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Types of mercury in glass thermometers
The introduction of the digital thermometer means less Indoor/Outdoor mercury thermometers are now in use.
This thermometer is typically placed indoors with a remote sensor is placed outdoors. Both temperatures can then be read from the indoor thermometer.
A maximum thermometer is used to capture the temperature of the process liquid after it has been removed. This thermometer is reset to ambient by shaking down the mercury.
Daniel Gabriel Fahrenheit (1686-1736) was the German physicist who invented the alcohol thermometer in 1709 and the mercury thermometer in 1714.
In 1724 he introduced the temperature scale that bears his name - Fahrenheit Scale.
Did you know?
- Mercury doesn't expand when frozen.
- Mercury freezes at -38.83°C.
- Mercury boils at 356.73°C.
- Mercury thermometers can be used as a primary standard to calibrate digital thermometers.
Mercury is a very dangerous substance and under no circumstances should it be ingested or the fumes inhaled. Mercury disposal is controlled and kits are available from us for this purpose, all mercury that is sent to us for disposal is cleaned before being recycled.
This thermometer is often used in the horticultural world and considered essential for greenhouse cultivation and seed germination. It is ideal for using in your home conservatory when you need to measure high and low temperatures over a period of time. This thermometer captures temperature by way of leaving a small pointing device in place as the mercury retracts. The pointing device is reset by means of releasing the magnet.
An everyday use thermometer often called a clinical or low resolution thermometer. This thermometer is extremely versatile and useful in many industries including medical and educational sectors.
High resolution thermometer
This thermometer is not widely used and has specific uses within industry. The petrochemical industry uses them to measure the flash point or melting points of various oils. It is also heavily used within the pharmaceutical industry in research laboratory work.
Mercury thermometer standards
- BS = British Standard
- IP = Institute of petroleum
- ASTM = American Society for testing materials
- STPTC = Standardisation of tar products test committee
Calibration of mercury thermometers
All of our equipment is certified to UKAS or NPL (National Physical Laboratory) standards and we are regularly audited by UKAS.
We can calibrate mercury thermometers with an uncertainty of 0.05°C. This means we can provide accurate calibration within 0.05°C.
The following steps describe the process:
The thermometer is physically inspected on arrival as we look for a broken mercury column or cracked glass. If it appears to be OK we will measure the dimensions to ensure that it meets with the required specifications: BS, ASTM, or IP.
The thermometer is then placed in a calibration bath at the depth required by the type of thermometer that we are calibrating.
We compare the readings of the thermometer against a high accuracy AC bridge thermometer using two reference probes. Any corrections that need to be made are noted on the certificate.
Mercury thermometer repair
Charnwood Instruments can often repair and calibrate your damaged thermometers. Broken glass cannot be replaced but we can sometimes recondition thermometers with split mercury columns.
Manufacturing mercury thermometers
Charnwood Instruments do not manufacture mercury thermometers but we are the exclusive importer of Ludwig Schnieder (LSW) products.