Charlotte Pipe ChemDrain User Manual
ChemDrain
TECHNICAL AND INSTALLATION MA NU AL
CPVC Chemical Waste Drain System
(Updated August 2011)
®
TM-CD
© 2005-2011 Charlotte Pipe and Foundry Company
TECHNICAL MANUAL
Monroe, North Carolina
Muncy, Pennsylvania
INTRODUCTION
Charlotte Pipe and Foundry is a privately held company
committed to providing the highest quality products and
service to the plumbing industry. We offer a full line of pipe
and fittings in a wide range of materials. Our ChemDrain®
Chemical Waste Drain System uses CPVC pipe and fittings
specifically designed for management of chemical waste.
The ChemDrain® System is designed and manufactured to
provide easier installation, fewer callbacks and virtually
trouble-free service for as long as the system is in use.
Charlotte Pipe and Foundry’s investment in state-of-theart production equipment and outstanding customer service
have created an excellent source of supply for our customers.
We are constantly focusing on process improvement to find
better ways to further enhance customer service. We’ve
invested millions in increasing manufacturing efficiency,
productivity and capacity. Because we manufacture for
inventory, we are able to ship orders complete and in a
timely manner.
ChemDrain® Technical Manual
Cameron, Texas
Huntsville, Alabama Cedar City, Utah
Manufacturing Facilities
• Monroe, North Carolina • Wildwood, Florida
Wildwood, Florida
Charlotte Pipe, ChemDrain and “You can’t beat the system” are registered trademarks of Charlotte Pipe and Foundry Company.
2
• Muncy, Pennsylvania • Huntsville, Alabama
• Cameron, Texas • Cedar City, Utah
TABLE OF CONTENTS
GENERAL INFORMATION Page
Introduction to Charlotte Pipe and Foundry ..................................................................... 2
Understanding Safety Alert Messages .............................................................................. 4
Major Advantages of CPVC Pipe ...................................................................................... 5
Benefits of CPVC ........................................................................................................... 6
Recommended Product Applications ................................................................................ 6
Best Uses of CPVC ........................................................................................................ 6
Product Certification ..................................................................................................... 8
Recommended Product Specification ............................................................................... 9
ChemDrain® CPVC-CW Schedule 40 Pipe and Fittings ................................................... 9
Handling and Storage of CPVC Pipe ............................................................................... 10
Receiving Pipe ............................................................................................................ 10
Handling Pipe ............................................................................................................. 10
Storing Pipe ............................................................................................................... 10
DESIGN AND ENGINEERING DATA
Weathering ...................................................................................................................... 11
UV Exposure .............................................................................................................. 11
Cold Weather Considerations ....................................................................................... 11
Fluid Flow Properties ................................................................................................. 12-13
Gravity Flow .............................................................................................................. 12
Manning Roughness Factor .......................................................................................... 12
Fluid Flow Rate .......................................................................................................... 13
Expansion and Contraction of CPVC Pipe ................................................................. 13-14
Expansion Loops ................................................................................................... 13-14
Support Spacing for CPVC Pipe ................................................................................ 14-15
Chemical Resistance ....................................................................................................... 16
Chemical Resistance Charts ....................................................................................... 17-24
CONVERSION CHARTS ................................................................................................... 25-26
INSTALLATION PROCEDURES
Connection Options ......................................................................................................... 27
Exclusive Charlotte Pipe TrueFit® System .................................................................... 27
Advantages of Solvent Welding .................................................................................... 27
Installation Procedures for ChemDrain CPVC Systems ................................................... 28
Basic Principles of Solvent Welding ............................................................................. 28
Cements ...................................................................................................................... 28
Making the Joint .................................................................................................... 29-30
Applicators ................................................................................................................. 30
Applicator Type ........................................................................................................... 31
Joint Curing ................................................................................................................ 31
Flanging CPVC Pipe .................................................................................................... 31
Connecting CPVC to Other Materials ........................................................................... 32
Making Joints with ChemDrain Chemical Couplings ...................................................... 32
Installation of Threaded Connections ............................................................................ 32
External Taper Thread Dimensions ............................................................................... 33
Underground Installation ........................................................................................... 34-35
Trenching ................................................................................................................... 34
Bedding and Backfilling ............................................................................................... 35
TESTING AND INSPECTION
Testing a ChemDrain CPVC System ................................................................................ 36
Hydrostatic Test .............................................................................................................. 36
LIMITED WARRANTY ........................................................................................................... 37
REFERENCE STANDARDS ................................................................................................... 38
Charlotte, Charlotte Pipe, ChemDrain and “You can’t beat the system” are registered trademarks of Charlotte Pipe and Foundry Company.
3
GENERAL INFORMATION
ChemDrain® Technical Manual
Understanding safety alert Messages
It is important to read and understand this manual. It contains information to help protect your safety and prevent problems.
“WARNING” Indicates a hazardous situation which, if not
avoided, could result in severe injury or death.
“CAUTION” Indicates a hazardous situation which, if not
avoided, could result in minor or mo derate injur y.
“NOTICE” Indicates a hazardous situation which, if not
avoided, may result in system failure and property damage.
READ & SAVE THESE INSTRUCTIONS
4
GENERAL INFORMATION
Major advantages of CPvC
Charlotte Pipe’s ChemDrain® CPVC chemical waste system,
manufactured with CPVC, provides a durable and economical
disposal solution for many chemical waste applications.
For more than 50 years, CPVC has been used in a variety
of chemical processing applications. Now, Charlotte Pipe
is offering ChemDrain CPVC pipe and fittings specifically
engineered for laboratory chemical waste disposal systems.
Commercial and academic laboratories generate liquid waste
that must be treated or neutralized before reaching the sewer
system. One of the major benefits of CPVC is its resistance to
a broad range of acids and corrosive chemicals. This range
makes it an ideal system for labs, which use an unusually wide
variety of chemicals. Additionally, a chemical waste drainage
system must be able to handle the routine disposal of both hot
and cold chemicals.
CPVC is an attractive alternative to glass, stainless steel, lined
steel, high silicon cast iron, PP (polypropylene) and PVDF
(polyvinylidene fluoride) for chemical waste and an excellent
choice for long-term value.
Chemical waste piping systems must be designed to convey
the mixtures of corrosive liquids generated by commercial
and institutional laboratories to a point where it is either
sufficiently diluted or neutralized before being discharged into
the sanitary sewer system. CPVC is particularly well-suited to
the task because it exhibits excellent chemical resistance to
a broad range of chemicals including strong and dilute acids,
bases, caustics, salts, aliphatic solutions and other common
reagents. In addition, ChemDrain CPVC can convey liquids in
gravity drainage applications at temperatures up to 220° F.
CPVC also overcomes many common problems that have
been inherent in chemical waste piping systems up until now.
Glass and high silicon iron systems are cumbersome, fragile,
and have a high initial cost. Polypropylene lacks the ability
to withstand the elevated temperatures that are common
in some systems and isn’t as good as CPVC in some highly
concentrated acids. PVDF is excellent in strong acids but
not recommended for many common alkaline solutions. And
both polypropylene and PVDF are usually installed using
time-consuming, complicated and at times unreliable fusion
joining methods. It’s easy to make consistent reliable joints
in the ChemDrain system using simple hand tools, a specially
formulated one-step solvent cement and easily trained labor.
Bottom line, the ChemDrain CPVC system is often the best
single choice for chemical waste drainage.
The ChemDrain CPVC pipe and fitting system is much easier to
join than the mechanical or heat fusion PP or PVDF systems.
CPVC pipe is lightweight, approximately one-sixth the weight
of iron and requires no special tools for cutting. Each piece
is manufactured by Charlotte Pipe to exacting standards to
avoid time-consuming trouble or delays during installation.
And there’s no expensive heat fusion equipment to buy or rent.
Failure to follow safety precautions may result in
misapplication or improper installation and testing which
can cause severe personal injury and / or property damage.
Primers and cements are extremely flammable and may
be explosive. Do not store or use near heat or open
flame, or death or serious injury may occur.
• Solvent fumes created during the joining process are
heavier than air and may be trapped in newly installed
piping systems.
• Ignition of the solvent vapors caused by spark or flame
may result in injury or death from explosion or fire.
• Read and obey all manufacturers' warnings and any
instructions pertaining to primers and cements.
• Provide adequate ventilation to reduce fire hazard and
to minimize inhalation of solvent vapors when working
with cements, primers and new piping systems.
CPVC is joined by solvent cement – the most commonly used
technique for thermoplastic pipe and fittings in the chemical
processing industry – which results in a permanent weld. Solvent
cementing has been employed for decades to join thermoplastic
pipe and fitting systems for a variety of applications including
corrosive fluids at elevated temperatures.
ChemDrain one-step solvent cement is designed to create a
intermolecular bond between pipe and fitting surfaces. Once
properly applied and cured, the joint is permanent. Melted
joints, corrosion of exposed internal heating wires and burnthrough, all problems in the joining systems of heat-fused
plastic products, are not possible with CPVC.
Our ChemDrain CPVC Solvent Cement has been specially
formulated for chemical resistance to caustics including
hypochlorites, mineral acids and other corrosive chemicals.
Charlotte Pipe manufactures both ChemDrain pipe and fittings
to our exacting tolerances, meaning everything is designed
to fit together properly. This is the exclusive Charlotte Pipe
TrueFit® System.
5
GENERAL INFORMATION
compressed air or gas in PVC / ABS / CPVC
Benefits of CPVC Include:
Cost Effective
• CPVC is easy to install, reliable and durable, lowering your
total costs of ownership over the life of the system. CPVC
piping is extremely lightweight, convenient to handle and
competitively priced against alternative materials. When
properly installed and used, its durability and resistance
to chemical corrosion make it a long-term, cost-effective
option.
Easy Installation
• CPVC pipe is lightweight, approximately one-half the
weight of aluminum and one-sixth the weight of steel,
and requires no special tools for cutting. Each piece is
manufactured by Charlotte Pipe to exacting standards
to avoid time-consuming trouble or delays during
installation. Also, CPVC has smooth, seamless walls and
can be installed with fast and reliable solvent welded
joints.
Failure to follow proper installation practices,
procedures, or techniques may result in personal injury,
system failure or property damage.
• Use a solvent cement / primer applicator that is 1/2 the
size of the pipe's diameter. Too large an applicator will
result in excess cement inside the fitting. Too small an
applicator will not apply sufficient cement.
• Cut pipe square.
• Do not use dull or broken cutting tool blades when
cutting pipe.
• Do not test until recommended cure times are met.
ChemDrain® Technical Manual
Testing with or use of compressed air or gas in PVC / ABS
/ CPVC pipe or fittings can result in explosive failures and
cause severe injury or death.
• NEVER test with or transport/store
pipe or fittings.
• NEVER test PVC / ABS / CPVC pipe or
fittings with compressed air or gas, or air
over water boosters.
• ONLY use PVC / ABS / CPVC pipe for water
or approved chemicals.
• Refer to warnings in PPFA User Bulletin
4-80 and ASTM D 1785.
Corrosion Resistance
• CPVC is inert to most acids, bases, salts and a variety
of organic media, within certain limits of concentration
and temperature. A chemical waste management system
of CPVC piping provides the chemical resistance for a
wide variety of dedicated and mixed chemical applications
when properly diluted by flushing with water. CPVC also
eliminates the disadvantages found in alternative piping
materials, such as borosilicate glass, high-silicon cast iron
or double-containment piping, which can be heavy, fragile
and expensive to purchase, install and maintain.
reCoMMended ProdUCt aPPliCation
A ChemDrain® CPVC chemical waste management system
offers a wide-ranging solution to the dilution and disposal needs
of institutional and academic laboratories. When properly
designed, installed and utilized, the system will deliver years
of reliable, problem-free service.
Best Uses of CPVC
One of the key advantages of a ChemDrain CPVC system is its
resistance to a broad range of acidic and caustic chemicals.
The inherent wide-ranging chemical resistance has led to the
Charlotte ChemDrain system being tested and certified for
chemical waste drainage by NSF International and bears the
mark NSF-cw.
CPVC compares favorably to other commonly used nonmetallic chemical wast e piping mate rials and has a
To the best of our knowledge the information contained in this publication is accurate. However, Charlotte Pipe and Foundry does not
assume any liability whatsoever for the accuracy or completeness of such information. Final determination of the suitability of any
information or product for the use to be contemplated is the sole responsibility of the user. The manner of use and whether there is any
infringement of patents is also the sole responsibility of the user.
6
GENERAL INFORMATION
“recommended” rating for widely-used concentrations of
many corrosive chemicals and common laboratory reagents.
Please refer to the comprehensive chemical resistance chart
on pages 17 through 23 for information on both CPVC as well
as the fluoroelastomer which is used in ChemDrain Transition
fittings as well as important notes concerning the use of CPVC
in chemical waste applications.
The Chemical Resistance data located in this manual is
for CPVC in a typical laboratory drainage environment.
To reduce the risk of system failure, always evaluate the
chemical resistance information and project specific
factors.
• Laboratory Drainage is defined as: The routine noncontinuous disposal of a wide variety of hot and cold
chemicals in relatively small quantities in a gravity
drainage system accompanied by water sufficient for the
purpose of dilution and flushing.
• Refer to the Plastics Technical and Installation Manual
available at www.charlottepipe.com for chemical
resistance information for industrial or continuous
chemical drainage applications.
• Chemical resistance of plastics is dependent on
concentration, possible interactions with other
chemicals, temperature, stress and other factors.
7
GENERAL INFORMATION
ChemDrain® Technical Manual
Product Certification
ChemDrain® CPVC chemical waste system is a complete system of pipe, fittings, solvent cement and accessories. Charlotte Pipe
and Foundry CPVC pipe and fittings are listed for chemical waste systems by NSF International and bear the mark NSF-cw.
For additional information log on to www.nsf.org.
Physical Properties of CPVC Material
PROPERTY CPVC 4120 UNITS STANDARD
Mechanical Properties
Specific Gravity 1.55 ASTM D 792
Tensile Strength (73°F) 7,000 psi ASTM D 638
Modulus of Elasticity in Tension (73°F) 360,000 psi ASTM D 638
Flexural Strength (73°F) 15,100 psi ASTM D 790
Izod Impact Cell Class 23447 (notched at 73°F) Min. 1.5 Fittings ft lb/ in. ASTM D 256
Hardness (Durometer D) – ASTM D 2240
Hardness (Rockwell R) 119 ASTM D 785
Compressive Strength (73°F) 10,100 psi ASTM D 695
Hydrostatic Design Stress 2,000 psi
Thermal Properties
Heat Distortion Temperature at 264 psi Minimum 212°F (Cell Class 23447) degrees F ASTM D 648
Coefficient of Thermal Conductivity .95 BTU/ hr/sq ft/ °F/ in. ASTM C 177
Coefficient of Linear Expansion 3.4 x 10-5 in./ in./ °F ASTM D 696
Specific Heat 0.34 BTU/lb°F ASTM D 2766
Water Absorption (24 hrs at 73°F) .03 % weight gain ASTM D 570
Cell Classification 23447-Pipe and Fittings ASTM D 1784
Flammability
Limiting Oxygen Index 60% ASTM D2883
Burning Rate Self Extinguishing ASTM D 635
Burning Class V-0 UL 94
Flame & Smoke Rating
Flame Spread 0 CAN/ULC S 102.2
Smoke Developed2 8-22
Solvent Cement Heavy Body, ASTM F 493
Mustard Yellow Color
1
Above data is based upon information provided by the raw material manufacturers. It should be used only as a recommendation and not as a guarantee of
performance.
1
Based on test of physical product, as opposed to test of material only. Test was conducted on 11⁄2” - 6” pipe.
2
Results vary based on pipe diameter.
8
GENERAL INFORMATION
reCoMMended sPeCifiCation
System: ChemDrain
Scope: This specification covers CPVC Schedule 40 pipe and fittings for chemical waste drain applications.
ChemDrain is intended for use in non-pressure drain applications where the temperature will not exceed
220° F.
Specification: Pipe and fittings shall be manufactured as a system, be the product of one manufacturer and be manufactured
in the United States. All pipe, fittings and solvent cement shall be supplied together as a system, as
Charlotte Pipe ChemDrain chemical waste system manufactured by Charlotte Pipe and Foundry. Pipe
and fittings shall conform to National Sanitation Foundation Standard (NSF) 14.
Special drainage systems for corrosive chemical or acid waste shall be manufactured from CPVC Type
IV, Grade I, ASTM Cell Class 23447. All system components shall be certified by NSF International for
use in chemical waste drain systems and bear the mark NSF-cw. All system piping shall be Schedule 40
CPVC produced to the dimensional requirements of ASTM F 2618 and the manufacturer’s specifications.
All pipe fittings shall be CPVC drainage patterns meeting the requirements of ASTM F 2618 and the
manufacturer’s specifications, as applicable.
Installation shall comply with the latest installation instructions published by Charlotte Pipe and Foundry
and shall conform to all applicable plumbing, fire and building code requirements. Buried pipe shall be
installed in accordance with ASTM D 2321 and ASTM F 1668. Solvent welded joints shall be made with
ChemDrain One-Step solvent cement conforming to ASTM F 493. The system shall be protected from items
that are not compatible with CPVC compounds; materials like thread sealants, plasticized vinyl products,
fire stopping devices or other aggressive chemical agents. Systems shall be hydrostatically tested after
installation. WARNING! Use of compressed air or gas in CPVC pipe or fittings can result in explosive
failures and cause severe injury or death.
®
CPVC-CW Schedule 40 Pipe and Fittings
Significance and Use:
The requirements of this specification are intended to provide pipe, fittings and drains suitable for use in
chemical waste disposal within the limitations described in this manual.
Reference Standards*:
ASTM D 1784 Rigid CPVC Vinyl Compounds
ASTM D 2321 Underground Installation of Thermoplastic Pipe (non-pressure applications)
ASTM F 493 Solvent Cements for CPVC Pipe and Fitting
ASTM F 1668 Procedures for Buried Plastic Pipe
ASTM F 2618
NSF Standard 14 Plastic Piping Components and Related Materials
*Note: Latest revision of each standard applies.
Standard for Chlorinated Poly (Vinyl Chloride) Chemical Waste Drainage Systems
reCoMMended sPeCifiCation short forM
Special drainage systems for corrosive or acid waste shall be manufactured from CPVC Type IV, Grade I compounds with a
minimum cell classification of 23447. Pipe and Fittings shall conform to ASTM F 2618. Pipe shall be Schedule 40 dimensions.
One-Step Solvent Cement shall be specially formulated for chemical waste applications and conform to ASTM F 493. All pipe,
fittings and cement shall be supplied as a system by a single manufacturer and shall be certified by NSF International for use
in corrosive waste drain systems and shall bear the mark “NSF-cw”. Special Drain system is to be the ChemDrain® system
as manufactured by Charlotte Pipe and Foundry Co. Installation to be in accordance with manufacturer’s instructions and all
applicable code requirements. Buried pipe shall be installed in accordance with ASTM D 2321 and ASTM F 1668. The special
drainage system is intended for the listed chemicals for use in non-pressure chemical waste applications with a maximum
working temperature of 220° F.
9
GENERAL INFORMATION
ChemDrain® Technical Manual
handling and storage of CPvC PiPe
Receiving Pipe
When receiving CPVC pipe, thoroughly inspect pipe before
unloading. For pipe transported on an open truck bed, examine
for shipping damage from over-tightened tie-down straps,
improper treatment or a shift in load. If pipe is delivered in a
closed trailer, the inspection should happen when the trailer is
first opened. Make sure the pipe has not been damaged by a
load shift, rough handling or having other materials stacked
on top of it.
To inspect CPVC pipe:
• Examine visually for cracks, splits, gouges or other forms
of damage.
• Check for severe deformation of pipe as this may cause
joining problems during assembly.
• Inspect interior for internal splits or cracks in all pipes
measuring 4 inches in diameter or more. A flashlight
may be necessary to perform this part of the inspection
satisfactorily.
If damage is found, all parties involved, including the driver,
must be made aware of the damage. Also note damage on the
bill of lading and/or delivery ticket. Notify Charlotte Pipe and
the carrier within 24 hours of any damage, as well as delivery
errors or shortages.
Handling Pipe
CPVC piping is incredibly sturdy. As a result, workers sometimes
have a tendency to treat it as if it is indestructible. However,
reasonable care should be used during handling to reduce the
risk of damaging the pipe. Refrain from unnecessary abuse when
unloading, storing and handling. Do not drop pipe from trucks,
drag pipe over the ground or step on pipes. When unloading,
do not drag or push pipe from truck bed. Remove and handle
pallets of pipe with a forklift.
NOTE: Avoid contact with sharp objects such as rocks, angle
irons or the forks of a forklift. Pipe should never be lifted or
moved by inserting forks of a forklift into the pipe ends.
NOTE: In addition to following these guidelines, extra care
should be used when handling CPVC pipes measuring 4 inches
in diameter or more. Because of the additional pipe weight, even
a minor impact can cause cracking. Plastic pipe also becomes
more brittle as the temperature decreases. Use extra precautions
when handling pipe at temperatures of 50°F and lower.
Storing Pipe
Store CPVC pipe in a heated, ventilated area, preferably
indoors. If CPVC pipe is stored outdoors for long periods, cover
it with a non-transparent material to avoid UV exposure. When
storing outside, place pipe on level ground that is dry and free
of sharp objects. CPVC pipe with the thickest walls should be
placed on the bottom of the pile if different schedules of pipes
are stacked together.
Pipe that is in pallets should be stacked with the pallet boards
touching. Pallet boards should not be placed directly on CPVC
pipe, as they can damage the pipe or cause it to bow. If pipe
is stored in racks, the pipe should be supported continuously
along its length. If this is impossible, supports should be no
more than 3 feet apart.
10
DESIGN AND
ENGINEERING DATA
Weathering
UV Exposure
Ultraviolet (UV) radiation from sunlight can cause surface
discoloration in CPVC pipe. The reaction occurs when energy
from the sun excites the molecular bonds in the plastic, but
affects only the exposed surface of the pipe to a shallow depth
of 0.001 to 0.003 inches. The reaction ends when exposure
to sunlight ends.
Placing an opaque shield between the sun and the pipe prevents
UV degradation. CPVC pipe should be covered with an opaque
material when stored outdoors for long periods of time.
Burying CPVC pipe provides protection against UV attack.
Painting pipe with latex (water-based) paint also will help
protect CPVC pipe installed above ground. However, proper
surface preparation is crucial for painted pipe. First, clean
the CPVC pipe to remove moisture, dirt and oil, and then wipe
dry with a clean cloth. NOTICE: Do not use petroleum-based
paints as the petroleum will prevent the paint from properly
bonding to the pipe.
Cold Weather Considerations
CPVC is a ductile material that expands and contracts more
than metallic plumbing pipe does. However, like all plumbing
materials, CPVC must be protected from freezing with proper
insulation in accordance with all plumbing codes.
Like other piping materials, CPVC may split when liquids
freeze in it, causing potential system failure and severe
personal injury.
If a CPVC line should freeze, it is crucial to thaw the line if
possible. If the frozen section of pipe is accessible, blow heated
air directly onto the pipe using a low wattage heater/blower.
When thawing a frozen CPVC line, the heat source should
not exceed 180°F. Electrical heat tapes also can be applied
to the area.
Also, eliminate the source of cold air that caused the pipe to
freeze. Until this can be done, drain the system if overnight
temperatures are likely to drop below 32°F.
11
DESIGN AND
ENGINEERING DATA
Charlotte Pipe’s ChemDrain® System offers a complete
solution for creating a state-of-the-art CPVC chemical waste
drain system that can deliver years of reliable, trouble-free
service. From proper installation techniques to chemical
resistance to fluid flow calculations, the pages that follow
lay out everything needed to design and install a ChemDrain
system for optimum performance.
Charlotte Pipe urges users to carefully study this information
and to follow it precisely. ChemDrain has been created as a
total system, and all warranties and guarantees depend on
designing and implementing the system as recommended.
flUid floW ProPerties
Gravity Flow
CPVC is an extremely smooth material. Its low surface friction
properties make CPVC as smooth as glass, but without its
disadvantages (weight, high breakability). To determine the
fluid velocity, pipe size and hydraulic slopes for a gravity
drain, it is best to use the Manning’s equation shown below.
In the equation:
V = Velocity of flow in feet/second
N = Manning’s value (see “Manning Roughness
Factor”, below)
R = The hydraulic radius, in feet. This is obtained by dividing
the cross-sectional area of flow by the wetted perimeter
of the pipe in contact with the flow. (R is a special case
for V with pipes that are either 1/2 full or full; in those
cases, R = inside diameter / 4, in feet)
S = Upstream elevation – Downstream elevation/(ft./ft.)
pipe length
V = 1.486 R
N
2/3 S1/2
ChemDrain® Technical Manual
Example 2:
Calculate the gravity flow for a 4”-diameter Schedule 40
CPVC pipe, flowing half full over a 10-foot pipe run with a
1.5-inch drop.
S = 20”-18.5” / 12” = 0.0125 ft./ft.
10 ft.
R = 4.026” / 12” = 0.0839 ft.
4
Assume “N” to be 0.010. Then:
V = 1.486 (0.0839)
0.010
V = 3.2 ft./second
Charlotte Pipe generally recommends a flow velocity of
at least 2.0 feet per second for self-cleaning drain lines.
In both examples shown, the design being evaluated exceeds
this recommendation.
2/3
(0.0125)
1/2
Manning Roughness Factor
(“N” Value)
The Manning “N” value is a commonly used flow coefficient.
This coefficient expresses the “smoothness” of the interior
walls of various types of piping material. The Manning value is
used when making calculations for liquids with a steady flow,
at a constant depth, in a prismatic open channel.
The “N” value for CPVC pipe ranges from 0.008 to 0.012,
making it comparable in smoothness to glass, polypropylene
and PVDF and som ewhat smo other on average than
competitive high-silicon iron systems.
Example 1:
Calculate the gravity flow for a 2”-diameter, Schedule 40
CPVC pipe, flowing full over a 30-foot pipe run with a 7.5inch drop.
S = 17.5”-10.0” / 12” = 0.0208 ft./ft.
30 ft.
R = 2.067” / 12” = 0.043 ft.
4
2/3
V = 1.486 R
N
Manning’s “N” value can range from 0.008 to 0.012.
However, for gravity sewer systems, we generally use 0.009.
V = 1.486 (0.043)
0.009
V = 2.9 ft./second
12
S
1/2
2/3
(0.0208)
1/2
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