Delta-T Devices AP4, User Manual

Page: 29 / 64

HOW TO READ
Page 29
INSERT LEAF SCREEN DISPLAY
The left-hand box on the display refers to what has changed since the AP4 was last
recalibrated. When one or more of the items flash it is time to recalibrate.
"RH :" shows the difference between the current set point and that used at the last
calibration.
%RH stands for relative humidity, the porometer cycles around the set point.
The reading is displayed in
inverse , denoting that this setting can be altered.
"Temp:" refers to the change in cup temperature since the last calibration. The AP4
automatically corrects for changes in temperature. When the difference is too big the
porometer will keep on doing its best for you, but the display will flash a warning.
Open the head and wave it about to equilibrate. The "Head RH" reading indicates the
ambient RH. Using this, change the RH "Set" value in the right-hand box.
Use the + and
— keys to do this until close to ambient. This will cause the least
disturbance to the stomata, and minimise any errors due to leakage between the cup
seal and leaf.
If the pump comes on, press + or — . This disables the pump until you press GO.
Recalibrate when you change the RH Set point.
You may alter the leaf and plant number if you wish. This will never cause you to lose
data. The AP4 will automatically increment the leaf number if you do nothing.
The AP4 stores readings in groups which you can name via the keyboard. Each group is
also given a number which you cannot alter.
Example group names: - Treatment, Control.
The AP4 will create a new group number whenever you change one or more of the
following: 'group' name, 'plant' name or 'leaf' name and also units or RH Set.
READINGS SETTINGS SCREEN DISPLAY
Press SET to access this.
If you wish you can change the names of the labels used to identify groups and
subgroups of readings here. Their use can be appreciated by studying the sample
printout of data, see the sample printout on page 38.
To begin with, do add an output title, but do not change the name "plant" or "leaf".
Later you might want to change these labels to match the way your samples are
organised. Any name of up to 5 characters long is OK. Each reading is given a unique
number by the porometer anyway. You can also add a short note after each reading.
Do not worry. It will become clear later.