LOW-PRESSURE EXCESS FLOW NATURAL GAS VALVES PLUMBING CODE APPLICATION REQUIREMENTS

Transcription

1 LOW-PRESSURE EXCESS FLOW NATURAL GAS VALVES UNIFORM PLUMBING CODE APPLICATION REQUIREMENTS Prepared For: Carl Strand Strand Earthquake Consultants 1436 S. Bentley Avenue, #6 Los Angeles, CA and James C. McGill Smart Safety Systems 4312 Lisa Drive Union City, CA Prepared By: J. Marx Ayres, P.E. Consulting Mechanical Engineer 1180 South Beverly Drive, Suite 600 Los Angeles, California (310) January 21, 2002

2 Low-Pressure EFVs Table of Contents Section Table Of Contents Page Table of Contents Tables & Figures (see attached) ii Execu t Ive Summary "'f' 111 IV Acknowledgements V 1 Introduction Background 1.2 Purpose 1.3 Excess Flow Valves 2 Calculations UPC Requirements 2.2 Spitzglass Formula 2.3 Pipe System 2.4 Certifications 2.5 Spread Sheet Calculations 3 Discussion Conclusions & Recommendations 4-1 Appendices A & B i J. Marx Ayres, P.E. Page i

3 Low-Pressure EFVs Table of Contents Tables & Figures Tables Page 2-1 Low-Pressure EFVs UMAC Quake Breaker At Meter UMAC Quake Breaker At Meter & At Each Appliance Sanders At Meter Sanders At Meter And At Each Appliance UMAC Quake Breaker At Meter & Magne-Flo At Each Appliance Sanders At Meter & Magne-Flo At Each Appliance Pressure-Drop Calculations Without EFVs 2-21 Figures 2-1 Model of Residential Piping System Isometric Piping Diagram of EFV At Meter Isometric Piping Diagram of EFV At Meter & At Each Appliance Isometric Piping Diagram Without EFV UMAC Quake Breaker At Meter UMAC Quake Breaker At Meter & At Each Appliance Sanders At Meter Sanders At Meter & At Each Appliance UMAC Quake Breaker At Meter & Magne-Flo At Each Appliance Sanders At Meter & Magne-Flo At Each Appliance Pressure-Drop Calculations Without EFVs 2-22 J. Marx Ayres, P.E. Page ii

4 Low-Pressure EFVs Executive Summary Executive Summary The performance of low-pressure gas systems in buildings during earthquakes, and the potential for fire due to pipe breaks or leaks, are vital public life/safety issues. Manufactured products designed to shut-off or limit the supply of gas during an earthquake have been developed and installed. Earthquake-actuated seismic gas shut-off valves (SGSVs), which are generally installed downstream from the gas utility meters, have been mandated by some Building Codes. Excess flow valves (EFVs), which are designed to limit the flow of gas when the pressure-drop across the valves exceeds their manufacturer's specified limit, have been developed for installation downstream from the meter or at each flexible appliance connector. The installation and operation of gas systems on customers' premises is regulated by the National Fuel Gas Code and local Building Codes. The Uniform Plumbing Code (UPC) requires that each low-pressure gas system be so designed that the total pressure drop between the meter (or other point of supply) and any outlet, when full demand is being supplied to all outlets, will at no time exceed 0.5" of water column (WC) pressure. For low-pressure (6" to 8" WC) systems with 250 CFH maximum demand and 250 Ft. maximum length from the meter (or other point of supply) to the most distant outlet, pipe sizing tables are provided. The UPC also provides for pressure-drop calculations on each pipe section, fitting, valve, or control device, following basic fluid flow engineering formulas to meet the 0.5" maximum total pressure-drop criteria. The pressure drops required to actuate (Le., close) EFVs are determined by certified testing laboratories following the CSA U.S. No Requirements. The purpose of this study was to determine the impact of these valves when applied in a model residential building with 7.0" WC pressure gas service. Plan check calculations were prepared for the gas system with and without EFVs (manufactured by UMAC, Sanders, & Brass Craft / Magne-Flo) located: (1) downstream of the meter, and (2) at the meter and at each appliance connector. Spitzglassformula pressure-drop calculations for all components in the system were prepared, and the results of the spread sheet calculations are presented in tabular and graphical form. Difficulties in obtaining EFV and appliance - connector pressure - drop data are discussed. J. Marx Ayres, P.E. Page iii

5 Low-Pressure EFVs Executive Summary The study's conclusions and recommendations are: When EFVs are installed in typically sized low-pressure gas systems, the total pressure drop of the systems will exceed the UPC maximum allowed 0.5" WC. Building Codes should require plan checks for any low-pressure gas systems using one or more EFVs. Pressure drops across flexible appliance connectors should be listed with a defined number and radii of bends or loops. For flexible appliance connectors that are provided with an attached or encapsulated EFV, the pressure drops should be listed both with and without the EFV. J. Marx Ayres, P.E. Pageiv

6 Low-Pressure EFVs Acknowledgements Acknowledgements This report was prepared by J. Marx Ayres, P.E., Past President of Ayres, Ezer & Varadi, Consulting Engineers, now renamed AEV Inc. Technical assistance was provided by Ivan Varadi, C.I.P.E., Vice President and Director of Plumbing & Fire Protection Engineering at AEV. The assistance of Carl Strand, President of Strand Earthquake Consultants, in providing background information, product brochures, and test reports obtained from State agencies is gratefully acknowledged. J. Marx Ayres, P.E. Page v

7 Low-Pressure EFVs Introduction Section 1 Introduction 1.1 Background The performance inside buildings of gas systems during earthquakes and the potential for fire due to failure of one or more system components (pipe segments, fittings, valves, flexible appliance connectors, or appliances), has been the subject of intense study by government agencies, utilities, researchers, and design engineers. Manufactured products designed to shut-off or limit the supply of gas during an earthquake have been developed and installed. Seismic gas shut-off valves (SGSVs), which close when they detect a certain level of ground or pipe shaking, are generally installed downstream from gas-utility meters in low - pressure lines serving buildings. Excess flow valves (EFVs) are designed to restrict the flow of gas when they detect a sufficiently large drop in pressure on the downstream side of the valve, which may occur due to a downstream pipe failure. EFVs, normally used in gas-utility high-pressure lines upstream from the meter, have been developed for application downstream from the meter (like the SGSVs) and also at each appliance connection. Building Codes & Standards, which are designed to regulate an industry and protect the public, are revised and upgraded after each major earthquake. Most of the Standards developed by professional organizations follow strict consensus procedures that define manufacturing performance and testing requirements. Building Codes define the minimum standards and construction procedures allowed by the governmental agency having jurisdiction. Organizations that develop and publish Standards, Codes, and Certifications that are of interest in this study include: American Gas Association (AGA) American National Standards Institute (ANSI) American Society of Civil Engineers (ASCE) American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) American Society of Plumbing Engineers (ASPE) California Division of the State Architect (DSA) Canadian Gas Association (CGA) Canadian Standard Association (CSA) International Approval Services (IAS) International Association of Plumbing & Mechanical Officials (IAPMO) National Fire Protection Association (NFPA) On July 3, 1997, the CSA, an independent North American Standards-development, product-certification, and management-systems-regulation organization, acquired IAS (formerly a joint venture of AGA and CGA). The professional organizations that develop Standards operate through Technical or Task Committees (TC's) where members are appointed to represent most of the J. Marx Ayres, P.E. Page 1-1

8 Low-Pressure EFVs Introduction interested parties in a specific industry, (Le., manufacturers, application design engineers, users, installers, and governmental agencies). The industry discussions regarding SGSVs and EFVs are currently focused in the ASCE-25 Task Committee on Earthquake Safety Issues for Gas Systems. The ASCE-25 TC is an ad hoc committee consisting of ASCE-25 members and others, and was formed by the California Seismic Safety Commission (SSC) to study the use of seismic gas safety valves as well as products and methods related to earthquake safety. 1.2 The purpose of this study was to assist in the evaluation of EFV applications in building low-pressure natural gas systems. The specific assignment was to prepare plan-check calculations for a typical residential installation using the test results submitted by the manufacturers to the California Office of the State Fire Marshal and the DSA. The technical approach was to select a model building and prepare pipe-sizing calculations for the gas system both with and without EFVs. The residential system shown on page 105 of the 1979 edition of the Uniform Plumbing Code (UPC) was selected as the model. The pressure-drop calculations presented in this study are limited to natural gas systems with specific gravity of 0.6 at 60 F. See Section 2.0. The component and system pressure drops using natural gas at other specific gravities, and / or vaporous propane gas with specific gravity of 1.53 at 60 F., were not a part of this study. 1.3 Low-Pressure EFVs Low-pressure (LP) EFVs are designed for installation downstream of the gas-utility pressure regulator and meter, or at the end of the gas line after the gas cock at the entry to the flexible appliance connector. They are constructed with a mechanical means that is intended to prevent gas flow in excess of 80% to 110% of their manufacturer's specified closing flow rate at the system's normal operating pressure. The manufacturers of LPEFVs included in this study are UMAC (Quake Breaker, Gas Breaker, & GASP brands), Sanders Valve, and Brass Craft (Magne-Flo brand). J. Marx Ayres, P.E. Page 1-2

9 Low-Pressure EFVs Calculations Section 2 Calculations 2.1 UPC Requirements The requirements for gas pressure regulators and piping size are based on a natural gas having a specific gravity (SG) of at standard conditions (60 F and 14.7 Psi) supplied at 6" to 8" WC pressure at the outlet of the meter (UPC Section ). The maximum demand shall not exceed 250 cubic feet per hour (CFH), and the maximum length of piping between the meter and the most distant outlet shall not exceed 250 feet. The size of each section of pipe and each outlet of any system shall be determined by means of UPC Table 12-3 (Section ). UPC Table 12-3 is based on the maximum delivery capacity in CFH of iron pipe size (IPS) carrying natural gas with a maximum pressure drop of 0.5" WC pressure. This table-simplified "longest run" method was developed by NFPA and AGA (National Fuel Gas Code NFPA 54; ANSI Z 223.1). For conditions other than those covered in UPC Section , the size of each piping system shall be determined by standard engineering methods acceptable to the Administrative Authority. Each such system shall be so designed that the total pressure drop between the meter (or other point of supply) and any outlet, when full demand is being supplied to all outlets, will at no time exceed 0.5" WC pressure. This type of calculation is often referred to as the "pressuredrop" method. 2.2 Spitzglass Formula The design of piping systems for gas is a fluid-flow problem. Where the required flow rate is determined, the pressure losses due to friction are calculated, and the required residual pressure at each appliance is known. Using basic engineering formulae, the engineer can tabulate the various quantities, establish the pipe sizes for each section of piping, and determine the pressure and flow rate at any point in the system. The flow rate of gas (at standard conditions) in a pipe with pressures not exceeding 1 Psi (28" WC) can be computed using the following Spitzglass formula (ASPE Data Book, 1999, Page 8, Equation 1-24): Q = 3550 K I hsl Q K (.ll-\yz SU Q = 3550 Where [ d5h ] SL (1 + 3;t + O.03d) hs dl Q = Gas =Pressure =Specific =Length =Inside flow pipe of gravity rate drop pipe diameter (In ofcfh) Inches Feet) the(in gas Inches) WC) J. Marx Ayres, P.E. Page 2-1

10 Low-Pressure EFVs Calculations The length used in the formula must be corrected to allow for the additional resistance to flow caused by valves and fittings in the piping. The pressure drops expressed in "equivalent lengths" of pipe for standard pipe fittings are available in the UPC and other piping design handbooks. Pressure drops through control valves and other devices inserted into the system should be obtained from their manufacturer's published data, because flow patterns through valves can vary significantly. 2.3 Pipe System The model piping system with connected appliances and pipe sized by the "longest run" method per UPC Table 12-3 is shown in Figure 2-1. The typical residential customer receives gas from the serving utility at 6" - 8" WC pressure. In California, the Southern California Gas Company (SCG) provides gas at 8" WC pressure to their residential customers and Pacific Gas & Electric (PG&E) provides gas at 7" WC pressure. For purposes of this study, the pressure-reducing valve (regulator) was set at 7-1/2" WC pressure and 0.5" WC pressure drop was assumed through a typical meter. Thus the pressure entering the piping system is 7" WC. The piping is terminated at each appliance with a shut-off cock and a flexible metal connector. Isometric drawings of the piping system with EFVs are shown in Figures 2-2 and 2-4. The UPC limits the piping system's total pressure drop from the meter to the outlet to a maximum of 0.5" WC. The outlet is not clearly defined in the Code, but it is interpreted to mean the shut-off cock at the end of the piping system. If an EFV is inserted into the piping system at the appliance, it would be located upstream from the shut-off cock. If the EFV is located downstream from the shut-off cock, its pressure drop must be included in the 0.5" WC maximum total pressure loss. Note that in the following isometric piping diagrams, the EFV is located downstream from the shut-off cock as a practical matter to facilitate maintenance or replacement. 2.4 Certifications The design, construction, and performance of all gas-system components (appliances, flexible connectors, SGSVs, EFVs, and other devices) must be tested following a published standard and certified (listed) by a recognized agency. In the U.S. gas industry, the criteria is established in the National Fuel Gas Code, (ANSI Z 223.1/NFPA 54) and other ANSI.CGA standards. The manufactured products are tested by approved laboratories (such as AGA) to assure that they meet that criteria. The currently accepted criteria for EFVs are published in the CSA U.S. No Requirements. It should be noted that the Requirements were developed by the CSA non-consensus "industry standard" development function and not their "consensus standard" development function. The performance of listed appliance connections for low-pressure (8" WC or less) systems based on 0.2" WC pressure drop for various lengths and flow rates, are presented in UPC Table The appliance connectors offered by one manufacturer (Brass Craft) are tested and listed per ANSI Z / CGA 6.10 for pressures that do not exceed 0.5 psi (14" WC) and are based on 0.5" WC pressure drop for various straight lengths and flow rates (expressed in BTU/HR with 0.64-SG, 1000-BTU/CF gas). See Appendix A. J. Marx Ayres, P.E. Page 2-2

11 Low-Pressure EFVs Calculations The performance data and description of the LPEFVs included in this study are presented in Table 2-1. See Appendix B for the available manufacturer's literature and CSA-certification test data. Note that the UMAC test data are based on 0.6-SG with 1000-BTU/CF gas; and the Sanders and Magne-Flo test data are based on 0.64-SG 1000-BTU/CF gas. The calculations shown in Section 2.5 used the CSA's 0.64-SG based pressure drop (h) without correction to 0.6 SG, which would have an insignificant impact on the calculated pressure drops. Calculations were also prepared so the performance of the various LPEFVs could be compared using the same values for SG and BTU/CF. 2.5 Spread-Sheet Calculations The Spitzglass formula used in the Excel Spread-Sheet calculations is as follows: Q hd KS L Where Q = ={D".5/(1 3550(K){(h =Gas =The =Specific Inside Length pressure flow pipe of +(3.6/D)+(0.03)(D)]}".5 gravity rate pipe )/(S)(L)y.5 diameter drop (In (In ofcfh) the Feet) (In (In gas Inches) WC) The calculations were performed using the pipe sizes shown in the model depicted in Figure 2-1 with (1) an EFV only at the meter, and (2) an EFV at the meter and at each appliance. See piping isometric diagrams shown in Figures 2-2 and 2-3. The data points shown on the diagrams are identified as sections in the left column of Tables 2-2 through 2-8, which present the calculated pressure drops in the longest run (i.e., the piping between the meter and the most remote outlet). Pressure drops that were interpolated from Table 2-1 were used for the UMAC, Sanders, and Magne-Flo EFVs. Flexible-connector pressure drops from Brass Craft for straight-length applications were used for all flexible connectors. Pressure drops calculated for the model system without the EFVs are presented in Table 2-8. Note that the " WC total pressure drop for the piping system without flexible connectors meets the UPC maximum 0.5" WC requirement. This would be expected because the lines were sized per UPC Table 12-3, which was designed to help prevent low-pressure systems from exceeding 0.5" WC total pressure-drop. Also note that all of the systems with one or more EFVs exceed the UPC 0.5" WC maximum total pressure drop requirement. The system pressure drops for the various configurations are presented graphically in Figures 2-4 through J. Marx Ayres, P.E. Page 2-3

12 ro :E I '"0.., (l) /Jl /Jl s::.., (l) m." Jl () o s:: IIIō' ::I /Jl c.. s: III.., CD /Jl :0 m " " " Brand Name Manufacturer Max 289, , ,000 26,000 Omni Not Rate Load " Magnetic Vertical Inlet 275, , ,000 Specified Required Spring mounting 125,000 Directional 70,000 Gravity DP -at ,400 Range, 289, Capacity (1/2" B/Hr , , , Max Automatic Across Closure Reset (2) or Quake Load, CFH 3/4 Force Valve 1 Flow SV-1B NPT) xi Inches Breaker 1 Inlet 3/4#(3) 1 & xi outlet 3/4 1(1) 1.0 (5/8" 0.5 or 1/2" flare) 70,000 C-1 Table 2-1 Low-Pressure EFVs Notes: (1) The GASP and Gas Breaker brands have the same performance characteristics as the Quake Breaker brand. (2) Inlet 0.5" - WC minimum /2-Psi maximum. 0.6-SG 1000-BTU/CF gas. (3) Valve can be configured in 6 ways using various size washers for a range of minimum and maximum flow rates; 7" - WC system pressure, 0.64-SG 1000-BTU/CF gas; valves actuate within 80%-110% of the closure flow rate, with a 5-CFH bypass flow. (4) 0.5-Psi system pressure; 0.64-SG 1000-B/CF gas; 1-CFH bypass flow. '"0 III lc (l) I\,) 01:>0

13 G= 5' 1/.2' 6B GAS REFRIG. 3 CFH ro ;,.., CD (II (II c.., m" CD < (II o III 0" c," Figure 2-1 c.. III l> '<.., CD Y' :tj rn Model of Residential Piping System FURNACE 136 CFH OD 30 GAL YJATER HEATER 27 CFH OA C = 20' 3/4' H = 10' 112' l' (225 CFH) B = 20' 3/4' (89 CFH) D = 10' 1/2' (30 CFH) F = 10' A=10' E= 15' 112' - -:."'" I J GAS METER l' 225 CFH 6C RANGE " 59 CFH "'tj III CO CD N I CJl iii' roto' ::J (II

14 HEATER.' Figure 2-2 c.. :s: III» '<., CD en Isometric Piping Diagram EFV At Meter ro I "'0., CD en en s::., CD m "T1 <en "'0 rn en 4. S COCK - METER

15 Figure 2-3 t.. s: l:u» '<., CD l/l :u rn Isometric Piping Diagram EFV At Meter & At Each Appliance YATER HEATER ro ::E -b., CD l/l l/l c:., CD m"< l/l FLEX, CONECTOR <TYP,) EFV <TYP,) GAS COCK (TYP,) --l METER GAS COCK

16 ro I '"tj... CD (JI (JI I::., CD m"<(ji (') (") I:: :!: o ::J (JI.' Figure 2-4 (.. :s::» '<... CD (JI Isometric Piping Diagram Without EFV '"tj!'l later HEATER '"tj co CD I\J I ():)

17 Low-Pressure EFVs Calculations Table 2-2 Pressure-Drop Calculations With UMAC Quake Breaker At Meter SECT d RES NOMINAL SKh FT d PRESS INWC ACTUAL QL INWC 1.1 TOT PRESS DROP PRESS DROP EXCLUDING FLEX CONNECTOR J. Marx Ayres, P.E. Page 2-9

18 Low-Pressure EFVs Calculations a0 «0I"- 0::: " I- 0::: m UJ 0::: 0::: UJ ::::s::: :2: <9, <' " ::::s::: -Yo. «UJ c? "" <?" «<5> 0" ->'", "/ 0:2: I- 0Z ::l I UJ UJ 0...J "'< C 0::: 0fl. ::I: L".&" P" 0 0!:i ""V'v> "'< 6'6> UJ <' -Yo. I9S.&, C' 015" 0 "{...J C' ' L ui 0L{) <D <0.,f 1--'U J. Marx Ayres, P.E. Page 2-10

19 Low-Pressure EFVs Calculations Table 2-3 Pressure-Drop Calculations With UMAC Quake Breaker At Meter And At Each Appliance SECT d RES NOMINAL SKh FT d1 PRESS INWC ACTUAL QL INWC TOT PRESS DROP PRESS DROP EXCLUDING FLEX CONNECTOR J. Marx Ayres, P.E. Page 2-11

20 Low-Pressure EFVs Calculations " Zc«c UJ u«:2: D::: :Ju :Jo. r.n L' :::c S'" +.;y/. 'Y "/ «u I- D::: v"!;;:!;;: D::: "1'Y.;y -Yo. "'/ c? "'" "" e " 0 «aj «UJ U:J UJ < Oz :2:0. «::i ' "'< 0" 0'6, :::c«z0...j I a. D::: r.n0l() q 0 <9 U0D::: :J r.n -Yo. < "/ 0 <.ci.,r ui " C' <9, 0',) J.;y 0 "{ 6'6> ' I- /v.-u J. Marx Ayres, P.E. Page 2-12

21 Low-Pressure EFVs Calculations Table 2-4 Pressure-Drop Calculations With Sanders At Meter SECT d RES NOMINAL SKh FT dactual PRESS INWC QL INWC 0.5 TOT PRESS DROP PRESS DROP EXCLUDING FLEX CONNECTOR J. Marx Ayres, P.E. Page 2-13

22 Low-Pressure EFVs Calculations «I- 0 W...I ::i!: " " 0:: EL' 1.9 I-L' (J) 0 & 0L' Wz :I:!;( c? 0L' p.,,,) z0 U 0:: " u «c. (J) 0L!)...I I W 0'<t l!'i r-...: <0,,) cd "<l' (J) w0:: "'< C' 1.9 :lsl' V" s <9 L' -Yo. 0 L'L' 0, p., ->'L', -Yo. <9, 6'6> "? -ty), '''( E C' /v J. Marx Ayres, P.E. Page 2-14

23 Low-Pressure EFVs Calculations Table 2-5 Pressure-Drop Calculations With Sanders At Meter And At Each Appliance SECT d RES NOMINAL SKh FT d PRESS INWC ACTUAL QL INWC TOT PRESS DROP PRESS DROP EXCLUDING FLEX CONNECTOR J. Marx Ayres, P.E. Page 2-15

24 Low-Pressure EFVs Calculations «z u " 0z «c /. L y; W $1..( 0-0 U ::i C W w:;) UJ w [>..( "{ a. a. Ua. Zi= 0::: 0.6..( '1'y; -Yo. c? L'..( U'b. \9 :!: C UJ " 6' Z«I-...J I 00 C'.6, U'b. \9 0..( «...J U0::: UJ 0::: w :;) :I: UJ <9..(..( < -Yo. "/ 0..( (' 6' '1'y; L' 0r--: 0l!') 0l!') <9,..n -q' c.d ' /V"U 00 N e::s C) LL J. Marx Ayres, P.E. Page 2-16

25 Low-Pressure EFVs Calculations Table 2-6 Pressure-Drop Calculations With UMAC Quake Breaker At Meter And Magne-Flo At Each Appliance SECT d RES NOMINAL SKh FT d PRESS INWC ACTUAL QL INWC TOT PRESS DROP PRESS DROP EXCLUDING FLEX CONNECTOR Notes: (1) Pressure-drop calculation for Magne-Flo 5/8" valve Given 1" 70CFH (Table 2-1) Ratio: Q=(hY.5 h@27 CFH: 70/27=(1)A.5/(h)A.5 =O.62106"WC J. Marx Ayres, P.E. Page 2-17

26 ro I "'1J ci III III s:: ci m "T1 <III (") III C'l s:: III o ::s III Figure 2-9 c.. s: III ci 1Il :0 m :::.. -III 0U... ::J a.. (J) Ql 6.0 J: s:: wa:: (.) G ::s "'1J III lq CD I\.) " ':? '"fl,,,". 'l: ",'v.l ":1 0' x <t:f cp 0 ".v " ro','v 0 '\,««foj,,-( OJ,,<:J,,-( PRESSURE-DROP CALCULATIONS WITH UMAC QUAKE BREAKER AT METER AND MAGNE FLO AT EACH APPLIANCE " '" \;f",," "fl, 0*- 0"'\,,'" cp,,":1 o C::J 0,,",, v,.s;

27 Low-Pressure EFVs Calculations Table 2-7 Pressure-Drop Calculations With Sanders At Meter And Magne-Flo At Each Appliance SECT d RES NOMINAL SKh FT d 1225 PRESS INWC ACTUAL L Q INWC TOT PRESS DROP PRESS DROP EXCLUDING FLEX CONNECTOR Notes: (1) Pressure-drop calculation for Magne-Flo 5/8" valve Given: 1" 70 CFH (Table 2-1) Ratio: Q=(hy.5 h@ 27 CFH: 70/27=(1 )A.5(h)A.5 = "wc J. Marx Ayres, P.E. Page 2-19

28 ro.=- w 0:: ::J 5.5 en en w 0:: Il. en c.. s: III 7.5 Figure !' (1) :-c rn 7.0 ::E ;,... (1) 1Il 1Il r::::... (1) m "T1 <1Il '265 E. ::::l '0 ()... Ql... III s: 6.0.c: (J < '"C III (Q (1) I\) I I\) o 4.0 &a 00 V)- C1l "CJ C:J (j x"'::" ",,'1-- 0*",,,'" 00 x!',,":1 C:J 0 PRESSURE-DROP CALCULATIONS WITH SANDERS AT METER AND MAGNE-FLO AT EACH APPLIANCE (j,,,,0 _. O '" C; <v+ «.v (') III 0" r:::: III-0" ::::l 1Il

29 Low-Pressure EFVs Calculations Table 2-8 Pressure-Drop Calculations Without EFVs SECT d RES lkvi-' u_vv NOMINAL SKh FT U.t5LL U.::> d PRESS 89 INWC ACTUAL QL 225 L,f0.5 INWC U.::>t51 PRESS DROP EXCLUDING FLEX CONNECTOR J. Marx Ayres, P.E. Page 2-21

30 Low-Pressure EFVs Calculations em LJoul)3nSS3d S" c I z :::I: W < >LL en "< < W e:( :J0 :J U...J 0i= ud.. 0 <6> 6'6> I- en c:: c:: :J enw ",< <9, <9 L' 0L'L' " o O> 0 tsl tslt>-0 L' '..< C'L' +0. c? {y +0. "< Sis 6 0CD Lr.l 0Lr.l /V"k Page 2-22 J. Marx Ayres, P.E.

31 Low-Pressure EFVs Discussion Section 3 Discussion 3.1 CSA U.S. a. The CSA U.S. Requirements No are for EFVs that are designed to limit the flow of gas in the event that the flow through the valve exceeds the level specified by the manufacturer. The criteria are for valves with nominal sizes of 2" or smaller, maximum operating pressures of 250 psi or less, and capability of operating in 32 to 125 F environments. The test requirements include the size of by-pass area in automatic reset type valves to allow for equalization of pressures. The closing flow rates are based on 0.64-SG, 1000-BTU/CF gas. The performance requirements include specified operational positions of the valve, maximum operating pressures, leakage rates not to exceed 20 CC/Hr at 1-1/2 times the maximum operating pressure, 10 CFH maximum bypass rate, and operation to reduce the flow of gas through the device to no more than its bypass flow rate (which must be no more than 2 CFH for manual reset type EFVs, and no more than 10 CFH for automatic reset type EFVs) whenever the flow reaches that particular device's closing flow rate, which can be anything between 80% and 110%, inclusive, of the manufacturer's specified closing flow rate for that model. b. The procurement of the CSA test results and other manufacturer literature was difficult. The latest UMAC and Sanders data were obtained from attachments to the Los Angeles Mechanical Testing Laboratory's Research Reports, and the Magne-Flo data from submissions to the DSA. 3.2 Appliance Connectors a. b. CSA U.S. test data for appliance connectors were not available, and publications from one manufacturer provided CSA pressure-drop data for straight flexible metal tubing without bends that normally occur in the field. See Appendix A. The published data provided flow capacities at 0.5" WC pressure-drop with 0.64-SG, 1000/BTU/CF gas per ANSI Z CGA 6.10 for 3/8",1/2", and 5/8" nominal 0.0. connectors. The UPC Table provides capacities of "listed" appliance connectors in 8" WC or less systems based on 0.2" WC pressure drop with 1100 BTU/CF gas. Note 3 under UPC Table states that tests were based on complete assemblies, including fittings and valves. The test configuration, definition of valve type, and test data were not available to the author, so all of the spread sheet calculations incorporated 0.5" WC pressure drop for the appliance connectors. It should be noted that Brass Craft has recently purchased Magne-Flo and plans to offer the EFVs with their flexible connectors. If this is true, their connector and EFV should be tested and listed as a unit. 3.3 Pressure Drops J. Marx Ayres, P.E. Page 3-1

32 Low-Pressure EFVs Discussion The objective of this study was to determine the impact of EFVs on the upe 0.5" we maximum piping system pressure-drop allowance. Examination of Tables 2-2 through 2-8 and Figures 2-2 through 2-11 allows the reader to identify the various pressure drops, starting with a 7" we service. It should be noted that minimum pressures necessary for safe and efficient appliance operation can vary from 5" to 3-1/2" we. It is known that the designer can in some circumstances use larger size pipe to off-set the EFV pressure losses, but it is not practical due to the additional construction costs. J. Marx Ayres, P.E. Page 3-2

33 Low-Pressure EFVs Conclusions Section 4 Conclusions & Recommendations 4.1 Conclusions 1. When EFVs are installed in typically sized low-pressure gas systems, the total pressure drop of the systems will exceed the UPC maximum allowed 0.5" WC pressure drop. 4.2 Recommendations 1. Building Codes should require mechanical plan checks for any low-pressure gas systems using one or more EFVs. 2. Pressure drops across flexible appliance connectors should be listed with a defined number and radii of bends or loops. 3. If a flexible connector is provided with an EFV, the pressure drops should be listed both with and without the EFV. J. Marx Ayres, P.E. Page 4-1