HCl Concentration: Hydrochloric Acid Density Table and How to Choose % for the Plant

HCl Concentration: Hydrochloric Acid Density Table and How to Choose % for the Plant

What units are used to calculate commercial HCl concentration?

In B2B transactions and production operations, the concentration of hydrochloric acid solution is calculated in weight percent (wt%). This index represents the number of grams of pure HCl gas dissolved in 100 grams of the complete acid solution. For example, a 32% HCl solution contains exactly 32 grams of HCl and 68 grams of pure water.

According to reference documents from PubChem CID 313, hydrochloric acid (CAS code 7647-01-0) has a chemical formula of HCl and a molecular weight of 36.46 g/mol. At a temperature of 20°C and standard pressure of 1 atm, saturated HCl gas dissolved in water reaches a maximum concentration of about 37% to 38%. Therefore, in industrial production, there is no liquid HCl solution at a concentration of 100%.

Tank operators need to note that converting from weight percent to volume for tank filling must go through the density index (mass density ρ, units g/mL or kg/L). Although technical documents show standard ranges, the actual % value of each shipment is always accurately based on the analysis certificate COA provided with the delivery batch.

Hydrochloric Acid Density Table by Weight % and Baumé at 20°C

Below is a reference table for the density of HCl solution by weight percentage at standard temperature 20°C and pressure 1 atm. The data is extracted from a specialized chemical engineering handbook (CRC class) serving as a basis for inventory verification and tank filling quantification.

The data from the table shows a linear relationship between % concentration and the density of the solution. As the acid concentration increases from 10% to 38%, the density increases correspondingly from 1.048 g/mL to 1.189 g/mL. The Baumé (°Bé) measured by the hydrometer at the tank is converted using the mathematical formula °Bé = 145 - (145 / ρ).

The HCl concentration of 35% with a density of 1.174 g/mL is a technical interpolated value between 34% and 36%. This index is approximated in practical operational references at warehouses and production lines.

32% – 35% Concentration Range at Loc Thien Chemicals: When to Check Tank Density?

Loc Thien Chemicals primarily distributes the hydrochloric acid HCl 32% – 35% commercial product line. This concentration range helps the plant optimize packaging costs, road freight, and tank storage area.

Depending on the technological process, production units will dilute the acid to the required concentration:

• Steel Pickling Line: The metal pickling tank maintains HCl concentration from 10% to 18%. Technicians dilute from the raw material concentration of 32% or 35%. Read more in the guide how to dilute 32% HCl in water treatment.
• Dyeing and ETP Wastewater Treatment: HCl is used to neutralize excess alkalinity or adjust the pH of the reaction tank. Read more in the article understanding HCl chemicals in dyeing.
• Overview of Properties and Applications: Explore the full role of the chemical at what is HCl acid and its important applications.

High concentration HCl has a strong fuming property when exposed to humid air. The escaping HCl gas gradually reduces the concentration of the solution in the storage tank over time. Regularly checking the tank density helps operators promptly detect concentration decreases to accurately supplement the acid.

Methods for Measuring Density and Limitations When Inferring % Actual Concentration?

The common method for measuring the density of HCl at the plant site is to use a hydrometer to directly measure the solution sample. Although convenient, when inferring % concentration from the measured density, operators need to pay attention to three technical limitations:

1. Environmental Temperature Variation: The reference lookup table is established at 20°C. The temperature of storage tanks in Vietnam typically ranges from 28°C to 35°C, causing the solution to expand and reduce the measured density. It is necessary to adjust the temperature to 20°C before consulting the table.
2. Accumulation of Iron Salts in the Pickling Tank: In the metal pickling tank, the content of iron salts FeCl2 and FeCl3 dissolving into the solution increases the overall density. The hydrometer will inaccurately reflect the remaining free HCl concentration. In this case, it is mandatory to use the acid-base titration method with a standard NaOH solution.
3. COA Certification Principle: The density measurement results at the site are only quick check data. The official % concentration value in B2B transactions is always based on the COA certification issued by the QC department for the shipment.

Comparison of Density and Corrosive Properties Between HCl and H₂SO₄

The 32%–35% HCl solution has a relatively low density, ranging from 1.159 g/mL to 1.174 g/mL. In contrast, the 98% sulfuric acid H2SO4 product line has a very high density, reaching 1.84 g/mL. This density difference significantly impacts the design of pressure resistance at the bottom of the tank and the capacity of the filling pump system.

Regarding storage properties, HCl tends to fume corrosively, affecting surrounding equipment and structures, while concentrated H2SO4 does not fume but generates a lot of heat when in contact with water. Readers can view an in-depth comparative analysis at which is stronger HCl or H2SO4.

Refer to the density parameters of the alkaline line in the article NaOH concentration and density table in the chemical catalog of Loc Thien Chemicals.

Transportation Specifications, COA Certification, and Safe Storage of HCl Acid

Loc Thien Chemicals distributes HCl at concentrations of 32% – 35% with a full range of flexible packaging forms: specialized plastic cans, 200L plastic drums, 1000L IBC tanks, and delivery by chemical tank trucks with a load capacity of 10 to 30 tons. Specific packaging specifications are detailed in accordance with the plant's order.

Each shipment comes with a quality certificate COA and safety documentation MSDS. The materials for HCl storage tanks must use PE, PP, PVC, or Composite (FRP) lining to prevent acid corrosion causing leaks. Operators must be equipped with acid vapor masks, gloves, and chemical-resistant rubber boots.

Frequently Asked Questions About Hydrochloric Acid Concentration and Density

What is the density of 32% HCl at 20°C?

Under standard temperature conditions of 20°C, a 32% hydrochloric acid solution has a density of 1.159 g/mL (corresponding to a Baumé of 20.0 °Bé). This is the standard technical index that Loc Thien Chemicals commits to accurately publish on the COA certificate issued with the shipment to the plant.

How does the density of 35% and 36% HCl differ?

At 20°C, a 35% HCl solution has a density of approximately 1.174 g/mL (technical interpolation), while 36% HCl reaches a density of 1.179 g/mL. Although the density difference is only 0.005 g/mL, the 35% HCl has a lower vapor pressure, resulting in less fuming, which helps minimize the risk of concentration loss during open tank storage.

Can % concentration be inferred solely from the hydrometer?

Measuring density with a hydrometer only provides accurate results when the HCl solution is completely pure. If the solution in the pickling tank has accumulated iron salts FeCl2 or the environmental temperature is higher than 20°C, the density will be skewed. The plant must perform chemical titration to accurately determine the % free HCl.

How should the plant choose the 32–35% HCl range for optimization?

The 32% – 35% HCl concentration range helps optimize transportation costs and tank storage volume. Enterprises with closed storage tanks should choose the 35% concentration to reduce storage costs; if the storage tank is located in a well-ventilated area and at high temperatures, the 32% concentration will be stable and minimize acid fume escape.

What should be done if the COA of the shipment differs from the label on the can/tank?

When there is a small discrepancy between the values recorded on the packaging and the accompanying COA analysis certificate, the operating unit always relies on the value on the COA. The COA document reflects the actual test results of that specific shipment before it is released for delivery to the customer.

How does Loc Thien deliver HCl and where can I get a quote?

Loc Thien Chemicals distributes HCl 32% – 35% nationwide in cans, drums, IBC tanks, or by tank trucks directly to the plant's tank. For technical consultation and the latest quotes, please contact the hotline 0979 891 929 or submit a request at Loc Thien Chemicals quote request.