03-0506 Fuel Gas Pipe Sys

Low- and Medium-Pressure Natural Gas SystemsThe composition, specific gravity, and heating value of

natural gas vary depending upon the well (or field) fromwhich the gas is gathered. Natural gas is a mixture of gas-es, most of which are hydrocarbons, and the predominanthydrocarbon is methane. Some natural gases contain sig-nificant quantities of nitrogen, carbon dioxide, or sulfur(usually as H2S). Natural gases containing sulfur or carbondioxide are apt to be corrosive. These corrosive sub-stances are usually eliminated by treatment of the naturalgas before it is transmitted to the customers. Readily con-densable petroleum gases are also usually extracted be-fore the natural gas is put into the pipeline to preventcondensation during transmission.

The specific gravity of natural gas varies from 0.55 to 1.0and the heating value varies from 900 to 1100 BTU/ft3

(33.9 to 41.5 mJ/m3). Natural gas is nominally rated at1000 BTU/ft3 (37.7 J/m3), manufactured gas is nominallyrated at 520 BTU/ft3 (20 mJ/m3), and mixed gas is nomi-nally rated at 800 BTU/ft3 (30.1 mJ/m3). Liquefied petrole-um gases (LPG) are nominally rated at 2500 BTU/ft3 (94.1mJ/m3). Natural gas is transmitted from the fields to the lo-cal marketing and distribution systems at very high pres-sures, usually in the range of 500 to 1000 psi (3447.4 to6894.8 kPa). Local distribution systems are at much lowerpressures. The plumbing engineer should determine thespecific gravity, pressure, and heating value of the gasfrom the utility company or LPG provider serving the proj-ect area.

This chapter covers fuel-gas systems on consumers’premises—that is, upstream and downstream from the gassupplier’s meter set assembly—and includes system de-sign and appliance gas usage, gas train venting, ventila-tion, and combustion air requirements. Since natural gasis a depletable energy resource, the engineer should de-sign for its efficient use. The direct utilization of naturalgas is preferable to the use of electrical energy when elec-tricity is obtained from the combustion of gas or oil.However, in many areas, the gas supplier and/or govern-mental agencies may impose regulations that restrict theuse of natural gas. Refer to the chapter “EnergyConservation in Plumbing Systems” in Data Book Volume1 for information on appliance efficiencies and energyconservation recommendations.

Design ConsiderationsThe energy available in 1 cubic foot (cubic meter) of nat-

ural gas, at atmospheric pressure, is called the heating (orcaloric) value. The flow of gas, expressed in cubic feet perhour (cfh) or cubic meters per hour (m3/h), in the distribu-tion piping depends on the amount of gas being consumedby the appliances. This quantity of gas depends on the re-quirements of the appliances. For example, 33,200 BTU/h(35 mJ/h) are required to raise the temperature of 40 gal(151.4 L) of water from 40 to 140°F (4.4 to 60°C) in 1 hour.This value is obtained as follows:

Q = m × Cp × ∆T Equation 1

whereQ = Energy required, BTU/h (J/h)m = Mass flow, gal/h (L/h)Cp = Specific heat of water, 1 BTU/°F (J/°C)∆T = Temperature rise, °F (°C)Q = (40 gal/h)(8.33 lb/gal)(1 BTU/lb-°F)(100°F) =

33,320 BTU/h[Q = (151 L/h)(1 kg/L)(6.1 kJ/kg-°C)(38°C) = 35 MJ/h]

If the water heater in this case is 80% efficient, then41,650 BTU/h (43.8 mJ/h) of gas will be needed at the ap-pliance’s burner (33,320 BTU/h/.80). If natural gas with aheating value of 1000 BTU/ft3 (37.7 mJ/m3) serves the ap-pliance, the piping system must supply 41.7 cfh (1.2 m3/h)of gas to the appliance with adequate pressure to allowproper burner operation. The formula for the flow rate ofgas is shown below:

Q = Output Equation 2(Eff x HV)

whereQ = Gas flow rate, cfh (m3/h)Output = Appliance’s output, BTU/h (J/h)Eff = Appliance’s efficiency, %HV = Heating value of the fuel gas, BTU/ft3 (J/m3)

The difference between the input and the output is theheat lost in the burner, the heat exchanger, and the fluegases. Water heating and space heating equipment is usu-ally 75 to 85% efficient, and ratings are given for both in-put and output. Cooking and laundry equipment is usually75 to 85% efficient, and ratings are given for both input andoutput. However, cooking and laundry equipment is

Fuel-Gas Piping Systems

32 Plumbing Systems & Design • May/June 2003

Continuing Education

Reprinted from American Society of Plumbing Engineers Data Book: Vol. 2. Plumbing Systems, 2000, Chicago: American Society ofPlumbing Engineers. Chapter 7, “Fuel-Gas Piping Systems” (pp. 173–174, 176–178, 183–185), Joseph J. Barbera, PE CIPE, John P.Callahan, CIPE, Paul D. Finnerty, CIPE, Ronald W. Howie, CIPE, Robert L. Love, PE CIPE, Steven T. Mayer, CIPE CET, Jon G. Moore,& Rand J. Refrigeri, PE, Contributors. © 2000, American Society of Plumbing Engineers.

usually rated only by its input requirements. When the in-put required for the appliance is known, Equation 2 is ex-pressed as follows:

Q =Input

Equation 3HV

whereQ = Gas flow rate, cfh (m3/h)Input = Appliance’s input, BTU/h (J/h)HV = Heating value of the fuel gas, BTU/ft3 (J/m3)

The gas pressure in the piping system downstream of themeter is usually 5 to 14 in. (127 to 355.6 mm) of water col-umn (wc). Design practice limits the pressure losses in thepiping to 0.5 in. (12.7 mm) wc, or less than 10%, when 5 to14 in. (127 to 355.6 mm) wc is available at the meter outlet.However, local codes may dictate a more stringent pressuredrop maximum; these should be consulted before the systemis sized. Most appliances require approximately 5 in.(127mm) wc; however, the designer must be aware that largeappliances, such as boilers, may require higher gas pressuresto operate properly. Where appliances require higher pres-sures or where long distribution lines are involved, it may benecessary to use higher pressures at the meter outlet to satis-fy the appliance requirements or provide for greater pressurelosses in the piping system. If greater pressure at the meteroutlet can be attained, a greater pressure drop can be allowedin the piping system. If the greater pressure drop design canbe used, a more economical piping system is possible.Systems are often designed with meter outlet pressures of 3to 5 psi (20.7 to 34.5 kPa) and with pressure regulators to re-duce the pressure for appliances as required. The designerhas to allow for the venting of such regulators, often to theatmosphere, when they are installed within buildings.

When bottled gas is used, the tank can have as much as150 psi (1044.6 kPa) pressure, to be reduced to the burnerdesign pressure of 11 in. (279.4 mm) wc. The regulator isnormally located at the tank for this pressure reduction.

To size the gas piping for a distribution system, the de-signer must determine the following items:1. The appliance requirements, including the gas con-

sumption, pressure, and pipe size required at the ap-pliance connection (total connected load). Is the ap-pliance provided with a pressure regulator?

2. The piping layout, showing the length of (horizontaland vertical) piping, number of fittings and valves,and number of appliances.

3. The fuel gas to be supplied, where and by whom; alsothe specific gravity and heating value of the fuel gasand the pressure to be provided at the meter outlet.

4. The allowable pressure loss from the meter to the appliances.

5. The diversity factor—the number of appliances oper-ating at one time compared to the total number of

connected appliances. This should be provided by theowner and/or user.

Standard engineering methods may be used to determinepipe sizes for a system, or the acceptable capacity/pipe sizetables may be used when such tables are available for thespecific operating conditions of the system under consider-ation. The diversity factor is an important item when deter-mining the most practical pipe sizes to be used in occu-pancies such as multiple-family dwellings. It is dependenton the type and number of gas appliances being installed.Refer to the “pipe sizing” section later in this chapter.

The most common material used for gas piping is blacksteel; however, many other materials are utilized, includingcopper, wrought iron, plastic, brass, and aluminum alloy.The proper material to be used depends on the specificinstallation conditions and local code limitations. Any con-dition that could be detrimental to the integrity of the pip-ing system must be avoided. Corrosion and physical dam-age are the most obvious causes of pipe failure. The pip-ing material itself and/or the provisions taken for the pro-tection of the piping material must prevent the possibilityof pipe failure. Corrosion can occur because of electrolysisor because a corrosive material is in contact with either theexterior or the interior surface of the piping.

Coatings are commonly applied to buried metallic pipeto prevent corrosion of the exterior surface. The gas sup-plier should be contacted to determine if the gas containsany corrosive material, such as moisture, hydrogen sulfide(H2S), or carbon dioxide (CO2). Due to the grave conse-quences of leakage in the gas piping system, the designermust carefully consider the piping material to be used andthe means to protect the piping and protect against leaks.

Gas piping should be installed only in safe locations.Buried piping should be installed deep enough to protectthe pipe from physical damage. When piping is installed inconcealed spaces, care should be taken so that, in theevent of gas leakage, gas will not accumulate in the con-cealed space. The installation of gas piping in an unventi-lated space under a building should be avoided. Such con-ditions have resulted in disastrous explosions. A gas leakanywhere along the length of a buried pipe can flow in theannular space around the pipe and accumulate in a cavityunder the building. Ignition of this accumulated gas can re-sult in an explosion. For this reason, it is best to try to lo-cate the gas main above grade at the point of entrance intothe building. If this is not feasible, the main can be installedin a ventilated sleeve (containment pipe). The designershould carefully detail this installation so that leaked gaswill be harmlessly vented to the atmosphere and not accu-mulated in the building. Gas piping should be locatedwhere it will not be subject to damage by such things asvehicles, forklifts, cranes, machinery, or occupants. Supportof piping should be in accordance with codes and as de-scribed in the chapter “Hangers and Supports,” in DataBook Volume 4 (forthcoming).

May/June 2003 • Plumbing Systems & Design 33

Valves, controls, pressure regulators, and safety devicesused in gas systems should be designed and approved forsuch use. Shut-off valves should be installed in accessiblelocations and near each appliance, with a union betweenthe valve and the appliance. Shut-off valves should be of theplug or cock type with a lever handle. Larger sizes shouldbe of the lubricated plug type. The quarter-turn lever han-dle provides visual indication of whether the valve isopened or closed. An approved assembly of semirigid orflexible tubing and fittings, referred to as an “appliance con-nector,” is sometimes used to connect the piping outlet tothe appliance. Appliance connectors are rated by capacity,based on a specified pressure, flow, and pressure drop.

Laboratory GasNatural gas or propane gas is used in laboratories at lab

benches for Bunsen burners and other minor users. TypicalBunsen burners consume either 5000 cfh (141.6 m3/h)(small burners) or 10,000 cfh (283.2 m3/h) (large burners).The maximum pressure at the burner should not exceed 14in. wc (355.6 mm wc).

The gas distribution piping should be sized in the man-ner discussed later in this chapter; however, the followingdiversities may be applied:

Number Minimum Flowof Outlets Use Factor (m3/h)1–8 100 9 (0.26)9–16 90 15 (0.43)17–29 80 24 (0.68)30–79 60 48 (1.36)80–162 50 82 (2.32)163–325 45 107 (3.03)326–742 40 131 (3.71)743–1570 30 260 (7.36)1571–2900 25 472 (13.37)2901 and up 20 726 (20.56)

Branch piping that serves one or two laboratories shouldbe sized for 100% usage regardless of the number of out-lets. Use factors should be modified to suit special condi-tions and must be used with judgment after consultationwith the owner and/or user.

Some local codes require that laboratory gas systems, es-pecially those in schools or universities, be supplied withemergency gas shut-off valves on the supply to each labo-ratory. The valve should be normally closed and openedonly when the gas is being used. It should be located in-side the laboratory and used in conjunction with shut-offvalves at the benches or equipment, which may be re-quired by other codes. The designer should ensure that lo-cations meet local code requirements.

Where compressed air is also supplied to the laboratory,aluminum check valves should be provided on the supplyto the laboratory to prevent air from being injected back

into the gas system. An alternative to aluminum checkvalves is gas turrets with integral check valves.

Gas Train VentsGuidelines for the use of vents from pressure regulators,

also referred to as “gas-train vents,” can be found in the lat-est editions of NFPA 54 and Factory Mutual (FM) LossPrevention Data Sheet 6-4, as well as in other publicationsof industry standards, such as those issued by IndustrialRisk Insurers (IRI) and the American Gas Association(AGA). As a practical matter, many boiler manufacturerscan provide resource materials, such as gas-train ventingschemes, that reference standards organizations. Factorsthat determine which standard to reference are based uponthe input (BTU/h) and the owner’s insurance underwriter.The plumbing designer must be aware of the existence ofthese standards—especially when designing piping forboilers with input capacities of 2,500,000 BTU/h (732 kW)or more that are not listed by a nationally recognized test-ing laboratory agency, e.g., equipment that does not bear aUL label or have Factory Mutual Research Corporation(FMRC) approval listing.

Industrial-boiler gas trains often require multiple, piped,gas-train vents to the atmosphere. These are usually 3/4 in.,and the material used should follow the classification asspecified in NFPA 54 under the heading “Gas Piping SystemDesign, Materials, and Components.” Where multiple gas-train vents are indicated, each shall run independently tothe atmosphere. Care must be exercised in the location ofthe termination points of these pipes. Vent pipes shouldterminate with 90° ells turned down vertically and be pro-tected with an insect screen over the outlet.

It should be noted that when the pressure regulators ac-tivate they can release large amounts of fuel gas. It is notuncommon for a local fire department to be summoned toinvestigate an odor of gas caused by a gas-train vent dis-charge. Every attempt should be made to locate the termi-nal point of the vents above the line of the roof and awayfrom doors, windows, and fresh-air intakes. It should alsobe located on a side of the building that is not protectedfrom the wind. Refer to NFPA 54 and local codes for ventlocations.

AppliancesMost manufacturers of gas appliances rate their equip-

ment by the gas consumption values that are used to de-termine the maximum gas flow rate in the piping.

The products of combustion from an appliance must besafely exhausted to the outside. This is accomplished witha gas vent system in most cases. Where an appliance has avery low rate of gas consumption (e.g., Bunsen burner orcountertop coffee maker) or where an appliance has an ex-haust system associated with the appliance (e.g., gasclothes dryer or range), and the room size and ventilationare adequate, a gas vent system may not be required.

Continuing Education: Fuel-Gas Piping Systems


Current practice usually dictates the use of factory-fabricat-ed and listed vents for small to medium-sized appliances.Large appliances and equipment may require specially de-signed venting or exhaust systems.

For proper operation, the gas vent system must satisfythe appliance draft and building safety requirements. Tomeet these conditions, consideration of combustion andventilation air supplies, draft hood dilution, startup condi-tions, flue gas temperatures, oxygen depletion, externalwind conditions, and pollution dispersion is required. Forexample, appliances equipped with draft hoods need ex-cess vent capacity to draw in the draft hood dilution air andprevent draft hood spillage. Inadequate combustion airsupply can cause oxygen depletion and inadequate firing.This condition can create a safety hazard because of a com-bination of draft hood spillage and inadequate flue gas re-moval. The motive force exhausting flue gases from an ap-pliance can be gravity (a natural draft due to the differencein densities between hot flue gases and ambient air) or me-chanical (induced-draft fan or forced-draft fan). The motiveforce involved affects the size and configurations that maysafely be applied to a vent system. The designer is referredto the chapter on gas vent systems of the local mechanicalor plumbing code and to the data developed by the man-ufacturers of gas vents for sizing information. Due to thefact that many codes require that appliances conform to anapproved standard, such as the American Gas Association(AGA), a simple approach to the design of vent systemscan be as follows:1. The vent system conforms to the manufacturer’s in-

structions and the terms of the listing.2. The gravity vents cannot exceed certain horizontal

lengths, must exceed certain minimum slopes upwardto their vertical chimneys, and cannot terminate lessthan 5 ft (1.5 m) above the appliance outlet.

3. The vent size cannot be smaller than the vent connec-tor collar size of the appliance.

4. The size of a single vent that services more than oneappliance must not be less than the area of the largestvent connector served plus 50% of the areas of the ad-ditional vent connectors.

Since vent chimney heights and flue gas temperatures de-termine the theoretical draft, there are many situationswhere the above approach will produce oversized vent sys-tems. Whatever approach is used, a great deal of care mustbe taken when designing vents that are horizontal. It is rec-ommended that every system be engineered and checkedfor compliance with codes. A conservative design is war-ranted in light of the hazards involved.

Combustion air is required for the proper operation ofgas appliances. In addition to the theoretical amount of airrequired for combustion, excess air is necessary to ensurecomplete combustion. Approximately 1 ft3 (0.03 m3) of airat standard conditions is needed for each 100 BTU (1055 J)

of fuel burned. Air is also required for the dilution of fluegases when draft hoods are provided. Some additionalamount of air is also needed for ventilation of the equip-ment room. This air for combustion, dilution, and ventila-tion is usually supplied by permanent openings or ductsconnected to the outdoors. Two openings should be sup-plied. One opening should be high (above the draft hoodinlet) and the other opening should be low (below thecombustion air inlet to the appliance). The size of theseopenings can be determined by standard engineeringmethods, based on the air balance in the equipment roomand taking into account the energy (natural draft or me-chanical) available to draw air into the room; however,these must comply with codes, which usually give moreconservative opening sizes, based on the area of the open-ing required per BTU (J) of gas consumed.

Pipe SizingA number of formulae can be used to calculate the capac-

ity of natural gas piping based on such variables as deliverypressure, pressure drop through the piping system, pipe size,pipe material, and length of piping. Most of these formulaeare referenced in numerous current model codes, as well asin the NFPA standards. The most commonly referenced for-mula for gas pressures under 11/2 psi (10.3 kPa) is the NFPAformula listed in the National Fuel Gas Code, NFPA 54. Theother commonly referenced equation, the Weymouth formu-la, is applicable only for initial gas pressures greater than 1psi (6.9 kPa). A third formula, the Spitzglass formula, is limit-ed to gas pressures under 1 psi (6.9 kPa).

The design of piping systems for gas flow is a basic flu-id flow problem and its solution is similar to that for anyother pipe-sizing problem. The required flow rate can eas-ily be determined, the pressure losses due to friction can becalculated, and the required residual pressure at each ap-pliance is usually known. Using basic engineering formu-lae, the engineer can tabulate the various quantities, estab-lish the pipe sizes for each section of piping, and demon-strate the pressure and flow rate at any point in the system.The flow of gas in a pipe with pressures not exceeding 1psi (6.9 kPa) is often computed using the Spitzglass formu-la, as shown below:

Q = 3550 K √h/SL Equation 4

Q = 3550 K (h/SL)1/2

Q = 3550 [d5h/SL (1 + 3.6/d + 0.03d)]1/2

whereQ = The gas at standard conditions, cfh (m3/h)K = Constant for a given pipe sizeh = The pressure drop, in. (mm) wcS = Specific gravity of the gasL = Length of pipe, ft (m)


The constant for a given pipe size (K) may be calculatedby using the following relation:

K = (D5/1 + 3.6/D + 0.03 x D)1/2 Equation 5

whereK = Constant for a given pipe sizeD = Inside diameter of the pipe, in. (mm)

The length used in the above formula should be correct-ed to allow for the added resistance to flow caused byvalves and fittings in the piping.

This corrected length is called the “equivalent length.”Table 1 gives the equivalent lengths for various valve andfitting sizes. The designer is cautioned to conform to appli-cable codes for the project location.

The above method is accurate and gives a solution that

has a definite technical basis. However, in actual practice,published tables showing the capacities for the variouspipe sizes and lengths give solutions that are quickly andeasily obtained and generally adequate for most situations.These tables are in many model codes and in National FireProtection Association (NFPA) Standard 54. The lengthsshown are developed lengths (lengths measured along thecenter line of the piping plus a fitting allowance). The pres-sure drops include an allowance for a nominal amount ofvalves and fittings.

To determine the size of each section of pipe in a gas-supply system using the gas pipe-sizing tables, the follow-ing method should be used:1. Measure the length of the pipe from the gas meter lo-

cation to the most remote outlet on the system. Add afitting allowance.

Table 1. Equivalent Lengths for Various Valve and Fitting Sizes Pipe Size, in. (mm)

3/4 1 1 1/2 2 2 1/2 3 4 5 6 8 Fitting (19.1) (25.4) (38.1) (50.8) (63.5) (76.2) (101.6) (127) (152.4) (203.2)

Equivalent Lengths, ft (m)90° elbow 1.00 2.00 2.50 3.00 4.00 5.50 6.50 9.00 12.0 15.0

(0.3) (0.61) (0.76) (0.91) (1.22) (1.68) (1.98) (2.74) (3.66) (4.57)Tee (run) 0.50 0.75 1.00 1.50 2.00 3.00 3.50 4.50 6.00 7.00

(0.15) (0.23) (0.3) (0.46) (0.61) (0.91) (1.07) (1.37) (1.83) (2.13)Tee (branch) 2.50 3.50 4.50 5.00 6.00 11.0 13.0 18.0 24.0 30.0

(0.76) (1.07) (1.37) (1.52) (1.83) (3.35) (3.96) (5.49) (7.32) (9.14)Gas cock 4.00 5.00 7.50 9.00 12.0 17.0 20.0 28.0 37.0 46.0(approx.) (1.22) (1.52) (2.29) (2.74) (3.66) (5.18) (6.1) (8.53) (11.28) (14.02)Note: The pressure drop through valves should be taken from manufacturers’ published data rather than using the equivalent lengths, since the various patternsof gas cocks can vary greatly.

Figure 1. Sample System for Pipe-Size Calculation



continued on page 37

Tabl

e 2.

Nat

ural

Gas

Pip

e-Si

zing

Tab

leA.

For

gas

pre

ssur

e <

1.5

psi


Tabl

e 2.

Nat

ural

Gas

Pip

e-Si

zing

Tab

le (c

ontin

ued)

B. F

or g

as p

ress

ure

< 10

.3 k

Pa



2. Select the column showing that distance (or the nextlonger distance, if the table does not give the exactlength).

3. Use the vertical column to locate all gas demand fig-ures for this particular system.

4. Starting at the most remote outlet, find in the verticalcolumn the selected gas demand for that outlet. If theexact figure is not shown, choose the next larger fig-ure below in the column.

5. Opposite this demand figure, in the first column at theleft, the correct size of pipe will be found.

6. Proceed in a similar manner for each outlet and eachsection of pipe. For each section of pipe, determinethe total gas demand supplied by that section.

7. To size all branches, other than the branch to themost remote outlet, measure the length of pipe fromthe outlet to the meter and follow steps 1 through 6above utilizing the new length.

For conditions other than those covered above, the sizeof each gas piping system may be determined by standardengineering methods acceptable to the authority having ju-risdiction. The maximum allowable pressure drop througha system should not exceed 10% of the supply pressure,which must be verified with the locally referenced codeand the authority having jurisdiction.

Where a gas of a different specific gravity is delivered orwhere the pressure differs from what the referenced gas

tables in the local code show, the size of the piping re-quired must be calculated by means of standard engineer-ing methods acceptable to the authority having jurisdiction.

As an example, calculate the following proposed sys-tem’s pipe size (see Figure 1):1. The distance from the gas meter to outlet “A” is 600 ft

(182.9 m).2. For sizing the pipe from outlet A to the meter, use

Table 2.• Section 1: 400-ft (123-m) length, carrying 150 cfh

(1.2 L/s)—using the 400-ft (123 m) column, the sizewould be 11/4 in. (31.8 mm).

• Section 2: 550-ft (168-m) length, carrying 600 cfh(4.7 L/s)—using an interpolation between the 500-ft(153.8-m) column and the 750-ft (230.7-m) column,the size would be 21/2 in. (63.5 mm).

• Section 3: 600-ft (183-m) length, carrying 2400 cfh(18.9 L/s)—using an interpolation between the 500-ft(153.8-m) column and the 750-ft (230.7-m) column,the size would be 4 in. (101.6 mm).

3. For sizing Section 4: from Table 2 on the 300-ft (91.4-m) column, carrying 450 cfh (3.5 L/s), size would be 2in. (50.8 mm)

4. For sizing Section 5: from Table 2 on the 100-ft (30.5-m) column, carrying 1800 cfh (14.2 L/s), size wouldbe 21/2 in. (63.5 mm). ■


Continuing Education from Plumbing Systems & DesignKenneth G. Wentink, PE CPD, and Robert D. Jackson, Chicago Chapter Vice President, Technical

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1. When multiple industrial gas train vents are required, the vents shoulda. be tied together prior to discharge to the atmosphere.

b. discharge in the room with the gas train.

c. independently extend to the atmosphere.

d. terminate in a weather-protected enclosure on the roof.

2. Which of the following must a designer determineto size the gas piping for a distribution system?a. Appliance requirements

b. Specific gravity and heating value of the gas to be used

c. Allowable diversity factor

d. All of the above

3. The maximum gas pressure that should be deliv-ered to a laboratory Bunsen burner isa. l0 in. wc.

b. l2 in. wc.

c. l4 in. wc.

d. l6 in. wc.

4. Natural gas is a mixture of gasses, most of whichare hydrocarbons. Which hydrocarbon is the mostpredominant?a. Nitrogen

b. Carbon dioxide

c. Sulfur as H2S

d. Methane

5. One of the motive forces that exhaust flue gasesfrom an appliance isa. mechanically induced.

b. air-pressure induced.

c. gas-pressure induced.

d. none of the above.

6. What percentage diversity may be applied to thegas serving 97 laboratory outlets?a. 45

b. 50

c. 60

d. None of the above

7. Which standard’s formula cannot be used to calcu-late the capacity of natural gas piping?a. NFPA

b. National Plumbing Code

c. Spitzglass

d. Weymouth

8. Natural gas has a nominal heating value of __ BTU/Ft3.a. 520

b. 800

c. 1,000

d. 2,500

9. Small Bunsen burners in a laboratory typically consume __ cfh of natural gas.a. 1,000

b. 5,000

c. 7,500

d. 10,000

10. The most common material used for gas piping distribution systems isa. plastic.

b. stainless steel.

c. copper.

d. black steel.

11. An 80% efficient water heater will require __cfh of nat-ural gas, with a heating value of 1,000 BTU/Ft3, to raise40 gallons of water 100º F in one hour.a. 35

b. 41.7

c. 33,200

d. 41,650

12. What percentage of the gas supply pressure is themaximum allowable pressure drop allowed in anatural gas piping system?a. 3

b. 5

c. 10

d. 15

CE Questions—”Fuel-Gas Piping Systems” (PSD 115)


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Appraisal QuestionsFuel-Gas Piping Systems (PSD 115)

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1. Make a photocopy of this form. Leaving this page in PSD allows others to use it to obtain continuing education units (CEUs).2. PRINT your name and address. Be sure to place your membership number in the appropriate space. This form is valid up

to 1 year from date of publication. The PSD continuing education unit program is approved by ASPE for up to 1 contact hour (0.1 CEU) of credit per article studied.

3. Answer the multiple-choice continuing education (CE) questions (found after each CE article) and the appraisal questions on thispage.

4. Submit this form and the answer sheet below, with the payment of the appropriate fee by check, money order made payable toASPE, or submit the credit card information to ASPE Education Credit, 8614 W. Catalpa Avenue, Suite 1007, Chicago, IL60656–1116.

5. Participants who earn a passing score (90%) on the CE questions will receive a letter of certification within 30 days ofPSD’s receipt of the application (no special certificates will be issued). (CEU information will be retained on the ASPEDatabase.) Participants who wish to retake the test should submit their retest along with an additional fee—$5 for an ASPEmember (currently waived) or $25 for a nonmember.

Please print or type; this information will be used to process your credits.

Name________________________________________________________________________________________________

Title ______________________________________________ ASPE Membership No. ______________________________

Organization __________________________________________________________________________________________

Billing Address ________________________________________________________________________________________

City __________________________________________ State/Province ______________________ ZIP ____________

Country __________________________________________ E-mail ____________________________________________

Daytime telephone __________________________________ Fax ______________________________________________

❏ ASPE Member ❏ NonmemberEach examination: $5 Each examination: $25Limited Time: No Cost to ASPE Member

Payment: ❏ Personal Check (payable to ASPE) $__________❏ Business or government check $__________❏ VISA ❏ MasterCard ❏ AMEX $__________

If rebilling of a credit card charge is necessary, a $25 processing fee will be charged. ASPE is hereby authorized to charge my CE examination fee to my credit card.

Account Number Expiration date

Signature Cardholder’s name (Please print.)

PSD Continuing Education Answer SheetFuel-Gas Piping Systems (PSD 115)Questions appear on page 40. Circle the answer to each question.

Q 1. A B C DQ 2. A B C DQ 3. A B C DQ 4. A B C DQ 5. A B C DQ 6. A B C DQ 7. A B C DQ 8. A B C DQ 9. A B C D

Q 10. A B C DQ 11. A B C DQ 12. A B C D

1. Was the material new information for you? ❏ Yes ❏ No2. Was the material presented clearly? ❏ Yes ❏ No3. Was the material adequately covered? ❏ Yes ❏ No4. Did the content help you achieve the

stated objectives? ❏ Yes ❏ No`5. Did the CE questions help you identify specific

ways to use ideas presented in the article? ❏ Yes ❏ No6. How much time did you need to complete the

CE offering (i.e., to read the article and answer the post-test questions)? _________________

03-0506 Fuel Gas Pipe Sys

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Transcript of 03-0506 Fuel Gas Pipe Sys