Relative Humidity and Temperature Measurements. TSI Quest Quest Environmental Monitor EVM Series, EVM-7

78 Relative Humidity and Temperature Measurements

Relative Humidity and Temperature Screen

5.

Or select the Detail soft key and a summary of all the measurements will appear. (Below is an explanation of measurements.)

Measurement values

LEVEL

MIN

MAX

AVG

STEL

TWA

Explanation

Level - Notation used to represent current live reading of the sensor. (This is updated once a second.)

Minimum - Minimum level value which occurred during a log session.

Maximum - Maximum level value which occurred during a log session.

Average - Arithmetic average of all level values which occurred during a log session.

Short term exposure level - is a calculation used to indicate an exposure level (to a toxin) over a short-term period. This value is calculated by averaging the last 15 one minute averages. This value is invalid for the first 15 minutes and is updated every minute thereafter.

Essentially, it is used when the building occupant/worker is exposed to high concentrations of chemical gases. The measurement will average after 15 minutes of data logging and continue to compute after each minute of logging, using measurements from the most recent fifteen minutes. If less than 15 minutes has elapsed, the STEL will be invalid by displaying dashes.

Time weighted average - is an average based on an 8-hour interval. The summing all of the level values taken and dividing by the number of samples in 8 hours (at one sample per second the total would be 28,800). The important thing here is that the average is calculated the same way regardless of whether you've run the instrument for 1 hour, 8 hours, 24 hours or any other amount of time (i.e. the number of samples used to divide by is the same). This value is updated once a second.

Table 5-3: Measurement values explained

Relative Humidity and Temperature Measurements

The relative humidity and temperature sensor will display on the left-hand side of the screen with two measurement values. The measurement displayed in the second column is user-selectable via

Enter .

Relative Humidity and Temperature Screen

To select a different measurement type, press the Enter key repeatedly.

Select , Trend , Detail soft keys (used to change the measurement view).

Figure 5-8: RH and temperature measurement screen

EVM Series User Manual