Ⅰ. Operation Keys:

1. <ON/OFF> — Switch key

2. < CAL > — Calibration key, to make meter enters into calibration mode.

3. < MODE > — Function key

(a) Short-time press（time<1.5s）switch the parameters, the meter will in turn display ISE → mV .

(b) Depress (time >2s) to enter into the parameter setting mode P1, and again short-time press, will in turn display P2 → P3→…

4. < UNIT > — Unit key

(a) When in mode, press the key to in turn alter unit symbol: pF →mol/L→mg/L→ppm;

(b) Press key to choose modified position of parameter when in the parameter setting mode.

5. < ENTER > —Entrance key, meter enters into measuring state after pressing the key.

6. < ▲ > and < ▼ > — Increase and decrease key

(a) When in MTC state, press the key to increase or decrease the temperature value.

(b)When in the state of parameter setting, press the key to alter the number or ON/OFF state.

7. < M+/RM > — The compound key of memory and recall

(a) Short-time press (time <1.5s) to save the measuring information.

(b) Depress (time > 2s) to recall the measuring information, again press < ▼ > or < ▲ > key, can query in turn.

(c) In the recalling mode, press thekey to return to measuring mode.

(d) In the recalling mode, depress the < M+/RM > key for 5 seconds to eliminate stored information and return to measuring mode.

Ⅱ. Fluoride Ion Concentration Measurement: