Hydrogen Chloride (anhydrous)
Hydrogen chloride (aHCl) is a distinctly different substance than hydrochloric acid (HCl). aHCl is a colorless gas at atmospheric pressure with a sharp, irritating odor. It is manufactured via synthesis in a burner unit where hydrogen gas is reacted with chlorine gas. It is very hydroscopic and in moist air, forms white fumes which are a mist of hydrochloric acid. Liquid aHCl has a high coefficient of thermal expansion, therefore, the pressure in equipment containing this substance must be closely monitored. aHCl is compressed (liquified) and shipped via railroad tank cars, cargo tank (trucks), tube trailers, and cylinders.
CI Resources
The Institute maintains the below resources for aHCl. Refer to CI's Resource Catalog for fuller details and visit the CI Bookstore.
- Pamphlet 170) Hydrogen Chloride, Anhydrous (aHCl), Refrigerated Liquid (UN 2186), Tank Car and Cargo Tank Handling Manual
- FACT-4) Anhydrous Hydrogen Chloride Release Fact Sheet
Hydrochloric Acid (aqueous)
Hydrochloric acid is a distinctly different substance than hydrogen chloride (anhydrous). HCl, commonly known as muriatic acid, is a solution of hydrogen chloride and water that contains less than 38 wt.% hydrogen chloride. It exists as a liquid under atmospheric conditions, however, is prone to fuming at higher concentrations or elevated temperatures. At chlor-alkali facilities, HCl is commonly produced via the absorption of aHCl into water. Other industrial manufacturing byproduct product sources of HCl are more prominent. HCl has many uses such as the production of pharmaceuticals and chemicals, food processing, steel pickling, natural gas and oil, and various water industry uses (resin regeneration, pH and scale control).
CI Resources
The Institute maintains the below resources for HCl. Refer to CI's Resource Catalog for fuller details and visit the CI Bookstore.
- Pamphlet 98) Recommended Practices for Handling Hydrochloric Acid in Tank Cars
- Pamphlet 150) Recommended Practices for Handling Hydrochloric Acid in Bulk Highway Transports
- Pamphlet 163) Hydrochloric Acid Storage and Piping Systems
- Wall Chart 3) Handling Hydrochloric Acid
HCL-VIDEO) Handling Hydrochloric Acid Safely
This video provides guidelines, recommended practices and other information for the safe handling, storage, loading and unloading of hydrochloric acid tank cars and tank trucks. This video also includes hydrochloric acid properties, reactivity, suitable materials of construction, and common uses.
HCLS-VIDEO) Preventing Non-Accident Releases by Properly Securing Hydrochloric Acid (HCl) Railcars
This video provides guidance for reducing non-accident releases (NARs) from tank car shipments of hydrochloric acid (HCl). Topics covered include the definition of an NAR, U.S. Department of Transportation incident reporting requirements, shipper responsibilities, best practices to reduce HCl tank car NARs and available guidance and resources, such as additional Chlorine Institute guidance.
CTS-VIDEO) Preventing Chlor-Alkali Releases during Cargo Tank Operations
This video provides an overview of best practices to prevent releases during cargo tank shipments of certain CI mission chemicals, namely sodium hydroxide, potassium hydroxide, hydrochloric acid, and sodium hypochlorite. Viewers, including plant operators and drivers, will learn requirements for reporting hazmat transportation releases to DOT, review related DOT-reported cargo tank incident data, understand the sources and cause of common releases during cargo tank transport and operations, and learn best practices for preventing these types of releases.