ISO 649-1-1981 PDF

Full title and description

ISO 649-1:1981 — "Laboratory glassware — Density hydrometers for general purposes — Part 1: Specification". Specifies the constructional and graduation requirements for glass hydrometers of constant mass intended to indicate density at standard reference temperatures.

Abstract

The standard sets out requirements for basic series and sub‑series of glass hydrometers of constant mass without built‑in thermometers. Hydrometers are graduated to indicate density at 20 °C and 15 °C respectively; the standard includes tables of standard surface‑tension categories (Annex A) and recommended stem diameters (Annex B).

General information

• Status: Withdrawn (international standard withdrawn; withdrawal process noted by ISO and distributors).
• Publication date: August 1981 (approved/issued 1981-08).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 17.060 — Measurement of volume, mass, density, viscosity.
• Edition / version: Edition 1 (1981).
• Number of pages: 9 pages.

Scope

Gives the specification for laboratory glass hydrometers of constant mass for general purposes — covering basic series and sub‑series, graduation for density readings at the reference temperatures 20 °C and 15 °C, surface‑tension categories and recommended stem diameters. Part 2 of ISO 649 (ISO 649‑2:1981) covers test methods and use.

Key topics and requirements

• Definitions of basic series and sub‑series of constant‑mass glass hydrometers and their intended accuracy classes.
• Graduation and calibration reference temperatures: density indications at 20 °C and 15 °C.
• Requirements for absence of built‑in thermometers (design for constant‑mass instruments).
• Annex A: standard categories of surface tension to be considered when selecting hydrometers.
• Annex B: recommended stem diameters for stable and readable graduations.

Typical use and users

Laboratories and calibration/measurement institutes, manufacturers of laboratory glassware and hydrometers, quality control departments in petrochemical and chemical industries, test houses performing density determinations, and standards bodies referencing hydrometer specifications for test methods. Users consult the standard for design, procurement and calibration reference.

Related standards

Preceded by ISO/R 649:1968 (withdrawn); paired with ISO 649‑2:1981 (Part 2 — Test methods and use). Both parts have been catalogued as withdrawn by ISO and by national standards bodies/distributors. When replacing or aligning procedures, users should check more recent ISO or EN standards covering density measurement and hydrometer methods.

Keywords

hydrometer, density hydrometer, laboratory glassware, density measurement, mass density, ISO 649, calibration, hydrometer specification, stem diameter, surface tension, reference temperature

FAQ

Q: What is this standard?

A: ISO 649‑1:1981 is Part 1 of ISO 649, providing specifications for laboratory glass density hydrometers for general purposes (construction, graduation and related design parameters).

Q: What does it cover?

A: It covers the physical and graduation requirements for constant‑mass glass hydrometers (no built‑in thermometer), the reference temperatures for density graduations (20 °C and 15 °C), and includes annexes for surface‑tension categories and recommended stem diameters.

Q: Who typically uses it?

A: Manufacturers of hydrometers and laboratory glassware, calibration laboratories, testing and quality control laboratories in chemical and petroleum sectors, and standards organizations.

Q: Is it current or superseded?

A: ISO 649‑1:1981 is listed as withdrawn. ISO’s lifecycle records show withdrawal activity and distributors/national bodies list the parts as withdrawn (withdrawal actions recorded in 2022–2023); users should verify if a newer ISO or regional standard now covers equivalent requirements.

Q: Is it part of a series?

A: Yes — it was published as Part 1 of ISO 649; ISO 649‑2:1981 is Part 2 (test methods and use). Both parts were issued in 1981 and are associated as a two‑part standard for density hydrometers.

Q: What are the key keywords?

A: Hydrometer, density, laboratory glassware, calibration, reference temperature (20 °C, 15 °C), stem diameter, surface tension.