Electronic Surface Contact

5.2.3 Electronic Surface Contact

Thermometer

Electronic surface contact thermometers use

a thermocouple in contact with the surface to measure temperature ( Figure 5.7 ). Some models are available with a variety of inter- changeable probes that may allow measure- ment of a number of surfaces, including liquids, over a wide temperature range.

An advantage of electronic thermometers is the speed at which readings are delivered. They deliver temperature readings much more quickly (usually < 1 second) than mag- netic surface contact thermometers, because the instrument does not require a stabiliza- tion period.

Remember that as a reading is taken the tem- perature measurement is only for that pre- cise spot on the surface. If readings are being taken prior to a coating application over a large area, a number of readings should be taken throughout the entire area

with high or low readings taken into account.

Proper use of an electronic surface contact thermometer is very simple:

• Ensure the proper probe is used for the surface and the expected temperature range

• Turn on the instrument • Place the probe on the surface where mea-

suring the temperature ( Figure 5.8 ) • Read the display screen

Figure 5.7 Digital Thermometer

Figure 5.8 Digital Surface Contact Thermometer

Environmental Testing 5-7

Calibration of these instruments must be easy to use. Their care and use is detailed in done in-house by the manufacturer. Do not

this section.

attempt calibration at the jobsite. Periodic It is an inspector’s responsibility to know

(annual) calibration should be carried out by and understand the proper use of the elec-

the manufacturer or a third party laboratory tronic digital hygrometers ( Figure 5.9 ).

to ensure that the most qualitative measure- ments are achieved.

Be aware that when moving from one tem- perature/humidity extreme to another the

The operating parameters (temperature meter needs time to stabilize. After opening

range) of this instrument vary. Check manu-

the sensor’s protective shutter, press the

facturer’s instructions. The Elcometer 1

“on” button then start taking measurements. 213/2, has a measuring range of -56°F to

Temperature readings are displayed in either 2500°F (–49°C to 1372°C).

Celsius or Fahrenheit. Users may switch The accuracy and precision (resolution) of

between the two as needed when readings instruments, again, may vary between manu-

are taken.

facturers. The accuracy of the Elcometer 213/2 is ±1% of the reading is ± 1 digit and the precision (resolution) is 1°F (1°C).

As with all other temperature sensing instru- ments, question readings with either very high or low variation compared with the actual temperature of the substrate. If there are questions about the accuracy of the read- ings, send the instrument immediately to the manufacturer for service and calibration or replacement.

Some common errors and causes encoun- tered when using this type of instrument are inaccurate readings from using the wrong

Figure 5.9 Electronic Hygrometer

sensing probe, using an instrument that is After stabilizing, the temperature and rela- not correctly calibrated, or not verifying

tive humidity are displayed. substrate temperature across the entire area.

To display the:

5.3 Relative Humidity Instruments

• dew point temperature, press the “wet

bulb” button once