Chlorine Gas Disinfection Facilities: Design and Installation Guidelines for Water or Wastewater

www.ablewright.com

By Doug Mitch / Able Wright, Inc.

When designing a new gas feed installation, or upgrading an existing one, the following guidelines will assist in the arrangement of the system. This technical data has been provided as an industry service by Severn Trent Services / Capital Controls…

Chlorine Room Layout

1. Provide chlorine storage and equipment rooms with doors opening outward to the outdoors, and equipped with panic hardware.

2. Provide a viewing window into chlorine storage and equipment rooms for operator security.

3. Provide visual and audible emergency alarms at the chlorine room entrance.

4. Exhaust fans should have sufficient rating to changeover the air every minute.

5. Provide a chlorine gas detector to alarm when a leak occurs, and an ammonia bottle to help locate a leak.

6. Provide a proper emergency kit to repair leaking containers.

7. Provide a lifting bar and electric hoist for ton containers rated for 4000 lbs.

8. Provide cylinder hand trucks with chains for 150 lbs. cylinders.

Chlorine Containers

1. Never expose a gas 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 at less than 4,000 Lbs capacity.

7. Store containers in marked areas protected from direct heat.

8. Use and store containers above ground level and always in a vertical position.

9. Secure all containers with chocks, trunnions, chains, etc.

Chemical Storage

1. Store gas containers in separate or divided rooms (i.e. store chlorine separately from sulfur dioxide).

2. Store containers separately from flammable materials.

3. Shield chlorine containers from external heat sources.

4. Ensure protective hood is secure on unused containers.

Safety Equipment

1. Provide

a. 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.

b. Chlorine gas detector

c. Chlorine Institute approved Emergency Repair Kit

d. Emergency eye wash

2. Have available:

a. Colored vests

b. Flash lights

c. Safety helmets, goggles

d. Life lines

e. Communication devices

Piping

All piping must be done in accordance with Chlorine Institute Pamphlet #6, "Piping Systems for Dry Chlorine". Use all vacuum gas delivery whenever possible; avoid pressure delivery. All pipe, valves, and fittings must be thoroughly cleaned of all oils and foreign matter (grease, pipe chips, dirt, etc.) prior to assembly. Failure to properly clean may result in undesirable chemical reactions and non-warrantable equipment failure.

Gas Vacuum (Chlorine, Sulfur Dioxide, Ammonia)

Vacuum lines should be polyethylene tubing, PVC pipe (Schedule 80), or similar materials resistant to moist gas. Routing tubing through unventilated conduit is discouraged. A minute portion of gas flowing through tubing will slowly diffuse at the molecular level through its walls and collect in the closed conduit over an extended period of time. Vacuum connections must not be over-tightened (hand tight only) to prevent cracking of plastic components.

Chlorine Liquid or Gas Pressure

Pressure lines, where necessary, should be seamless carbon steel, Grade B, Schedule 80, Type S, ASTM A-106. Avoid re-liquefaction. Heat trace pressure pipe (Reference: Capital Controls Bulletin 010.3002)

Thread Coating

Coat all threads on PVC pipe and fittings with Teflon (PTFE) tape and, on carbon steel pipe, with Teflon tape or a mixture of litharge and glycerin. IMPORTANT: A litharge and glycerin joint cures forming a permanent joint. These joints cannot be taken apart once set.

Vent Piping

Terminate vents outdoors in an area that can tolerate gas discharge. Vent piping should be made of polyethylene tubing, PVC pipe (Schedule 80), or similar materials suitable for use with moist gas service. Vent lines should not exceed more than 20 feet (6 meters) in height. The termination point must be open, pointing downward and covered with a fine mesh screening. Vent piping should always be discharged to atmosphere. NEVER MANIFOLD VENT LINES. Separate vent lines from each component are recommended to assure safe operation.

Safety Check List

The following guidelines should be used to prepare and evaluate a chlorine facility:

1. Provide proper instructions and supervision to workers; establish an Emergency Action Plan.

2. Provide proper and approved self-contained breathing apparatus.

3. Establish fast access and exit routes. 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 eye wash stations near the chlorine equipment.

5. Provide Chlorine Institute approved Emergency Repair Kit.

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 to prevent the fusible plug from melting). Water sprayed on a leaking container will make the leak worse.

9. Position a leaking container so the chlorine escaping is gas, not liquid.

Summary

Failure to follow these guidelines may endanger human life, reduce the life of the equipment, and/or void manufacturer´s warranties. Compliance with local codes and regulations must also be assured. For additional installation details, refer to the appropriate equipment installation manual and The Chlorine Institute´s manuals.

Engineers & Operators: If we can be of assistance to you during design or upgrade of a chlorine gas disinfection facility – give us a call. We offer design assistance, technical field service and prompt delivery of spare part kits & replacement components for gas feed equipment, as well as coordination of factory rebuilds.

Contact us at:

Able Wright, Inc.

PO Box 849

Plains, MT 59859

(406)250-8389

www.ablewright.com

AbleWright@blackfoot.net

Doug Mitch is the founder and President of Able Wright, Inc. – a provider of water treatment equipment and technical services, specializing in disinfection and chemical feed applications in Montana, Wyoming, Idaho, and Washington.

www.AbleWright.com