YL-1A Portable residual chlorine meterDetailed product description：

One Purpose:
The YL-1A portable residual chlorine meter is suitable for detecting residual chlorine concentration in domestic or industrial water used by large, medium, and small water plants, industrial and mining enterprises, swimming pools, and other places, in order to control the residual chlorine in water to meet the specified water quality standards.

II Principle:
The YL-1A portable residual chlorine analyzer adopts the tetramethylbenzidine or ortho toluidine method, which uses the principle of photoelectron colorimetric detection instead of traditional visual colorimetric method. Eliminating human error, the measurement resolution is greatly improved. When measuring, when the tested water sample is dropped with tetramethylbenzidine or ortho toluidine reagent, the water sample will turn yellow. Then place this water sample into a photoelectric colorimetric stand, and the instrument will compare the depth of yellow to determine the concentration of residual chlorine.

III Technical Indicators:
1. Measurement range: 0-2.5mg/L
2. Power supply voltage: DC9V
3. Resolution: 0.01mg/L
4. Repeatability: 3%
5. Linear error: ± (5% FS+1 word)

4 Features:
1. Easy to use. This instrument adopts a unique constant light source with stable performance. The water sample can be read by adding reagents, and the residual chlorine value is displayed digitally.
2. The light source has a long service life. This instrument adopts a unique
Semiconductor emitter (patent application number 99226785.2),
Its light source has a longer lifespan than incandescent lamps (about 350 hours)
Several orders of magnitude, about tens of thousands of hours.
3. High resolution. The instrument resolution reaches 0.01mg/L.

Five Usage:
1. Turn on the power switch (on the right side of the instrument), pour the water sample into the glass sample box until the water level reaches the 10 mL mark of the glass sample box. Use a roll of paper to dry the water stains outside the glass sample box, cover it with a black square cover, and use a zero potentiometer to adjust the zero to make the digital display show 0.00mg/L. Then add 3-5 drops of ortho toluidine reagent, stir well, and place it in the sample holder. Cover it with a black square cover, and the value displayed on the digital display is the residual chlorine value.
2. Precautions:
a) The engraved lines on the glass sample box should face the operator;
b) After using the glass sample box, rinse it with distilled water. After rinsing, it should be inverted to avoid dust entering.
c) Before each use, it is necessary to charge it. The charging time is about 2 hours, and it can be used for 4 hours, which means it is ready to use.

VI Calibration of instruments:
Turn on the power switch, pour zero degree water into the glass sample box and place it in the sample holder, cover with a black square cover. Adjust the zero potentiometer on the panel to display 0.00mg/L on the digital display. Then put 2.5mg/L residual chlorine standard solution into a glass sample box. Use a small screwdriver to adjust the amplitude potentiometer in the small hole at the bottom left of the front of the instrument, so that the digital display shows 2.5mg/L.

7 Preparation of residual chlorine standard solution
a) The preparation of permanent residual chlorine colorimetric solution shall refer to the "Standard Test Method for Drinking Water" GB5750-85.
b) Preparation of 2.5mg/L residual chlorine permanent standard solution: Take 25mL of 10mg/L standard solution and pour it into a 100mL volumetric flask. Then pour zero degree water into the volumetric flask until the 100mL mark is made, and shake well. This reagent should be stored away from light. The shelf life is six months.

8 Product Three Guarantees
This product comes with a three guarantee for product quality within one year from the date of purchase. Excluding damage caused by human factors.

Packing List

Random attachment name	Quantity
Instruction Manual	one
9V battery	one
Certificate of Conformity	one
Sample cover	one
Small screwdriver	one
Glass sample box	two