36 157/2001

CO2 Measurements in Breweries and

Marit FinneEditor-in-ChiefVaisala NewsVaisala HelsinkiFinland

Carbon dioxide is usedfor the carbonation ofbeverages. CO2 is thegas that gives the fizzto soft drinks andsparkling wines. Inbreweries, CO2 is re-covered as a by-prod-uct of fermentation.As high concentrationsof CO2 are clearly haz-ardous, most coun-tries, including theUSA, have set work-place exposure limits.Carbon dioxide moni-toring is essential foremployee safety in thebrewing and carbonat-ed drinks industry.

Breweries throughout the world poseunique challenges for carbon dioxidemonitoring. Pictured tanks in thebrewery.

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37157/2001

d Wineries

arbon dioxide canbe a safety hazard.When CO2 rises,people start feeling

tired. Very high concentrationscan lead to unconsciousness oreven death. Occupations wherecarbon dioxide can rise to dan-gerous levels include the brew-ing and carbonated drinks in-dustries, as well as wineries. It istherefore vital to measure thelevel of carbon dioxide in everyplace where there is a risk ofCO2 build-up or leakage.

Most countries have set work-place exposure limits for CO2.For instance, in the United States,OSHA’s (Occupational Safety &Health Administration, U.S.Department of Labor) general ex-posure limit of CO2 in weight tonot exceed 5,000 ppm during aneight hour working shift.

Carbon dioxide safety mea-surement is especially neededin beverage production, be-cause the fermentation tankshave pressure relief valves. Ifthe pressure in the tanks buildsup too high, the gas will exitthrough these valves. There isalso a risk that gas can leakfrom the tanks or pipelines.

Measuring CO2in breweries

Carbon dioxide is generated asa natural process of fermenta-tion and is found in most brew-ing tanks and around filler ma-chines, packaging and closerareas. Excessive levels of car-bon dioxide can displace oxy-gen, causing asphyxiation.

Breweries throughout theworld therefore pose uniquechallenges to employee safety.There are various areas within abrewery where fermentationgases may collect, becoming ahazard to employees.

In some breweries, CO2 is re-covered as a by-product of fer-mentation. It can then be puri-fied and compressed for further

use. In beverage production thegas for carbonation is usuallydelivered by gas suppliers, be-cause it has to be very clean inorder not to affect the taste.

Confined spaces are amongthe most hazardous places inbreweries. They include beerstorage tanks, brew kettles, vats,sumps, pits and other confinedareas where carbon dioxide maybe present.

Safe CO2 levels inwineries

Similar problems arise at winer-ies. During the fermentationprocess, wine grape sugar is me-tabolized by yeast which con-verts the sugar to water, alcoholand carbon dioxide. During theactive fermentation process,concentrations of carbon diox-ide within the headspace of a fer-menting tank may reach levelsapproaching 100 % by volume.

From the trucking in andcrushing of freshly harvestedgrapes to the final aging and bot-tling process, care must be takento protect people from potentialhazards. Areas of concern withinwineries include pits, sumps andstorage tanks, as well as fermen-tation rooms, barrel cellars andbottling rooms. Carbon dioxideis one of the main gas hazards.

The dangers posed by thistype of CO2 build-up includethe displacement of oxygen andthe potential asphyxiation ofemployees, as well as the dan-gers of being exposed to highconcentrations of carbon diox-ide for extended periods of time.

In wineries, too, the averageexposure limit of CO2 in weightshould be kept below 5,000ppm (0.5% by volume) duringan eight hour working shift. Inaddition, during the active fer-mentation process, closedbuildings should be monitoredfor carbon dioxide build-up be-fore entering, as concentrationsmay exceed safe levels. �

CO2 % Symptoms2 – 3 Symptoms of simple asphyxia occur3 – 8 Increased respiration and heart rate, headache< 10 Headache, nausea, vomiting, unconsciousness10 > Unconsciousness in less than 1 minute, death

Table 1. Effects of CO2 overexposures. Sources: NIOSH / OSHA andUniversity of California.

The following exposure limits are recommendedPEL-OSHA5000 ppm 9000 mg/m3 TWATLV-ACGIH5000 ppm 9000 mg/m3 TWA30000 ppm 54000 mg/m3 STELREL-NIOSH5000 ppm 9000 mg/m3 TWA30000 ppm 54000 mg/m3 STEL

Table 2. Recommended exposure limits

PEL = Permissible Exposure LimitTWA = Time Weighted AverageTLV = Threshold Limit ValueSTEL = Short Term Exposure LimitsREL = Recommended Exposure Limit

OSHA = Occupational Safety and Health AdministrationACGIH = American Conference of Governmental IndustrialHygienistsNIOSH = National Institute for Occupational Safety and Health

Carbon dioxide safety measurement is especially needed in breweries.

P H O T O C O U R T E S Y O F I N T E R B R E W ( © I N T E R B R E W ) .

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