The De Nora blog: Water Made Easy

Technical Data — Safe Handling of Chlorine Gas

Aug 13, 2020 8:44:00 AM / by De Nora


The safe handling of chlorine gas and a secure chlorination system includes a proper facilities design, an operation and maintenance program, the appropriate safety equipment and an emergency action plan. The following, while not all-encompassing, will cover the chemical and physical characteristics of chlorine, as well as the many safety steps and procedures that must be followed to keep your facility safe.

What is Chlorine?

Chlorine is a greenish-yellow gas (under ambient conditions), non-flammable and about 2.5 times heavier than air. It is also toxic and irritating to the skin, eyes, nose and mucus membranes. Liquid chlorine, which is amber in color, causes severe irritation and blistering of the skin. 

Chlorine should only be used in a well-ventilated area, with easy access to an eyewash station and showers. Exposure to low concentrations of chlorine gas will cause burning of the nose and throat, redness in the face and coughing. Higher concentrations will cause tightness in the throat and chest and pulmonary edema. Concentrations of 1000 ppm are rapidly fatal.


  • Permissible Exposure Level (PEL): 0.5 ppm/v
  • Short Term Exposure Limit (STEL) 15 minutes: 1.0 ppm/v
  • Immediately Dangerous to Life or Health (IDLH): 50 ppm/v

Effects Data

  • Slight symptoms after several hours exposure: 1 ppm
  • Least detectable odor: 0.02-0.2 ppm
  • The maximum amount that can be inhaled for one hour without serious disturbances: 4   ppm
  • Noxiousness, difficulty in breathing after several minutes :5 ppm
  • Irritation of the throat: 15 ppm
  • Causes coughing: 30 ppm

System and Facility Design — Chlorine Containers

  1. Never expose a container to direct heat.
  2. Never tamper with a fusible plug.
  3. Always keep the shipping hood in place except when the container is being used.
  4. Never lift a cylinder by its hood.
  5. When discharging liquid to a common manifold, the containers must have a separate  
      gas equalization manifold.
  6. Do not move ton containers with equipment rated under two tons capacity.
  7. Store containers in marked areas protected from direct heat.
  8. Use and store containers above ground level.
  9. Secure all containers with chocks, trunnions, chains, etc.

Chlorine Room Layout

  1. Provide chlorine storage and equipment rooms with doors opening outward to the  outdoors and equip them with panic hardware.
  2. Provide visual and audible emergency alarms at the chlorine room entrance.
  3. Exhaust fans should have sufficient ratings to change over the air every minute.
  4. Provide a chlorine gas detector to alarm when a leak occurs, and an ammonia bottle to help locate a leak.
  5. Provide a proper emergency kit to repair leaking containers.
  6. Provide a lifting bar and electric hoist for ton containers rated for 4,000 lbs.
  7. Provide cylinder hand trucks with chains for 150 lb cylinders.

Safety Equipment

1. Provide

  1.  Two (2) pressure-demand type air masks for working in a leak area. Locate one (1) at\a prominently marked, easily accessible location outside the chlorine room. Locate the second at a location remote to permit access in time of need. Provide spare 30-minute air tanks at a remote location.
  2. Escape respirators
  3. Protective clothing
2. Have Available 
  1. Colored vests
  2. Flashlights
  3. Safety helmets, goggles
  4. Lifelines
  5. Audio paks

Equipment Requirements

  1. Use only equipment with remote vacuum regulators to eliminate pressure lines.
  2. Use remote ejectors to reduce the number and length of chlorine solution lines.
  3. Do not manifold equipment vent lines. Run individual vent lines for each component to be vented.
  4. Terminate vents where a discharge of chlorine can be tolerated without exposure to personnel or equipment.
  5. Install an insect screen over the discharge of the vent lines. Discharge the vents downward.

Emergency Action Plan

  1. Ensure that community fire, medical and hazmat personnel are trained in chlorine  emergency procedures.
  2. Train plant emergency crew.
  3. Prepare a written emergency control plan.
    1. List do’s and don’ts.
    2. Establish training responsibilities.
    3. Conduct classroom training.
  4. Conduct a training program.
    1. Duplicate excitement
    2. Simulate gas with smoke bombs
    3. Enact worst case, day/night.
    4. Conduct unscheduled drills
    5. Conduct critiques drill.
    6. Record on videotape.
  5. Use Chlorine Institute Pamphlet #64 — “Emergency Control Planning” as a guide.
  6. Schedule regular drills.
  7. Establish fast access and exit routes.
  8. Contact CHEMTREC at 800-424-9300.

Safety Checklist

The following guidelines should be used to check a chlorine facility:

  1. Provide proper instructions and supervision to workers.
  2. Provide proper and approved self-contained breathing apparatus.
  3. Prepare escape plans from areas where there might be a chlorine emission 
    (move uphill and upwind of a chlorine leak).    
  4. Install safety showers and eyewash stations near the chlorine equipment.
  5. Provide Chlorine Institute emergency kits or coffins.
  6. Two persons should make the repairs on a leak. Never repair the equipment alone.
  7. Spray water on containers only if there is a fire hazard (water will cool the container 
  8. Position a leaking container so the chlorine escaping is gas, not liquid, to prevent the fusible plug from melting. Water sprayed on a leaking container will make the leak worse.           

First Aid For Chlorine Exposure

  1. Inhalation
    1. Remove the victim from the contaminated area.
    2. Keep the victim warm in a reclined position with the head and shoulders elevated.
    3. Give artificial respiration if necessary.
    4. Administer oxygen as soon as possible.
    5. Call a physician immediately.
  2. Skin Contact
    1. Shower victim, removing all contaminated clothing.
    2. Wash affected area with soap and water.
    3. Call a physician immediately.
  3. Eye Contact
    1. Irrigate eyes with water for 15 minutes holding the eyelids wide apart.
    2. Call a physician immediately.
    3. Irrigate for a second 15 minute period if the physician is not immediately available.

In addition to this blog article, the Chlorine Institute offers a series of free pamphlets concerning the safe handling of chlorine gas. These pamphlets can be found and downloaded from their website,

What Does Your Water Need? 

Better determine proper dosing based on water quality. Download our FREE dosing calculator. Click below for more information.

Get the Caluclator

Tags: water treatment, De Nora, gas feed, chlorine gas

De Nora

Written by De Nora

Lists by Topic

see all

Posts by Topic

See all

Recent Posts