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Monitoring Chlorine Purity

Chlorine is an extremely important chemical in the pharmaceutical, plastics and paper industries. It is also a reactive and corrosive substance that is extremely toxic, even at minute levels. Therefore, it must be sampled in a closed setting to prevent exposure and releases into the environment. Because chlorine has a high rate of thermal expansion, sample receptacles must be designed to allow for vapor space.

Consult this page to understand how BIAR COLUMBIA-LY sample cylinders provide sufficient vapor space to prevent volumetric expansion from causing excessive pressure in the cylinders.

Why It's Important to Take Chlorine Samples

  • To test for purity.

What to Look for in the Sample

  • Non-volatiles & iron: Liquid chlorine is evaporated in a flask and the remains are measured.
  • Inerts: Liquid chlorine is put through a gasifier then the gaseous chlorine is run through a Gas Chromatograph.
  • Other samples can be run using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) to test for organics.

How to Safely Take Chlorine Samples

  • BIAR Multi-Function Hastelloy C276 inline sample valve with spring-to-close function, bellows seal, stuffing box as secondary containment
  • BIAR Hastelloy C276 Cylinder
  • Bayonet Adapter (for connecting BIAR Cylinder to the valve)
  • Safety Plug (secondary containment)
Sample Cylinder Video

BIAR Sample Cylinders are the industry's only sample cylinders available with bellows. When a sample valve is fitted with bellows seals, it offers the most effective protection against fugitive emissions.

To prevent moisture from reacting with chlorine at the valve outlet, and to provide secondary containment when the valve is not in use, a safety plug is also incorporated into the valve design.

This system differs from traditional sample panel systems which feature a cylinder with dip tube and is safer because:

  • Fewer steps are needed to take a sample
  • No quick connects or tubing required
  • No moisture from outside can influence the sample
Cutaway view of sample cylinder & valve

Liquid Chlorine

1) Description

Name: ........................................................................................... Chlorine

Chemical Formula: ...................................................................Cl2

CAS No: ........................................................................................7782-50-5

Other Names: ............................................................................. Molecular chlorine

Uses: ..............................................................................................Industrial, Domestic

Physical state: .............................................................................Liquid, Gas, Liquefied Gas

Color: .............................................................................................Yellow-Green

Odor: ..............................................................................................Irritating, bleach-like

Boiling Point: ...............................................................................-34 ℃ -29 ℉

Freezing Point: ..............................................................................-101.5℃ (-150℉)

Flammability (solid, gas): .........................................................N/A

Vapor pressure: ...........................................................................6.8 atm

Viscosity (20℃ (liquid)): ...........................................................0.134 mPa.sec at 20℃ (gas); 0.346 mPa.sec

 

2) Hazards

Chlorine is considered Immediately Dangerous to Life or Health (IDLH). NIOSH (1994).

GHS Hazard Statements
H270: May cause or intensify fire; oxidizer.
H315: Causes skin irritation.
H319: Causes serious eye irritation
H331: Toxic if inhaled
H335: May cause respiratory irritation
H400: Very toxic to aquatic life
 

Reactivity: Strong Oxidizing Agent, Water-Reactive, incompatible with Alcohols. Reacts with most metals.

Specific Hazards Related to Sampling: Chlorine is an extremely hazardous and reactive chemical. Sampling must be carried out in sealed containers to reduce exposure risk and minimize releases into the environment. Chlorine will react with moisture, corroding metals such as carbon and stainless steel.

Alloys such as Hastelloy® or Monel are best suited for chlorine sampling due to their high corrosion resistance. Systems should also be designed so that no moisture can be introduced to influence the sample (e.g., condensation on the outside of fittings).

When sampling chlorine, allowance must also be made for thermal expansion within the receptacle. Ideally, there should be sufficient space within the container to prevent the danger of over-expansion.

 

HAZARD ICONS

3) Sampling Facts


a. Why plants need to sample
Plants need to sample chlorine to test its purity.

b. What are they looking / measuring in the sample
Non-volatiles and iron: Liquid chlorine is evaporated in a flask and the remains are measured.
Inerts: Liquid chlorine is put through a gasifier which turns it to gas, then it is run through a Gas Chromatograph (GC).  
Other samples can be run using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) to test for organics. 

4) Most common Sample Receptacles
Chlorine liquefied gas should be sampled into a closed container or cylinder. The receptacle should have sufficient volumetric space to allow for product expansion

 

 

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