ISO 2750-1974 PDF

Full title and description

ISO 2750:1974 — Urea for industrial use — Measurement of colour in Hazen units (platinum‑cobalt scale) of a urea‑formaldehyde solution. Defines a visual comparison method using a urea–formaldehyde test solution stabilized at a specified pH and reporting colour on the Hazen (Pt/Co) scale.

Abstract

This International Standard lays down the principle of visually comparing the colour of a solution of the urea sample in formaldehyde (stabilized at pH 10 ±0.1) with calibrated platinum‑cobalt colour standards and expressing results in Hazen units. It is intended for routine control (reference to ISO 2211 for liquid chemical products) and the method was noted as also approved by IUPAC.

General information

• Status: Withdrawn
• Publication date: August 1974
• Publisher: International Organization for Standardization (ISO)
• ICS / categories: 71.080.30 (Chemical products and testing)
• Edition / version: Edition 1 (1974)
• Number of pages: 2

Scope

Specifies a simple comparative, visual method for measuring the colour of industrial urea by preparing a urea‑formaldehyde test solution, stabilizing the solution at pH 10 ±0.1, and comparing its colour against platinum‑cobalt (Hazen/APHA/Pt‑Co) standards. Results are reported as Hazen units; for broader routine control methods the standard refers to ISO 2211 (measurement of colour in Hazen units for liquid chemical products).

Key topics and requirements

• Preparation of a urea–formaldehyde test solution for colour assessment.
• Stabilization of the test solution at pH 10 ±0.1 prior to measurement.
• Visual comparison with platinum‑cobalt colour standards (Hazen/APHA scale).
• Expression of results in Hazen units (Pt/Co scale) for reporting and specifications.
• Intended for routine control; instrumental alternatives (comparators, colorimeters, spectrophotometers) referenced via ISO 2211 when equivalence to visual matching is required.

Typical use and users

Used by chemical manufacturers, quality control and analytical laboratories, producers of urea and urea‑derived resins (e.g., urea‑formaldehyde resins), suppliers of industrial chemicals, and regulatory/inspection bodies requiring a standardized colour specification for urea for industrial use. The procedure is suited to routine QC where a rapid visual assessment of yellowish discoloration is sufficient.

Related standards

ISO 2211:1973 — Liquid chemical products — Measurement of colour in Hazen units (platinum‑cobalt scale) (referenced for routine control and for instrument-based equivalence). The Hazen/Pt‑Co (APHA) colour scale and ASTM D1209 (Standard Test Method for Color of Clear Liquids) are commonly associated references for platinum‑cobalt colour measurement practice.

Keywords

ISO 2750, urea, urea for industrial use, urea‑formaldehyde, colour measurement, Hazen units, platinum‑cobalt scale, Pt/Co, APHA colour, visual comparison, quality control.

FAQ

Q: What is this standard?

A: ISO 2750:1974 is an ISO International Standard that specified a visual method to measure the colour of industrial urea — using a urea‑formaldehyde solution compared to platinum‑cobalt (Hazen) colour standards.

Q: What does it cover?

A: It covers preparation of the test solution (urea in formaldehyde), stabilization at pH 10 ±0.1, visual comparison with Pt/Co standards, and expression of results in Hazen units. For routine control and instrument equivalence it refers to ISO 2211.

Q: Who typically uses it?

A: Chemical producers, QC/analytical labs, resin manufacturers and anyone specifying or verifying the colour of urea for industrial applications.

Q: Is it current or superseded?

A: ISO 2750:1974 is listed as Withdrawn. Users should check current ISO publications or successor documents and use related active standards such as ISO 2211 for general Hazen‑unit colour measurement practice.

Q: Is it part of a series?

A: It is part of ISO chemical product testing work by ISO/TC 47 and is associated with other ISO colour‑measurement standards (notably ISO 2211). It is a product‑specific application of the broader Hazen/Pt‑Co colour measurement approach.

Q: What are the key keywords?

A: Hazen units, platinum‑cobalt scale, Pt/Co, urea, urea‑formaldehyde, colour measurement, ISO 2750, ISO 2211, visual comparator, APHA colour.