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Page last updated
February 28, 2005

User Advisory

Overview

Small amounts of hazardous gases may be used for experiments at endstations on the ALS experiment floor. The use of these gases must be approved by ALS and EH&S staff before an experiment begins. The proper handling of gases, including the use of specialized regulators and ventilated gas cabinets, is essential to ensure the safety of ALS personnel and equipment. This advisory is intended to establish guidelines for the safe use and storage of toxic and corrosive gases at the ALS.

Policy

The guidelines provided in this advisory are designed to assist ALS users in meeting Berkeley Lab's health and safety requirements for the use of toxic and corrosive gases for experiments. All equipment and procedures for the use of such gases must ultimately satisfy the safety requirements set forth in the Laboratory Health and Safety Manual, PUB-3000 in Chapter 7, "Pressure Safety and Cryogenics," and in Chapter 13, "Gases." All users of tozic and corrosive gases at he ALS must follow the procedures detalied in this document.

All gases intended for experimental use at the ALS must be listed on the Experiment Form and approved by the ALS before the experiment is conducted. If any changes or additions are made to this list, EH&S Program Manager (ext. 7407) or the Beamline Coordination Section Leader (ext. 5527) must be notified. All changes must be approved by the ALS before the experiment may begin.

Shipping and Storage of Gases

All hazardous materials, including toxic and corrosive gases, shipped to or from the ALS must be packaged and handled according to U.S. Department of Transportation regulations, and each shipment must include the relevant Materials Safety Data Sheet (MSDS). Transportation of hazardous gases by private car or LBNL vehicle is prohibited. Gases shipped to the ALS must be contained in a commercial compressed gas cylinder and be clearly labeled with the user's name and the contents of the cylinder. Upon arrival at the ALS, all cylinders must be stored in a ventilated cabinet in the Gas Storage Room located in Building 10, Room 100 (across from the Chemistry Laboratory; enter through the parking lot between Buildings 10 and 80). Contact the Beamline Coordination Section Leader (ext. 5527) for access to the storage room and for additional information regarding storage procedures.

Gas Use at ALS Endstations

In order to maintain the highest level of safety when using toxic and corrosive gases for an experiment, it is ALS policy to require the use of ventilated gas cabinets and pressure-reducing regulators. It is also ALS policy to minimize the amount of hazardous gases used at experiment endstations.

Small Quantity of Gas Required

When very small amounts of gas are adequate, a small sample cylinder charged to a sub-atmospheric pressure may be used. Sample cylinders must be filled in a properly equipped fume hood before being taken to the experiment endstation. The use of sample cylinders for health-hazard gases must be approved by the EH&S Program Manager (ext. 7407).

Larger Quantities of Gas Required

When larger quantities of gas are needed, a commercial compressed gas cylinder may be used. Unless otherwise authorized, compressed toxic or corrosive gases must be contained in "lecture bottle"-size cylinders (50 liters or 2 cubic feet). When in use on the experiment floor, gas cylinders must be housed in ventilated gas cabinets provided by the ALS. Users wishing to borrow a gas cabinet should contact the Beamline Coordination Section Leader (ext. 5527). No compressed toxic or corrosive gas may be used until the gas cabinet system housing is approved on the Experiment Safety Sheet (ESS) and all intended users have been trained in ALS Procedure BL08-23: Hazardous Gases and Gas Cabinets Used at ALS Beamlines. If a toxic or corrosive gas is disconnected from its regulator, it must be returned immediately to the Gas Storage Room in Building 10.

Regulator Requirement

All compressed gases used at the ALS must be dispensed through a suitable pressure-reducing regulator. Manual valves alone are not acceptable. The purposes of this requirement are to provide better control of gas flows and to minimize the volume of any discharge due to possible leaks in the system.

When working with a vacuum system, users need a regulator designed to deliver only a few psi of line pressure. For toxic gases, a Matheson Model 3322 lecture bottle regulator (2004 cost: $175) is required. For corrosive gases, a new or rebuilt Matheson Model 3332 plastic lecture bottle regulator (2004 cost: $500) is required. (For corrosive gases, the cost of a new or rebuilt regulator is justified as insurance against corrosion of unseen internal parts.) As a service to users, the ALS maintains a stock of recommended lecture bottle pressure regulators for toxic and corrosive gases. These may be borrowed by users if their own regulator is unacceptable for use at the ALS; contact The Beamline Coordination Section Leader (ext. 5527) for more information. When not in use, all regulators should be vacuum purged through their delivery ports while they are still in the gas cabinet . This should always be done before disconnecting the regulator from the lecture bottle.

Experiment Setup

In addition to the use of pressure-reducing regulators and ventilated gas cabinets when toxic and corrosive gases are being used in an experiment, proper tubing, pressure relief valves (if applicable), and safe routing of vacuum pump exhaust from the experiment are required to ensure personnel and equipment safety at the ALS.

Stainless Steel Tubing

Stainless steel or copper tubing and fittings must be used to route toxic and corrosive gases from the gas cabinet to the experiment. This routing system must be thoroughly checked for leaks before the experiment begins.

Pressure Relief Valves

When a pressurized gas is introduced into a vacuum chamber, inadvertent pressurization of the chamber must be avoided. When the gas source is a lecture-bottle cylinder, a large vacuum chamber will be inherently safe if there is not enough gas to bring it from vacuum to a positive pressure. However, in cases where there is the possibility of pressurizing the chamber, a pressure relief valve must be used in the gas supply system (0.5 psi relief valves are available at the ALS for this purpose). When toxic or corrosive gases are used, the relief valve exhaust must vent to the building exhaust system, usually via the gas cabinet. Flexible plastic hose or tubing is acceptable for this purpose.

Vacuum Pump Exhaust

Vacuum pumps used to pump toxic or corrosive gases must have their exhaust flows routed to the building exhaust system.

More Information

For questions concerning the use or storage of toxic or corrosive gases at the ALS, contact Georgeanna Perdue (ext. 7407) or the Beamline Coordination Section Leader (ext. 5527).