2 Hydrometer Selection Specific Gravity (Pg. 4) Precision (Pg. 4) Tall Form High Precision (Pg. 4) Short Form High Precision (Pg. 4) Broad (Pg. 5) Baume (Pg. 5) Narrow (Pg. 5) Broad (Pg. 5) Dual Scale (Pg. 5) API/ASTM (Pg. 6) Ethanol (Pg. 6) Salt & Brine (Pg. 6) Cylinders (Pg. 7) Overview Hydrometers have been used for hundreds of years to measure the specific gravity or relative density of liquids. They are commonly used in beer and wine making, for measuring petroleum liquids, for the measurement of saltwater, and for measuring the density of sugar solutions. The specific gravity of a liquid is obtained by floating a hydrometer in the sample of interest and reading the meniscus on the graduated scale. Since the specific gravity of water equals 1.000, liquids lighter than water have a specific gravity below 1.000, and liquids heavier than water have a specific gravity greater than 1.000. A Kimble hydrometer consists of a long glass tube containing ballast at the base of the float bulb and a graduated scale in the stem. Unlike the older style of hydrometer, the ballast is now made from steel pellets, and it is free of lead and mercury. A serial number is printed on the scale, a certificate of traceability is included, and the hydrometer is calibrated to ASTM specifications to ensure accuracy. The certificate of traceability indicates that the hydrometers are manufactured using devices calibrated using NIST traceable standards. About Specific Gravity Specific gravity is a dimensionless number and is a measure of relative density. RD = ρ substance / ρ reference RD is relative density, substance is the substance being measured, and reference is the reference substance. Typically the reference substance is water, and the calibration temperature for Kimble hydrometers is 60 F, as specified in the ASTM standards. Conditions Affecting Hydrometer Accuracy Important considerations when assessing the accuracy of the hydrometer readings are: Cleanliness of the instruments Temperature of the sample Uniformity of the sample Proper immersion of the hydrometer in the sample Before a Kimble hydrometer is used it should be closely inspected for cracks or damage. It should be thoroughly cleaned with a laboratory detergent according to the manufacturer s recommendations, rinsed with water, and dried with a lint-free wipe. The hydrometer cylinder should also be washed and rinsed prior to use. The temperature of the sample should be near that of the surrounding atmosphere to prevent changes during reading of the scale. To standardize the relative density to 60 / 60 F, a temperature correction factor may be applied using a temperature correction factor table such as the one found in ASTM D1250 for glass hydrometers.
3 Method of Reading the Meniscus Where water or other wetting liquid is used, the method of reading advised by the National Institute of Standards and Technology and ASTM is illustrated in Figure 1 and described as follows: In all apparatus where the volume is defined by a concave-up meniscus, the setting or reading is made on the lowest point of the meniscus. In order that the lowest point may be observed, it is necessary to place a shade of some dark material immediately below the meniscus, which renders the profile of the meniscus dark and clearly visible against a light background. A convenient device for this purpose is a collar-shaped section of thick black rubber tubing, cut open at one side and of such size as to clasp the tube firmly. --April 2013, NIST, Pg.1, Good Measurement Practice Figure 1 How to Use a Hydrometer 1. Pour the sample into a hydrometer cylinder or appropriate test jar. 2. Make sure that the sample is well mixed. 3. The temperature of the sample should be near that of the surrounding atmosphere to prevent changes during reading of the scale. To standardize the relative density to 60 / 60 F, a temperature correction factor may be applied using a temperature correction factor table such as the one found in ASTM D1250 for glass hydrometers. 4. Holding the stem of the hydrometer, lower it into the sample to a level close to where it naturally floats and release it. 5. Make sure the liquid is at rest and free of bubbles. 6. Read the scale at the meniscus. 1 2 3 4 5 6
4 Certificate of Conformance The Certificate of Conformance indicates the ASTM specifications from which the hydrometers were designed, and states that the reference standards used to calibrate the devices are traceable to NIST. Types of Kimble Hydrometers Specific Gravity With over half of the Kimble hydrometer products falling into this category, this is the most common hydrometer classification. Specific gravity hydrometers are available in a variety of graduation ranges and overall lengths. Precision Specific Gravity Hydrometer 52110-0708 SG 0.700-0.810 0.001 SG 16 310 300 20058-38375 52110-0809 SG 0.800-0.910 0.001 SG 18 300 500 20058-50375 52110-0910 SG 0.900-1.000 0.001 SG 18 310 500 20058-50375 52110-1012 SG 1.000-1.220 0.002 SG 16 300 300 20058-38375 52110-1214 SG 1.200-1.420 0.002 SG 16 300 300 20058-38375 52110-1416 SG 1.400-1.620 0.002 SG 18 300 500 20058-50375 52110-1618 SG 1.600-1.820 0.002 SG 18 300 500 20058-50375 52110-1820 SG 1.800-2.000 0.002 SG 18 300 500 20058-50375 52110-2000 Set of Eight Precision SG Hydrometers (see above specifications) Tall Form High Precision Specific Gravity Hydrometer 52111-0708 SG 0.760-0.830 0.0005 SG 21 330 600 20058-50375 52111-0809 SG 0.820-0.890 0.0005 SG 21 330 600 20058-50375 52111-0810 SG 0.880-0.950 0.0005 SG 18 330 600 20058-50375 52111-0910 SG 0.940-1.010 0.0005 SG 18 330 600 20058-50375 52111-1011 SG 1.000-1.070 0.0005 SG 21 330 600 20058-50375 52111-1111 SG 1.060-1.130 0.0005 SG 21 330 600 20058-50375 52111-1112 SG 1.120-1.190 0.0005 SG 21 330 600 20058-50375 52111-1212 SG 1.180-1.250 0.0005 SG 21 330 600 20058-50375 52111-1213 SG 1.240-1.310 0.0005 SG 21 330 600 20058-50375 52111-1314 SG 1.300-1.370 0.0005 SG 21 330 600 20058-50375 52111-1414 SG 1.360-1.430 0.0005 SG 21 330 600 20058-50375 52111-1415 SG 1.420-1.490 0.0005 SG 21 330 600 20058-50375 Short Form High Precision Specific Gravity Hydrometer 52112-0809 SG 0.820-0.890 0.001 SG 18 165 140 52112-0909 SG 0.880-0.950 0.001 SG 18 165 140 52112-0910 SG 0.940-1.010 0.001 SG 18 165 140 52112-1011 SG 1.000-1.070 0.001 SG 21 165 140 52112-1111 SG 1.060-1.130 0.001 SG 21 165 140 52112-1112 SG 1.120-1.190 0.001 SG 18 165 140 52112-1113 SG 1.180-1.250 0.001 SG 18 165 140 52112-1213 SG 1.240-1.310 0.001 SG 18 165 140
5 Broad Specific Gravity Hydrometer for Liquids Lighter than Water 52113-0610 SG 0.650-1.000 0.001 SG 18 300 300 20058-50375 Baume The Baume scale originally was used in industrial chemistry and pharmacology, but today it is used in brewing, winemaking, sugar beet processing, ophthalmics, and the starch industry. Although specific gravity is a dimensionless number, the Baume scale is graduated in degrees Baume. According to Perry s Chemical Engineers Handbook (8th Edition), Be = 145 145/sp gr (heavier than water), and Be = 140/sp gr - 130 (lighter than water). Narrow Baume Hydrometer 52120-0012 0-12 Baume 0.10 Baume 18 300 500 20058-50375 52120-0921 9-21 Baume 0.10 Baume 18 300 500 20058-50375 52120-1931 19-31 Baume 0.10 Baume 18 300 500 20058-50375 52120-3951 39-51 Baume 0.10 Baume 16 300 300 20058-38375 Broad Baume Hydrometer 52121-0035 0-35 Baume 0.50 Baume 16 300 300 20058-38375 52121-0050 0-50 Baume 0.50 Baume 18 300 500 20058-50375 52121-0070 0-70 Baume 1.0 Baume 305 300 20058-38375 Dual Scale Baume/SG Hydrometer 52122-0026 52122-2443 52122-4255 52122-5465 52122-0072 0-26 Baume, SG 1.000-1.220 24-43 Baume, SG 1.200-1.420 42-55 Baume, SG 1.400-1.620 54-65 Baume, SG 1.600-1.820 0-72 Baume, SG 1.000-2.000 0.002 SG, 0.2 Baume 16 300 300 20058-38375 0.002 SG, 0.2 Baume 16 300 300 20058-38375 0.002 SG, 0.2 Baume 18 300 500 20058-50375 0.002 SG, 0.2 Baume 18 300 500 20058-50375 0.01 SG, 1.0 Baume 16 305 300 20058-38375
6 API ASTM The American Petroleum Institute scale is used to measure the specific gravity of a liquid relative to water. A sample with an API gravity value greater than 10 is lighter than water, and an API gravity value less than 10 is heavier than water. Although specific gravity does not have units, the API scale is graduated in degrees, and was designed such that most values would fall between ten and seventy API gravity degrees. According to Perry s Chemical Engineers Handbook (8th Edition), API = 141.5/sp gr -131.5. Plain form API ASTM Hydrometer 52130-0111 API -1 - +11 ASTM 1H 0.10 API 25 330 600 20058-63460 52130-0921 API 9-21 ASTM 2H 0.10 API 25 330 600 20058-63460 52130-1931 API 19-31 ASTM 3H 0.10 API 25 330 600 20058-63460 52130-2941 API 29-41 ASTM 4H 0.10 API 25 330 600 20058-63460 52130-3951 API 39-51 ASTM 5H 0.10 API 25 330 600 20058-63460 52130-4961 API 49-61 ASTM 6H 0.10 API 25 330 600 20058-63460 52130-5971 API 59-71 ASTM 7H 0.10 API 25 330 600 20058-63460 52130-6981 API 69-81 ASTM 8H 0.10 API 25 330 600 20058-63460 52130-7991 API 79-91 ASTM 9H 0.10 API 25 335 600 20058-63460 52130-8910 API 89-101 ASTM 10H 0.10 API 21 330 600 20058-63460 Ethanol The ethanol hydrometer has dual graduations in 0-100 % and 0-200 proof scales. Ethanol Hydrometer 52150-0200 0-100% Ethanol, 0-200 Proof 1%, 2 Proof 16 300 300 20058-38375 Salt and Brine The sodium chloride hydrometer is graduated from 0-26.4% sodium chloride, and is used to measure the percentage of a saturated salt solution. The salimeter is graduated from 0-100% saturated sodium chloride. It is used in the measurement of meat packing and pickling brines. Salt and Brine Hydrometers Body OD 52140-0100 0-100% Saturated Sodium Chloride 1% of saturation 16 300 300 20058-38375 52140-0264 0-26.4% Sodium Chloride 0.5% by weight 16 300 300 20058-38375
7 Hydrometer Cylinders - Kimble hydrometer cylinders are available from a 340 ml to a 1200mL capacity and from 375 mm to 460 mm tall. The cylinders are manufactured from 33 expansion, low extractable borosilicate glass conforming to USP Type I and ASTM E438, Type I, Class A requirements. The plain, ungraduated cylinders have a pourout spout and a hexagonal base. The internal diameter of the cylinder should be approximately 25 mm larger than the outer diameter of the hydrometer body. Additionally, the hydrometer should float at least 25 mm above the base of the cylinder. Hydrometer Cylinders Capacity (ml) Approximate Height Cylinder OD 20058-38375 340 375 41 20058-50375 600 375 51 20058-63460 1200 460 64 Serial Number Certificate of Conformance This hydrometer was manufactured to the highest quality standard in accordance with ASTM E100, Standard Specification for ASTM Hydrometers, and tested following the methodology of ASTM E126, Inspection and Verification of Hydrometers. The reference standards used to calibrate this hydrometer are tracable to NIST, and the calibration was strictly controlled to the guidelines set forth by ASTM and ISO. Certified By Plant Manager Certification Date
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