2 Reasons for a Safety Seminar To heighten the awareness of thedangers associated with compressedgasesTo encourage safe operating practicesin their everyday useTo help ensure the right equipment isused for your application
3 Definition Compressed Gas Any material or mixture with an in-container pressure exceeding 40 psia at 70F, or a pressure exceeding 104 psia at 130F, or any liquid flammable material having a vapor pressure exceeding 40 psia at 100F [sec (a)].
4 The Gas: Rule #1! Know the properties of the materials involved Gases may be:Under high pressureToxicCorrosiveFlammablePyrophoricOxidizers
5 High Pressure Gas Can cause equip. to fail with explosive force When released can diffuse into the atmosphere very rapidly, and an entire room may be thoroughly contaminated within seconds!A common 9” dia X 52” high cylinder pressurized to 2000 psi has the stored energy equivalent to one pound of dynamite!Cylinders are commonly filled to standard pressures of 2000 psi, 2490 psi, 3500 psi and 6000 psi.
6 Toxic GasesHave the ability to cause injury or death when ingested or absorbed by the skinExamples include Ammonia, Vinyl Chloride and Phosgene
7 Corrosive Gases Will attack and damage human tissue Will have an adverse effect on improper materials of constructionExamples of corrosive materials are Hydrogen Chloride, Hydrogen Fluoride
8 Flammable & Pyrophoric Gases Flammable gases easily catch fire and burn rapidly in airExamples of flammable gases are Acetylene, Hydrogen, Propane, and PropylenePyrophoric gases spontaneously ignite and burn when exposed to the atmosphereSilane is a pyrophoric gas which is commonly used in the electronics industry
9 Liquefied Compressed Gases Contents of a liquefied compressed gas cannot be determined by the pressure in the cylinder, and a cylinder scale must be used
10 Shipping RegulationsDept. of Transport (D.O.T.) regulations specify the familiar diamond shaped tag that must be affixed to each cylinder being shipped
11 Material Safety Data Sheets Required in workplaceSubstance fact sheet listingcharacteristics, hazards and asmuch detail as possibleconcerning the particular gasSECTION FIRST AID MEASURESINHALATION: If adverse effects occur, remove touncontaminated area. Give artificial respiration if not breathing. If breathing is difficult, oxygen should be administered by qualified personnel. Get immediate medical attention.SKIN CONTACT: If frostbite or freezing occur, immediately flush with plenty of lukewarm water( F; C).
12 Threshold Limit Values (TLV’s) Time Weighted Average (TWA)- Average 8 hour exposure, 5 days a weekShort Term Exposure Limit (STEL)- 15 minutes, 4 times a dayImmediately Dangerous to Life and Health (IDLH)
14 Compressed Gas Cylinders Come in many shapes and sizesCommonly constructed of Carbon Steel or AluminumStandard size 1A cylinder pressurized to 2200 psig holds approx. 225 ft3 of gas in an internal volume of 1 ½ ft3!
15 Cylinder Identification And Markings 1Specification number -consists of three sections.DOT- signifies that the cylinderconforms to Department ofTransportation (DOT) specification.3AA - specifies type and material ofcylinder construction.indicates service pressurefor which the cylinder is designedat 70F.
16 Cylinder Identification And Markings 2Cylinder serial number(Matheson Tri-Gas number)
17 Cylinder Identification And Markings 3Date of initial hydrostatic testing
18 Cylinder Identification And Markings 4Original inspector's insignia
19 Cylinder Retest Schedule Specification under which Minimum Retestcylinder was made retest pressure (psi) period (yearsDOT psi 53D 5/3 times service pressure 5psi 10DOT psi (maximum 600 psi) 526 for filling at over 450 psi 5/3 times service pressure 5psi 5
20 CGA Connections Compressed Gas Assoc. Reasons for CGA standards CGA gaskets/washersRestricted flow orifices
22 Matheson Tri-Gas Product Safety & Code Compliance Primary Governing Bodies / Safety CodesCompressed Gas Association (CGA)Semiconductor Equipment & Materials International (SEMI)US Environmental Protection Agency (EPA)Uniform Fire Code / Local City Regulatory Committee (UFC)Uniform Building Code (UBC) / BOCANational Fire Prevention Code (NFPC)International Conference of Building Officials (IBOC)Toxic Gas Ordinance (TGO)
23 Cylinder Handling and Transportation Upon receipt, visually inspect the cylinders for obvious defects such as dents, large amounts of rust and missing or loose safety caps.Cylinders shouldn’t be accepted unless identified with the appropriate labeling, and all them agree with one another!Use a cylinder cart and secure the cylinders with a chain when moving.Don’t use the protective valve caps for moving or lifting the cylinders.
24 Cylinder Handling and Transportation Don’t drop a cylinder, permit them to strike each other violently or be handled roughly.Unless cylinders are secured, regulators should be removed, valves closed and protective caps in place before cylinders are moved.Rolling cylinders in a vertical position on the bottom edge is to be avoided as much as possible. Gas cylinders must never be dragged or rolled in the horizontal position.
25 Cylinder StorageDouble restrain cylinders with non-combustible material (i.e., chain)Label Full versus EmptySigns for hazardous gasesKeep away from traffic areasStore in fire resistant, well ventilated, dry areas
26 Cylinder Storage Keep away from flames or sparks Keep caps on when not in useStore in areas <125°FKeep oxidizers 20 ft. from flammablesCorrosives should be stored less than 6 months
29 Single Stage Regulator Reduces the inlet supply pressure in “one step”, from the inlet supply pressure to the final outlet pressure
30 Single Stage Regulator Applications:Intermittent use - where asample of gas is requiredfrom a cylinderWhere pressure rise in a setdelivery pressure is notcriticalAs a line regulator wherethere is a second pressureregulator at the gas supplysource
31 Single Stage Regulator Characteristics:Rule of thumb: for every 100 psig drop on the inlet pressure, there will be 1 psig rise on the outlet working pressure
32 Two-Stage RegulatorReduces the pressure in “two steps” from a high pressure inlet source, to the final outlet working pressure
33 Two-Stage Regulator Characteristics: Delivery “set pressure” remains constant as the inletsupply pressure decaysBecomes a single stage regulatorwhen the source supply pressurebecomes less than the set pressureof the first stage (~300 psig)Can be supplied with an inter-stagerelief valve as insurance in theevent of first stage seat failure
34 Two-Stage Regulator Applications: Recommended for continuous use applications, such as carriergas supply to GC’s or otheranalytical instruments, whereit is critical that a constantdelivery set pressure bemaintained
35 Regulator Installation Do not use CGA adaptors or change CGA connections on regulators for a different gas service – unless work is done by qualified personnel!Always ensure there are no nicks and scratches on regulator CGA connectionsNever use Teflon tape to achieve a proper sealAlways leak check connections using a soap bubble solution or electronic leak detector
36 Regulator OperationAlways ensure the P/A knob is backed off counterclockwise to ensure there is no load on the regulator load spring – prior to opening the cyl valve!Never open a cylinder valve all the way. 1 ½ to 2 turns is usually sufficientAlways stand with the cylinder valve between you and the regulator when opening the cylinder valve and/or adjusting pressure on the regulatorDo not use the temporary shut-off valve to turn off gas flow if the shut-off duration will be longer than 20 min.Use cross or T-purge assemblies if regulators are to be used for toxic or corrosive gases!
37 Regulator Failures95% of regulator failures are due to seat failures, caused by:Corrosion buildup on the seatContamination (dirt, metal filings, Teflon tape) that scores the seat at a high velocitySet pressure creep on the delivery pressure gauge indicates a seat failure!
38 Regulator FailuresA Pressure gauge that will not read zero indicates the bourdon tube has been damaged and the gauge must be replaced!Gas leaking through the bonnet assembly of the regulator indicates a diaphragm failure(Typically caused by failure to ensure the regulator is shut off prior to installing it on a new cylinder)
39 Safety Devices: Check valve: prevents reverse gas flow Flash Arrestor: prevents ignition source from reaching regulator and cylinder for flammablesExcess Flow Valve: restricts flow in the event of a gas line break
40 Things Not To Do! Never roll a cylinder to move it. Never carry a cylinder by the valve.Never leave a cylinder unsecured.Never force improper attachmentson to the wrong cylinder.Never grease or oil the regulator, valveor fittings of an oxygen cylinder.Never refill a cylinder.Never attempt to mix gases in a cylinder.
41 Safe Gas UsageCompressed gases serve laboratories and industrial plants in many ways, but the cylinders and gases present a number of hazards.“Treat all gas cylinders, full or empty, as objects that have a very real potential to injure you severely.”
42 Consider Reduction/elimination of gas cyl’s in the lab Through a centralized gas distribution systemGas generators for H2, N2 or Zero Air
43 Emergency PlanEvery location where compressed gases are handled should have a written emergency plan covering steps to be taken in the event of an accidental release of gasThis plan should consider the nature of the gases being handled, that is their chemical and physical properties
44 At a minimum, the plan should specify the following : Plan ElementsAt a minimum, the plan should specify the following :Alarm System & Evacuation ProcedureResponse PersonnelEmergency EquipmentContainment or disposal methods
48 All rights reserved. No part of this presentation may be reproduced or used in any form whatsoever without the express written permission of Matheson Tri-Gas, Inc.; except in the case of brief quotations embodied in critical articles and reviews. Theinformation contained here is for the personal use of the reader and may not be incorporated in publications, databases, orsoftware programs without the written consent of Matheson Tri-Gas, Inc.This publication is intended to provide accurate information in regard to the subject matter covered and has been obtained fromsources believed to be reliable. Of necessity the information is abbreviated and other information, training and/or education isrequired of the user of this information. Accordingly, Matheson Tri-Gas, Inc. makes no warrantees, guarantees, or representations of any kind or nature with respect to the information published herein, either express or implied, and whetherarising by law or otherwise, including but not limited to any implied warranty of merchantability or fitness for any particularpurpose, and shall not be responsible for any errors, omissions, or damages arising out of use of this information. Matheson shall in no event be liable for any personal injuries, property or other damages of any nature whatsoever, whether special, indirect,consequential or compensatory, directly or indirectly resulting from the publication of, or reliance upon the information.