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Thermoplastic Thermal Stability Tester (congo red paper)

Thermoplastic Thermal Stability Tester (Congo red paper)

Model: UT4133; IEC 60811-3-2, ISO 182-1

UT4133 Thermal stability testing machine, suitable for high-temperature testing of plastic products and cable insulation sheaths in oil. The temperature control system adopts microcomputer control with PID function, which ensures high control accuracy and good stability; 

Equipped with a timed alarm function, it will automatically sound an alarm when the set time is reached; 

Install the mixing motor to ensure even temperature distribution in the oil tank.

General Introduction

IEC 60811-3-2, ISO 182-1 Thermoplastic Thermal Stability Tester (congo red paper) 


UT4133 Thermal stability testing machine, suitable for high-temperature testing of plastic products and cable insulation sheaths in oil. The temperature control system adopts microcomputer control with PID function, which ensures high control accuracy and good stability; 

Equipped with a timed alarm function, it will automatically sound an alarm when the set time is reached; 

Install the mixing motor to ensure even temperature distribution in the oil tank.


Key Features

  • Test principle
  • References Standard

Thermoplastics and PVC materials when exposed to continuous heat, degenerates and emit harmful acidic gases. The instrument is manufactured for testing PVC materials against their thermal stability at higher temperature. The basic principle is that the Congo Red paper changes its color when it come contact with halogen gases, released by PVC and its compounds on heating at higher temperatures. 

Place about (50+5)mg sample into a specified glass tube. The glass tube is placed into oil bath at the temperature of (200+0.5)℃. A Congo red paper or common PH paper is inserted into the glass tube; its other end is folded and hung on the top wall of glass tube. Record the time during the Congo red paper becomes from red to blue (the common PH paper becomes from PH5 to PH3). The time of color change is expression of the thermal stability.


ISO 182-1:1990 Plastics — Determination of the tendency of compounds and products based on vinyl chloride homopolymers and copolymers to evolve hydrogen chloride and any other acidic products at elevated temperatures Part 1: Congo red method


IEC 60811-3-2 Insulating and sheathing materials of electric and optical cables - Common test methods - Part 3-2: Methods specific to PVC compounds - Loss of mass test - Thermal stability test


SATRA TM324 Thermal stability of PVC - Congo red test


Main parameters

Temperature   rangeRoom temperature~300 ℃
Temperature   resolution0.1℃
Timer0-99.99 seconds
Test oil2 # lubricating oil, insulating oil are used
Temperature   deviation± 0.5℃
Glass tube specifications

Option   1: ISO 182-1 Congo paper methodLarge glass tube: outer diameter of about 17mm, wall thickness of about 0.4mm, length greater than 150mm Small glass tube: inner diameter of about 2-3mm, length of about 100mm

Option   2: IEC 60811-3-2 One end is sealed with a length of 110mm, an outer diameter of 5mm, and an inner diameter of 4mm 

Option   3, GB/T8815-2008 standard corresponds to glass fittingsInner diameter of 12-13mm, height of 95mm, with two circular markings engraved on the glass tube. The lower marking is 30mm from the bottom of the tube, and the upper marking is 70mm from the bottom of the tube

Power220V   50HZ
Heater power1.25KW
Weight  35kg
Dimensions420×200×250mm


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Beijing United Test Co., Ltd.