Sulfur Dioxide

This chemical standard operating procedure (SOP) is for your safety. Read, understand, and follow this document. If this is a paper copy, you should check for the most recent version on the IsoLab website. This document was created from a template modeled after the University of Washington Environmental Health and Safety Laboratory Safety Manual Standard Operating Procedures Components.

Is Sulfur dioxide a particularly hazardous substance? YES

What is a particularly hazardous substance? The University of Washington Environmental Health and Safety defines it here.

The SDS for Sulfur dioxide can be found here.

1. Process Sulfur dioxide is used as an isotope reference gas for a mass spectrometer.
2. Hazards Sulfur dioxide (SO2) is a hazard by inhalation, skin contact, swallowing, and eye contact. Refer to the SDS for more information.
3. Personal Protective Equipment Since the compressed SO2 cylinder is stored in a fume hood, only gloves (nitrile with extended cuff or similar) are required to open and close the cylinder.
4. Environmental / Ventilation Controls The SO2 cylinder is to be kept in the fume hood in JHN 302A and secured to its stand at all times. The regulator is left installed and a wrench is used to open and close the cylinder. An SO2 detector is left hanging on the cylinder so that lab users, even though the cylinder is in a fume hood, would be aware if the cylinder began leaking. Stainless steal tubing connects the cylinder to the Conflo III that is connected to the mass spectrometer Shrek. The Conflo III is ventilated with a snorkel or small exhaust pipe. All SO2 released from the Conflo III, and it is released with the Conflo III, either flows to the mass spectrometer or out the snorkel. An SO2 detector is also hanging near the Conflo III. If the fume hoods or snorkel flow are to be turned off for maintenance, or are off for any reason while SO2 is in use, the cylinder must be closed until fume hood functioning returns.
5. Special Handling Procedures & Storage Requirements

IsoLab is to have only one cylinder at a time and it must be stored in the fume hood. Ordering of this cylinder is to be through Praxair, part number SD 3.8-G. Praxair delivers the cylinder to the lab and picks the empty cylinder up from the lab. Contact Praxair for the details of each delivery / pickup.

The SO2 detectors (one at cylinder, one at Conflo III), should be checked for proper functionality prior to open the cylinder. If the Conflo III SO2 detector is alarming, note the SO2 concentration printed on the detector, leave the room, and call the lab manager. If you are certain of an SO2 release, call 911.

IsoLab monitors use of the SO2 by weighing the cylinder and its stand when the cylinder is in use. The pressure reading from the regulator is moderately useful when no liquid SO2 remains. The weight and pressure are recorded in the DailyLog excel file on the Shrek computer.

6. Spill and Accident Procedures

If SO2 has been released into the room, the SO2 detectors should be alarming. SO2 odor is pungent; similar to a just-struck match.

This is copied directly from the SDS - Immediately evacuate all personnel from danger area. Use self-contained breathing apparatus and protective clothing where needed. Reduce vapors with fog or fine water spray. Shut off flow if without risk. Ventilate area or move cylinder to a well ventilated area. Prevent runoff from contaminating surrounding environment. Toxic, corrosive vapors may spread from spill. Before entering area, especially a confined area, check atmosphere with an appropriate device. Reverse flow into cylinder may cause rupture.

From our safety poster - If the release of SO2 endangers anyone outside the lab, pull the nearest fire alarm and call 911.

7. Waste Disposal Do not dispose of unused quantities. Return cylinder to supplier. Contact Praxair or Airgas and make arrangements for pickup.
8. Special Precautions for Animal Use (if applicable) N/A
Particularly hazardous substance involved? YES, see 9-11
9. Approval Required

You must have taken Managing Laboratory Chemicals or similar UW EH&S condoned course before using SO2. You must have read and understood the SDS for SO2 as well as this SOP. All personnel manipulating the SO2 cylinder must also have be trained properly by the lab manager.

10. Decontamination Any tubing that is to be reused for another purpose or discarded, must first be flushed with an insert gas such as nitrogen, where the effluent is vented to a fume hood.
11. Designated Area The SO2 cylinder will only be used in the JHN 302A fume hood.


I have read and understood this Chemical SOP:

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Last updated: 2020-10-13 10:58:55