2012 January-February

Natural Gas Facts by Sheryl Long  You probably know that natural gas is good for your business, but it is also good for the United States economy. Check out these statistics from the American Gas Association. Jobs, Jobs, Jobs Homes and business served by American Gas Association (AGA) members are the largest consumers of natural Read More

Natural Gas Facts
by Sheryl Long 

You probably know that natural gas is good for your business, but it is also good for the United States economy. Check out these statistics from the American Gas Association.

Jobs, Jobs, Jobs

Homes and business served by American Gas Association (AGA) members are the largest consumers of natural gas in the country and the industry as a whole employees nearly 3 million people.

  • 622,000 jobs are directly involved in exploring for, producing and distributing natural gas (direct employment). Natural gas distribution employment provided between 116,000 and 122,000 (nearly 20%) of these direct jobs.
  • 723,000 additional jobs are created in industries such as agriculture and manufacturing that support and supply goods and services to the natural gas industry (indirect employment).
  • 1.5 million jobs are supported when direct and indirect natural gas employees introduce the income back into the economy and create demand for further goods and services (induced employment).

 

For more information, visit https://www.aga.org/our-issues/playbook/Pages/default.aspx

 

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Employment Impact

The number of direct jobs created by the natural gas industry increased 20% between 2006 and 2008.

The natural gas industry employs people in all 50 states.

The natural gas industry’s value-added economic impact totaled $385 billion in 2008, or 2.7% of U.S. output. In addition, the gas industry provided $70 billion of direct income for workers in 2008.

The industry projects that the Marcellus shale gas play alone will result in approximately 160,000 additional jobs by 2015.

KEY WATER HEATING CHARTS AND FORMULAS by Rich Grimes  It’s 2012 already and in this issue we will try to give you plenty of information and useful charts related to water heating. I don’t receive many requests so I am glad to accommodate on such a pertinent subject. The best part is that you won’t Read More

KEY WATER HEATING CHARTS AND FORMULAS
by Rich Grimes 

It’s 2012 already and in this issue we will try to give you plenty of information and useful charts related to water heating. I don’t receive many requests so I am glad to accommodate on such a pertinent subject. The best part is that you won’t have to read too much from me as these charts and formulas speak for themselves! So here we go…

BTU

A British Thermal Unit (BTU) is a measurement of heat energy. One BTU is the amount of heat energy required to raise one pound of water by 1ºF. Water weighs 8.33 pounds per gallon so we can calculate that one gallon of water requires 8.33 BTU to raise the temperature 1ºF.

BTU CONTENT OF FUELS

ENERGY SOURCE                        BTU PER HOUR

COAL

1 Pound                                         =       10,000 – 15,000

1 Ton                                              =       25 Million (app.)

ELECTRICITY

1 KW                                              =       3,412

OIL

1 Gallon #1 Fuel                            =       136,000

1 Gallon #2 Fuel                            =       138,500

1 Gallon #3 Fuel                            =       141,000

1 Gallon #5 Fuel                            =       148,500

1 Gallon #6 Fuel                            =       152,000

GAS

1 Pound of Butane                         =       21,300

1 Gallon of Butane                         =       102,800

1 Cubic Ft. of Butane                     =       3,280

1 Cubic Ft. of Manufactured Gas    =       530

1 Cubic Ft. of Mixed                        =       850

1 Cubic Ft. of Natural                     =       1,075

1 Cubic Ft. of Propane                   =       2,570

1 Pound of Propane                       =       21,800

1 Gallon of Propane                       =       91,000

HORSEPOWER

1 Boiler Horsepower (BHP)            =       33,475 BTU

1 Boiler Horsepower (BHP)            =       34.5 Pounds of Steam @ 212ºF

1 Boiler Horsepower (BHP)            =       9.81 KW

COOLING

1 Ton of Cooling                             =       12,000

GAS INFORMATION

NATURAL             PROPANE

Specific Gravity                                                          =       0.62                    1.52

Flammability Limits (GAS/AIR Mixture)           =       4%-14%             2.4%-9.6%

Maximum Flame Propagation (GAS/AIR Mixture) =       10%                    5%

Ignition Temperature                                                =       1200ºF                950ºF

1 Pound of Gas (1 PSI)         = 28″ Water Column (w.c.)

1 Pound of Gas (1 PSI)         = 16 Ounces (oz.)

1 Therm = 100,000 BTU

 

ELECTRICAL INFORMATION

1 Kilowatt (kW)   =       3412 BTU Per Hour

1 Kilowatt (kW)   =       1000 Watts Per Hour

1 Kilowatt Hour (kWH) will evaporate 3.5 pounds of water from and at 212ºF

 

Amperage – Single Phase (1 Ø)      =       KW x 1000                   or      WATTAGE
                                                                         VOLTAGE                               VOLTAGE

 

Amperage – Three Phase (3 Ø)      =       KW x 1000                   or      WATTAGE
                                                                      VOLTAGE x 1.732                  VOLTAGE x 1.732

 

WATER HEATING FORMULAS

 

BTU Per Hour Requirement

BTU OUTPUT        =       GPM x Temperature Rise x 8.33 Lbs/Gallon x 60 Minutes

 

BTU INPUT           =       (GPM x Temperature Rise x 8.33 Lbs/Gallon x 60 Minutes)

% Efficiency

 

Heat Transfer Efficiency

% EFFICIENCY    =       (GPH x Temperature Rise x 8.33 Lbs/Gallon)
BTU/Hr INPUT

 

Heat-Up Time

Time in Hours      =       (GPH x Temperature Rise x 8.33 Lbs/Gallon)
                                               (BTU/Hr INPUT x % Efficiency)

 

Temperature Rise

Temp. Rise (∆T)   =           (BTU/Hr INPUT x % Efficiency)   

(GPM x 60 Minutes x 8.33 Lbs/Gallon)

 

GPH Recovery

Electric                =       (kW INPUT x 3412 BTU/kW x % Efficiency)

(Temperature Rise x 8.33 Lbs/Gallon)

 

Gas                     =                (BTU/Hr INPUT x % Efficiency)       

(Temperature Rise x 8.33 Lbs/Gallon)

 

MIXED WATER FORMULA

% of Hot Water Required      =       (Mixed Water ºF – Cold Water ºF)

(Hot Water ºF – Cold Water ºF)

 

WATER INFORMATION

1 Gallon     =       8.33 Pounds

1 Gallon     =       231 Cubic Inches

1 Cubic Ft   =       7.48 Gallons

1 Cubic Ft   =       62.428 Pounds (at 39.2ºF – maximum density)

1 Cubic Ft   =       59.83 Pounds (at 212ºF – boiling point)

1 Ft of Water Column (w.c.) = .4333 PSI

 

Water expands 4.34% when heated from 40ºF to 212ºF

Water expands 8% when frozen solid

 

OPEN VESSEL

BOILING POINT @ 0 PSI      ALTITUDE

212ºF                                    0 Feet (Sea Level)

210ºF                                    1000 Feet

208ºF                                    2000 Feet

207ºF                                    3000 Feet

205ºF                                    4000 Feet

203ºF                                    5000 Feet

201ºF                                    6000 Feet

199ºF                                    7000 Feet

 

CLOSED VESSEL BOILING POINT @ PSI @ Sea Level

BOILING POINT             GAUGE PRESSURE

212ºF                                    0 PSI

240ºF                                    10 PSI

259ºF                                    20 PSI

274ºF                                    30 PSI

287ºF                                    40 PSI

298ºF                                    50 PSI

316ºF                                    70 PSI

331ºF                                    90 PSI

ONLINE RESOURCES

There are an unlimited number of online tools and calculators for every mathematical formula. The internet is full of helpful resources to get the job done quicker. Here are a few links to some useful websites:

 

WEBSITE/PROGRAM                                         WEB ADDRESS

Amtrol Expansion Tank Sizing                                   https://amtrol.com/support/sizing.html

Engineering Toolbox Calculators                      https://www.engineeringtoolbox.com/

State Water Heater Sizing (Online)                          https://www.statewaterheatersizing.com/

AO Smith Water Heater Sizing (Online)            https://www.hotwatersizing.com/

Lochinvar Water Heater Sizing (Download)     https://www.lochinvar.com/sizingguide.aspx

 

Cylinder Calculator (Storage Tanks) / Other Math Calculators https://www.calculatorfreeonline.com/calculators/geometry-solids/cylinder.php

Electrical/Mechanical/Industrial/Civil/Chemical/Aeronautical Calculators https://www.ifigure.com/engineer/electric/electric.htm

B&G System Syzer (Piping/Pressure Drop Tool Download) https://completewatersystems.com/brand/bell-gossett/selection-sizing-tools/system-syzer/

B&G Selection and Sizing Tools (Pumps, Regulators, Steam and Condensate) https://completewatersystems.com/brand/bell-gossett/selection-sizing-tools/

Taco Pump Selection Wizard (Online Pump Selector)                                        https://www.taco-hvac.com/en/wizard_pumps.html

Lawler Mixing Valve Sizing (Online – account setup) https://www.lawlervalve.com/index.php?p=page&page_id=Sizing_Program

DSIRE Database of State/Federal Renewable Energy Rebates      https://www.dsireusa.org/

ASCO Valve Online Product Selector (Valves – solenoid, pilot, pneumatic, etc.) https://www.ascovalve.com/Applications/ProductSearch/ProductSearch.aspx?ascowiz=yes

 

SUMMARY

There is a lot of other information that we could add such as Steam. It is a viable heating source and there are several factors that must be considered such as operating pressure, steam trap and condensate line sizing and so on. We will have to do a separate article on Steam in a future issue.

The charts and information above are all essential to water heating. They are proven mathematical formulas of algebra and geometry. If you input the accurate information then the results will be correct. It is also good to use the online tools and calculators. They are true time savers.

Thanks and we’ll see you in the next article!

 

Natural Gas Appliances: Selling the Safety Angle by Sheryl Long   From time to time, technicians will interact with a potential customer who is afraid of natural gas. This fear can have a number of causes, but to make that natural gas appliance sale or installation you need to put that person’s mind at ease. Make Read More

Natural Gas Appliances: Selling the Safety Angle
by Sheryl Long

 

From time to time, technicians will interact with a potential customer who is afraid of natural gas. This fear can have a number of causes, but to make that natural gas appliance sale or installation you need to put that person’s mind at ease.

Make sure you are familiar with the safety standards of our industry and can address any related safety issues that might arise. The safety information below can become a powerful selling tool for closing these sales.

Natural gas safety

The United States’ natural gas pipeline delivery system is one of the safest and most reliable in the world. Extensive industry safety programs are in place and are overseen by state officials and the U.S. Department of Transportation.

Natural gas utilities support the Common Ground Alliance (CGA) whose mission is to reduce damages to underground infrastructure. Since the inception of CGA in 2004, there has been, roughly, a 40 percent reduction in excavation damages to natural gas systems.

Natural gas utilities also have multiple measures in place to ensure the safety of everyone. These measures include built-in system safety mechanisms, regular inspections, operator qualification requirements, and damage prevention and public education programs.

Built-in Mechanisms

-System flow rate and pressures are continuously monitored to stay within safe operating ranges.

-Mechanical regulators control flow and if pressure rises above a set point, they close off the flow.

-Relief valves are installed on pipelines to vent gas harmlessly if a line becomes overpresurrized.

-Another regulator at the residential meter reduces pressure to under ¼ pound. This is less than the pressure created by a child blowing bubbles through a straw in a glass of milk.

Inspections

-Pipe and fittings used for natural gas go through extensive inspections at many stages, from the manufacturing process all the way to the actual installation.

-After pipe is installed in a home or business, it is tested at significantly increased pressures beyond normal operations.

-All interior piping work is inspected according to requirements of the Florida Southern Building Code, plus additional local and regional jurisdiction inspections also may apply.

-When the natural gas service is actually turned on, the local utility tests to ensure that the pressure is correct and that there are no leaks in the system.

-Pipelines are surveyed with leak detection equipment at regular federally-specified intervals.

-Gas appliances are approved by nationally recognized testing centers to ensure they meet national safety standards.

Appliance Safety Technology

-Water heaters have a temperature and pressure relief valve as a backup safety feature.

-Water heaters, space heaters and some furnaces are equipped with a valve that automatically shuts off the fuel supply through a flame safeguard control. In other words, if the pilot isn’t burning, the gas flow shuts off.

-Many gas appliances have high temperature switches. If conditions activate these safety controls, the unit shuts down safely.

-Ranges and dryers have electric ignitions. There is no standing pilot, so when the gas is turned on, it is then ignited electronically.

-Most new gas appliances have an automatic flame sensor. If the gas doesn’t light in a certain length of time, the gas flow is shut off.

-Current safety codes require a manual shut-off valve for every appliance.

Operator Qualifications

-All utility personnel and contractors who are licensed to install natural gas lines must have passed stringent qualification programs.

Damage Prevention Programs

Natural gas utilities provide extensive damage prevention programs and federally mandated pipeline awareness information to the general public. Examples include 811 – Call Before You Dig information, newspaper notices, excavator training, First Responder training, etc.

Leak Detection

-Natural gas is an odorless, colorless substance. To guarantee that leaks are noticed, a chemical odorant called mercaptan is added to the gas, which results in a readily identifiable “rotten egg” smell.

-All utilities publicize an emergency leak number where natural gas leaks are given the highest priority.

This basic primer of natural gas safety should cover most questions and issues that technicians come across. Easing the fears of potential customers can definitely help your bottom line. Invest the time to become aware of just how safe natural gas really is.

 

For more information check out these websites:

sunshine811.com

AGA.org

FNGA.com (Natural Gas Information/Safety)

 

B&I Contractors and VA Hospital Cape Coral FL

To view pdf version click hereWhen the new Cape Coral Veterans Administration (VA) Outpatient Clinic opens in spring 2012, military personnel and retirees on the Gulf Coast will be able to utilize a conveniently located, state-of-the-art facility for medical care and other services. As a key player on the con- struction team, B & I Read More

To view pdf version click hereWhen the new Cape Coral Veterans Administration (VA) Outpatient Clinic opens in spring 2012, military personnel and retirees on the Gulf Coast will be able to utilize a conveniently located, state-of-the-art facility for medical care and other services. As a key player on the con- struction team, B & I Contractors, Inc. in Fort Myers can take credit for the project’s complex plumbing and mechanical aspects.

“Everyone from our plumbers, pipefitters, and tin-knockers worked hand in hand with the general contractor and other subs to make this project a success,” said Vincent Cicchesi, supervisor/estimator, plumbing service & special projects, B & I Contractors, in an interview with Florida Plumbing Per- spective. Manhattan Construction (Florida), Inc., formerly Manhattan Kraft Construction in Naples, was the general con- tractor for the $53 million project.

Established in 1960, B & I Contractors specializes in com- mercial, institutional, and industrial construction with services that include HVAC, plumbing, pipefitting, sheet metal, electri- cal, and fire protection service. “This was a very significant project for the Gulf Coast,” said project manager Ashley Fernandez, B.S.M.E. “There were also a number of interest features about the job that point to where the Florida plumb- ing market is heading.”

PROJECT IMPACT

The new Cape Coral VA Outpatient Clinic has been an important stimulus to the southwest Florida economy. At the time of the January 2010 groundbreaking, Fred Pezeshkan, president and CEO of Kraft Construction Company, Inc., said about 600 subcontractors and ven- dors for the construction job will be hired from Lee, Charlotte, and Collier coun- ties. A few months later, Bob Koenig, senior vice president and area manager for Kraft Construction, told the Cape Coral Construction Industry Association that 80% of the suppliers and sub-contractors for the project were procured in Lee, Collier, and Charlotte counties.

The new clinic is designed to replace an older veteran’s clinic in Fort Myers that opened in 1979 and no longer has the capacity to meet the growing population of retired U.S. mili- tary personnel. Although there are an estimated 200,000 vet- erans in the region—including 68,000 in Lee County—the older clinic offers only a limited number of services. As a result, veterans who require advanced procedures have had to travel to St. Petersburg for treatment at the Bay Pines VA Healthcare System.

In a 2010 article in the Cape Coral Breeze, Ralph Santillo, founder of the Invest in America’s Veterans Foundation in Cape Coral, said the new clinic may encourage more veter- ans to relocate to the Fort Myers area, knowing about the convenient services. That benefit, plus a great deal of afford- able housing in the region, may help economic recovery process for Fort Myers and Cape Coral.

“We are talking to vets outside the area to relocate down here because we have the facility coming up, and we have a reasonable housing market right now,” he said. Currently, about 25% of the people living in southwest Florida are veter- ans, according to Santillo.

PROJECT SCOPE

The Cape Coral VA Outpatient Clinic is 224,000 square feet, three times the size of the older Fort Myers VA Clinic. The facility will occupy a 30-acre site, stand 89 feet tall, and include 900 parking spots. The building itself is split into two quadrants: a two-story section and a four-story section. Two thousand tons of steel and 26,000 cubic yards of concrete were being used for the clinic, according to a Kraft Con- struction article.

The facility will be a comprehensive, multi-disciplinary spe- cialty care and outpatient clinic offering services such as pri- mary care, mental health care, diagnostic radiology, labora- tory services, audiology, cardiology with cardiac non-invasive diagnostic services, urology, GI, orthopedics, ophthalmology, dermatology, minor surgery, and advanced imaging including CT, MRI, fluoroscopy, ultrasound, nuclear medicine, mam- mography, and vascular Doppler ultrasound. It will include a Women Veterans Healthcare center, serving female veterans on the Gulf Coast.

Faith Belcher, spokesperson for the Bay Pines VA Health- care System in St. Petersburg, the administrator for local vet- eran care, said in a 2010 article that the design of the facility allows for a tower to be constructed with beds and other in- patient services when the need arises. It may also be able to have an emergency room in the future.

B & I Construction was re- sponsible for the mechanical and plumbing scopes, said Fernandez. “The building in- cludes operating rooms (ORs) with their respective recovery rooms, dental surgery rooms, and many office spaces,” he said, noting there were about 100 bathrooms to be installed. “Months of detailed and ex- tensive overhead coordination between the many trades were a critical part of this project.”

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PLUMBING

Cicchesi noted that the plumbing scope includes sanitary, domestic water, condensate, medical gas piping, natural gas, and fuel piping. “For the domestic water system we furnished and installed a 30,000-gallon steel underground tank, a fully redundant booster pump package in a fiberglass exterior dog- house, and all interior equipment and plumbing fixtures,” he said.

Another challenging aspect of the project was plumbing for the operating rooms, which have a full welded stainless steel ductwork system with all stainless accessories, as well as a decontamination room for sanitizing surgical scalpels and other instruments.

Cicchesi said the B & I team had to install oversized sen- sor-operated hand-wash sinks for use by the clinic staff prior to entering the OR areas. “These were wall-mounted units, approximately 4.5 feet wide and 3 feet tall, with their own mix- ing valves,” he added.

There were also four water softeners—handling more than 300 gallons—with a 6-inch flow, added Cicchesi. “We handled all the stainless steel welding, piping, and ductwork, while subbing out the low-voltage electrical work.”

MECHANICAL

For B & I Contractors, the mechanical scope included three 350-ton water-cooled chillers, a 35-ton air-cooled chiller, a 70-ton heat recovery chiller, along with 17 air-handling units and 34 fan-coil units.

The mechanical system included ERVs on all air-handling units to recover the energy from the exhaust air. The main makeup water supply to three cooling towers is the conden- sate from the air conditioning units, which are capable of pro- viding 533 gallons per hour of condensate water at peak load. “This facility is 100% drained,” said Cicchesi. “All condensate lines run to one area and recirculate to the cooling tower.”

The heating hot water system is fed by three 2500-MBH boilers, which provide heat to more than 350 variable air vol- ume units with heating coils to control room temperature. B & I also handled the natural gas connections to the boilers and water heaters. The fuel system included two 25,000-gallon fiberglass fuel tanks, three generator day tanks, and a fuel oil maintenance system.

“The unique mechanical aspect of this project included a fully louvered generator room, which was made up of large, stackable hurricane-rated louvers,” said Fernandez. “The generator room is located on the second floor level, making this a very complex installation.”

MEDICAL GASES

The VA Outpatient Clinic’s medical gas system included all medical gas equipment, alarm panels, and the installation of 35-owner-supplied head wall units. “One of the biggest chal- lenges on the plumbing scope was the large amount of owner-supplied equipment requiring plumbing connections,” Fernandez said. “Close coordination was required with the owner and general contractor in order to correctly complete the required rough-in.”

TO READ IN FULL PDF VERSION CLICK HERE

 

Keeping Plumbing system free of microorganisms by Abigail Cantor, P.E. (Chemical Engineer) This is the third article in a series about the possibility of microorganisms growing in plumbing systems.  The first article warned that with high residence time, high surface area, and no disinfection, microorganisms can grow out-of-control in plumbing systems.  The second article provided Read More

Keeping Plumbing system free of microorganisms
by Abigail Cantor, P.E. (Chemical Engineer)

This is the third article in a series about the possibility of microorganisms growing in plumbing systems.  The first article warned that with high residence time, high surface area, and no disinfection, microorganisms can grow out-of-control in plumbing systems.  The second article provided a tour of a plumbing system, pointing out where and why microorganisms are likely to grow.

This article describes three actions that can prevent microorganisms from growing out-of-control in a plumbing system:

  1. Flushing
  2. Disinfecting
  3. Monitoring

Flushing Pipes

 

Unfortunately, while flushing of pipes with fresh water will keep the population of microorganisms down, it is not always practical for plumbing systems in buildings.  Flushing requires a large quantity of water, especially for buildings with a long, complicated piping system and a large volume of hot water storage.

In addition, a high velocity of water is required to remove biofilms from pipe walls once they are attached.  It may be impossible to reach these cleansing velocities if pipe diameter and tank volumes in the plumbing system are large or the water pressure is too low.  A high velocity, also, cannot be maintained in the multiple bends and branches of a building’s plumbing system.  Even if a scouring velocity can be achieved, some biofilms continue to adhere firmly to pipe walls.

Table 1 shows the flow rate of water required to achieve a flushing and scouring velocity of 6 feet per second.

Table 1.  Flow Rates of Water at a Scouring Velocity of 6 Feet per Second

Nominal Pipe Diameter (inches)

Internal Pipe Diameter (inches)

Flow at Scouring Velocity (gpm)

3/8

0.430

3

1/2

0.545

4

5/8

0.668

7

3/4

0.785

9

1

1.025

15

1-1/4

1.265

24

1-1/2

1.505

33

2

1.985

58

Notes:

  1. 1.     This table uses the internal diameter of Type L copper pipe
  2. 2.     Flow Rate = Velocity x Cross-Sectional Area of Pipe
  3. 3.     Unit conversion used in calculation: 12 inches = 1 foot
  4. 4.     Unit conversion in calculation: 448.8 cubic feet per second (cfs) = 1 gallon per minute (gpm)

Disinfecting Water

 

An alternative to flushing with a large volume or a high velocity of water is flushing with a low volume of disinfected water.   There are a number of types of disinfecting chemicals that can be used, but a common chemical for drinking water is sodium hypochlorite which provides chlorine as the active disinfecting ingredient.  Another name for sodium hypochlorite is bleach, which can be purchased at grocery and hardware stores.  It is important to purchase household bleach that has no additives along with the sodium hypochlorite.  In household bleach, about 5.7% of the product is active chlorine.  Even though this sounds like a small amount, the concentration of active chlorine in the bleach is very high —   about 62,700 mg/L chlorine.

Many municipal and community water systems use liquid sodium hypochlorite or gaseous chlorine to disinfect the drinking water before it enters the distribution system.  Enough chlorine is added to maintain a disinfecting concentration all the way to the farthest locations in the distribution system.  Disinfecting in a building that receives chlorinated drinking water would boost the existing chlorine concentration or replenish the chlorine concentration after on-site water treatment devices have removed the municipal disinfection.

Some municipal water systems use a combination of chlorine and ammonia to create monochloramine for disinfection.  Monochloramine is not as strong a disinfectant as chlorine and must be used at a higher concentration to achieve a similar disinfecting power as free chlorine.  In a building that receives chloraminated drinking water, household bleach can still be used for boosting or replenishing disinfection.  However, if monochloramine or ammonia is present in the water, it will take more bleach to reach the desired active chlorine concentration than if only chlorine was present.

Active chlorine is referred to as “free” chlorine because it is not combined with other chemicals and is available to react with microorganisms.  “Total” chlorine refers to free chlorine plus chemical compounds where chlorine is combined with other chemicals.  When disinfecting with sodium hypochlorite, the concentration of free chlorine is a measure of disinfecting power.  When disinfecting with monochloramine, total chlorine is used to estimate the disinfecting power because chlorine is combined with ammonia, but the measurement of total chlorine also includes any free chlorine and any other compounds of chlorine that have formed in the water.  A better measure of disinfection power, in this case, is to directly measure monochloramine concentration.  However, the Total Chlorine test kit is more widely used as a convenience.

If it is desired to boost or replenish chlorine in a plumbing system, chemical injection equipment is needed.  Chemical injection equipment consists of a chemical feed pump with accessory valves for proper operation (Figure 1).  A multi-function valve, typically purchased with a chemical feed pump, provides for venting of air trapped in the suction line, pressure release, provision of required backpressure, and prevention of siphoning.  A foot valve at the end of the suction tubing in the chemical storage tank prevents backflow of chemical solution from the tubing back into the tank.  A chemical injector is a device with a ball check valve that connects into a threaded tee in the main pipeline and allows only forward flow of the chemical into the drinking water pipeline.  Additionally, a pulsation dampener and/or a static mixer (a pipe section with interior vanes) may be necessary for proper mixing of the chemical into the drinking water.  Automatic control of the chemical feed pump can be added by using a flow meter in the drinking water pipeline that sends an electric signal to the chemical feed pump to dose the chemical based on flow of the water.

 

Figure 1.  Typical Chemical Injection Equipment

To maintain disinfection throughout a plumbing system, sodium hypochlorite can be injected at critical locations where disinfection needs boosting or replenishing.  The article, “Critical Locations for Microbiological Growth in Plumbing Systems” explains that those locations are typically after certain water treatment devices.  For buildings fed by private wells, disinfection is also needed in the well water as it is discharged from the well pump.  Refer to the article for more detailed information as every plumbing system should be assessed individually for disinfection needs.

Care must be taken in selecting a proper dosage of chlorine for disinfecting plumbing systems.  Federal drinking water regulations demand that free chlorine concentration stay below 4 mg/L.  Many municipal and community water systems maintain a free chlorine concentration between 0.2 and 0.5 mg/L in the distribution system.  Some systems may go up to 1 mg/L.  Dosage of monochloramine in municipal water systems is typically between 1 and 3 mg/L total chlorine.  See Table 2 for a summary of typical disinfection concentrations.

Table 2.  Typical Disinfection Concentrations

Circumstance

Disinfection Concentration

Disinfectant Measured

Federal drinking water regulations Maximum of 4 mg/L allowable Free Chlorine
Chlorine disinfection of public water supplies Typically, 0.2 to 0.5 mg/L. Sometimes around 1 mg/L. Free Chlorine
Chloramine disinfection of public water supplies Typically, 1 to 3 mg/L Monochloramine;  Total Chlorine is used as an estimate
Chlorine disinfection of swimming pools 1 to 5 mg/L Free Chlorine
Conventional shock chlorination of wells 200 to 300 mg/L Free Chlorine

 

Chlorine can break down plastic components used in modern plumbing systems.  There is not well-documented information on the chemical compatibility of various plastics and chlorine, but when asked, many manufacturers of plastic components that come in contact with drinking water cite the drinking water regulation of 4 mg/L maximum.  However, the more exposure to higher chlorine concentrations over time, the shorter the life of the plastic components, so it is better to stay below 1 mg/L free chlorine.

Resin beads inside water softeners and ion exchange water treatment devices also break down over time in contact with higher chlorine concentrations.  Manufacturers will allow the resin to come in contact with 1 mg/L free chlorine for short time periods, but staying in the lower 0.2 to 0.5 mg/L range is better for the life of the beads.

The maximum allowable chlorine concentration in hot water systems is not known.  The higher temperatures push the chlorine to be more reactive and there is danger that the chlorine can corrode metals.  It is best to stay closer to 0.1 to 0.3 mg/L.

As was noted previously, the concentration of chlorine in household bleach is very high so only a small quantity of bleach is added to water to achieve free chlorine concentrations found in drinking water.  Table 3 lists the amount of bleach that should be added to water to reach drinkable concentrations.

 

 

 

Table 3.  Free Chlorine Concentrations and Volumes of Household Bleach (5.7% active chlorine) in 100 Gallons of Water

Free Chlorine Concentration (mg/L)

mL of Household Bleach in 100 gallons of Water

Ounces of Household Bleach in 100 gallons of Water

0.10

0.6

0.02

0.20

1.2

0.04

0.30

1.8

0.06

0.40

2.4

0.08

0.50

3.0

0.10

1.00

6.0

0.20

1.50

9.1

0.31

2.00

12

0.41

2.50

15

0.51

3.00

18

0.61

3.50

21

0.71

4.00

24

0.82

Note:   To measure milliliters (mL) of bleach, purchase a container marked in milliliters, called a “graduated cylinder”, from a laboratory supply company.  Graduated cylinders come in various sizes with various precision of measurement, such as a 10 mL cylinder marked in gradations of 0.2 mL or a 25 mL cylinder marked in gradations of 0.5 mL.

Monitoring Water Quality

 

To prevent the growth of microorganisms in pipes, the goal is to provide just enough fresh water and just enough disinfection to continuously expose the pipes to a minimum of about 0.3 mg/L free chlorine in the water. Routine monitoring of chlorine concentrations throughout the plumbing system is necessary to determine if the pipes are getting the proper exposure to disinfected water.

Field test kits are available for measuring chlorine concentrations in water.  An example of a field test kit is the Pocket Colorimeter™ II from the Hach Company.  The test kit can measure both free and total chlorine concentration.  With sodium hypochlorite disinfection, free chlorine concentration should be measured.   With chloramine disinfection, total chlorine concentration should be measured as an estimate of monochloramine concentration.  The instructions for measuring the chlorine concentration come with the field test kit and are simple to follow.  These are relatively inexpensive, simple, and convenient tests that can routinely guide flushing and disinfection dosing in piping systems.

Unfortunately, the control of microorganisms is a little more complicated than merely maintaining a specific disinfection concentration.  The conditions in piping systems and water environments vary and microorganisms can still grow at disinfection concentrations that are typically effective elsewhere.  Monitoring of “microbiological activity” should be performed in addition to monitoring disinfection concentration.

The best method of monitoring for microbiological activity has not been determined at this time.  However, one test is typically used to estimate microbiological activity.  It is called Heterotrophic Plate Count (HPC).  The test should be performed by a commercial laboratory that uses a special nutrient in the incubation dish called R2A.  There are many laboratories that will perform an HPC test, but not all will use the R2A. Table 4 lists the criteria that the laboratory should use to run the test.   The tests are about $30 a sample but overnight transport to the laboratory should be considered in the overall cost. After finding a laboratory that performs these tests according to the criteria listed in Table 4, have the laboratory send sample bottles for HPC_R2A sampling in disinfected water.  To take HPC_R2A water samples from a plumbing system, the water in the plumbing system must sit stagnant for a minimum of six hours.  It is good to use a similar stagnation time each time.  When it is time to take samples, wipe the faucet or sample tap opening inside and out with an alcohol wipe, wiping off any excess alcohol.  Open the sample bottle carefully because it has been sterilized to prevent contamination of the water sample.  Do not touch the inside of the bottle, the rim of the bottle, or the inside of the cap.  Capture the first-draw stagnation water in the sample bottle and fill the bottle to the indicated line.  Cap and label the sample bottle.  Put the bottle on ice in a cooler and get the sample to the laboratory within twenty-four hours.

Table 4.  Laboratory Requirements for the HPC_R2A Water Analysis

HPC_R2A Criteria
HPC=Heterotrophic Plate Count
Send sampler sealed sterile bottles containing sodium thiosulfate to deactivate disinfection
For analysis, use R2A growth media in the incubation dishes
Incubation temperature range: 25 to 28 degrees Centigrade
Incubation period: 5 to 7 days
Run two dilutions: 1 mL sample per dish and 0.1 mL sample per dish
Run each dilution in duplicate

 

There is another test that has been found to be a better measure of microbiological activity than HPC.  It is a test that measures chemical compounds of metabolism (ATP) for organisms in the water.  A second generation method has been developed but is not readily available at this time in water testing laboratories.

Summary

 

Flushing of pipelines and disinfection of water are the available tools for preventing out-of-control microbiological growth in plumbing systems.  In order to determine the right amount of flushing balanced with the right amount of disinfection, water quality throughout the plumbing system must be monitored routinely.

This article describes the details of flushing and disinfecting plumbing systems and testing for chlorine and microbiological activity.  Future articles will use this information to suggest a practical approach for building and plumbing contractors for preventing out-of-control microbiological growth in modern plumbing systems.