How to sample and test lithium bromide, and what indicators need to be tested

Sources：www.worldbrom.com | PublishDate：2026.09.28

1、 Sampling equipment
Vacuum sampling bottle/sampler, vacuum pump, vacuum rubber tube, vacuum grease, 250mL polyethylene sample bottle (cannot be stored in ordinary glass bottles for a long time, lithium bromide can corrode glass), graduated cylinder, thermometer, and specific gravity meter; label.
2、 Negative pressure sampling operation steps
1. Sampling of stable operating status of the unit; Confirm that the sampling valve is intact, apply a little amount of vacuum grease to the valve interface, and connect the sampling bottle to the vacuum pump.
2. Turn on the vacuum pump and vacuum the sampling bottle for 1-3 minutes until there is no obvious airflow sound.
3. First, open the sampling valve, and the lithium bromide solution flows into the sampling bottle under the pressure difference; Take 200-300mL.
4. Sequential valve closing: First, close the sampling valve of the unit → stop the vacuum pump to prevent air from being sucked back into the unit and damaging the vacuum.
5. Transfer the sample into a polyethylene bottle and seal it; Tag: Unit number, sampling location (dilute/concentrated solution), sampling temperature, date.
6. Visual initial inspection: Normal light yellow/transparent; Yellowing, turbid, precipitated, and black brown indicate severe corrosion.
Attention: Separate the sampling equipment for refrigerant water and lithium bromide solution, strictly prohibit mixing, and avoid cross contamination; Restore the sealing of the sampling valve and check the vacuum of the unit.
Sampling of new lithium bromide raw materials in barrels: Mix well, insert a glass sampling tube into the barrel to a depth of 3/4, sample ≥ 500g, divide into two bottles, one bottle for testing and one bottle for sample retention, and store in the dark for 3 months for future reference
3、 Required testing indicators (HG/T2822-2022 Lithium Bromide Solution for Refrigeration Machines)
On site rapid testing (operation and maintenance self-test)
1. Lithium bromide mass concentration (LiBr): density+temperature lookup table, or refractive concentration meter; Dilute solution is about 50%, concentrated solution is 58-62%; Excessive concentration leads to crystallization, while insufficient cooling capacity results in low concentration
2. pH value (100g/L dilution solution)
Lithium chromate system: 9.0-10.5
Lithium molybdate chromium free system: 9.0-11.5
Low pH → corrosion intensifies; Excessive height can easily lead to precipitation
3. Appearance: Transparent liquid, with or without suspended solids, sediment, or discoloration
Third party laboratory full analysis (required for annual testing and corrosion abnormalities)
1. Corrosion inhibitor content
Lithium chromate Li ₂ CrO ₄: 0.15-0.25% (old unit)
Lithium molybdate Li ₂ MoO ₄: 0.01~0.05% (chromium free environmentally friendly unit)
2. Metal impurities (corrosion products, determining the degree of corrosion of the unit)
Fe iron ≤ 0.0001%
Copper ≤ 0.0001%
Ca calcium ≤ 0.005%
Mg magnesium ≤ 0.001%
Na+K total ≤ 0.05%
3. Anionic impurities
Cl ⁻ chloride ion ≤ 0.07% (highly corrosive, key monitoring)
SO ₄² ⁻ sulfate ≤ 0.02%
Bromate salt BrO ∝⁻ (required by some manufacturers)
4. Alkalinity (lithium hydroxide), crystallization temperature, viscosity
4、 Sampling and laboratory precautions
1. Sampling must be carried out under stable operating conditions of the unit, and sampling should not be taken at the moment of start stop fluctuations;
2. Send the sample for testing as soon as possible to avoid prolonged exposure to air and absorption of CO ₂, which can cause a decrease in pH and precipitation of lithium carbonate;
3. Lithium chromate is a hazardous chemical containing chromium, and waste liquids and samples should be treated as hazardous waste;
4. Regular operation and maintenance: monthly self testing of pH and concentration on site; Send third-party comprehensive chemical analysis once a year; If the color of the solution is abnormal, the vacuum continues to deteriorate, and the heat exchange deteriorates, urgent sampling and testing should be carried out immediately.

Prev： None

Next： What are the main differences between sodium brom…

News Center