H-25C Instruction Manual
Instruction 3015-0216
18
2.2.5 Setting the “MODE” (Measurement Mode Selector) Switch
Select the measurement mode using the MODE (measurement mode selector) switch.
There are two measurement modes, A-type and B-type. For detecting leaks in a normal atmosphere,
set the switch to B-type. (The factory setting is A-type mode.) Select A-type mode if the atmosphere
at the measurement site is always clean (extremely small quantity of unwanted gas). For details, see
Subsection 4.2.2
Note: When first using this switch, select A-type mode and check it is working.
2.2.6 Setting the Alarm Point
Note: Alarms (intermittent tone from the speaker, flashing indicator lamp) are output when the
measured value is greater than or equal to 100% on the bar graph. The value at which the alarm
output trips is called the alarm output trips is called the alarm point. Although this point can be freely
set by the user, there are restrictions on the lower limit. Also, when A-type measurement mode is
selected, the search mode sensitivity is restricted depending on the value set (see Subsection 2.2.9).
Generally, set the alarm point used to detect leaks to the highest possible value of leakage.
The alarm point value is set using the “ALARM” switches. The “ALARM” switches consist of three
digital switches. The two on the left set a 2-digit number, and the “EXPNT” switch on the right sets
the exponent.
Note that if the instrument is equipped with the alarm contact output function, then the contact signal
will also be output at alarm output time. The alarm annunciation and contact signal will remain on
until the measurement value drops to 20% below the alarm point. (That is, a hysteresis band of
20%.)
