SIST ISO 387:1995 PDF

Name: SIST ISO 387:1995 — Hydrometers -- Principles of construction and adjustment
SKU: SIST ISO 387:1995
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Hydrometers -- Principles of construction and adjustment

Название (английский):

SIST ISO 387:1995

Hydrometers -- Principles of construction and adjustment

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 7
Дата публикации:: 1 августа 1995 г.
ICS:: 71.040.10
Технический комитет:: I12 - Imaginarni 12 Imaginarni TC za ISO področje - vzdrževani privzeti ISO standardi

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Описание (английский):

Glass hydrometers of constant mass which do not incorporate a thermometer are considered. Basis of scale, reference temperature, surface tension and reference levels for adjustment and reading are specified. In annex A the standard categories of surface tension are tabled, and annex B deals with the adoption of density as preferred basis of scale.

Abstract

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Стандарты, упомянутые в описании

Overview

ISO 387:1977 - Hydrometers: Principles of construction and adjustment - defines the requirements for glass hydrometers of constant mass that do not incorporate a thermometer. The standard specifies the basis of scale, reference temperature, surface tension categories for adjustment, reference reading levels, and essential requirements for shape, materials, calibration conditions, graduations and inscriptions. Annex A tabulates standard surface‑tension categories; Annex B explains why density is the preferred basis of hydrometer scales.

Key topics and technical requirements

Scope: Glass hydrometers, constant mass, without built‑in thermometers.

Basis of scale: Preferentially density (kg/m3); relative density (to water) is permitted but less preferred (Annex B explains advantages of density).

Reference temperature: Standard reference for density hydrometers is 20 °C (alternatives: 15 °C or 27 °C in special cases). For relative density scales the reference temperature is 60 °F (15.56 °C).

Surface tension: Hydrometers must be adjusted for surface tension. Annex A defines standard surface‑tension categories (low/medium/high) and example liquids (organic liquids, oils, aqueous solutions, acids); precise mN/m values can be marked on the instrument.

Calibration conditions: Emergent stem dry except near meniscus; stable meniscus behavior when displaced.

Materials & workmanship:

Transparent, low‑stress glass with cubic thermal expansion coefficient (25 ± 2) × 10‑6 °C‑1 (per ISO 1768).
Loading material fixed in the bulb base; mercury is prohibited.
Stem must remain essentially vertical (recommended max tilt 1.5°) and extend at least 15 mm above top graduation.

Shape & stem: Symmetrical outer surface; tapered bulb design preferred to avoid trapped air.

Scale & graduations: Rules for line spacing (centers 0.8–3.0 mm, preferably 1.2–2.0 mm), long/medium/short line sequencing per smallest interval, clear figured numbers and vertical alignment.

Inscriptions: Must include basis of scale (e.g., “kg/m3”), standard reference temperature, surface tension or category, maker ID, instrument ID and reference to the standard.

Applications and users

ISO 387 is used by:

Hydrometer manufacturers (design, marking and production).

Calibration and test laboratories (verification and adjustment).

Quality control and R&D in industries handling liquids: petroleum, chemicals, oils, alcohols, food & beverage, fermentation and laboratory services.

Regulatory and trade bodies concerned with accurate density/relative density measurement.

Practical benefits include improved interoperability of instruments, consistent readings across liquids (with surface‑tension adjustment), and traceable manufacture/calibration practices.

Related standards

ISO 1768 - referenced for the conventional value of the glass cubic thermal expansion coefficient.

A corresponding ISO for hydrometers with incorporated thermometers is noted (separate document).

Keywords: ISO 387:1977, hydrometers, glass hydrometer, density scale, surface tension, calibration, reference temperature, hydrometer graduations.

SIST ISO 387:1995 PDF

Abstract

Похожие стандарты

Overview

Key topics and technical requirements

Applications and users

Related standards

Технические детали

ISO 387:1977

Hydrometers — Principles of construction and adjustment

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