ALLA FRANCE : Frequently Asked Question for Thermometer

ALLA FRANCE : Frequently Asked Question for Hydrometer & Thermometer

1 - ► THERMOMETERS - HEALTH / I broke a thermometer containing mercury

Remove all non essential personnel and ventilate the affected area. Wearing suitable protective clothing, clean the area where mercury has been spilt ensuring that all droplets are recovered. Use suitable tools such as a suction pipette or spoon. Under no circumstances should mercury be allowed to enter into the drains. The mercury recovered after spillage should be stored in a suitably adapted sealed container and sent to a specialized treatment centre for disposal.  Consult the supplier who provided you with these thermometers.

2 - ► THERMOMETERS - HEALTH / What is the chemical composition of the liquid used in red or blue filled thermometers ?

These liquids are made from a distillation of oil. These are organic compound hydrocarbons to which a stain has been added.

3 - ► THERMOMETERS - HEALTH / I inhaled the red or blue liquid of the thermometer

The effects are negligible at ambient temperature.

At high temperatures a vapour can be given of that can irritate the mucous membranes. In this case, avoid breathing the vapour and ventilate the affected area.

4 - ► THERMOMETERS - HEALTH / I received a projection of red or blue liquid in the eyes

The product is mildly irritating, but does not cause lasting damage to the eyes. In case of irritation, it is necessary to rinse the eye thoroughly. If the irritation persists, consult a physician.

5 - ► THERMOMETERS - PRACTICAL ADVICE / What is the chemical composition of the liquid used in red or blue filled thermometers ?

These liquids are made from a distillation of oil. These are organic compound hydrocarbons to which a stain has been added.

6 - ► THERMOMETERS - PRACTICAL ADVICE / How to regroup a separated liquid column ? - Cooling method

Immerse the reservoir of the thermometer into a mixture of dry ice and salt or dry ice and alcohol. 

Maintain the thermometer in a vertical position until all the liquid descends entirely into the reservoir. 

When achieved, swing the thermometer in a short arc forcing all the mercury into the bulb, and stand the thermometer vertically at ambient temperature.

7 - ► THERMOMETERS - PRACTICAL ADVICE / How to regroup a separated liquid column? - Heating method

Heat the reservoir gently (never use a naked flame) until the separated liquid and a part of the main column enter the expansion chamber. 

Do not completely fill the expansion chamber, as too much pressure could cause the instrument to explode. 

Gently tap the thermometer to re-unite the liquid column. 

Stand the thermometer vertically and allow to cool slowly.

8 - ► THERMOMETERS - METROLOGY / What is total immersion ?

The thermometer must be immersed to the same level as the temperature reading. 

9 - ► THERMOMETERS – METROLOGY / What is partial immersion ?

The thermometer is calibrated to be partially immersed to a depth of 76 mm. (75 for ISO). 

When immersed to a different depth to that for which it is calibrated, an emergent column correction must be made. 

10 - ► THERMOMETERS – METROLOGY / What is complete immersion ?

Very rarely used. 

The thermometer is completely immersed in the liquid.

11 - ► THERMOMETERS – METROLOGY / How to convert total immersion to partial immersion ?

In some cases, it is not possible to immerse a total immersion thermometer until the summit of the liquid column. Therefore a measure error will occur due to the part of the liquid column that is not immersed. The emergent column correction C1 can be calculated with an accuracy of approximately 10% by using the formula : C1 = k N (t1-t) In the case of mercury k is a coefficient having for value 0.00016 °C-1. In the case of thermometers filled with red or blue liquid, the value of k varies according to the temperature. As a first approximation, use 0.001 °C-1. N is the number of degrees Celsius equivalent to the length of the emergent liquid column. (t1-t) is the difference between the temperature t1 of the reservoir of the thermometer and the average temperature t of the emergent column. Example : A thermometer is immersed until the 70 °C graduation, whereas the column of liquid reaches the 100°C graduate. In this case, N equals 30°C (100-70). If the temperature t1 of the reservoir of the thermometer is 100 °C and the average temperature t of the emergent column is 58 °C, the correction then becomes : C1 = 0,001 x 30 x (100-58) soit +1,3°C

12 - ► THERMOMETERS – METROLOGY / How to convert partial immersion to total immersion ?

The correction of immersed column, C2, can be calculated with an accuracy of approximately 10% from the formula: C2 = k (t2-t3) (t4-t5) In the case of mercury k is a coefficient having for value 0.00016 °C-1. In the case of thermometers filled with red or blue liquid, the value of k varies according to the temperature. As a first approximation, use 0.001 °C-1. t2 corresponds to the reading at the immersion depth the thermometer is being used at. t3 is the value of temperature extrapolated which corresponds to the level of immersion indicated. t4 is the temperature as indicated in the following table :  t5 is the average temperature of the immersed column. Example : The thermometer is immersed to the 80°C graduation - t2. The thermometer is calibrated for a partial immersion of 76 mm. The extrapolated temperature value for the instrument at 76 mm immersion is t3 : -17 °C. The temperature reading being 80°C, according to the table, t4 = 35 °C. The temperature reading being 80 °C, one can assume that the average temperature of the immersed column t5 is the same. So t5 = 80°C. The correction then becomes : C1 = 0,001 x (80-(-17)) x (35-80) soit -4,4°C.

13 - ► THERMOMETERS – METROLOGY / How to convert °C to °F and vice-versa ?

        °F = 32 + (1.8 x °C)      ou        °C = (°F - 32) / 1.8