VEE GEE 675xHTS are ASTM/API Thermo-Hydrometers — borosilicate glass instruments combining an API gravity scale with a built-in thermometer in the body, 15 in (38 cm) overall length. The API scale is the petroleum industry standard for density measurement, selected by the American Petroleum Institute, the U.S. Bureau of Mines, and NIST. Six models (ASTM 52H–57H) cover the full API gravity range from 9° to 71° in overlapping 10° increments at 0.1° API resolution. The built-in 0–150°F thermometer (2°F subdivisions) allows simultaneous temperature measurement for applying the temperature correction required by ASTM D1298 / IP 160 crude oil and petroleum products density procedures. All calibrated at 15°C (60°F). Made in USA. Select the ASTM number covering your API gravity range.
Model Selection — ASTM Number & API Gravity Range
| SKU | ASTM No. | API Range | Typical Petroleum Products |
|---|---|---|---|
| 6752HTS | 52H | 9 to 21° API | Heavy fuel oils, residual fuels (SG ~1.00–0.93) |
| 6753HTS | 53H | 19 to 31° API | Diesel, heating oil, crude oil (SG ~0.93–0.87) |
| 6754HTS | 54H | 29 to 41° API | Kerosene, jet fuel, light crude (SG ~0.88–0.82) |
| 6755HTS | 55H | 39 to 51° API | Gasoline, naphtha (SG ~0.82–0.78) |
| 6756HTS | 56H | 49 to 61° API | Light naphtha, ligroin (SG ~0.78–0.74) |
| 6757HTS | 57H | 59 to 71° API | Very light naphtha, light petroleum ether (SG ~0.74–0.70) |
Features & Benefits
- API Gravity Scale — Petroleum Industry Standard: The API gravity scale (°API = 141.5/SG@60°F − 131.5) was selected as the standard measurement for petroleum products by the American Petroleum Institute, the U.S. Bureau of Mines, and NIST. Higher °API indicates lower density (lighter product). These instruments are appropriate for ASTM D1298 and IP 160 petroleum density measurement procedures.
- Built-In Thermometer (0–150°F, 2°F subdivisions): The thermometer is located inside the body of the hydrometer. Temperature is measured simultaneously with the API gravity reading — essential for applying the temperature correction factors in ASTM petroleum tables, since API gravity at observed temperature must be corrected to the standard 60°F reference.
- 0.1° API Subdivisions — High Resolution: Each graduation represents 0.1° API — the standard precision for petroleum product grading and custody transfer measurements.
- Calibrated at 15°C (60°F): Factory-calibrated at the petroleum industry standard reference temperature.
- 15 in (38 cm) Overall Length: Full-size ASTM petroleum hydrometer format for stable readings in standard petroleum sampling containers and hydrometer cylinders.
- Borosilicate Glass Construction: Chemically resistant to petroleum products; transparent for unambiguous meniscus reading.
- Made in USA — 1-Year Warranty.
Frequently Asked Questions
What is the API gravity formula and how does it relate to specific gravity?
°API @ 60°F = (141.5 / SG@60°F) − 131.5. API gravity increases as density decreases — a light gasoline at SG 0.72 is approximately 65°API, while a heavy crude at SG 1.00 is 10°API. To convert back: SG = 141.5 / (°API + 131.5). The API scale was designed so that water is exactly 10°API at 60°F (SG 1.000).
Why do I need the built-in thermometer?
Petroleum density changes significantly with temperature — approximately 0.0006–0.0007 SG per °F for most distillates. ASTM D1298 requires that the observed hydrometer reading be corrected to the reference temperature of 60°F using published volume correction tables (ASTM Table 6B or equivalent). The thermometer reading at the time of the hydrometer reading is required to apply this correction. The HTS thermo-hydrometer captures both measurements in one operation.
How do I select the correct ASTM number?
Choose the model whose API range covers the expected API gravity of your product, ideally with your typical reading near the center of the range. The ranges overlap by 2° at each boundary — for example, 52H covers 9–21° and 53H covers 19–31°, so a 20°API reading could be made with either. If your product frequently reads near a range boundary, select the model where that reading falls near the center for best graduation spacing and readability.
Ordering
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