HF scientific MicroTOL Online Turbidimeter - Manual (Page 25)

MICRO TOL (5/10) 19
Rev. 4.8
These three items are described below:
Alarm Function: The alarms can either be turned OFF or programmed to operate in one
of three different manners:
1. HI alarm: the relay changes state when the measured turbidity level is higher than the
programmed alarm level for a prescribed amount of time.
2. LO alarm: the relay changes state when the measured turbidity level is lower than the
programmed alarm level for a prescribed amount of time.
3. Error: the relay changes state when a system error occurs. If a system error occurs a
message will appear on the lower row of the screen describing the problem.
Alarm Set Point: The level at which an alarm activates is called the alarm set point. On
the instrument, the alarm set point is designated as “S/P”. The set point is adjustable to
any valid turbidity level over the range of the instrument in steps of 0.01 NTU.
Alarm Delay Time: The alarm delay times are used to prevent ringing of the alarm when
the measured turbidity level is close to the set point. The function of the delay times is as
follows:
Delay On: The turbidity level must exceed the alarm set point continuously for at least
this number of seconds before the alarm activates.
If the delay on time is set at 5 seconds and the process turbidity exceeds the set
point continuously for only 4 seconds, the alarm will not be activated.
However, process turbidity exceeds the set point continuously for 5 seconds or
more, the instrument will activate the alarm.
Delay Off: The turbidity level must not exceed the alarm set point continuously for at
least this number of seconds prior to deactivation of the alarm.
If the delay off time is set to 5 seconds and the process has exited out of the
alarm condition, the alarm will be reset only if the process is out of the alarm
condition for a continuous 5 seconds. Otherwise, the instrument will still
signal an alarm condition.
7.5.1 Alarm 1
Alarm 1 Function:
The ALM1 is displayed and the display indicates the current function
of alarm 1 (HI, LO, OFF or Error). Use the
toru buttons to cycle through and select
the desired function. Press the
↵ button to accept the selection.
If the alarm was turned OFF a prompt will appear to set up alarm 2 (go to section 7.5.2).
If, on the other hand, one of the other functionalities was selected a prompt will appear to
set the delay times.
Alarm 1 Set Point: This prompt is used to select the set point for this alarm; this is
indicated by “S/P” shown on the lower row of the display. Select the desired alarm level
by using the
t and u buttons. Once the desired set point has been set, press the ↵ button
to accept it.