Crown Markings of a Nitrous Oxide Cylinder

The Department of Transportation (DOT) and Transport Canada (TC) require that cylinders made in compliance to their specifications be marked on the crown with certain information. Over the years the format used by Catalina Cylinders and Catalina East Division to display these markings has changed a few times. Shown below is an example of the current crown marking stamped on the standard 10 # N2O cylinders manufactured at Catalina Cylinders, Garden Grove, CA. Under the example of the crown marking is a list of each of the specific crown markings, followed by a brief explanation of that marking. The descriptions of the markings are the same regardless of the different stamping formats used over the years.

Example of crown markings on a 10# N2O Cylinder:


DOT-3ALThe U.S. regulatory authority, the Department of Transportation (DOT), and specification, 3AL, to which the cylinder is manufactured in compliance (required mark).
1800The service pressure, in pounds per square inch (psi), of the cylinder (required mark).
ELXXXXXXXThe serial number of the cylinder. For Catalina Cylinders - West, the serial number prefix of “EL” is specific to the 10# N2O cylinders followed by a seven digit number.
M4002The M-number or Manufacturers Number issued by the DOT to the manufacturer, Catalina Cylinders - West.
MMCYYThe original hydrostatic test date of the cylinder, month followed by year, performed at the time of manufacture of the cylinder. The “C” represents the symbol of the Independent Inspection Agency (IIA) performing the inspection of and certifying the acceptance of the cylinder at the time of manufacture (required mark).
NO10The cylinder identifier (product name). It identifies the market, “NO” for Nitrous Oxide, and capacity “10” for a capacity of 10# of N2O charge, of the cylinder.
U18The cylinder outlet thread designation as specified in CGA V-19.
TC-3ALMThe Canadian regulatory authority, Transport Canada (TC), and specification, 3ALM, to which the cylinder is manufactured in compliance (required mark).
124The service pressure of the cylinder expressed in metric units, bars (required mark).
CATALINAThe name of the manufacturer of the cylinder.

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