in API Manual of Petroleum Measurement
Standards, Chapter 10.3 by a recognized independent inspection agency.
Tube certifications shall be conducted using air free water at 68 ºF (20 °C). All certification readings shall be made at the bottom of the shaded meniscus.
CENTRIFUGES
CAUTION: The centrifuge and its components shall be capable of withstanding the required centrifugal force. The
trunnion cups shall firmly support the tubes when the centrifuge is in motion. The centrifuge shall be
enclosed with a metal shield that is strong enough to protect the operator in case of tube breakage or
dislodging of a centrifuge trunnion.
The centrifuge shall be verified to furnish a minimum relative centrifugal force (rcf) of 600 at the tips of two opposing
tubes: The minimum speed of the centrifuge necessary to produce this relative centrifugal force may be calculated usingeither of the following formulas:
where: rpm = revolutions per minute
rcf = relative centrifugal force (600 minimum)
d = diameter of swing measured between tips of opposite tubes when in rotating position (millimeters)
D = diameter of swing between tips of opposite tubes when in rotating position (inches)
The centrifuge heater shall be capable of maintaining the sample temperature to within ±5 ºF (±3 oC) of the designated
test temperature throughout the entire spinning portion of the test. The centrifuge shall be suitable for use in a Zone 1
hazardous area.
CONSTANT TEMPERATURE BATHS
A constant temperature bath shall be used to water saturate the toluene solvent. The bath shall have sufficient depth to
permit the surface of the toluene at a level below the surface of the bath liquid. This bath shall be capable of controlling
the toluene temperature to within ±5 ºF (±3 oC) of the designated sediment and water (S&W) test temperature. The bath
shall be of sufficient depth to immerse all of the toluene and water in the solvent container. The bath shall be suitable for
use in a Zone 1 hazardous area.
SAMPLE HEATERS
The sample heater shall be either a metal block-type electric heater or a constant temperature water bath with sufficient
depth for immersing the centrifuge tubes in the vertical position to the 100-milliliter mark. The sample heater shall be
capable of heating the sample to a temperature within ±5 ºF (±3 oC) of the required test temperature. The sample heater
shall be suitable for use in a Zone 1 hazardous area.
SAMPLE THERMOMETERS
The sample thermometer shall be a bi-metallic, laboratory thermometer with 1-inch (minimum) dial, 5-inch (minimum)
length and 0.15-inch diameter. The thermometer shall have a range of –40 to 160 ºF (–40 to 70 oC) and dial graduations
of 2 ºF (1 °C) or less. The thermometer shall be accurate to within ±2 ºF (±1 oC).
SOLVENT CONTAINER
A one-liter glass bottle with screw cap shall be used for preparing and maintaining the water saturated toluene for use in
the sediment and water (S&W) test.
SOLVENT
Toluene shall conform to ASTM D362 or to the EI Specification for Toluene. Typical properties shall be as follows:
Molecular weight 2.14
Color (APHA) 10
Boiling Range (initial to dry) 3.6 ºF (2.0 °C)
Residue after evaporation 0.001 percent
Substances darkened by H2SO4 Passes A.C.S. test
Sulfur compounds (as S) 0.003 percent
Toluene shall be saturated with distilled water at test temperature prior to use in the sediment and water (S&W) test.
DEMULSIFIER SOLUTION CONTAINERS
The demulsifier solution container shall be a dark bottle.
DEMULSIFER SOLUTIONS
A mixture of 25 percent Baker Tretolite F-46 (SAMS Catalog No. 26-301-809-00) and 75 percent toluene shall be used
as the demulsifier solution for the sediment and water (S&W) test.
Demulsifier solutions shall be valid for a period of six months after their preparation.
