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ASPE/ASSE Meeting February 10, 2010 Cleveland, OH. Fuel Gas Systems. Natural Gas Propane Butane. By: Ron George, CPD, President President, Ron George Design & Consulting Services 3525 N. Dixie Hwy., Monroe, MI Monroe, Michigan 48162 Ph: (734) 322-0225 Cell: (734) 755-1908.

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fuel gas systems

ASPE/ASSE Meeting February 10, 2010

Cleveland, OH

Fuel Gas Systems

Natural Gas

Propane

Butane

By: Ron George, CPD, President

President, Ron George Design & Consulting Services

3525 N. Dixie Hwy., Monroe, MI

Monroe, Michigan 48162

Ph: (734) 322-0225 Cell: (734) 755-1908

fuel gas codes standards
Fuel Gas Codes & Standards
  • Mechanical Codes covering Fuel Gasses:
  • BOCA - Basic Mechanical Code (no longer updated in favor of The International Codes)
  • IAPMO - Uniform Plumbing Code (UPC) (Coordinated with NFPA 54)
  • IMC - International Mechanical Code (Prior to 2000)
  • IFGC - International Fuel Gas Code (Fuel gas sections from IMC were used to develop IFGC in 2000.
  • Standards/Organizations dealing with Fuel Gas:
  • AGA - American Gas Association
  • NFPA 54 - National Fire Protection Association
  • CSA - Canadian Standards Association
  • ASME - Power & Process Piping Standards
how do i size gas piping
How do I Size Gas Piping?
  • Determine the heating and equipment loads in BTU’s, convert to CFH and size the piping based on acceptable pressure drops using the appropriate code approved pipe material.

BTU/H

CFH

Distance

Pipe Size Chart

Equipment Label

what does btu stand for
What does BTU stand for?
  • BTU stands for “British Thermal Unit”.
  • A British Thermal Unit is the amount of heat required to raise one pound of water one degree Fahrenheit.
british thermal unit btu
British Thermal Unit (BTU)

One pound of waterwill increase by 1 degree F when 1 BTU is added.

Example: One pound of 60 degree F water plus 1 BTU = one pound of 61 degrees Fwater.

1 pound of 60 degree water

1 BTU

1 pound of 61 degree water

what is cfh
What is CFH?
  • CFH is an industry term used to describe the quantity of gas in Cubic Feet delivered during a specified time period. (Usually 1 hour)
  • So CFH stands for Cubic Feet per Hour.
  • 1 Cubic foot of gas = 1000 BTUs + -

(950-1100 BTUs/CF depending on the supplier)

natural gas properties
Natural Gas Properties

1 Cubic Foot of Natural Gas

= 1,000 BTU’s

  • Heat of combustion is measured in BTU’s/cu.ft. Natural Gas = 1,000 BTU’s/CF (Caloric Value)
  • Specific Gravity of Nat. Gas = .60 - .65(Air =1.00)
    • Natural Gas is Lighter than air. (It will dissipate)
  • Flammability Limits (% Volume in air)
    • Lower = 3.9%, <<<<< Flame >>>>> Upper = 15.0% Below 3.9% too lean for Combustion 9-10% = Good Above 15% too rich for combustion
  • Combustion air requirements in Cubic Feet:
    • Per cu. foot of Natural Gas = 10 cubic feet of air.
    • Per 100 BTU’s = 1 cubic foot of air.
fuel gas properties table
Fuel Gas Properties Table:

Odor Additives

Source: NFPA 54 Handbook

fuel gas is explosive3
Fuel Gas is Explosive!

On May 19, 2008 a natural gas leak caused an explosion that injured 14 construction workers and damaged four floors on the unfinished hotel.

fuel gas is explosive5
Fuel Gas is Explosive!

New Braunfels, TX. 1 dead, 1 seriously burned.

natural gas distribution pressures
Natural Gas Distribution Pressures
  • Three Pressure Classifications
    • High Pressure (1,000’s PSI to 100’s)
    • Medium Pressure (5 PSI to 100’s PSI)
    • Low Pressure (Less Than 5 PSI)

High Pressure gas is in typically only utilized in utility distribution lines, so most plumbing engineers will deal with only Medium or Low Pressure Gas

natural gas high pressure
Natural Gas High Pressure
  • High Pressure - 1,000’s to 100’s PSI
    • Transmission mains from pumping stations to Local utility distribution mains.
    • Typically High Pressures are utilized over long distances to reduce pipe sizes.

Pumping Station

Medium press. 60 psi +-

PRV

PRV

Well

Low press.

High press. 900 psi+- Energy Company lines

1/2 psi +-

natural gas medium pressure
Natural Gas Medium Pressure
  • Medium Pressure
    • Local Utility Distribution
    • Large Industrial users.
    • Typically 5psi to 100’s of PSI

Local Gas Utility Co. Distribution lines

Pumping Station

Medium press. 60 psi +-

PRV

PRV

Low press.

High press. 900 psi +-

Well

1/2 psi +-

natural gas low pressure
Natural Gas Low Pressure
  • Low Pressure
    • Commonly used inside buildings
    • Commercial and residential users.
    • Typically less than 5 PSI (code requirement indoors)

Pumping Station

Medium press. 60 psi +-

PRV

furnace

PRV

Low press.

High press. 900 psi +-

1/2 psi + -

Homeowner Responsibility

fuel gas pressure conversions
Fuel GasPressure Conversions

Gas pressures in buildings are often given in Pounds, Ounces or Inches. Make sure you convert to the proper units for sizing.

Often a manufacturer refers to equipment pressure in inches or ounces of pressure because it is a more accurate measurement.

  • 1 PSI = 2.31 feet of head = 28 inches of Water Column (WC)
  • 1 PSI = 16 Ounces =28 Inches =2.31 feet of head
  • 1/2 PSI = 8 Ounces = 14 Inches WC =1.16 feet of head
  • 1/3 PSI = 6 Ounces = 10 Inches WC =.77 feet of head
  • 1/4 PSI = 4 Ounces = 7 Inches WC =.58 feet of head

Gas Pressure Conversion Chart

gas regulator operation
Gas Regulator Operation

60 PSI

½ PSI

1/2 PSI

odor added to fuel gas
Odor Added to Fuel Gas

Odor is added by most gas companies so leaks can be detected.

The physical properties of natural gas include color, odor, and flammability. The principal ingredient of gas is methane, which is colorless, odorless, and highly flammable. Some of the associated gases in natural gas include Mercaptin, a hydrogen sulfide additive, it has a distinct and penetrating sulfur or Rotten Egg odor, and a few parts per million is sufficient to impart a decided odor in the gas.

A Volcanic Problem - The engineers for the Mirage Casino in Las Vegas needed to use Natural Gas to enhance the special effects for the volcano eruption in front of the casino. The concern was prior to eruption a distinctive odor of of Natural Gas or the sulfury Rotten Egg smell would be noticeable to the crowds if gas with Mercaptin was used. The officials insisted on having some kind of odorso they could detect a gas leak. The engineers designed a scrubber to remove the Mercaptin odor and replace it with a Pina’ Colada odor.

slide23

Natural Gas Pipe Material

  • Cast IronNot recommended/allowed on fuel gas piping systems. Older cities used CI (½ PSI limit)
  • Black Steel (Schedule 40) ASME B36.10, 10M or ASTM A53 or ASTM A106
  • Polyethylene (PE) Underground outside building where approved)
  • Stainless Steel (CSST) ANSI/AGA LC 1.
  • Copper (Not recommended if gas is more than 0.3 Grains of Hydrogen Sulfide/100 CF) Often used as semi rigid tubing for appliance connections.
  • Aluminum ASTM B241 (Alum. Alloy 5456 is Prohibited)
  • (All piping material selections should meet the local code’s approved materials list.)

Pumping Station

Copper or

Polyethylene or

CSST

wrapped & coated Black Steel U.G.

PRV

furnace

PRV

Black Steel/CSST

PE or asphalt wrapped Sch 80 - 160 Black steel W/ Cathodic Protection (Pressure often dictates material)

Abv. ground

corrugated stainless steel tubing csst
Corrugated Stainless Steel Tubing (CSST)
  • CSST has made residential and light commercial gas-distribution much easier. Black steel pipe is still preferred for mains and trunks to manifolds. From the manifold the branch piping can be installed with ease.
  • CSST is lightweight and flexible and will cut down on installation time up to 50%.
slide25

Underground Gas Piping Installations

Clearances - Far enough from U.G. structures to avoid contact and provide protection against damage. U.G. plastic piping shall be clear of or insulated from heat sources. (U.G. Steam mains, Htg HW pipes Etc.)

Protection Against Damage - Unstable soil, Foundation Walls, Heavy vehicles: Provide sufficient depth of cover or a pipe sleeve.

When gas piping is buried in planting areas, bury piping sufficiently below cultivating depth.

Warning Tape/Wire - Always put a tracer wire with plastic piping and bury “WARNING BURIED GAS LINE” tape in trench above all gas piping to warn excavators of pipe below.

protection against damage
Protection Against Damage
  • Provide sufficient depth of cover or a pipe sleeve where there is unstable soil, a foundation wall penetration or heavy vehicle traffic.
  • When gas piping is buried in planting areas, bury piping sufficiently below cultivating depth.

G

warning tape tracer wire
Warning Tape/Tracer Wire
  • Engineers should always require a tracer wire when using plastic piping to allow pipe locators to find the pipes.
  • Also specify warning tape that states: “WARNING BURIED GAS LINE BELOW”. The tape should be in the trench at least 12 inches above the gas piping to warn excavators of the gas pipe below

Warning Tape

Tracer Wire (In trench above plastic pipe)

(In trench 12”above pipe)

Caution - Buried Gas Line

Caution - Buried Gas Line

Buried Gas Line

slide28

Underground Gas Piping Installations

Cover Depth - Should be installed with at least 18 inches of cover. Can be 12 inches in areas where external damage is not likely. If less than 12 inches provide a protective conduit or bridging. Always use warning tape. & tracer wire for plastic piping.

Backfilling Trenches - Pipe should have a firm, continuos bearing on trench bottom. When installing gas piping, especially plastic, in a flooded trench care should be exercised to prevent the pipe from floating up in the trench during backfilling operations.

Caution Tape

Tracer Wire (for plastic pipe)

Continuous pipe bedding

Gas Pipe

slide29

Underground Gas Piping Installations

Protect Against Corrosion - Ferrous metal piping that is in contact with earth should be protected from corrosion by asphalt coating and wrapping piping below grade.

Protect Against Freezing - If the fuel gas supplier indicates, hydrates or moisture is high, the gas piping should be protected from freezing. Freezing of water in drip legs or low points in the piping can split piping and lead to gas leaks and possibly and explosion or fire.

Locate Gas line below frost line or in a heated space.

If Gas line is subject to freezing provide heat tracing and Insulation.

Wet gas condenses

water to this point

Freezing can crack pipe

allowing gas to leak out of pipe

Boom

dirt leg for dry gas
Dirt Leg (For Dry Gas)

Clean Gas

Sediment falls

Source: NFPA 54

Handbook

emergency gas shut off valve earthquake valve
Emergency Gas Shut-off Valve (Earthquake valve)
  • Some seismic areas of the country require an Emergency Gas shut-off valve that automatically closes when there is an earthquake.
  • The Earthquake Valve Industry has emerged because of the recent earthquakes and ensuing fires that have struck California and other parts of the world. Designers, Building Officials and Utility companies have become aware of the need for Earth Quake Valves (EQVs) after experiencing and viewing these disasters.

Source: Safe-T-Quake Co.

slide32

Gas Pipe through Foundation Wall Below Grade not allowed in most areas!

Piping through foundation walls below grade should have a sleeve with the annular space sealed from the building.

Gas Meter/ Regulator

M

Void space

Sealed sleeve

Expansive or Clay Soil

Foundation Wall

Gas Pipe

Section at Foundation Wall

End view U.G. Pipe

slide33

Gas Pipe Should enter Building above Grade!

Piping walls should have a sleeve sealed from inside the building.

Sealed sleeve

Gas Meter/ Regulator

M

Foundation Wall

Section at Foundation Wall

bonding of csst gas pipe inside buildings
Bonding of CSST Gas Pipe Inside Buildings
  • Proper bonding and grounding of Corrugated Stainless Steel Tubing (CSST) systems may reduce the risk of damage and fire from a lightning strike. Lightning is a highly destructive force. Even a nearby lightning strike that does not strike a structure directly can cause systems in the structure to become electrically energized. Differences in potential between systems may cause the charge to arc between systems.
  • Such arcing can cause damage to CSST, including blowing holes that can leak flammable gasses.
  • Bonding and grounding should reduce the risk of arcing and related damage.
  • Arcing from lightning strikes has been known to blow holes in un grounded CSST fuel gas lines causing Gas leaks and Fires.
  • The building owner should confirm that a qualified contractor has properly bonded the CSST gas system to the grounding electrode system of the premises. Refer to the manufacturers installation manual for bonding and grounding instructions for CSST.
    • (Section 4.10 Electrical Bonding/Grounding in the Gastite Design & Installation Guide for details on bonding & grounding CSST.)
lightning protection systems for csst piping
Lightning Protection Systems for CSST Piping
  • All ownersshould consult a lightning safety consultant to determine whether installation of a lightning protection system would be required to achieve sufficient protection for all building components from lightning. Factors to consider include whether the area is prone to lightning. Areas with high lightning risk include but are not limited to: Alabama, Arkansas, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maryland, Michigan, Mississippi, Missouri, New Mexico, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Virginia and West Virginia.
  • One currently available source of information regarding areas more prone to lighting than others is the flash density map provided by the National Weather Service which can be found at http://www.lightningsafety.noaa.gov/lightning_map.htm.
  • Lightning protection systems are beyond the scope of this presentation and the manufacturers installation guidelines, and are covered by National Fire Protection Association, NFPA 780, the Standard for the Installation of Lightning Protection Systems, and other standards.
dielectric connections in all gas pipes
Dielectric Connections in all Gas Pipes
  • The owner should confirm with the local gas supply utility company that a suitable dielectric union is installed at the service entry of the structure between underground metallic piping and the gas pipes going into the building as required by code.
national electrical code
National Electrical Code
  • National Electric Code (NEC), Section 250.104b, states that “bonding all piping and metal air ducts within the premises will provide additional safety”. Manufacturer’s recommend that all continuous metallic systems be bonded and grounded. The owner should confirm with an electrical or construction specialist that each continuous metallic system in a structure has been bonded and grounded by an electrical professional in accordance with local building codes. This should include, but is not limited to metallic chimney liners, metallic appliance vents, metallic ducting and piping, electrical cables, and structural steel.
separation of fuel gas pipe from electrically conductive systems
Separation of Fuel Gas Pipe from Electrically conductive systems.
  • Care should be taken when installing any type of fuel gas piping (including CSST, iron, or copper) to maintain as much separation as reasonably possible from other electrically conductive systems in the building. Refer to the manufacturers’ Installation Manual. (Gastite D&I Guide sec. 4.3 Routing, for installation techniques.) Consult local building codes as to the required separations for CSST from such conductive systems including metallic chimney liners, metallic appliance vents, metallic ducting and piping, and electrical cables. See for instance the Indiana Residential Code, section 675 IAC 14-4.3-155.5 Section G2411.1; gas pipe bonding.
local building codes have jurisdiction
Local Building Codes Have Jurisdiction
  • Local building codes have jurisdiction, however, as a general practice, fuel gas piping, including CSST, should not be installed within a chase or enclosure that houses a metallic chimney liner or appliance vent that protrudes through the roof. In the event such an installation is necessary and conforms to local building codes, the metallic chimney liner or vent must be bonded and grounded by a qualified electrical professional, and a separation distance, as specifically permitted by the applicable local building code between the CSST and the metallic chimney liner or vent, is required. Physical contact between CSST and the metallic chimney liner and/or vent is prohibited. If this physical separation cannot be specifically identified in the local building code and achieved or any local building code requirements cannot be met along the entire length, then rerouting of the CSST is required unless such installation is specifically permitted by the local building inspector.
2009 national fuel gas code update
2009 National Fuel Gas Code Update
  • As of October 2008 – the National Fuel Gas Code requires bonding of ALL CSST systems per section 7.13 – Electrical Bonding and Grounding.
hybrid multi unit condo building
Hybrid Multi-Unit Condo Building

CSST Branches

Steel Riser

hybrid system w local gas regulator and csst
Hybrid System w/ Local Gas Regulator and CSST

(4) 50,000 BTU/H

5 PSI

CAP.

IP

OP

1/4 PSI

slide48

Gas Pipe Inside Buildings

Gas Piping Prohibited Locations:

In Circulating Air Duct

Through Circulating Air Duct

Clothes chutes

In Chimney

In Gas Vent

In Ventilation duct

In Dumb Waiter

In Elevator Shaft

Boom

Leaks in concealed locations can allow explosive gasses to accumulate unnoticed

slide49

Gas Pipe Inside Buildings

Gas Piping in concealed Locations:

Should have a casing or chase for solid walls

No unions, valves or joints in concealed spaces

No compression couplings

No Bushings

No swing joins made by multiple fittings

Exceptions:

Brazed Tubing

Fittings listed for concealed locations

Boom

Leaks in concealed locations can allow explosive gasses to accumulate unnoticed

how do you test for a gas leak
How Do You Test For A Gas Leak?
  • With a Match? No
  • With Soap? Sometimes (Must be non-corrosive)
  • With a Gas Detector? Yes
how do purge fuel gas lines
How Do Purge Fuel Gas Lines?
  • Disconnect from the equipment at a union.
  • Connect a grounded purge hose the end of the pipe.
  • Use a Gas Detector at the end of the hose. (Odor Fade)
  • Route the end of the hose outdoors to a well ventilated space away from any ignition sources.
fuel gas valves
Fuel Gas Valves
  • Valves above 0.5 psi should meet ANSI/ASME B16.33 (Ball Va, Plug Va.)
  • Valves below 0.5 psi should meet ANSI Z21.15 (Lubricated Plug) or ANSI/ASME B16.33
  • Access should be provided to each valve (No Va’s in Concealed Spaces)
  • Protect valves from Damage
  • Provide a valve prior to the Gas Meter
  • Shut off valve locations:
    • Each building or tenant
  • Identification of service should be on each gas shut-off Valve.
  • A listed shut-off valve should be installed ahead of each regulator.
  • Equipment shut-off valve should be installed upstream of the union and within 6 feet of gas equipment. (There are exceptions for vented decorative appliances and gas fireplaces)
fuel gas valve types
Fuel Gas Valve Types

Ball Valve Lubricated Plug Valve

Plug

Grease Seal

gas pressure regulators
Gas Pressure Regulators
  • Regulator should be selected for inlet and outlet pressures for the application.
  • Regulator should maintain a reduced outlet pressure at no-flow condition.
  • Capacity of the regulator should be determined by the manufacturers published flow rates.
  • Access to the regulator should be provided.
  • Sediment trap and test plug upstream of Regulator after 1st shut-off valve.
  • Test Plug 10 diameters downstream of regulator before 2nd shut-off valve.
  • Regulator should be protected from damage.
  • Indoor Regulators should be vented to the outdoors.
gas regulator failure
Gas Regulator Failure

60 PSI

½ PSI

1/2 PSI

slide63

60 PSI - 2 PSI Regulator

2 PSI – 1/2 PSI Regulator

slide64

2 PSI gas

Kitchen Hood

Gas Shut-off Valve

50,000 BTU/h at 6 in’s WC = ¼ PSI

199,000 BTU/h at 6 in’s WC = ¼ PSI

local gas regulator w csst
Local Gas Regulator w/ CSST

(4) 50,000 BTU/H

CSST

5 PSI

CSST

CAP.

IP

OP

1/4 PSI

vented indoor gas regulator
Vented Indoor Gas Regulator

Gas regulator vent to outside provide weatherproof cap or gooseneck with insect screen

Roof

Truss Space

Gas Pressure Regulator located indoors

Downstream shut-off valve

Upstream Shut-off valve

Plugged tee for downstream pressure measurement

Plugged tee in dirt leg for upstream pressure measurement

typical gas appliances
Typical Gas Appliances

Donut Fryer

Consult Manufacturer’s Literature for BTU’s/H Input

typical gas appliances1
Typical Gas Appliances

AGA Appliance Nameplate

Consult manufacturer’s literature for BTU’s/H input

typical aga appliance nameplate
Typical AGA Appliance Nameplate

Source: NFPA 54 Handbook

Input BTUH

Fuel Type

Venting Category

Max. Press.

Manifold Press.

Min. Press.

Units (In. WC)

Min. Clearances

typical water heater installation
Typical Water Heater Installation

Source: NFPA 54 Handbook

Flue to Category I Type “B” vent

Appliance Regulator/Controls

single vs double wall flue
Single vs Double wall Flue

Source: NFPA 54 Handbook

Double wall provides a safer installation

Single wall more susceptible to carbon monoxide leaks

typical appliance flue installation
Typical Appliance Flue Installation

Source: NFPA 54 Handbook

combustion air
Combustion Air
  • Transfer Grille
  • Ventilation louvers through ceiling & floors

Source: NFPA 54 Handbook

combustion air1
Combustion Air
  • Transfer grille / combustion air duct from attic to one foot above floor.
  • Ducted to outside walls.

Source: NFPA 54 Handbook

commercial propane properties
Commercial PropaneProperties

1 Cubic Foot of Propane

= 2,500 BTU’s

  • Heat of combustion is measured in BTU’s/cu.ft. Propane = 2,500 BTU’s/CF (Caloric Value)
  • Specific Gravity of Propane = 1.52 (Air =1.00)
    • Propane is heavier than air. (It will pool in low places)
  • Flammability Limits (% Volume in air)
    • Lower = 2.4%, <<<<< Flame >>>>> Upper = 9.6%
    • Below 2.4% too lean for CombustionAbove 9.6% too rich for combustion
  • Combustion air requirements in Cubic Feet:
    • Per cu. foot of Propane = 25 cubic feet of air.
    • Per 100 BTU’s = 1 cubic foot of air.
commercial butane properties
Commercial Butane Properties

1 Cubic Foot of Butane

= 3,200 BTU’s

  • Heat of combustion is measured in BTU’s/cu.ft. Butane = 3,200 BTU’s/CF (Caloric Value)
  • Specific Gravity of Butane = 1.95 (Air =1.00)
    • Butane is heavier than air. (It will pool in low places)
  • Flammability Limits (% Volume in air)
    • Lower = 1.9%, <<<<< Flame >>>>> Upper = 8.6%
    • Below 1.9% too lean for CombustionAbove 8.6% too rich for combustion
  • Combustion air requirements in Cubic Feet:
    • Per cu. foot of Propane = 32 cubic feet of air.
    • Per 100 BTU’s = 1 cubic foot of air.
multipliers for gases other than 6 specific gravity
Multipliers for Gases other than .6 Specific Gravity

Convert CFH in Gas pipe sizing tables to CFH for a fuel with a specific gravity other than 0.6

Nat. Gas

Propane

Butane

determining gas loads for sizing
Determining Gas Loads for sizing
  • Gas pipe sizing is accomplished by converting the gas input loads for HVAC, domestic water heating, cooking equipment and process equipment from BTUH to CFH of gas.
  • A delivery pressure and acceptable pressure drop are selected and the proper sizing chart or calculation can be used to size the pipe.
converting from btu s h to cfh of natural gas
Converting from BTU’s/H to CFH of Natural Gas
  • Determine heat load by calculating demand in BTU’s
  • Convert BTUH into CFH by dividing by 1000 for Natural Gas
  • Example: 2,500,000 BTUH divided by 1000 = 2,500 CFH
hvac heating load calculation
HVAC Heating Load Calculation
  • Engineer determines temperature to maintain
  • Engineer calculates BTUH heat loss through walls, floors and ceiling exposures.
  • This is basis of BTU’s/Hour required to maintain space heating. (Heating Load)
domestic hw load calc
Domestic HW load Calc.

Review

  • Determine HW demand in GPH or GPM:
  • For the following sizing examples we will assume 500 GPH demand of 140 degree HW
  • Determine if Storage, Semi-instantaneous or Instantaneous Water heaters will be used. Instantaneous Heaters require greater fuel loads.

500 Gallon

calculating hw demand
Calculating HW Demand

Review

  • Multiply: (Gallons Per Hour) x (8.33 pounds per gallon) = (pounds of water/hr. at 1 deg. rise)
    • Example: 500 GPH x 8.33 pounds per gallon = 4165 Pounds of HW per hour at 1 degree rise.
  • Multiply pounds of HW per hour by Temperature Rise (40 Degree to 140 degree rise = 100 degree rise) to get BTU’s/H.
    • Example: 4165 Pounds of HW x 100 degree rise = 416,500 BTU’s/H
  • Convert BTU’s to CFH
    • Example: 416,500 BTU’s/H divided by 1000 BTU’s / Cubic Foot = 416.5 CFH
fuel gas pipe sizing
Fuel Gas Pipe Sizing
  • Determine the total developed length of pipe from the Gas Regulator to farthest the appliance connection.
  • Select a delivery pressure and determine allowable pressure drop. (0.3 - 0.5 in WC for low press. Up to 10% for medium pressure)
  • Total the CFH and select appropriate pipe sizes from the appropriate gas sizing tables.
  • For Branch sizing you can continue using the same developed length column for sizing or you can measure the actual developed length to the farthest fixture in each branch and use the appropriate developed length table for sizing only the branch piping.
gas pipe sizing longest run method

250 feet includes equivalent length allowance for fittings and valves.

See following page for equivalent length allowances table.

Gas Pipe SizingLongest Run Method

Total developed length = 250 feet.

Regulator

Water

Heater

Furnace

400,000BTUH / 400 CFH burner

2,000,000 BTUH / 2,000 CFH burner

Meter

Determine length of piping from farthest appliance to gas pressure regulator and refer to sizing chart column that exceeds that length. (2,400 CFH total load @ 250 feet)

nat gas pipe sizing table 1 2 psi cfh of gas at 6 specific gravity press drop 0 3 in wc

Distance from Regulator

To farthest outlet

All sizing should be done from this column for 250’ system

Nat. Gas Pipe sizing Table - 1/2 psiCFH of Gas at .6 specific gravity, Press. drop = 0.3 in WC

Pipe

Length of tubing, Feet

Diam.

50

100

250

500

1000

1”

215

148

90

62

43

1-1/4”

442

304

185

127

87

1-1/2”

662

455

277

191

131

2”

1275

877

534

367

252

3”

3594

2470

1505

1034

711

4”

7330

5038

3069

2109

1450

6”

21472

14758

8990

6178

4246

Source: NFPA 54

gas pipe sizing 1 2 psi
Gas Pipe Sizing - 1/2 PSI

(See sizing charts on following page for pipe sizing for 1/2 PSI gas.)

Total developed length = 250 feet.

4” @ 2,400 CFH (250’ Column)

2”@ 400 CFH

Length for Branch Sizing = 100’

Regulator

Water Heater

Furnace

3” @ 2,000 CFH

400,000 BTUH = 400 CFH

2,000,000 BTUH = 2,000 CFH

Meter

Determine length of piping from branch piping appliance to gas the pressure regulator and refer to sizing chart column that exceeds the branch length for sizing only the branch piping. (2,000 CFH branch load @ 100 feet)

nat gas pipe sizing table 1 2 psi cfh of gas at 6 specific gravity press drop 0 3 in wc1
Nat. Gas Pipe sizing Table - 1/2 psiCFH of Gas at .6 specific gravity, Press. drop = 0.3 in WC

Pipe

Length of tubing, Feet

Diam.

50

100

250

500

1000

1”

215

148

90

62

43

1-1/4”

442

304

185

127

87

1-1/2”

662

455

277

191

131

2”

1275

877

534

367

252

3”

3594

2470

1505

1034

711

4”

7330

5038

3069

2109

1450

6”

21472

14758

8990

6178

4246

gas pipe sizing 5 psi
Gas Pipe Sizing - 5 PSI

(See sizing charts on previous pages for pipe sizing for 5 PSI gas.)

Total developed length = 250 feet.

1-1/2” @ 2,400 CFH (250’ Column)

1”@ 400 CFH

Length for Branch Sizing = 100’

Regulator

Water Heater

Furnace

1-1/4” @ 2,000 CFH

400,000 BTUH = 400 CFH

2,000,000 BTUH = 2,000 CFH

Meter

Determine length of piping from branch piping appliance to gas the pressure regulator and refer to sizing chart column that exceeds the branch length for sizing only the branch piping. (2,000 CFH branch load @ 100 feet)

slide97

Nat. Gas Pipe sizing, Table - 5 psiCFH gas at .6 specific gravity, Press. drop = 10% or 1/2 psi

Pipe

Length of tubing, Feet

Diam.

50

100

250

500

1000

1”

1989

1367

833

572

393

1-1/4”

4084

2807

1710

1175

808

1-1/2”

6120

4204

2562

1761

1210

2”

11768

8101

4934

3391

2331

2-1/2”

18785

12911

7865

5405

3715

3”

33209

22824

13903

9556

6568

4”

67736

46555

28358

19490

13396

sizing exercise 2
Sizing Exercise #2

Use 1/2 PSITable to Size Gas Piping to Gas Roof Top Units on a the roof of the “ASPE Industrial Building”

Place Sizing Chart on Overhead Projector

nat gas pipe sizing table 1 2 psi cfh of gas at 6 specific gravity press drop 0 3 in wc2
Nat. Gas Pipe sizing Table - 1/2 psiCFH of Gas at .6 specific gravity, Press. drop = 0.3 in WC

Pipe

Length of tubing, Feet

Diam.

50

100

250

500

1000

1”

215

148

90

62

43

1-1/4”

442

304

185

127

87

1-1/2”

662

455

277

191

131

2”

1275

877

534

367

252

3”

3594

2470

1505

1034

711

4”

7330

5038

3069

2109

1450

6”

21472

14758

8990

6178

4246

slide100

________ CFH / ___”

________ CFH / ___”

______ CFH / ___”

______ CFH / ___”

________ CFH / ___”

______ CFH / ___”

______ CFH / ___”

______ CFH / ___”

______ CFH / ___”

Gas Pipe Sizing Exercise #2

Size the Natural Gas Piping for 1/2 PSI Gas at .03 PSI Press. Drop.

20’ down to Regulator

Roof Top AHU 200,000 BTUH (Typical)

80’

Regulator

6

(PRV)

1800

100’

Meter

1600

6

200 CFH 1000’- 2”

200

2

100’

200 CFH 150’ - 1-1/2”

400

3

Pipe Guard

(Typical)

100’

200 CFH - 2”

1400

4

600

3

1200

4

800

4

200 CFH 210’ 1-1/2”

100’

1000

4

100’

100’

100’

100’

200 CFH 320’ - 2”

200 CFH - 2”

200 CFH 520’ - 2”

200 CFH 420’ - 2”

Total feet of piping from PRV to last appliance = _____________

900’+90’(10% Fit’gs)=990’

North

Use 1000’ Column on 1/2 PSI Chart

Big Box Industrial Bldg. - Mech. Roof Plan

No Scale

nat gas pipe sizing table 1 2 psi cfh of gas at 6 specific gravity press drop 0 3 in wc3

1800 CFH

Nat. Gas Pipe sizing Table - 1/2 psiCFH of Gas at .6 specific gravity, Press. drop = 0.3 in WC

Pipe

Length of tubing, Feet

Diam.

50

100

250

500

1000

1”

215

148

90

62

43

1-1/4”

442

304

185

127

87

1-1/2”

662

455

277

191

131

2”

1275

877

534

367

252

3”

3594

2470

1505

1034

711

4”

7330

5038

3069

2109

1450

6”

21472

14758

8990

6178

4246

sizing exercise 3
Sizing Exercise #3

Use 5 PSI Table to Size Gas Piping to the same Gas Roof Top Units on a the roof of the “ASPE Industrial Building”

slide103

Nat. Gas Pipe sizing, Table - 5 psiCFH gas at .6 specific gravity, Press. drop = 10% or 1/2 psi

Pipe

Length of tubing, Feet

Diam.

50

100

250

500

1000

1”

1989

1367

833

572

393

1-1/4”

4084

2807

1710

1175

808

1-1/2”

6120

4204

2562

1761

1210

2”

11768

8101

4934

3391

2331

2-1/2”

18785

12911

7865

5405

3715

3”

33209

22824

13903

9556

6568

4”

67736

46555

28358

19490

13396

slide104

________ CFH / ____

________ CFH / ____

______ CFH / ____

______ CFH / ______

________ CFH / ____

______ CFH / ____

______ CFH / ____

______ CFH / _____

______ CFH / ____

Gas Pipe Sizing Exercise #3

Size the Natural Gas Piping for 5 PSI Gas at 10% (0.5 PSI) Press. Drop.

20’ down to Regulator

Roof Top AHU 200,000 BTUH (Typical)

80’

Regulator

2”

(PRV)

1800

100’

Meter

1600

2”

200 CFH 810’= 1”

200

1”

100’

200 CFH 150’ = 1”

400

1-1/4”

200 CFH 710’ = 1”

Pipe Guard

(Typical)

100’

1400

2”

600

1-1/4”

1200

1-1/2”

800

1-1/4”

200 CFH 210’ = 1”

100’

1000

1-1/2”

100’

200 CFH - 620’ = 1”

100’

100’

100’

200 CFH 320’ = 1”

200 CFH 520’ = 1”

200 CFH 420’ = 1”

Total feet of piping from PRV to last appliance = _____________

900’+90’(10% Fit’gs)=990’

North

Use 1000’ Columnon 5 PSI Chart

ASPE Industrial Bldg. - Mech. Roof Plan

No Scale

slide105

1/2 PSI gas required 6 inch pipe size.

Nat. Gas Pipe sizing, Table - 5 psiCFH gas at .6 specific gravity, Press. drop = 10% or 1/2 psi

Pipe

Length of tubing, Feet

Diam.

50

100

250

500

1000

1”

1989

1367

833

572

393

1-1/4”

4084

2807

1710

1175

808

1-1/2”

6120

4204

2562

1761

1210

1800 CFH

2”

11768

8101

4934

3391

2331

2-1/2”

18785

12911

7865

5405

3715

3”

33209

22824

13903

9556

6568

4”

67736

46555

28358

19490

13396

increasing gas pressure
Increasing Gas Pressure
  • Increasing gas pressure can increase the pipe CFH capacity and reduce pipe sizes.
  • The following are some examples of ¾ inch pipe and 1 inch pipe at various pressures.
  • Note the one inch pipe capacity at ½ PSI = 100 CFH and at 50 PSI = 6,138 CFH.
slide108
Capacity of Semi-Rigid Tubing in CFH for 0.5 PSI or less gas pressure and pressure drop of 0.3 Inches WC(0.60 Specific Gravity Gas)

Source: NFPA 54 Handbook

0.5 PSI - 3/4” Pipe @ 200 feet = 30 CFH

slide109
Capacity of Semi-Rigid Tubing in CFH for 0.5 PSI or less gas pressure and pressure drop of 0.5 Inches WC(0.60 Specific Gravity Gas)

Source: NFPA 54 Handbook

0.5 PSI - 3/4” Pipe @ 200 feet = 39 CFH

slide110
Maximum Capacity of Pipe in CFH for 0.5 PSI or less gas pressure and pressure drop of 0.3 Inches WC(0.60 Specific Gravity Gas)

Source: NFPA 54 Handbook

1 PSI - 1” Pipe @ 200 feet = 100 CFH

slide111
Maximum Capacity of Pipe in CFH for 0.5 PSI or less gas pressure and pressure drop of 0.5 Inches WC(0.60 Specific Gravity Gas)

Source: NFPA 54 Handbook

0.5 PSI - 1” Pipe @ 200 feet = 135 CFH

slide112
Maximum Capacity of Pipe in CFH for 1 PSI gas pressure and a pressure drop of 10%(0.60 Specific Gravity Gas)

Source: NFPA 54 Handbook

1 PSI - 1” Pipe @ 200 feet = 338 CFH

slide113
Maximum Capacity of Pipe in CFH for 2 PSI gas pressure and a pressure drop of 10%(0.60 Specific Gravity Gas)

Source: NFPA 54 Handbook

2 PSI - 1” Pipe @ 200 feet = 525 CFH

slide114
Maximum Capacity of Pipe in CFH for 5 PSI gas pressure and a pressure drop of 10%(0.60 Specific Gravity Gas)

Source: NFPA 54 Handbook

5 PSI - 1” Pipe @ 200 feet = 940 CFH

slide115
Maximum Capacity of Pipe in CFH for 10 PSI gas pressure and a pressure drop of 10%(0.60 Specific Gravity Gas)

Source: NFPA 54 Handbook

10 PSI - 1” Pipe @ 200 feet = 1,539 CFH

slide116
Maximum Capacity of Pipe in CFH for 20 PSI gas pressure and a pressure drop of 10%(0.60 Specific Gravity Gas)

Source: NFPA 54 Handbook

20 PSI - 1” Pipe @ 200 feet = 2,680 CFH

slide117
Maximum Capacity of Pipe in CFH for 50 PSI gas pressure and a pressure drop of 10%(0.60 Specific Gravity Gas)

Source: NFPA 54 Handbook

50 PSI - 1” Pipe @ 200 feet = 6,138 CFH

questions
Questions?

Fuel Gas Systems

by: Ron George, CPD

Ron George Design & Consulting Services

5818 Newport South Rd.

Newport, MI 48166

Ph: 734-322-0225

Cell: 734-755-1908