TE-LP-001 — Preparation and use of an ice point as a reference temperature

TE-LP-001 Preparation and use of an ice point as a reference temperature (PDF, 95 KB, 7 pages)

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Record of Change

Version	Date	Description
01	2005-11-01	Original release
02	2008-05-14	Added "controlled copy" statement in the document header
03	2009-06-03	Added clarification to the instructions.
04	2012-02-15	Added Log sheet for ice point check

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Table of Content

• 1 Introduction
  • 1.1 Purpose
  • 1.2 Scope
  • 1.3 Applicable Documents.
  • 1.4 Abbreviations and Symbols
• 2 Procedure
  • 2.1 Equipment Required
    • 2.1.1 Basic equipment
  • 2.2 Safety Requirements
  • 2.3 Set-up
  • 2.4 Instructions
• Appendix 1 : Recommended Log sheet for ice point checks

1 Introduction

1.1 Purpose

This Laboratory Practice describes a method of preparing, maintaining, and using an ice point temperature bath.

1.2 Scope

This procedure can be used to realize the ice point (0°C) as a reference temperature for the purpose of thermometer adjustment or as a check temperature for all thermometer types.

1.3 Applicable Documents

Document Number: GN-LP-003
Document Title: Vocabulary of Technical and Metrological Terms

1.4 Abbreviations and Symbols

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2 Procedure

2.1 Equipment Required

2.1.1 Basic equipment

Equipment Description

• Distilled water
• Trays of ice from distilled water
• Blender
• Thermos
• Plastic gloves
• Utensils/Forceps
• Beaker

2.2 Safety Requirements

Refer to applicable Measurement Canada Health and Safety documentation.

2.3 Set-up

All equipment that comes in contact with the water and ice of an ice-point bath shall be clean and rinsed with distilled water before use.

2.4 Instructions

Use either clean plastic gloves or clean and rinsed utensils to handle the ice and equipment.

Empty a tray of ice made with distilled water into the blender's container. Add enough distilled water to have the ice flow freely in the blender container. Put lid on container and crush ice by using the highest setting on the blender. Add water if the ice slurry clings to the wall of the blender container. The resulting mixture will be composed of fine shavings of ice in water where all of the ice has been crushed.

Pour the water from the container into the beaker. Transfer all the ice into the thermos making sure there are not any ice pieces left. When filling the bath with ice shavings, ensure there are not any air bubbles. Repeat the ice crushing until the thermos is full. Pack the ice to remove any remaining air in the ice.

Empty out any excess water until there is no free flowing water. However, the top layer of the ice has to stays moist (not white).

Cover the ice-point bath by using the opaque and thermally insulating cover. Allow the bath and vessel to thermally equilibrate for 15 minutes before using.

Pre-cool the test object in the beaker filled with cold distilled water obtained from the ice bath and extra ice. This reduces the time to reach equilibrium at the ice point and helps to preserve the bath at the ice point for prolonged use. Insert the sensor portion of the thermometer, such as the bulb of a liquid in glass thermometer or the sensing element of a probe, to a depth of at least 7 cm (or sufficient depth to eliminate immersion errors) below the bath surface. (This does not apply to full immersion liquid-in-glass thermometers.) Keep the sensor portion of the thermometer several cm above the bottom of the bath to avoid the zone at the bottom where the water will accumulate.

The melt water accumulating at the bottom has a temperature slightly warmer than 0°C. Hence, surplus water should be removed as it accumulates. The bath will maintain a temperature of 0°C for approximately 30 min. depending on usage and equipment.

Note: Impurities in the water usually lower the temperature. Excessive water in the bath can cause an increase in temperature as denser warm water settles to the bottom. Large chunks of very cold ice added to a bath can produce local temperature depression.

Note: The ice point can be reproduced with an uncertainty of about 10 mK. When prepared by rigorous application of this procedure the uncertainty can be reduced to approximately 2 mK.

Appendix 1: Recommended Log sheet for ice point checks

Thermometer serial number

Enter the serial number of the thermometer used to perform the ice-point test.

Standard number

Enter the standard number of the thermometer used to perform the ice-point test.

P1 Ice point (°C) As left from calibration certificate

Enter the "as left" temperature, in degrees Celsius, for the thermometer's first probe from the thermometer's calibration certificate.

P2 Ice point (°C) As left from calibration certificate

Enter the "as left" temperature, in degrees Celsius, for the thermometer's second probe from the thermometer's calibration certificate.

Date	Inspector ID	P1 As Found °C	P1 Deviation °C	P2 As Found °C	P2 Deviation °C	Comment
Enter the date on which you performed the ice-point test.	Enter your identification	Enter the "as found" temperature, in degrees Celsius, for the thermometer's first probe.	Enter the deviation between the "as left" and the "as found" readings, in degrees Celsius, for the thermometer's first probe.	Enter the "as found" temperature, in degrees Celsius, for the thermometer's second probe.	Enter the deviation between the "as left" and the "as found" readings, in degrees Celsius, for the thermometer's second probe.	If applicable, enter any comment.