Transcript Fuel Gas Systems - ASSE International

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
 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 BOCA - Basic Mechanical Code (no longer updated in favor of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?
 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
Equipment Label
Distance
Pipe Size Chart
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)
One pound of water
will increase by 1
degree F when 1 BTU
is added.
1 pound of 60
degree water
1 BTU
1 pound of 61
degree water
Example: One pound
of 60 degree F water
plus 1 BTU = one
pound of 61 degrees F
water.
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
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:
Odor Additives
Source: NFPA 54 Handbook
Fuel Gas is Explosive!
Fuel Gas is Explosive!
Fuel Gas is Explosive!
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 Explosive!
Fuel Gas is Explosive!
New Braunfels, TX. 1 dead, 1 seriously burned.
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
 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
PRV
Low press.
1/2 psi +-
Medium press. 60 psi +-
PRV
High press. 900 psi+Energy Company lines
Well
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
PRV
Low press.
1/2 psi +-
Medium press.
60 psi +PRV
High press. 900 psi +-
Well
Natural Gas Low Pressure
Low Pressure
– Commonly used inside buildings
– Commercial and residential users.
– Typically less than 5 PSI (code requirement indoors)
Pumping Station
PRV
furnace
Medium press. 60 psi +-
PRV
Low press.
1/2 psi + Homeowner Responsibility
High press. 900 psi +-
Fuel Gas Pressure 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.
Gas Pressure Conversion Chart
 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
How Do we Change from a High
Pressure to a Low Pressure?
 Pressure Regulators.
Gas Regulator Operation
60 PSI
½ PSI
1/2 PSI
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 odor so they
could detect a gas leak. The engineers designed a scrubber to remove the
Mercaptin odor and replace it with a Pina’ Colada odor.
Natural Gas Pipe Material
 Cast Iron Not 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.)
Copper or
CSST
PRV
furnace
Black Steel/CSST
Abv. ground
Pumping Station
Polyethylene or
wrapped & coated
Black Steel U.G.
PRV
PE or asphalt wrapped Sch 80 - 160
Black steel W/ Cathodic Protection
(Pressure often dictates material)
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%.
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
 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
 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
(In trench 12”above pipe)
Caution - Buried Gas Line
Buried Gas Line
Tracer Wire (In trench above plastic pipe)
Caution - Buried Gas Line
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)
Gas Pipe
Continuous pipe bedding
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.
Freezing can
crack pipe
allowing gas to
leak out of pipe
Wet gas condenses
water to this point
Boom
Locate Gas line below frost line or
in a heated space.
If Gas line is subject to freezing
provide heat tracing and Insulation.
Dirt Leg (For Dry Gas)
Clean Gas
Sediment falls
Source: NFPA 54
Handbook
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.
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/
M
Regulator
Void space
Sealed sleeve
Foundation Wall
Expansive or
Clay Soil
Gas Pipe
Section at Foundation Wall
End view U.G. Pipe
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
 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
 All owners should 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
 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 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.
 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, 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
 As of October 2008 – the National Fuel
Gas Code requires bonding of ALL CSST
systems per section 7.13 – Electrical
Bonding and Grounding.
CSST Coils and Fittings
CSST Pipe Layouts
CSST Pipe Layouts
CSST Pipe Layouts
Hybrid Multi-Unit Condo Building
CSST
Branches
Steel Riser
Hybrid System w/ Local Gas
Regulator and CSST
(4) 50,000 BTU/H
5 PSI
CAP.
IP
OP
1/4 PSI
Multiple Manifold System
Gas Pipe Inside Buildings
Gas Piping Prohibited Locations:
In Circulating Air Duct
Through Circulating Air Duct
Clothes chutes
Boom
In Chimney
In Gas Vent
In Ventilation duct
In Dumb Waiter
In Elevator Shaft
Leaks in concealed
locations can allow
explosive gasses to
accumulate unnoticed
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
Boom
No swing joins made by multiple fittings
Exceptions:
Brazed Tubing
Fittings listed for concealed locations
Leaks in concealed
locations can allow
explosive gasses to
accumulate unnoticed
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?
 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
 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)
Lubricated Plug Valve exposed to more than ½ PSI
Fuel Gas Valve Types
Ball Valve
Lubricated Plug Valve
Plug
Grease Seal
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 shutoff valve.
Test Plug 10 diameters downstream of regulator before 2nd shutoff valve.
Regulator should be protected from damage.
Indoor Regulators should be vented to the outdoors.
Gas Meter with Protection Post
Gas Regulator Failure
60 PSI
½ PSI
1/2 PSI
60 PSI - 2 PSI
Regulator
2 PSI – 1/2 PSI
Regulator
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
(4) 50,000 BTU/H
CSST
5 PSI
CSST
CAP.
IP
OP
1/4 PSI
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
Upstream Shut-off
valve
Downstream shut-off
valve
Plugged tee for downstream
Plugged tee in dirt leg for
pressure measurement
upstream pressure measurement
Rooftop Piping
Typical Gas Appliance Piping Connection
Typical Gas Appliances
Donut Fryer
Consult Manufacturer’s Literature for BTU’s/H Input
Typical Gas Appliances
AGA
Appliance
Nameplate
Consult manufacturer’s literature for BTU’s/H input
Typical AGA Appliance Nameplate
Source: NFPA 54 Handbook
Input BTUH
Fuel Type
Venting Category
Max. Press.
Min. Press.
Manifold Press.
Units (In. WC)
Min. Clearances
Typical Water Heater Installation
Source: NFPA 54 Handbook
Flue to Category I Type “B” vent
Appliance Regulator/Controls
Single vs Double wall Flue
Source: NFPA 54 Handbook
Double wall provides a
safer installation
Single wall more
susceptible to carbon
monoxide leaks
Corroded Flue Pipe from High Efficiency
Condensing Equipment.
Typical Appliance Flue Installation
Source: NFPA 54 Handbook
Combustion Air
 Transfer Grille
 Ventilation louvers
through ceiling &
floors
Source: NFPA 54 Handbook
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
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 Combustion
Above 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
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 Combustion
Above 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
Convert CFH in Gas pipe sizing tables to CFH for a fuel with a specific gravity other than 0.6
Nat. Gas
Propane
Butane
Sizing Exercise #1
Approximate Gas input for Typical Gas Appliances
Source: NFPA 54 Handbook
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
 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
 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.
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
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
 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
250 feet includes equivalent length
allowance for fittings and valves.
Longest Run Method
See following page for equivalent
length allowances table.
Total developed length = 250 feet.
Water
Heater
400,000 BTUH /
400 CFH burner
Regulator
Furnace
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
from Regulator
Pipe
Length of tubing, Feet Distance
To farthest outlet
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
All sizing should be done from this column for 250’ system
Equivalent Lengths in Feet of Straight pipe.
For fittings and Valves
Source: NFPA 54 Handbook
1/2 PSI
Example:
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.
2”@ 400 CFH
4” @ 2,400 CFH
(250’ Column)
Length for Branch
Water
Heater
400,000 BTUH =
400 CFH
Furnace
Sizing = 100’
Regulator
3” @ 2,000 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 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
5 PSI
Example:
Gas Pipe Sizing - 5 PSI
(See sizing charts on previous pages for pipe sizing for 5 PSI gas.)
Total developed length = 250 feet.
1”@ 400 CFH
1-1/2” @ 2,400 CFH
(250’ Column)
Length for Branch
Water
Heater
Furnace
Sizing = 100’
Regulator
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)
Nat. Gas Pipe sizing, Table - 5 psi
CFH 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
Use 1/2 PSI Table 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 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 Exercise #2
Size the Natural Gas Piping for 1/2 PSI Gas at .03 PSI Press. Drop.
Roof Top AHU 200,000
BTUH (Typical)
100’
1000’- 2”
200
2
400
200 CFH 150’ - 1-1/2”
3
1400
Pipe Guard
(Typical)
4
______
600 CFH / ___”
3 ________ CFH / ___”
1200
100’
800
200 CFH - 2”
Meter
1600
6
________ CFH / ___”
______ CFH / ___”
______ CFH / ___”
200 CFH - 2”
6
1800
________ CFH / ___”
100’
200 CFH
80’
20’ down to
Regulator
Regulator
(PRV)
4
4
______ CFH / ___”
______ CFH / ___”
1000
100’
200 CFH 520’ - 2”
4
______ CFH / ___”
100’
100’
200 CFH 210’ 1-1/2”
200 CFH 320’ - 2”
200 CFH 420’ - 2”
900’+90’(10% Fit’gs) =990’
Total feet of piping from PRV to last appliance = _____________
Big Box Industrial Bldg. - Mech. Roof Plan
No Scale
North
Use 1000’ Column
on 1/2 PSI Chart
Nat. Gas Pipe sizing Table - 1/2 psi
CFH 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
1800 CFH
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”
Nat. Gas Pipe sizing, Table - 5 psi
CFH 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
Gas Pipe Sizing Exercise #3
Size the Natural Gas Piping for 5 PSI Gas at 10% (0.5 PSI) Press. Drop.
Roof Top AHU 200,000
BTUH (Typical)
810’= 1”
200 CFH
100’
200 CFH
________ CFH / ____
1”
200
______ CFH / ____
400
200 CFH 150’ = 1”
1-1/4”
2”
1400
100’
800
620’ = 1”
Pipe Guard
(Typical)
______
____ ________ CFH / ____
600 CFH /1-1/4”
1200
200 CFH -
Meter
1600
2”
________ CFH / ____
______ CFH / ______
710’ = 1”
80’
2”
1800
100’
20’ down to
Regulator
Regulator
(PRV)
1-1/4”
1-1/2”
______ CFH / ____
______ CFH / _____
1000
100’
200 CFH 520’ = 1”
1-1/2”
______ CFH / ____
100’
100’
200 CFH 210’ = 1”
200 CFH 320’ = 1”
200 CFH 420’ = 1”
900’+90’(10% Fit’gs) =990’
Total feet of piping from PRV to last appliance = _____________
ASPE Industrial Bldg. - Mech. Roof Plan
No Scale
North
Use 1000’ Column
on 5 PSI Chart
Nat. Gas Pipe sizing, Table - 5 psi
CFH 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”
1/2 PSI gas required 6 inch pipe size.
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
1800 CFH
Gas Sizing Tables
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.
Capacity of Semi-Rigid Tubing in CFH for 0.5 PSI or less
gas pressure and pressure drop of 0.3 Inches WC
Source: NFPA 54 Handbook
(0.60 Specific Gravity Gas)
0.5 PSI - 3/4” Pipe @ 200 feet = 30 CFH
Capacity of Semi-Rigid Tubing in CFH for 0.5 PSI or less
gas pressure and pressure drop of 0.5 Inches WC
Source: NFPA 54 Handbook
(0.60 Specific Gravity Gas)
0.5 PSI - 3/4” Pipe @ 200 feet = 39 CFH
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
Maximum Capacity of Pipe in CFH for 0.5 PSI or less gas
pressure and pressure drop of 0.5 Inches WC
Source: NFPA 54 Handbook
(0.60 Specific Gravity Gas)
0.5 PSI - 1” Pipe @ 200 feet = 135 CFH
Maximum Capacity of Pipe in CFH for 1
and a pressure drop of 10%
(0.60 Specific Gravity Gas)
PSI gas pressure
Source: NFPA 54 Handbook
1 PSI - 1” Pipe @ 200 feet = 338 CFH
Maximum Capacity of Pipe in CFH for 2
and a pressure drop of 10%
(0.60 Specific Gravity Gas)
PSI gas pressure
Source: NFPA 54 Handbook
2 PSI - 1” Pipe @ 200 feet = 525 CFH
Maximum Capacity of Pipe in CFH for 5
and a pressure drop of 10%
(0.60 Specific Gravity Gas)
PSI gas pressure
Source: NFPA 54 Handbook
5 PSI - 1” Pipe @ 200 feet = 940 CFH
Maximum Capacity of Pipe in CFH for 10
and a pressure drop of 10%
(0.60 Specific Gravity Gas)
PSI gas pressure
Source: NFPA 54 Handbook
10 PSI - 1” Pipe @ 200 feet = 1,539 CFH
Maximum Capacity of Pipe in CFH for 20
and a pressure drop of 10%
(0.60 Specific Gravity Gas)
PSI gas pressure
Source: NFPA 54 Handbook
20 PSI - 1” Pipe @ 200 feet = 2,680 CFH
Maximum Capacity of Pipe in CFH for 50
and a pressure drop of 10%
(0.60 Specific Gravity Gas)
PSI gas pressure
Source: NFPA 54 Handbook
50 PSI - 1” Pipe @ 200 feet = 6,138 CFH
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