National Board Inspection Code for CO2 Monitoring

High pressure CO2 tanks used by restaurants for their soft-drink systems are regulated by the National Board Inspection Code (NBIC). The NBIC was first published in 1946 as a guide for chief inspectors. Since that time, it has become the recognized standard for the installation, inspection, and repair and/or alteration of boilers, pressure vessels, and pressure relief devices. Even in states that do not officially follow the NBIC, it is often used as the defacto standard for local inspection and code enforcement.

The NBIC and its explanations are revised every 2 years to insure that the regulations meet the changing nature of technology. The codes are created by a rotating committee of pressure vessel engineers and experts. These experts update the code and provide guidance and information to those organizations that manufacture, install, repair, and own/use any pressure vessels. It also provides direction to government organizations and inspectors as to how to fairly apply the regulations for the installation and use of the equipment.

The NBIC speaks very directly to the storage of CO2. And not just bulk tanks but cylinders as well. This is explained in an excerpt below from Part 1 - Supplement 3 of the most recent NBIC relating to Installation of Liquid Carbon Dioxide Storage Vessels


Rooms or areas where carbon dioxide storage vessel(s) are located indoors or in enclosed or below grade outdoor locations shall be provided with a gas detection and alarm system for general area monitoring that is capable of detecting and notifying building occupants of a CO2 gas release. Alarms will be designed to activate a low level pre-alarm at 1.5% concentration of CO2 and a full high alarm at 3% concentration of CO2 (which is the OSHA & ACGIH 15 minute and NIOSH 10 minute Short Term Exposure Limit for CO2.) These systems are not designed for employee personal exposure monitoring.  Gas detection systems shall be installed and tested in accordance with manufactures installation instructions and the following requirements;

  1. Activation of the gas detection system shall activate an audible alarm within the room or area in which the carbon dioxide storage vessel is located.
  2. Audible alarms shall also be placed at the entrance(s) to the room or area where the carbon dioxide storage vessel and/ or fill box is located to notify anyone who might try to enter the area of a potential problem.


Warning Signs shall be posted at the entrance to the building, room, enclosure, or enclosed area where the container is located. The warning sign shall be at least 8 in (200mm) wide and 6 in (150 mm) high. The wording shall be concise and easy to read and the upper portion of the sign must be orange as shown in figure S3.5. The size of the lettering must be as large as possible for the intended viewing distance and in accordance with jurisdictional requirements. When no jurisdictional requirements exist, the minimum letter height shall be in accordance with NEMA American National Standard for Environmental and Facility Safety Signs (ANSI Z535.2). The warning signs shall state the following:

  • WARNING – CARBON DIOXIDE GAS. Ventilate the area before entering. A high carbon dioxide (CO2) gas concentration in this area can cause suffocation.”

Figure S3.5

Additional instruction signage shall be posted outside of the area where the container is located and such signage shall contain at minimum the following information:

  • Carbon Dioxide Monitors for general area monitoring (not employee personal exposure monitoring) are provided in this area. These monitors are set to alarm at 15,000ppm (1.5% concentration) for the low level alarm and at 30,000ppm (3% concentration) for high level alarm.
  • Low Level Alarm (15,000ppm) – Provide appropriate cross ventilation to the area. Personnel may enter area for short periods of time (not to exceed 15 minutes at a time) in order to identify and repair potential leaks.
  • High Level Alarm (30,000ppm) – Personnel should evacuate the area and nobody should enter the affected area without proper self contained breathing apparatus until the area is adequately ventilated and the concentration of CO2 is reduced below the high alarm limit.

Download the correct signage to print here (pdf).

The RAD-0102 Remote CO2 Storage Safety Dual Alarm Meter meets the increased requirements for dual level alarms for OSHA STEL (Short Term Exposure Limit) with the 1st alarm at 1.5% / 15,000ppm and the 2nd alarm at 3% / 30,000ppm.  The meter is designed to protect people who work near carbon dioxide stored in closets or confined spaces.

Depending on the regulation, this device is available with single or double strobe models.


Posted by CO2 Meter on November 12, 2014.
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