May/June 2000

IN THIS ISSUE

Celebrating the New Steel . . . . . . . . . . .1

Guest Column: Energy Savings in 

Industry Through Use of Insulation 

and Refractories . . . . . . . . . . . . . . . . . . .2

Understanding Your Compressed 

Air System is Important to Managing 

it Well . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Advanced Level Compressed Air 

Management Training Now Available . . .5

Performance Optimization Tips: Field

Measurements in Pumping Systems—

Practicalities and Pitfalls . . . . . . . . . . . .6

New Feature: Ask the Clearinghouse . .8

New Feature: BestPractices Tools—

Knowledge at Your Fingertips . . . . . . . .8

Uncover “New” Tools and Resources 

for Improving Steam Systems . . . . . . . . .9 

BestPractices Debuts . . . . . . . . . . . . . . .11

Letters to the Editor . . . . . . . . . . . . . . . .11

Calendar of Events . . . . . . . . . . . . . . . .12

ISSUE FOCUS: 

Industrial Energy 

Systems Management

T OF ENERGY

DEPARTMEN

U

E

NITED STAT S OFA

ERICA

M

A BestPractices PUBLICATION ON IMPROVING INDUSTRIAL ENERGY EFFICIENCY

OFFICE OF INDUSTRIAL 

TECHNOLOGIES • 

U.S. DEPARTMENT OF ENERGY 

www.oit.doe.gov 

www.oit.doe.gov/bestpratices

Once again, innovative technologies have

galvanized the U.S. steel industry to realize

significant energy savings and productivity

increases. On May 4 and 5, DOE’s Office

of Industrial Technologies (OIT), the State

of Pennsylvania, the American Iron and

Steel Institute (AISI), and the Steel Manufacturers Association cohosted an event

called “A Celebration of the New Steel—

Pittsburgh Regional Technology Showcase.” Held in the

heart of the U.S. steel industry,

the 2-day event included plant

tours, technical sessions, and

new technologies.

Plant improvements based

on new DOE-sponsored technologies were installed and

demonstrated at U.S. Steel

Group’s Edgar Thomson Plant

in Braddock, Pennsylvania,

and at Weirton Steel Corporation in Weirton, West Virginia.

These plant improvements will

help the steel industry forge

ahead in their efforts to save

energy, save costs, and increase productivity. In fact, both showcase

companies are already reaping the benefits

of the new technologies.

Heating Up Productivity at U.S. Steel

With a company-wide commitment to

continuous improvement, the U.S. Steel

Group has already implemented more than

40 energy- and resource-saving technologies—with an estimated annual savings of

about $2 million. These projects include

modifying natural gas pilots on boilers, insulating steam lines, repairing steam traps, recovering condensate, and repairing leaks in

compressed air systems. That commitment

was further evidenced by the technologies

showcased at the Edgar Thomson Plant. This

time the focus was on sensors and controls.

The showcased projects included:

■ A blast furnace burden monitor that

uses an infrared imaging camera to detect where the bulk of the heat is located. Operators can distribute the

burden to keep heat in the center of the

furnace, which increases the furnace’s

life and fuel efficiency. Maintenance

costs are also decreased.

■ A KTB degasser lance incorporates a

video camera, a vessel preheat burner,

and an oxygen blower to adjust the

chemistry of a batch of steel. An operator can see alloy additions more clearly

to enhance the steel quality. The

process can now be done in one step

instead of three, and it eliminates the

burner’s high maintenance costs. 

■ A basic oxygen process (BOP) vessel

contour sensoring system measures the

thickness of a vessel lining. This helps

locate weaknesses in the vessel to prevent molten steel from seeping through,

which can cause damage and injury.

The new system reduces downtime to

do vessel lining checks from 30 minutes

to 30 seconds, and it saves $10,000 a

month for a contractor to do vessel lining measurements once a day. 

■ A BOP vessel off-gas sensor measures

carbon levels and predicts slopping

(when hot steel erupts and splashes out

of the vessel) using an infrared sensing

system. It eliminates the downtime

Celebrating the New Steel 

(continued on page 10) 

Following several energy- and cost-saving 

projects, U.S. Steel embarked on sensors and

control projects for process improvements.

Best Practices debuts, see page 11.
2 Energy Matters, May/June 2000

ENERGY MATTERS

is published bimonthly by the

U.S. Department of Energy’s

(DOE) Office of Industrial 

Technologies. 

Information contained in the

newsletter can be reproduced

without permission provided due

acknowledgement is given (the

U.S. Department of Energy’s 

Energy Matters newsletter) and 

a copy of the publication is 

supplied to the editor.

■

EDITORIAL BOARD

Rob Boteler, representing 

National Electrical Manufacturers

Association

Lynda Butek, representing 

Electrical Apparatus Service 

Association

Don Casada, OIT BestPractices

Program

Keith Davidson, Onsite Sycom

Energy

Bob Gemmer, U.S. DOE,

Process Heat

Glenn Hahn, Spirax Sarco

Fred Hart, U.S. DOE, Steam 

Chris Hunter, Johnson & Johnson

Roy Jones, representing

Compressed Air and Gas Institute

Aimee McKane, Lawrence

Berkeley National Laboratory,

Compressed Air Challenge

Rick Payton, Rockwell 

Automation/Reliance Electric

Bill Stafford, Technical 

Association of the Pulp and 

Paper Industry

Chuck Whelan, DuPont

■

COMMENTS? 

Contact: 

Julia Oliver, DOE, at 

(510) 637-1952, or e-mail

julia.oliver@oak.doe.gov

Michelle Mallory, 

Energy Matters Editor, at 

(303) 275-3627, or e-mail 

michelle_sosa-mallory@nrel.gov

1617 Cole Blvd., MS 1713

Golden, CO 80401

Guest Column

Energy Savings in Industry

Through Use of Insulation

and Refractories 

By Arvind C. Thekdi, Executive Vice 

President, CSGI, Inc., Rockville, MD

Role of Insulation

and Refractories 

Insulation and refractories, individually or in combination, are used to

contain heat in all applications where heat

is generated, transferred, transmitted, or recovered. Typical industrial applications include boilers, steam and hot fluid piping,

furnaces, ovens, heaters, and storage tanks.

The terms “refractories” and “insulation” refer to a large family of inorganic,

nonmetallic materials used primarily to reduce heat losses or for thermal insulation.

Insulating materials include those with

low-thermal conductivity that divide an air

space into very small pockets, thereby

minimizing solid and gas conduction and

radiation, and, for most applications, eliminating convection. Figure 1 shows several

types of refractory and insulating materials

used by industry. Properly designed refractory and insulation systems reduce heat

losses, conserve energy, maintain desired

process temperatures, assist in heat transfer, and safely contain process atmosphere,

such as flammable toxic or hazardous

gases, vapors, or liquids. 

Potential for Energy and Cost Savings 

U.S. industries use more than 15 quads

(one quad equals 1000 trillion Btu) of energy per year in the form of heat generated

from fuels (natural gas, fuel oils, etc.) and

electricity. Many industrial processes require proper insulation to be carried out.

However, inadequate or improper use of

insulation in industry accounts for 10% to

30% of total industrial energy loss. These

losses amount to 1.5 to 3 quads of energy

and represent a $3 to $5 billion in annual

energy costs for industries.

Although it is not feasible, or in some

cases, not advisable, to eliminate all losses,

industry can reduce losses by 10% to 25%

and achieve cost savings of $.5 to $2 billion. This requires plant personnel to review

process requirements, know available and

applicable insulation materials, and select

materials to meet the process requirements.

It also requires proper design, installation,

and preconditioning of insulation systems

during startup. This should be followed by

proper operation of the equipment to avoid

damage to the insulation, periodic maintenance, repairs, and replacement of the 

insulation. In certain high-temperature

processes, such as steel or glass melting or

steel reheating, properly installed and maintained insulation can eliminate or greatly reduce the use of water or air-cooling, which

can represent 15% to 40% of the total heat

input to the process. 

Refractories and Insulation Materials 

Refractories are classified by chemical

composition or physical properties. The

main classes are silica, alumina-silica, high

alumina, basic, and insulating. With the

exception of insulating refractories, most

high-temperature refractories, such as firebricks, are high-density (>120 lb/ft3). They

offer excellent resistance in challenging

operating environments, such as slags with

different chemical compositions, fumes,

Figure 1. Commonly available forms of refractories and 

insulation materials.

(continued on page 3) Source: Thermal Ceramics
Energy Matters, May/June 2000 3

dust, and gases. Insulating refractories have

lower densities (50 to 70 lb/ft3) and provide

insulating properties, while offering resistance to corrosion and chemical reactions

with the operating environment.

The three basic types of insulating materials for industrial use are: 1) thin (less

than 20 micrometers), low-density (less

than 12 lb/ft3) fibers made from organic or

inorganic materials; 2) cellular material in

closed or open cell form made of organic

or inorganic material; and 3) flaked or

granular inorganic materials bonded in the

desired form. In most cases, glass (silica),

mineral wool, high alumina, mulite, or zirconia are the base materials and can be

used to temperatures as high as 2900°F.

This class of materials has a lower density

that varies from 4 lb/ft3 to 12 lb/ft3 and offers higher thermal resistance compared to

firebricks or insulating firebricks. 

In all cases, thermal conductivity of the

insulation increases significantly as temperature increases. Figure 2 shows the

thermal conductivity values of commonly

used refractories and insulating materials. 

Selecting Refractories and Insulation for

Industrial Use

Proper design and installation of refractories and insulation play important roles in

a system’s performance and life and the

overall economics of plant operation and

profits. Selecting insulation materials and

designing insulation systems requires consideration of four factors: 

■ Thermal performance, which involves

temperature limit; melting or fusion

temperature; thermal conductivity that

represents insulation capability; heat

capacity or storage; thermal expansion;

and thermal shock (spalling) resistance. 

■ Physical properties, which include density or porosity; abrasion; wear and erosion resistance; electrical resistivity for

use in electric heating; mechanical

strength; and other structural properties

at high temperatures. 

■ Chemical considerations, which include

uniformity of composition; reactions 

between base materials and operating

environment; and issues such as

volatilization of the constituents or binding agents, corrosion, chemical attack, or

diffusion and reactions with the product.

■ Economics, which mean initial installation labor; maintenance and repair; and

replacement costs.

In most applications, economics and

performance require use of more than one

type of insulating material. All major suppliers offer guidelines and help in application and installation of insulation systems.

In some cases, special tools and techniques are developed, and personnel must

be trained for proper installation work.

Design and Selection Tools 

The cost of an insulation material relates to its temperature capability. Hence,

insulation and refractory systems are designed to include several layers of different

materials that offer optimum economic

performance. Selecting the most economical system requires consideration of its cost

compared to potential savings from reduction of heat losses. Figure 3 shows a typical

system cost vs. savings for different insulation thicknesses in a furnace application. 

In some cases, the most economical

thickness may not meet regulatory requirements for the safety of personnel and property. In such cases, appropriate design and

materials should be used. In other cases,

thickness may be reduced when there is a

danger of exceeding the limiting refractory

or insulating temperature. 

A number of tools and design methods

are available for selecting the most economical or appropriate refractories or insulation.

For example, 3E Plus Insulation Thickness

software, developed jointly by DOE’s Office

of Industrial Technologies (OIT) and the

North American Insulation Manufacturer’s

Association (NAIMA), can be used to calculate and select the insulation thickness for a

variety of conditions. Download the program at www.oit.gov/bestpractices/

software_databases/software.html.

For high-temperature furnaces, many

layers of insulation are needed that may include different types of materials, such as

refractory bricks, fiber blocks or blankets,

or, in rare cases, loose fiber wool or granular material. Other programs on the market

allow users to select a number of material

combinations of the available materials and

calculate heat losses, surface temperature,

and heat storage for the selected system. 

Resources on the Horizon

Currently, a number of private and publicly funded programs are underway to develop new refractory and insulating

materials. These programs will result in the

development and application of new

equipment design that can make significant

reductions in energy loss from industrial

heating processes, while improving productivity and safety for all major industries.

Go to Energy Matters Extra at www.oit.

doe.gov/bestpractices/explore_library/

emextra to link to information about insulation resources. ●

Contact Arvind Thekdi by phone at 

(301) 948-3033 or by e-mail at athekdi@

ctisinc.com

Figure 2. Typical thermal conductivity 

values for commonly used refractory and 

insulating materials.

Mean Temperature (°F)

14

10

12

8

6

4

2

0

500 1000 1500 1800 2000

Thermal Conductivity (Btu in/[hr ft2 °F]) 

Firebrick

Insulating firebrick

Ceramic fiber

Microporous insulation

Figure 3. Trends in costs, savings, and 

payback.

Relative Values of Insulation Thickness

140

100

120

80

60

40

20

0

01234567

Relative Values of Cost and Payback Period 

Payback Period

Insulation Cost

Energy Cost

continued from page 2
4 Energy Matters, May/June 2000

The first step in improving a plant’s compressed air system is to understand how

compressed air is used. This will determine

the system’s compressed air requirements.

Start with an assessment of your plant’s

end-use applications to identify highpressure, high-volume/intermittent, and inappropriate applications. Use this information to devise an effective system-level

strategy for each application. Then, with

the best strategy selected, implement the

plan to optimize each application’s compressed air consumption. 

The example below describes one company’s steps to understand its compressed air

system use and requirements, then to implement improvements. In this case, the results

were substantial cost savings, improved

product quality, and increased productivity. 

CASE STUDY: 

CUTTING COSTS AND IMPROVING

PRODUCTIVITY AT WEIRTON STEEL

Weirton Steel recently completed a project to improve the compressed air system

at its Tin Mill facility. New compressors,

new air treatment equipment, and the repair of leaks significantly reduced compressor shutdowns, production downtime,

and product rejects. In addition, the new

system operates more efficiently, leading to

lower energy and maintenance costs. The

total project cost was $246,000, with expected annual savings of $136,000 and a

simple payback of 1.8 years.

Weirton Steel’s plant in Weirton, West

Virginia, is one of North America’s most

advanced integrated steel production facilities. Compressed air is an integral part of

the production process, with compressed

systems located in four main areas: the

Steel Works and Utilities, the Tin Mill, the

Strip Steel Mill, and the Sheet Mill. Of

these, the Tin Mill and the Strip Steel Mill

use the greatest volume of compressed air.

The Tin Mill uses compressed air mainly

for pneumatic cylinders, blowing operations, and spray guns in producing steel

rings for metal cans. Prior to the implementation, the Tin Mill’s compressed air system

was a combination of six aging, watercooled, manually controlled centrifugal and 

sliding vane compressors

totaling 2200 connected

brake horsepower. With

this system, the mill experienced a high degree

of product rejects and frequent production interruptions. 

Assessing the System 

Weirton’s management performed a compressed air system

assessment of the Tin Mill

that began with an evaluation of compressed air

applications. The assessment identified inadequate treatment of the compressed air and

the aging compressors as major contributors to excess water and lubricant in the

system. 

In this case, inadequate treatment

caused large amounts of water to carry over

into the system’s air cylinders. This produced two consequences. First, it prevented

the compressors from maintaining a stable

system pressure as water steadily increased

the pressure gradient. Second, it led to periodic stoppages in production because the

cylinders had to be manually drained. 

Lubricant that leaked from compressor

bearings was mixing with the compressed

air. The lubricant migrated onto steel rings

in cans during the coating process, which

resulted in an unacceptably high degree of

contaminated cans that had to be destroyed. In addition, the old and poorly operated compressors only produced 70% of

rated airflow, which meant the mill had to

bring extra compressors online. 

Implementing Solutions

Weirton replaced its old compressors

with five 350-hp rotary screw compressors

that supply approximately 8500 scfm at 90

psig. Each new compressor has a dedicated

thermal mass refrigerated dryer, and the

compressors have been sequenced to respond to varying compressed air demands.

The mill also replaced leaking filters and

old valves. Additionally, air cylinders that

had been damaged from years of water

buildup were rebuilt. To ensure the quality

of the compressed air used in the coating

process, the mill installed a dedicated, lubricant-free, rotary screw 100-hp compressor with a desiccant dryer, a conventional

filter, and two charcoal filters to supply

compressed air for that application. 

Taking Stock of the Benefits

Weirton’s Tin Mill overhaul resulted in

improved production and substantial savings. The dryers have eliminated water

buildup in the air cylinders, which means

there is no longer a need to drain and perform maintenance on the cylinders. The

dedicated system that supplies lubricantfree compressed air has drastically reduced

the rejection of cans. Production downtime

has also been reduced, while productivity

at the Tin Mill has increased. With the new

system, the mill operates more effectively,

using less total energy for production. In

addition, less water buildup means the resistance to the airflow has been reduced,

allowing compressors to more easily maintain system pressure. By fixing valve leaks,

the mill has also cut its air demand. 

Learning by Example

For Weirton Steel, the key to a proper compressed air system configuration was to understand the needs of its end-use

applications. The company also determined the appropriate level of treatment

and its air quality requirements. By taking

similar steps, other companies might

achieve similarly positive results. ●

Understanding Your Compressed Air System is Important to Managing it Well

Weirton Steel took stock of its Tin Mill compressed air systems

for improved performance and cost savings.

Turn to page 5 to learn about the Compressed Air

Challenge’sTM Advanced Compressed Air Management Training and the 8-Step Action Plan to

guide you to better system performance.
Energy Matters, May/June 2000 5

The Compressed Air ChallengeTM (CAC)

announces the newly developed Advanced

Management of Compressed Air Systems

training. The 2-day training builds on the

system approach to compressed air management presented in the Fundamentals of

Compressed Air Systems, the training

course previously introduced by CAC in

the spring of 1999. This approach is part of

the DOE’s Office of Industrial Technologies’ (OIT) diverse portfolio of assistance

with near-, medium-, and long-term strategies to increase the resource efficiency and

competitiveness of U.S. industry. 

Designed for facility engineers, maintenance supervisors, equipment distributors,

and engineering consultants, Advanced

Management of Compressed Air Systems is

an intensive training that provides up-todate, in-depth technical information on

troubleshooting and improving industrial

compressed air systems. 

Participants will learn to:

■ Collect and use data and tools to assess

system efficiency and the cost-effectiveness of compressed air systems.

■ Develop and use a system profile.

■ Implement a system maintenance program.

■ Address air quality, pressure requirements, and high-volume intermittent

applications.

■ Understand complex control system

strategies.

■ Align supply-side to demand-side operation.

■ Explain the value of heat recovery.

■ Successfully sell compressed air improvement projects to management.

The training is organized around a comprehensive 8-Step Action Plan for Improving Compressed Air System Performance.

By following this plan, training participants

will be able to operate their compressed

air systems at a lower cost and with greater

efficiency and reliability. CAC has qualified

10 instructors to teach the advanced training, all experts in compressed air systems

and all with extensive field experience and

strong training skills.

The first training sessions were in May

and early June. Other sessions will be

scheduled in several cities across the country. Be sure to check the calendar page in

each issue of Energy Matters or Energy

Matters Extra at www.oit.doe.gov/

bestpractices/explore_library/emextra for

dates and locations. And to find out more

about upcoming sessions, how to register

for the training, or the instructors, go to the

BestPractices Web site at www.oit.doe.

gov/bestpractices/compressed_air.

DOE is one of 15 cosponsors of CAC, a

voluntary collaboration of industrial end

users, manufacturers, distributors and their

associations, facility operating personnel

and their associations, consultants, state research and development agencies, energy

efficiency organizations, and utilities.

Learn more about the resources available

through the Compressed Air ChallengeTM

by calling the OIT Clearinghouse at (800)

862-2086. ●

Advanced Level Compressed Air Management Training Now Available

8-STEP ACTION PLAN FOR

IMPROVING COMPRESSED AIR SYSTEM PERFORMANCE

1. Develop a system block diagram.

2. Create a system pressure profile.

3. Address point-of-use issues:

• Determine actual air quality requirements and treat air appropriately.

• Investigate and reduce point-of-use pressure requirements.

• Investigate and address high-volume, intermittent applications.

• Take stock of what you have and challenge point-of-use requirements and appropriateness or inappropriateness of applications.

4. Develop a compressed air system maintenance program.

5. Analyze existing compressor(s) and system control, and implement an effective 

control strategy.

6. Align supply-side with demand-side operation.

7. Implement strategies to maintain system alignment.

8. Communicate to gain support of plant and production management:

• Target decision-makers.

• Develop a cost-benefit analysis that addresses life-cycle cost savings, benefits

to production (such as reliability and productivity), and return-on-investment.

• Report to management using an effective format.

• Use pre-measurement and post-measurement of kWh and production output

to document cost savings from actions taken with production’s support, and 

report to management.
6 Energy Matters, May/June 2000

Performance

Optimization Tips

Field Measurements in

Pumping Systems—

Practicalities and Pitfalls

By Don Casada, 

OIT BestPractices Program

This article is the 5th

in a series dealing

with practical considerations and pitfalls

of field measurements needed to understand pumping

systems.

In the March/April 2000 issue of Energy

Matters, we discussed the estimation of

flow rate from pump head-capacity curves.

In this issue, we’ll look at two other methods of estimating flow rate in systems with

no installed flow meters. 

Method 1: Level Change over Time

A frequently used method measures

change in the level of tanks or other storage devices over time. It can be used to

both determine flow rate in unmetered systems and to verify the accuracy of existing

flow meters.

Figure 1 shows a simple system that

uses a pump to transfer fluid from one tank

to another. By measuring the change in

level (∆L) in Tank 1 in the period from 

“Start of Test” to “End of Test,” the average

flow rate can be determined. 

In some industrial applications, a tank

that receives incoming flow is periodically

pumped down, with pump stop and start

being controlled by low- and high-level

switches. In such situations, the average

pump flow rate can be estimated as follows:

1. Calculate the volume between the highand low-level switches.

2. Measure the fill time (from pump stop to

pump start).

3. Determine the individual

cycle’s inflow rate during

the fill period by dividing

the volume (Step 1) by

time (Step 2).

4. Measure the time from

pump start to pump stop

(pump run time).

5. Estimate the average

pump flow rate by multiplying the inflow rate (Step

3) by the pump run time,

and add this volume* to

the volume between the

level switches.

Repeat the steps a few (or many) times,

as needed, to get the distribution of the inflow rate. Figure 2 shows an example of

many readings that represent a year’s observations. Figure 3 shows an alternative

representation, usually called a flow-duration diagram. These types of graphs are

critical to understanding system needs and

selecting the most suitable pumps. 

Method 2: Bernoulli-based Estimating

Venturi and orifice flow meters estimate

flow rate by measuring the difference in

pressure between two points with different

velocities. The Bernoulli equation below is

the general basis for this type of metering.

P1 + z1 +

V1

2

= P2 + z2 +

V2

2

γ 2g γ 2g

(P = pressure, V = velocity, z = elevation, 

γ = specific weight, g = gravitational constant, and subscripts 1 and 2 refer to two

streamline locations).

IS THERE A BETTER WAY?

The method Don describes above is

one way to determine the flow rate for

this configuration, but not necessarily

the only way. Do you have another idea

how it can be done? How would you

run the test to get the most accurate and

useful information?

Submit your idea to the “Think Tank”,

an Energy Matters Extra online discussion forum at www.oit.doe.gov/

bestpractices/explore_library/emextra.

Other readers will be interested in your

ideas, so we’ll print some of them in an

upcoming issue of Energy Matters.

Learn about two BestPractices demonstration

projects where this estimating method was used.

Go to Energy Matters Extra at www.oit.doe.gov/

bestpractices/explore_library/emextra for details

about the Town of Trumbull and the City of Milford, Connecticut. 

Figure 1. Fluid transfer between tanks.

P1

Tank 1

End of Test

Tank 2

∆L

L1

L2

P1

Tank 1

Start of Test

Tank 2

L1

L2

Figure 3. Flow-duration diagram for Figure 2 distribution.

Hours/year

1600

1200

1400

1000

800

600

400

0 2000 4000 6000 8000 10000

Flow rate, gpm

(continued on page 7) 

Figure 2. Example flow rate distribution curve.

Flow rate, gpm

100

80

60

40

20

0

400 600 800 1000 1200 1400 1600

Hours/year

F. P. O.
Energy Matters, May/June 2000 7

In some field applications, the Bernoulli

principle can be used, albeit in a cruder

sense, to estimate flow rate by observing

the pressure difference between two points

in a flow path where the velocity differs.

The most typical situation for this technique is when the suction lines of several

parallel pumps are connected to a common header or tank, and one pump is running and one or more others are not.

Photo 1 shows an example of an actual

installation where a Bernoulli-based estimate was made. Transparent plastic tubing

filled with dyed water connects to the suction of two parallel pumps. Only the one

on the right is running. The 16-inch suction lines for each of the two pumps connect to a common suction header (behind

the test engineer).

Photo 2 shows a close-up of the plastic

tubing. A simplified flow diagram for this

system section is shown in Figure 4. The

difference in column elevation between

the idle pump (left column) and the running pump (right column) is about 17

inches. In this case, the velocity in the idle

pump’s suction is zero. Thus, the difference in liquid level in the tubing is attributable to the running pump’s suction line

velocity. If we were to chug through the

numbers, the 17 inches would correspond

to a velocity of about 9.55 ft/sec, or about

5400 gpm. 

But notice a tee (obscured by the gate

valve body) followed by a full-open gate

valve through which the fluid must traverse. We must account for the frictional

losses induced by these components.

Using generic values from the Hydraulic

Institute (Reference 1), a total loss coefficient of 0.5 to 0.6 was estimated. Adjusted

for the head loss from these components,

the estimated flow rate was between 4300

and 4440 gpm. 

Two other methods of estimating flow

rate were used for comparison:

1. A transit time ultrasonic flow meter,

which indicated 4280 gpm.

2. The pump head-capacity curve, used in

conjunction with measurements of the

pump discharge and suction pressures,

suggested 4420 gpm.

The fact that three independent methods agreed within 4% provided strong confirmation. In my experience, one shouldn’t

count on field flow estimates to be more

accurate than around 5% (excluding volume-based determination discussed above,

which can be better than 1% under the

right conditions).

Two important points can be drawn

from this example:

1. Basic principles, applied with reasonable prudence, can provide at least

rough indication of flow rate.

2. It is always useful to estimate flow rate

by independent means. ●

E-mail Don Casada with questions or comments at: doncasada@icx.net.

References

1. Hydraulic Institute Engineering Data Book, 2nd Edition, 1990.

*A variation uses the average of the inflow rate before

and after the pump run period.

Photo 1 (above left). General layout of 

pump installation.

Photo 2. (above right) Plastic tubing 

close-up. 

Figure 4. Simplified flow diagram for 

Photo 1 installation; L1 and L2 indicate 

locations for plastic tubing level indicators

shown in Photo 2.

L1 L2

continued from page 6
8 Energy Matters, May/June 2000

Through the Office of Industrial Technologies (OIT) Clearinghouse, you can access

the full portfolio of OIT resources to help

make your industry more energy efficient,

productive, and competitive. The OIT

Clearinghouse can help you find hundreds

of resources such as publications and software, or information about working with

OIT and cost-sharing opportunities.

You should also think of the

Clearinghouse as a resource

that specializes in providing

technical advice to customers on topics such as

motor, steam, and compressed

air systems. The Clearinghouse

also has access to industry experts

around the country. Clearinghouse engineers and technical staff expertly answer a

wide range of industrial efficiency questions, 11 hours a day, Monday-Friday.

Energy Matters introduces “Ask the

Clearinghouse” to highlight some key

questions from industrial customers on energy systems. Here is what one customer

recently wanted to know, and what was

recommended after consulting with CAC

technical experts. It might be helpful advice for your operation, too. 

Q: We plan to purchase a new 75-hp

rotary screw compressor with inlet

valve modulation followed by unloading

power controls. “Manufacturer A” claims

its unit will deliver 20 cfm more than the

unit proposed by its competitor. Is this the

most efficient compressor? 

A: A compressor with a full-load capacity of 20 cfm more than another having the same power consumption is more

efficient at full load than the other. However, a compressor with modulation followed by unloading controls uses a

throttle, turn, or poppet valve to modulate

airflow to match plant air requirements.

The compressor unloads when the

plant air requirements fall below

the unload point, usually

about 40% of full capacity.

Most rotary screw compressors unload by venting or

“bleeding down” the lubricant

sump/separator pressure, with

the residual pressure used to provide for oil circulation. Simultaneously, a

valve at the intake of the compressor closes

to prevent air from being drawn into the intake. Some compressor models are

equipped with low-unloaded power controls or oil circulation pumps, so they can

blow down closer to atmospheric pressure. 

To properly evaluate the efficiency of

compressors from two manufacturers, obtain performance values taken in accordance with a standardized testing protocol.

To compare “apples versus apples,” obtain

the specific package power for each compressor at rated conditions (kW/100 acfm),

the capacity control method, the percent of

full flow before unloading, the unloaded

power in kW, and the sump/separator

blowdown time. 

Compressor power requirements, when

unloaded, vary significantly because of differences in blowdown time and the residual sump pressure. Compressor A might

use 30% of full load power when unloaded, while Compressor B only requires

20%. However, Compressor A might modulate to 40% of full airflow before unloading, while Compressor B unloads at about

60%. The importance of each performance

characteristic depends on your system requirements and plant airflow profile.

Adequate receiver capacity is required

to obtain the benefits of load/unload capacity control. To determine the most efficient compressor for your application, you

must first determine your air flow requirements, then estimate the percentage of operating time that each compressor would

run fully loaded, modulated, and unloaded. Annual energy consumption (kWh)

is calculated by multiplying the number of

hours in each operating mode times the

appropriate power. 

Compressed Air ChallengeTM training

materials include graphs of the different

control strategies, and the training sessions

are recommended for a better understanding of compressors and the systems in

which they operate. For more about Compressed Air ChallengeTM materials and

training dates go to www.oit.doe.gov/

bestpractices/compressed_air. ●

Call the OIT Clearinghouse at (800) 

862-2086, or go to www.oit.doe.gov/

clearinghouse for additional information. 

Ask the Clearinghouse

Now Featuring: Pump System 

Assessment Tool (PSAT)

BestPractices keeps knowledge at your fingertips with its collection of software and

database tools. One of these tools, the Pump

System Assessment Tool (PSAT), helps industrial users assess the efficiency of pumping

system operations. PSAT software uses 

achievable pump performance data from the

Hydraulic Institute standards and motor performance data from the MotorMaster+ database to calculate potential energy and

associated cost savings. Using PSAT, industrial users can measure flow rate, head,

speed, power, and duration to find ways to

quantify savings opportunities. This downloadable software is available online at

www.oit.doe.gov/bestpractices/software_

databases/software.shtml. ●

Find out about upcoming PSAT training

dates on the Energy Matters Extra calendar at

www.oit.doe.gov/bestpractices/explore_

library/emextra. ●

BestPractices Tools—Knowledge at Your Fingertips 

NEW
Energy Matters, May/June 2000 9

What was true 50 years ago about steam

system efficiency still applies today—many

economic opportunities exist to improve

industrial steam systems. The idea seems

new again, though, as industry becomes

more aware of opportunities and techniques to improve steam systems.

OIT’s Steam BestPractices aims to

renew the concept by helping steam users

adopt a systems approach to managing

steam. Fred Hart, OIT’s Steam BestPractices Manager, explains the importance of

a systems approach: “Significant savings

can be obtained from ‘low-hanging fruit’—

boiler tune-ups, traps, leaks, and insulation.” But, Hart says, “Looking at the steam

system across generation, distribution, and

recovery will yield savings and increased

productivity, reliability, and safety.”

One important way OIT’s program

helps steam users move toward system efficiency and improved productivity is by

identifying and making available many

tools and resources they need. At the recent Industrial Energy Technology Conference (IETC), in Houston, Texas, the Steam

BestPractices team described an extensive

group of steam tools and resources brought

together through the program. The presentation, “Steam BestPractices Resources and

Tools: ‘Old’ News Is ‘New’ News,” emphasized the benefits of having information

from many sources available in one place.

The tools and resources are easily accessible and usable—that’s something new. 

“There have been lots of discussions

about steam over the years,” explains Anthony Wright of the Steam BestPractices

program, who coauthored the presentation. “A lot of information is available,

from many sources, on opportunities to improve steam systems. The idea of one-stop

shopping makes it less overwhelming,”

Wright adds.

What is Available?

Among the resources Steam BestPractices has compiled are: 

■ Technical tools and information, including technical references; steam tips

that provide a description and specific

actions for implementing an improvement; insulation thickness software; and

an energy efficiency handbook.

■ Case studies that provide detailed descriptions that document steam improvement projects, their energy-savings and

cost benefits, and demonstrate opportunities for improving steam systems.

■ Training information that describes 80

steam training courses provided by 31

organizations throughout the United

States.

■ Awareness resources, such as the BestPractices Web site; the OIT Information

Clearinghouse; the Steaming Ahead

newsletter; Energy Matters newsletter;

and Steam Awareness workshops that

help steam users and service providers

stay current on Steam BestPractices 

efforts. 

How to Access Resources

All of the steam systems tools and 

resources brought together by Steam BestPractices can be found on the BestPractices Web site at www.oit.doe.gov/

bestpractices/steam. Steam users should

tap in to these resources as part of a new

approach—a systems approach—to improve steam efficiency and enhance productivity in their plants. 

You can find the OIT presentation

“Steam BestPractices Resources and Tools:

‘Old’ News Is ‘New’ News” on Energy 

Matters Extra at www.oit.doe.gov/

bestpractices/explore_library/emextra. ●

Uncover “New” Tools and Resources for Improving Steam Systems

WHAT OTHERS ARE DOING

At the April 2000 IETC, some

companies and service providers

described what they are doing to

help customers achieve steam efficiency and savings. For example, Nalco Chemical Company

offers its customers a 7-step

method for implementing boiler

best practices to achieve plantwide benefits. One customer expects to reap benefits of more

than $1.3 million in operational

savings and improved profits. In

another example, Enbridge Consumers Gas, a natural gas distributor, began a program to identify

steam efficiency and fuel savings

opportunities for its steam customers. The program has identified $4.3 million in savings from

audits of 30 steam plants. 

These two steam efficiency presentations from IETC are available

on Energy Matters Extra at www.

oit.doe.gov/bestpractices/

explore_library/emextra. Find

out how these companies have

helped their industrial customers

improve steam systems. A similar

approach might be the answer for

your company and service

provider. 

“LOOKING AT THE

STEAM SYSTEM ACROSS

GENERATION, DISTRIBUTION,

AND RECOVERY WILL

YIELD SAVINGS AND INCREASED

PRODUCTIVITY, RELIABILITY, 

AND SAFETY.”
10 Energy Matters, May/June 2000

needed to take samples. Predicting

slopping and then taking preventive

measures increases yield and safety.

Many of the demonstrated technologies

are too new yet to quantify savings, although savings will be documented as part

of the projects. Still, U.S. Steel is already

achieving increases in productivity and decreases in the amount of maintenance required in their processes. “The showcase

gives us the opportunity to apply continuous improvements to our steelmaking

processes,” says Bill Federoff, U.S. Steel’s

Power, Steel, and Environmental Facilities

Supervisor. “Even though some of the technologies may still be experimental, once

they’re installed at the plant for the showcase, we get to keep the equipment and

the technologies and their resulting improvements permanently.” 

Strengthening Profits at Weirton Steel

Howard Snyder, Weirton’s Technical Director of Operations, is similarly positive

about his company’s experience with the

showcase and with the new technologies

that have been implemented at Weirton’s

facilities. “The technologies that have already been installed have resulted in energy savings and productivity increases,”

says Snyder. 

In 1997 and 1998, with DOE’s assistance, Weirton upgraded its control systems to replace antiquated equipment with

modern, computer-controlled systems that 

are monitored from a central location. The

successful implementation of this project

improved both the productivity and efficiency of the plant’s steam and electrical

generating facilities. What formerly required 110 operators to manually monitor

and adjust now requires just two computer

operators. The company has saved more

than $17 million annually from reductions

in purchased fuels and maintenance costs,

resulting in a project payback of less than

one year.

With the success of this project, the staff

at Weirton has taken on several new projects, many of which were highlighted 

during the showcase. These unique technologies include:

■ A galvanneal temperature measure system is a fluorescence-based system that

allows Weirton to achieve more accurate and repeatable strip temperature

measurements and better real-time adjustments, resulting in improved quality.

■ Nickel aluminide burner tubes and furnace rolls can continuously withstand

the 1800°F temperatures inside the annealing furnaces, maintain strength, and

provide increased life. The new rolls

and tubes provide greater heating efficiency and safety, and also prevent the

loss of millions of Btu per hour.

■ Compressed air improvements consisted of replacing six aging compressors at Weirton’s Tin Mill with five

350-hp rotary screw compressors, and

sequencing them to respond more appropriately to system demands. A dedicated 100-hp, lubricant-free compressor

was installed to purify the air used in

the coating process. These system improvements are expected to save about

$136,000 annually in energy and maintenance costs, and have dramatically

improved product quality. (See page 4

for more.) 

With OIT’s help, Weirton also recently

discovered that insulating steam pipes could

result in significant energy savings. After applying 3E Plus Insulation Thickness software,

Weirton realized that for every 100 feet of

piping insulated, energy savings could be

$19,000 each year. In addition, a review by

OIT’s BestPractices staff confirmed that, with

proper level control, the boiler at the basic

oxygen furnace could be operated with a

single pump, dropping energy consumption

by about 2/3 of the original level. Snyder

and his team plan to continue implementing

these and other energy efficiency technologies at Weirton Steel’s plants and have several projects in progress or planned for the

next few months.

“Even the simple improvements have

helped increase the awareness at Weirton

about how energy costs affect the cost of a

ton of steel,” explains Snyder. “My business plan targets a certain cost per ton of

steel, and energy and process efficiency

improvements like these help reduce those

costs, improve our steel quality, and increase our profit margin.”

Forging Partnerships for the Future

Both U.S. Steel Group and Weirton

Steel Corporation have been working with

OIT for several years, with the help of

AISI. Based on their successes to date,

both plan to continue those partnerships

for the foreseeable future. The positive relationship with OIT that both companies

have experienced is summed up nicely by

Snyder. “The expertise that OIT brings to

the table is invaluable. They help us pinpoint projects with a short payback that

we might otherwise overlook. It’s a good

partnership.” ●

Download 3E Plus software used by Weirton at www.oit.doe.gov/bestpractices/

software_databases/software.shtml.

Celebrating the New Steel

continued from page 1

Plant improvements have saved Weirton Steel more than

$17 million annually in fuel and maintenance costs.
Energy Matters, May/June 2000 11

Letters to the Editor 

Energy Matters welcomes

your typewritten letters and

e-mails. Please include your

full name, address, organization, and

phone number, and limit comments to 200

words. Address correspondence to:

Michelle Mallory, Letters to the Editor

NREL, MS 1713

1617 Cole Blvd.

Golden, CO 80401

E-mail: michelle_sosa-mallory@nrel.gov

We publish letters of interest to our readers

on related topics, comments, or criticisms/corrections of a technical nature.

Preference is given to letters relating to articles that appeared in the previous two issues. Letters may be edited for clarity,

length, and style. 

Energy Matters columnist Don Casada received this inquiry from one of our readers: 

I am trying to get a better understanding

of what systems use control valves and how

the control valve system works, i.e., for flow

control or otherwise. Are there any good references that explain the purpose of flow

control valves and the general design concepts around using them for flow control?

Craig Forsyth, P.Eng.

Senior Industrial Systems Engineer

Business Engineering Services

Manitoba Hydro

Winnipeg, Manitoba, Canada

We’ve summarized Don’s reply to 

Mr. Forsyth:

The ISA Handbook of Control Valves,

edited by J.W. Hutchison has good coverage of control valve types and issues. A

more recent book, entitled Valve Handbook, by Philip W. Skousen, addresses a

broader spectrum of valves, including

check, manual, and relief valves. But first,

I’d encourage you to see what some of the

valve vendors have available, particularly

if their stuff is free! 

A caution: valves that have good control

characteristics are usually high-loss valves,

even when full open. Where the system is

operating most or all of the time and the

flow rate (and/or head) varies considerably,

consider adjustable speed drives for flow

control. When making the switch, also consider replacing the existing control valve

with a lower loss valve (e.g., replace the

globe with a butterfly). Read more about

control valve replacement in a previous

Performance Optimization Tips article on

Energy Matters Extra: www.oit.doe.gov/

bestpractices/explore_library/emextra/

casada_july98.shtml.

Mac Smith, guest columnist in the January/February 2000 issue, received several

positive comments about his article on Reliability Centered Maintenance. Here are

a few of them: 

Your explanations on RCM are simple

and to the point! The concepts are powerful and timely as ever.

Terrence O’Hanlon

Reliabilityweb.com

Blair, NE

Great article. Hope to start implementing such a program.

Phillip Koundakjian, Treatment Manager

Des Moines Wastewater Reclamation 

Facility

Des Moines, IA

(Editor’s note: Mr. Koundakjian expresses his own opinion and not any present or future policy of his employer.)

Your article was well written and right

on target. The RCM approach not only

makes sense in the reliability/maintenance

domain, but is in many ways analogous to

the systems approach we recommend in

looking for energy savings opportunities.

Don Casada

OIT Best Practices Program

Knoxville, TN

With a goal of plant-wide improvements in

costs and energy efficiency, the Office of Industrial Technologies (OIT) has rolled out the

BestPractices initiative. This new approach

provides integrated delivery of energy-saving

products, services, and technologies to help

industry increase efficiency, reduce waste,

and boost productivity.

All the resources, tools, and expertise

that previously made up OIT’s Challenge

programs—Motor Challenge, Steam Challenge, Compressed Air Challenge, and the

Industrial Assessment Centers—are now

part of BestPractices. OIT has brought together a BestPractices team to help plants

take a look at energy-consuming components as part of a total system where significant savings can be achieved and emerging

technologies best applied. The team also includes IOF industry representatives who

provide specific knowledge of energy savings opportunities and emerging technology

needs valued by their industries. Working

with BestPractices, industries can tap into

technical assistance and explore technology

solutions to improve industrial processes.

One way to tap in is through the new

BestPractices Web site, which encompasses the program’s array of resources.

Whether you want to assess your plant, are

interested learning from other plants’ successes, or you want to explore an extensive

library of technical tools and 

publications, begin at www.oit.doe.gov/

bestpractices.

Another way to find out about plant efficiency opportunities is through Energy

Matters. The newsletter will focus on plantwide benefits industry can gain from improvements to energy consuming systems.

In addition, future issues will introduce

OIT-supported emerging technologies that

could work in a plant like yours. To reflect

the new approach, we’ve launched two

new features—Ask the Clearinghouse and

BestPractices Tools (see page 8)—that highlight some BestPractices resources. We’ve

also updated the newsletter’s look. 

BestPractices is OIT’s new and improved way of delivering products and services to industrial customers. It’s part of an

ongoing effort to assist industry in applying

energy smart technology for today—and

the future. ●

BestPractices Debuts

Back issues of Energy Matters are on Energy 

Matters Extra at www.oit.doe.gov/bestpractices/

explore_library/emextra.
INFORMATION

CLEARINGHOUSE

Do you have questions about 

using energy-efficient process

and utility systems in your industrial facility? Call the OIT Information Clearinghouse for answers, Monday through

Friday 9:00 a.m. to 8:00 p.m. (EST).

Fax: (360) 586-8303, or access our 

homepage at www.oit.doe.gov/

clearinghouse.

HOTLINE: (800) 862-2086

DOE Regional Support Office 

Representatives

■ Tim Eastling, Atlanta, GA, 

(404) 347-7141

■ Scott Hutchins, Boston, MA, 

(617) 565-9765

■ Julie Pollitt, Chicago, IL, 

(312) 886-8579

■ Gibson Asuquo, Denver, CO, 

(303) 275-4841

■ Julia Oliver, Seattle, WA, 

(510) 637-1952

■ Maryanne Daniel, Philadelphia, PA, 

(215) 656-6964

This document was produced for the Office 

of Energy Efficiency and Renewable Energy at

the U.S. Department of Energy (DOE) by the National Renewable Energy Laboratory, a DOE national laboratory.

DOE/GO-102000-1071 • May/June 2000

T OF ENERGY

DEPARTMEN

U

E

NITED STAT S OFA ERICA

M

Printed with a renewable-source ink on paper

containing at least 50% wastepaper, including

20% postconsumer waste

CAPTURING THE VALUE OF STEAM EFFICIENCY

■ August 25 in Atlanta, GA

■ September 15 in Charlotte, NC 

Call the OIT Clearinghouse at (800) 862-2086 for information.

FUNDAMENTALS OF COMPRESSED AIR SYSTEMS

■ August 17, Morristown, NJ, GPU Headquarters

Call Karen Paine of GPU (973) 401-8544 for registration information.

■ September 7 in Yakima, WA

■ September 12 in Bend, OR

Call the OIT Clearinghouse at (800) 862-2086 for information.

■ September 14 in Eatontown, NJ, Eatontown Sheraton

Call Karen Paine of GPU (973) 401-8544 for registration information.

■ September 27 in Boise, ID 

Call the OIT Clearinghouse at (800) 862-2086 for information.

PUMP SYSTEMS/PUMPING SYSTEM ASSESSMENT TOOL WORKSHOP (PSAT)

■ September 11, Louisville, KY, Pump Users Expo 

Call Vestal Tutterow at (202) 484-0884, ext. 108 for information.

National Renewable Energy Laboratory

1617 Cole Boulevard

Golden, CO 80401-3393

First Class

U.S. Postage

PAID

Permit No. 258

Golden, Colorado

BestPractices

The Office of Industrial Technologies (OIT)

BestPractices initiative and its Energy Matters newsletter introduces industrial end

users to emerging technologies and wellproven, cost-saving opportunities in motor,

steam, compressed air, and other plantwide systems. For overview information

and to keep current on what is happening

office wide, check out the newsletter—The

OIT Times—at www.oit.doe.gov/oit-times.

Coming Events

To keep up-to-date on OIT training and other events, check the calendar regularly on

Energy Matters Extra at www.oit.doe.gov/bestpractices/explore_library/emextra.