Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone: 408.943.6900, Fax: 408.943.7943
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Background Statement for SEMI Draft Document 5892
Revision to SEMI S5-0310 With Title Change From: SAFETY GUIDELINE FOR SIZING AND IDENTIFYING FLOW LIMITING DEVICES FOR GAS CYLINDER VALVES
To: SAFETY GUIDELINE FOR SIZING AND IDENTIFYING FLOW LIMITING DEVICES FOR GASES
Notice: This background statement is not part of the balloted item. It is provided solely to assist the recipient in reaching an informed decision based on the rationale of the activity that preceded the creation of this Document.
Notice: Recipients of this Document are invited to submit, with their comments, notification of any relevant patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this context, “patented technology” is defined as technology for which a patent has issued or has been applied for. In the latter case, only publicly available information on the contents of the patent application is to be provided.
Notice: Additions are indicated by underline and deletions are indicated by strikethrough. Text that has been moved is shown as deleted in its original location and added in its new location. Due to software limitations, not all of the numbering changes are indicated.
This ballot consists of proposed changes to address concerns identified in the failed Reapproval ballot for SEMI S5-0310, including:
· Addition of a statement that the release could result from failure anywhere downstream of the cylinder valve.
· Expansion of the scope to include flow limiting devices (FLDs) for applications other than gas cylinder valves
· Updating usages of “material safety data sheet” and “MSDS” to “safety data sheet” and “SDS”
· Addition of consideration of those gases that can react with air to form solids.
· Correction of several grammatical and typographical errors
The ballot results will be reviewed and adjudicated at the meetings indicated in the table below. Check www.semi.org/standards under Calendar of Events for the latest update.
Review and Adjudication Information
Task Force Review / Committee AdjudicationGroup: / S5 Revision TF / EHS NA TC Chapter
Date: / November 2, 2015 / November 5, 2015
Time & Timezone: / 15:30-17:00 PDT / 9:00-18:00 PDT
Location: / SEMI HQ / SEMI HQ
City, State/Country: / San Jose, California/USA / San Jose, California/USA
Leader(s): / Eric Sklar (Safety Guru) / Bert Planting (ASML)
Chris Evanston (Salus)
Sean Larsen (Lam Research)
Standards Staff: / Kevin Nguyen ()
408-943-7997 / Kevin Nguyen ()
408-943-7997
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline. Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
Page 8 Doc. 5892ã SEMIâ
Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone: 408.943.6900, Fax: 408.943.7943
hb khghgh1000A5829
Safety Checklist for SEMI Draft Document 5892
Revision to SEMI S5-0310 With Title Change From: SAFETY GUIDELINE FOR SIZING AND IDENTIFYING FLOW LIMITING DEVICES FOR GAS CYLINDER VALVES
To: SAFETY GUIDELINE FOR SIZING AND IDENTIFYING FLOW LIMITING DEVICES FOR GASES
Developing/Revising Body
Name/Type: / Flow Limitation TFTechnical Committee: / EH&S
Region: / NA
Leadership
Position / Last / First / AffiliationLeader / Sklar / Eric / Safety Guru, LLC
Documents, Conflicts, and Consideration
Safety related codes, standards, and practices used in developing the safety guideline, and the manner in which each item was considered by the technical committee
# and Title / Manner of ConsiderationNo other codes, standards, or practices were used in developing this revision proposal.
Known inconsistencies between the safety guideline and any other safety related codes, standards, and practices cited in the safety guideline
# and Title / Inconsistency with This Safety GuidelineNone
Other conflicts with known codes, standards, and practices or with commonly accepted safety and health principles to the extent practical
# and Title / Nature of Conflict with This Safety GuidelineNone
Participants and Contributors
Last / First / AffiliationJumper / Steve / Applied Materials
Karl / Edward / Applied Materials
Planting / Bert / ASML
Crane / Lauren / KLA-Tencor
Larsen / Sean / Lam Research
Greenberg / Cliff / Nikon Precision
Brody / Steven / Product EHS Consulting
Sklar / Eric / Safety Guru, LLC
Evanston / Chris / Salus Engineering
Visty / John / Salus Engineering
Fessler / Mark / TEL
Barsky / Joseph / TRNA
Pochon / Stephan / TRNA
The content requirements of this checklist are documented in Section 15.3 of the Regulations Governing SEMI Standards Committees.
SEMI Draft Document 5892
REVISION TO SEMI S5-0310 With Title Change To:
SAFETY GUIDELINE FOR SIZING AND IDENTIFYING FLOW LIMITING DEVICES FOR GASES CYLINDER VALVES
This safety guideline was technically approved by the global Environmental Health & Safety Committee. This edition was approved for publication by the global Audits & Reviews Subcommittee on December 16, 2009. Initially available at www.semi.org in February 2010. Originally published in 1993; previously published July 2003.
NOTICE: This document was completely rewritten in 2009.
Contents
1 Purpose 3
2 Scope 3
3 Limitations 4
4 Referenced Standards and Documents 4
5 Terminology 4
6 Safety Guidance 5
7 Flow Limiting Device Criteria 6
8 Calculations 8
9 Related Document 11
Related Information 1 Critical Pressure Ratios For Several Gases 12
Tables
Table 1 Hazardous Gases for Which Flow Limiting Devices Should be Used 6
Table 2 Critical Nitrogen Flow Rates (QNT) for Flow Limiting Devices 8
Table 3 Mixing Gases 9
Table R1-1 Heat Capacities and Critical Pressure Ratios 13
Figures
Figure 1 Nitrogen Flow Rate 7
1 Purpose
1.1 The purpose of this safety guideline is to provide information and methods related to flow limiting devices (FLDs) that limit the rate of release of hazardous gases from gas cylinder valves during transportation, storage, and use.
2 Scope
2.1 This safety guideline pertains to flow limiting devices FLDs for valves on cylinders containing hazardous gases. These devices are intended to limit the flow rate of uncontrolled releases of gases at or downstream of the FLDsvalve outlet.
2.2 This safety guideline pertains to flow limiting devices operating at critical flow rates that result from cylinder pressures greater than 103 kPa (15 psig).
NOTE 1: Generally, flow limiting devices FLDs are not used for cylinders pressurized gases at gauge pressures less than 103 kPa (15psig) because the size required to provide adequate flow for the process is so large that flow reduction resulting from the flow limiting device FLD would be minimal.
2.3 This safety guideline pertains to FLDs operating at critical flow rates that result from the ratio of the pressure upstream of the FLD to the pressure downstream of the FLD being at least the critical pressure ratio.
NOTE 2:For all gases with at least two atoms in molecule, this ratio is less than two. For monatomic gases (He, Ar, Ne, Xe, Kr), it is 2.04 or 2.05. RELATED INFORMATION 1 contains a table of critical pressure ratios for several gases.
2.4 This safety guideline provides a method of identifying flow limiting devices FLDs by size.
2.5 This safety guideline provides methods for calculating the approximate maximum and minimum flow rates of several gases, and their mixtures, through such devices.
2.6 This safety guideline provides a method for selecting the size flow limiting device FLD for an application, based on the gas and the needed flow.
NOTE 3: Specific safety guidance is contained in § 6.
NOTICE: This safety guideline does not purport to address all of the safety issues associated with its use. It is the responsibility of the users of this safety guideline to establish appropriate safety and health practices and determine the applicability of regulatory or other limitations prior to use.
3 Limitations
3.1 This guideline does not pertain to gas releases caused by failure upstream of an FLD, such as of the:
· cylinder or of the valve connection to the cylinder,
· actuation of the cylinder pressure relief device, or
· some failures of the valve.
3.2 This guideline does not pertain to FLDs at which the ratio of inlet pressure to outlet pressure is less than the critical pressure ratio.
NOTE 4: FLD manufacturers, gas suppliers, and other qualified personnel can provide assistance is determining FLD behavior for non-critical flow.
4 Referenced Standards and Documents
4.1 SEMI Safety Guidelines
SEMI S2 — Environmental, Health, and Safety Guideline for Semiconductor Manufacturing Equipment
SEMI S10 — Safety Guideline for Risk Assessment and Risk Evaluation Process
SEMI S26 — Environmental, Health, and Safety Guideline for FPD Manufacturing Systems
4.2 NFPA Standard[1]
NFPA 704 — Standard System for the Identification of the Hazards of Materials for Emergency Response
NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.
5 Terminology
5.1 Abbreviations and Acronyms
5.1.1 MSDS — material safety data sheet [SEMI S12]
5.1.2 FLD — flow limiting device
5.1.3 SDS — safety data sheet
5.1.4 slm — standard liters per minute [SEMI E56, SEMI E69, SEMI E77, SEMI F43, SEMI F70]
5.2 Definitions
5.2.1 equivalent orifice — a passage that will allow fluid flow equivalent to the fluid flow allowed by a round hole with an orifice coefficient of 80%.
5.2.2 downstream (adjective) — on the side to which fluid flows.
5.2.3 flow limiting device (FLD) — a device that will reduce maximum flow rate under full flow conditions.
NOTE 5: As described in § 2, the scope of this Safety Guideline is limited to flow limiting devices in gas cylinder valves. However, the methods described in this Safety Guideline may be applicable to other uses of flow limiting devices.
5.2.4 flow rate — the quantity of fluid passing a specified point per unit time. Flow rates in this guideline are given in standard liters per minute (slm) at the standard conditions of 0°C (32°F) and 101 kPa absolute (14.7 psia). This corresponds to the standard conditions used for calibration of mass flow controllers used in semiconductor processing systems.
5.2.5 hazardous gases — gases that have a degree of hazard rating in health, flammability, or reactivity of 3 or 4 in accordance with NFPA 704, or equivalent rating by a regional standard.
5.2.6 material safety data sheet — written or printed material concerning chemical elements and compounds, including hazardous materials, prepared in accordance with applicable standards. [SEMI S2, SEMI S26]
5.2.7 mixing gas — an inert gas used to dilute another gas.
5.2.8 orifice coefficient — the ratio of actual flow to the theoretical flow through an orifice.
NOTE 6: The orifice coefficient will typically vary from 65% (0.65) for a sharp entrance to 95% (0.95) for a well-rounded entrance. A flow rate tolerance of ±20% is used in Table 1 to allow for variations in the entrance geometry and passage size. Figure 1 illustrates the flow rate variation resulting from this tolerance for different equivalent orifice sizes.
5.2.9 safety data sheet (SDS) — document that describes a chemicals properties and hazards and provides appropriate safety precautions and protective measures for handling, storing, and transporting it.
NOTE 7:The specific requirements are stated in regulations. In most jurisdictions of interest, the regulations are consistent with the UN Globally Harmonized System of Classification and Labelling of Chemicals (GHS). GHS is available at http://www.unece.org/trans/danger/publi/ghs/ghs_rev00/00files_e.html
NOTE 8:“Safety data sheet” has replaced the term “materials safety data sheet”.
5.2.10 size — designation of a flow limiting device an FLD, stated as the nominal internal diameter of an equivalent orifice.
NOTE 9: Table 2 lists several sizes and provides flow rates for several pressures.
5.2.11 upstream (adjective) — on the side from which fluid flows.
6 Safety Guidance
6.1 General
6.1.1 Verification — When a flow limiting device an FLD is required, the user should always verify that the size is identified by tag, label, or marking and verify that the device size indicated matches the requirement. If a required flow limiting device is missing, flow should not be permitted.
6.1.2 Blockage — Some hydrides, such as diborane, can polymerize and cause partial or total obstruction of FLDs. Some hydrides, such as silane, can react with oxygen or water vapor in air to form liquids or solids. Some hydrides can exhibit both behaviors. Care should be taken with containers, piping, and devices that seem to be empty, but may contain product.
6.1.3 Purging — An FLD may restrict gas flow during purging. The user should assure that adequate purging methods are used to prevent plugging the flow limiting device.
NOTE 10: This is important to prevent contamination downstream of the flow limiting device and reduce the probability of creating a risk of Medium, High, or Very High, as evaluated in accordance with SEMI S10.
6.2 Gas Cylinder Valves
6.2.1 Installation — Only the gas supplier or cylinder owner should install, remove, or otherwise service the flow limiting device. Special equipment and procedures may be required to perform any installation or service operation safely. No other person should install, remove, replace, clean, adjust, or otherwise alter the flow limiting device unless authorized by the cylinder owner.
6.2.2 Verification — When a flow limiting device is required, the user should always verify that the size is identified by tag, label or marking on the cylinder or cylinder valve exterior and that the device size indicated matches the requirement. If a required flow limiting device is missing, the cylinder should be rejected prior to use.
6.2.3 Purging — The addition of a flow limiting device in the cylinder valve may restrict gas flow during purging. The user should assure that adequate purging methods are used to prevent plugging the flow limiting device. As a minimum, the operator should purge the valve outlet after use with the same procedure used for purging the valve outlet just after installation of the cylinder.