Why are glass thermometers not recommended?
Table of Contents
Why are glass thermometers not recommended?
Liquid in glass thermometers tend to be fragile and hence easily broken, can only be used where the liquid column is visible, cannot be used for surface temperature measurements, cannot be read from a distance and are unsuitable for high temperature measurements.
Are glass thermometers accurate?
The accuracy of a typical glass thermometer is ±1 scale division. These are available in partial immersion or total immersion types and typically have to be considerably longer to achieve the same specifications as a mercury thermometer.
What are the advantages and disadvantages of liquid in glass thermometer?
| THE LIQUID-IN GLASS THERMOMETER | |
|---|---|
| Advantage | Disadvantage |
| no power source required | limited to applications where manual reading is acceptable, e.g. a household thermometer |
| repeatable, calibration does not drift | have a limited useable temperature range |
| easy to use & cheap | cannot be digitised or automated |
Why is mercury not used in thermometers anymore?
The reason: Mercury released into the environment from a broken thermometer is highly poisonous. So government and state agencies have mounted campaigns to end the use of thermometers that contain the liquid metal. Federal and state authorities have lobbied since 2002 for bans on medical mercury thermometers.
Why is a mercury in glass thermometer not suitable for measuring a temperature of C?
Physical properties. Mercury thermometers cover a wide temperature range from −37 to 356 °C (−35 to 673 °F); the instrument’s upper temperature range may be extended through the introduction of an inert gas such as nitrogen. Mercury cannot be used below the temperature at which it becomes solid, −38.83 °C (−37.89 °F).
Is mercury thermometer banned?
Since 2001, 20 states have banned mercury “fever thermometers” for medical use, and regulations tighten every year. It’s a neurotoxin—exposure can cause tremors, partial blindness, deafness, memory loss, and many, many other problems—and, if mercury does spill, it’s very hard to clean up.
Which is more accurate digital or glass thermometer?
Digital thermometers are safer to use Mercury thermometers are most often made of glass, which is inserted into food to gauge the temperature. Mercury is a toxic chemical, which if released could contaminate the body as well as surrounding areas, rendering it unsafe.
What are the advantages and disadvantages of resistance thermometer?
| THE RESISTANCE THERMOMETER (RTD) | |
|---|---|
| Advantage | Disadvantage |
| the platinum resistance detector is stable and resistant to corrosion and oxidation | RTDs do not allow point measurement of temperature because of the dimension of the sensing element |
What is the advantage of glass thermometer?
They are comparatively cheaper than other temperature measurement devices. They are handy and convenient to use. Unlike electrical thermometers, they do not necessitate power supply or batteries for charging. They can be frequently applied in areas where there is problem of electricity.
What are the disadvantages of using mercury in thermometers?
Disadvantages of Mercury: It cannot measure very low temperature, because its freezing point is high (-40ºC) Mercury is poisonous, so it harmful if its tube is broken. Its price is very high.
What are the disadvantages of using mercury as a thermometric substance in thermometer?
The disadvantages of mercury as thermometric liquid are: i) its temperature coefficient of expansion is very low and it cannot be used to measure the temperature below –39°C and above 357°C. ii) Mercury thermometer cannot be used in very cold regions like arctic regions because it freezes below a temperature of 39o C.