T OF ENERGY

DEPARTMEN

U

E

NIT ED STAT S OF A ERICA

M

An Office of Industrial Technologies 

Bimonthly Publication Focusing on

Energy Efficiency Opportunities for Today

www.oit.doe.gov

www.motor.doe.gov

Formerly Turning Point • July 1999

Issue Focus: 

Selling an Energy-Efficient 

Project to Management 

IN THIS ISSUE

Malden Mills Demonstrates CHP System . . . . 1

Two New Steam Resources Online . . . . . . . . . 1

Inspect Steam Traps for Efficient System . . . 2

Guest Column: Making a More Compelling

Energy Efficiency Case to Management 

by Quantifying Non-Energy Benefits. . . . . . . 3

Hard Sell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Root Cause Failure Analysis on 

AC Induction Motors . . . . . . . . . . . . . . . . . . . . 5

Performance Optimization Tips . . . . . . . . . . . 6

Letters to the Editor. . . . . . . . . . . . . . . . . . . . . 7

Water/Wastewater Forum . . . . . . . . . . . . . . . . 7

Coming Events. . . . . . . . . . . . . . . . . . . . . . . . . 8

Two New Steam Resources Online

Take a look at these new online resources

for steam system tools and information.

■ A Technical Standards and References

List. This list, compiled and reviewed

by industry experts for the Steam Challenge, contains 80 titles and summaries

of handbooks, specifications and guidelines, articles, and videos. Check out

the list at www.oit.doe.gov/steam/.

■ Steam Tip Sheets. These four information sheets provide easy-to-apply

actions your plant can take to improve

steam efficiency, and they highlight

potential cost savings. Find the tip

sheets at www.oit.doe.gov, or call 

(800) 862-2086 beginning July 30 to

order hard copies.

Last New Year’s Eve, Malden Mills Industries, in Lawrence, Massachusetts, celebrated the start of its long-awaited Combined Heat and Power (CHP) system.

Malden had been trying to self-generate

electricity and steam since the late 1980s. 

When Malden Mills, a manufacturer of

the innovative PolartecTM fabric, first presented the Massachusetts environmental

department with a plan for a CHP system

in 1992, the state rejected the company’s

request. Even though that system would

cut Malden’s emissions in half by replacing

1920s era boilers, the state required that

the company use an expensive ammoniabased, exhaust-gas, after-treatment technology to meet its new NOx emissions

standards. Malden argued that the state’s

standards ignored emissions reductions

from boiler replacement and higher efficiency on-site electric generation. Malden

also was concerned about the safety risk

ammonia posed to workers.

After a famous 1995 fire that destroyed

three buildings, Malden’s CEO pledged to

keep all employees, and President Clinton

pledged assistance to the company. This

led to a partnership between Malden and

the Department of Energy’s (DOE’s)

Advanced Turbine Systems (ATS) Program.

In 1997, Massachusetts approved a technology demonstration permit for an ultralow-NOx CHP system, developed through

the ATS program. 

The first phase of the partnership was

completed with the December startup of

two 4.3 MW turbines made by ATS partner,

Solar Turbines. Later this year, the company will retrofit the two turbines with a

ceramic combustor liner to reduce NOx by

another 40%. The permit requires a 2-year

demonstration period to prove that the

new liner is durable and meets the state’s

emissions requirements.

If successful, Malden could begin the

third phase by installing the first commercial ATS engine, Solar’s Mercury, a 4.6 MW

CHP system with a 40% simple-cycle electric efficiency and 85% system efficiency.

This system would virtually eliminate SO2

emissions, reduce NOx emissions by 75%,

and cut CO2 emissions by 25%, compared

to the pre-fire system. 

DOE teamed with Malden Mills to

demonstrate its ATS technology; however

the project also demonstrates the barriers

companies must overcome to use CHP.

With the new CHP Challenge Program,

DOE will aggressively promote the energy,

environmental, and economic benefits of

CHP to federal, state, and local officials.

For more information, visit the CHP Challenge Web site at www.oit.doe.gov/

chpchallenge/.

Malden Mills will install the Mercury turbine in

the next phase of its CHP demonstration project.

Malden Mills Demonstrates CHP System
2 Energy Matters, July 1999

ENERGY MATTERS

(formerlyTurning Point) 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

Floyd Barwig, Iowa Energy 

Center, representing Compressed

Air Challenge

Rob Boteler, representing

National Electrical Manufacturers

Association

Lynda Butek, representing 

Electrical Apparatus Service 

Association

Don Casada, Oak Ridge National

Laboratory

Keith Davidson, Onsite Sycom

Energy

Glenn Hahn, Spirax Sarco

Fred Hart, U.S. DOE, Steam 

Challenge

Chris Hunter, Johnson & Johnson

Roy Jones, representing

Compressed Air and Gas Institute

John Machelor, Macro 

International

Rick Payton, Rockwell 

Automation/Reliance Electric

Bill Stafford, Technical 

Association of the Pulp and Paper

Industry

Howard Snyder, Weirton Steel

Chuck Whelan, DuPont

■

COMMENTS? 

Contact: 

Julia Oliver, DOE, at 

(510) 637-1952, or e-mail

julia.oliver@oak.doe.gov

Erika Ericksen, 

Energy Matters Editor, at 

(303) 275-3914, or e-mail 

erika_ericksen@nrel.gov

1617 Cole Blvd., MS 1713

Golden, CO 80401

By Bruce Gorelick, Enercheck Systems,

Charlotte, NC, and Alan Bandes, UE 

Systems, Inc., Elmsford, NY

When it comes to steam traps, plants often

ignore them. Complacency about them

costs steam users more than they realize.

Losses from wasted energy, damaged

equipment, misused personnel hours, or

poor product quality can be in the hundreds of thousands of dollars.

Fortunately, much of these potential

losses can be averted by a vigilant steam

management system that includes steam

trap surveys. Once a maintenance engineer can see what is going on, he or she

can take corrective actions, which can add

substantially to a company’s bottom line as

“found money.” 

When a Trap Fails

Most traps fail in the open mode. When

this occurs, a boiler works harder to produce energy. This can create high backpressure to the condensate system, which

inhibits discharge capacities of some traps

and affects steam quality.

A closed trap produces condensate

backup in the steam space. The equipment

will not produce the intended heat. 

Excluding design problems, two of the

most common causes of trap failure are

oversizing and dirt. Oversizing causes

traps to work too hard. In some cases this

can result in blowing of live steam. Dirt is

always created in a steam system. Excessive buildup causes plugging or prevents a

valve from closing.

Trap Failure Affects Equipment

When blocked or plugged steam traps

cause a backup of condensate in a steam

main, the condensate is carried with the

steam. It lowers steam quality and increases

the potential for waterhammer. Energy is

wasted and equipment can be destroyed.

Condensate in a system causes valves to

become wire-drawn and unable to hold temperatures as required. Little beads of water

in a steam line can eventually cut any small

orifices the steam normally passes through.

Wire-drawing eventually cuts enough of

the metal in a valve seat to prevent adequate closure, producing system leakage.

Testing Methods

Before testing a steam trap, be familiar

with its function, review typical types of

traps, and know various pressures within

the system. This helps avoid misdiagnosis

and allows proper interpretation of trap

conditions. 

The three categories of online trap

inspection are visual, thermal, and

acoustic. Visual inspection depends on a

release valve situated downstream of certain traps. Thermal inspection relies on

upstream/downstream temperature variations in a trap. Acoustic techniques require

an inspector to listen to and detect steam

trap operations and malfunction. 

Recordkeeping

It is one thing to just inspect traps,

another to be able to determine costs, efficiencies, inefficiencies, and trouble spots.

Traps should be tagged and mapped to

assure that all traps are maintained.

There are many ways to systematize

data and to keep records. Rather than

“reinventing the wheel,” take advantage of

commercially available software packages

that can help successfully implement a

good steam management system.

In-House Survey Ideal

Ideally, trained in-house inspectors will

conduct surveys and routinely inspect steam

traps. Professional services can also conduct

surveys and issue reports without involving

in-house staff. Or, an expert can be brought

in to set up a program and train personnel. 

In summary, any plant with a steam trap

system should set up a comprehensive survey program. Whether it has 50 traps or

5,000 traps, substantial savings can be

generated in energy, equipment, personnel

hours, and product by keeping on top of

the system.

For more information contact Bruce 

Gorelick at (704) 841-9550 or Alan Bandes

at (800) 223-1325. 

Inspect Steam Traps for Efficient System

Testing traps can include acoustic techniques. 
Energy Matters, July 1999 3

Guest Column

Making a More Compelling

Energy Efficiency Case to

Management by Quantifying

Non-Energy Benefits

By Miriam Pye, American Council for an

Energy-Efficient Economy and Aimee 

McKane, Motor Challenge Program,

Lawrence Berkeley National Laboratory

Making a compelling case to management

begins with a profit motive. Energy efficiency is generally not a primary driver in

industrial decision making. Your company’s chief executive officer (CEO) and

chief financial officer (CFO) are probably

much more interested in approaches in

which the impact on profit is more apparent, such as productivity enhancements.

However, experience shows that an energy

efficiency project’s non-energy benefits

often exceed the value of energy savings.

Therefore, your case to management

should help them view energy savings

more correctly, as part of the total benefits,

rather than the focus of the results.

Quantifying the total benefits of energy

efficiency projects can help your company

understand the financial opportunities of

investments in energy-efficient technologies.

Whether their perspective is that energy efficiency is a byproduct of productivity gains,

or that productivity gains are a byproduct

of energy efficiency, generally productivity

gains motivate management to take action. 

Quantify All Costs and Benefits 

Regardless of whether energy efficiency

is the driver or the byproduct of a project,

management must understand all costs and

benefits associated with an investment in

efficiency to make decisions that enhance

shareholder value. Start by quantifying projected benefits beyond energy savings,

which might include: 

■ Increased productivity

■ Reduced costs of environmental 

compliance

■ Reduced production costs 

■ Reduced waste disposal costs 

■ Improved product quality 

■ Improved capacity utilization 

■ Improved reliability

■ Improved worker safety

While estimating energy and nonenergy benefits, it is also critical to estimate all incremental costs, including

indirect costs. To gain credibility with managers, quantify both the upside and the

downside potential of proposed projects.

For example, many projects require

process line shutdown during implementation, causing production losses. 

Use Financial Analyses

The financial analysis of an efficiency

project is the basis for making the investment decision. This can range in sophistication from a simple payback (investment/

annual net savings) or rate of return (average annual net savings/total investment) to

more accurate calculations, such as net

present value (NPV) or internal rate of

return (IRR), which take into account the

time value of money. Regardless of which

calculation is used, the most important part

of a financial analysis is the estimation of

total incremental project costs and benefits.

As the positive correlation between

energy efficiency and productivity becomes

more widely understood, businesses will be

more motivated to invest in (1) energy-efficient technologies that have productivity 

benefits and (2) productivity technologies

that have energy efficiency benefits. 

Cite Examples 

Business case studies have been developed with financial analyses for several 

DOE Motor Challenge Showcase Demonstration projects. The case summarized

below shows how one industry has implemented a project with significant benefits

beyond energy savings. Such an example

could be presented to your CEO or CFO to

fully explain a project’s potential financial

ramifications. 

When you, as an efficiency advocate in

the company, understand the business

decision-making perspective and can communicate with management using financial

and strategic arguments, your case for

energy efficiency is greatly strengthened.

Making business sense of energy efficiency

reduces its perceived risk to management,

which may, in turn, reduce the hurdle rate

(or payback period) that a company 

(continued on page 7)

A Business Case Study 

Background

In 1995, Alcoa (then Alumax), an aluminum

refiner, decided to improve the energy efficiency of its four pot line dust collection systems at its Mt. Holly, South Carolina, plant.

The company considered two options: one

to install variable frequency drive (VFD) controls on the four-fan system; and one to modify the existing system with a three-fan,

variable inlet valve (VIV) controlled system. 

Decision

Based on a review of the options and a

recommendation from Motor Challenge, the

company proceeded with the three-fan VIV

system. Compared to the VFD proposal, it

required no capital investment, was the most

efficient, and would reduce system energy

costs by $103,700 per year. The project

involved opening the VIVs wider to reduce

pressure loss. This increased fan efficiency

and allowed for one fan in each of the four

systems to be shut down. The system operated

in this configuration for 21⁄2 years, until the

fourth fan was required to accommodate a

7%-8% increase in production. 

Benefits

As a result of this project, Alcoa achieved

several benefits: 

■ Energy savings resulted from shutting

down one fan in each of four systems.

■ Potential to increase aluminum production by more than 500,000 pounds/year

by redirecting electricity Alcoa committed

to purchasing from its utility. Energy savings from operation of the dust collection

system could be used for production.

■ Emissions reductions of 1%-2% resulted

from lower flow rates.

■ Life of the dust collection bags extended

by at least 10% also resulted from lower

flow rates.

■ Potential to save hours of downtime—the

fourth fan can be used as a spare if needed. 

■ Modifications can be easily replicated at

other Alcoa sites.

Total Value Added

Initial Costs (consulting $5,000

fees):

Potential Incremental $375,000

Annual Revenue

Annual Profit Potential:

Estimated profit on $75,000 (assumes 20% 

incremental revenue marginal profit)

Energy savings $103,700 (3,346 MWh 

saved x $0.031/kWh)

Reduction in Dust $123,500 (10% x 16,896

Collection Bags bags x $73.08/bag)

Labor $10,000 (est’d 10% time 

savings x $48/hr (fully 

loaded) x 2,080 hrs/yr)

Total savings $312,200/yr

ALUMINUM SMELTER IMPROVES DUST COLLECTION SYSTEMS
4 Energy Matters, July 1999

Hard Sell

Reprinted from Building Operating Management magazine, November 1997 issue,

with permission. 

The CFO is often an energy upgrade’s

worst enemy. Here’s a four-step plan to

change that.

Step 1: Understand Your CFO

If you are ready to take on your CFO, it

is vital that you understand their way of

thinking and that perspective on corporate

life. You must put on your sales hat and promote your project in the best possible light,

while at the same time viewing the project

from the same perspective as your CFO.

A key trait to first understand is that a

person doesn’t become a CFO for taking

large risks. For this type of personality, it is

best to present, in a detailed and rational

format, the many benefits of implementing

a project. You should, therefore, attempt to

answer the following key questions that a

CFO typically asks when reviewing a

request for funds for a project:

■ What is the timeline of cash flows invested in and returned from the project?

■ What are the payback and return on

investment of the project?

■ How certain are the total costs, projected

revenues, and projected expenses?

■ What could go wrong, and what are the

possible solutions and mitigating factors?

■ What are the non-financial/non-quantifiable impacts of this project on the

organization?

■ How does the project compare to other

projects using the parameters just

described?

■ What are the ramifications (short- and

long-term) of various funding options

(e.g., cash, debt, pay from performance/service contract, etc.)?

Make every attempt to answer these

questions systematically. If information is

not readily available in-house, and you are

working with an energy services company

(ESCO), enlist the support of your ESCO. 

Step 2: Understand Your Company’s 

Budgeting Process

As part of your preparation, you should

learn as much as you can about your company’s budgeting process. If budgeting and

financial issues are a challenge for you,

there are very useful reference books and

courses available from your bookstore or

the American Management Association

with titles like “Finance

for the Non-Financial

Manager.” 

Don’t hesitate to ask as

many questions as it takes

for you to understand the

philosophy and reasoning

behind the budgeting

process. An annual budget is, in many ways, the

CFO’s bible. While a CFO

is not motivated to allocate additional capital for

non-essential projects,

every budget has some room to replace

one project with another. Your goal, therefore, is to make your project stand out from

the other options in order to get the CFO’s

attention. One option is to develop alternatives for funding the project without affecting the annual budget. 

Step 3: Understand Your Project’s 

Financing Options

Researching the current financing marketplace may enable you to bring to your

CFO some innovative options for your project’s financing. This is another area where

your ESCO may be able to provide information and guidance.

Keep in mind that each option has pros

and cons depending on your company’s

financial philosophy. Some companies do

not like debt while others can’t have enough

of it. Some firms take educated risks while

others prefer to pay upon performance.

The more options on the table, the higher

the likelihood of structuring a solution.

Let’s assume that your CFO likes the

concept of your project but is stalling on

deciding how to pay for it. Plan a threepronged attack of cash, loan, and project

finance. If you do an outstanding job of

reaffirming the benefits of your project, it is

possible that your CFO will give in, exercise the simplest option and pay for it from

internal funds. 

When a CFO strongly believes that cash

is better applied to other corporate uses

than energy projects, one alternative is to

borrow from a bank or leasing company.

You should be knowledgeable regarding

your company’s average cost of debt. The

use of debt to finance a project, as with the

use of internal funds, has a major financial

impact on the budgeting process. Also,

many companies have limitations on how

much debt they can take on.

If a lease option is evaluated, there are

two main types of leases to consider: operating and capital. A capital lease is considered

a debt by your company while an operating lease can be structured as “off-balance

sheet.” This means that the lease does not

appear on your company’s financial statements (balance sheet) as a debt obligation. 

The hurdles are fewer and lower if the

method for paying for a project can be

shifted from a debt obligation to an operating expense (similar to a utility bill or a service contract). Project financing (or

performance contracting) often achieves this

objective and is a structure that is fast gaining popularity throughout the United States. 

Step 4: Put It in Writing

Once you have gathered all of the information necessary to present your energy

project to your CFO, the main thrust of

your attack should be a cover memorandum with supporting documentation organized in an easily scannable and readable

format. This memorandum to your CFO is

the most important component of your

project proposal and should be an executive summary that does the following.

■ Explains the benefits of your project.

■ Answers your CFO’s key questions, as

described above in Step 1.

■ Creates a sense of urgency by quantifying the high costs of not moving forward with your project.

Maximize the number of benefits and

carefully explain the risks in order to

achieve the best results.

For more information, contact Marcia 

O’Carroll, ABB Energy Capital: phone

(617) 574-1128; e-mail: marcia.o’carroll@

energycapital.com.

Sell your energy project’s benefits and explain risks to your CFO.
Energy Matters, July 1999 5

Root Cause Failure Analysis On AC Induction Motors

By John M. Machelor,

Motor/Drives Systems 

Specialist, Motor Challenge

Program, MACRO International, Inc.

This is the fifth in a

series of articles by

Mr. Machelor. In the

May 1999 issue,

John began his discussion of mechanical motor failures by

addressing the components most likely to fail—the bearings.

This article continues the investigation of

bearing failures and their root causes.

We began our discussion of bearing failures

in the last issue by looking at vibrationrelated bearing wear. Specifically, we examined a wear pattern called “false brinelling,”

which occurs in non-rotating bearings, and

we identified a number of possible root

causes. There are also some conditions

that cause excessive vibration/stress in

rotating bearings of the motor or the driven

equipment. The three most common conditions encountered in the field are misalignment, imbalance, and soft foot. Each

of these can result in excessive wear on the

races and rotating elements of the bearings, followed by premature, if not catastrophic, failure. Let’s examine each one.

Misalignment: The illustration at right

shows the two most common types of misalignment, angular and parallel. Angular

misalignment occurs when the axial centerlines of the two shafts being connected

(normally the motor and the load) are

angularly displaced. Parallel misalignment

occurs when the shafts are displaced linearly, even though the axes of the two

shafts are parallel. Often, when these conditions are not recognized (or are ignored),

the two shafts are “forced-coupled.” In

either case, the result is excessive vibration, as first one shaft and then the other

attempts in vain to return to its normal

unstressed position. 

The good news is misalignment can be

easily avoided at a relatively low cost.

Laser alignment has largely replaced the

old “dial indicator” method of alignment,

and it is much more precise. A growing

number of reputable firms are marketing

laser alignment equipment. Companies

whose maintenance departments have

established Reliability Based Maintenance 

(RBM) programs routinely have a full-time

maintenance person (or team) doing laser

alignment as part of their preventative

maintenance arsenal. The payback from

this approach is well worth the investment

in manpower and equipment.

Imbalance: This condition can occur in

any component of a motor system’s rotating assembly. Most components of the system (motor, coupling, pump, fan, etc.)

come from the manufacturer already meeting the manufacturer’s balance specification. Or, for an additional charge, most

manufacturers can balance their component to meet a buyer’s more precise balance specification.

Most newly installed motor systems are

well balanced, although it is still a good

idea to check out such systems using vibration analysis. Imbalance problems usually

develop gradually in running systems with

the main trouble makers being motor cooling fans, couplings, and driven equipment

such as pumps and blowers.

■ Cooling fans. Over time, these shaftmounted fans can become clogged with

dirt, debris, and various other contaminants. Corrosion can occur, resulting in

cracked or missing fan blades. I have

seen cases where the whole fan is missing with only its mounting hub left on

the shaft! A routine maintenance/inspection program is imperative to identify

these types of problems in their early

stages and to take corrective actions.

■ Couplings. Imbalanced couplings result

from eccentric boring, missing bolts and

nuts, missing set screws, and even

improperly sized shaft keys. Imbalanced

couplings are very common but are

often overlooked.

■ Pumps. With pumps, imbalance results

from a number of sources. A progressively worsening mechanical imbalance

may be caused by uneven wear or corrosion. Pump rotors are particularly susceptible to corrosion and erosion from

sources such as the liquid being pumped

and abrasive contaminants in the liquid. 

■ Blowers. These experience the same

problems as motor cooling fans but are

often mounted inside the ducts of air

handling systems, hidden from view.

Drive motor bearings routinely fail

because of vibration transmitted from

an imbalanced blower. But the blowers 

themselves, being hard to get at, often

have no routine maintenance or inspection performed on them, and so they

can remain out of balance for years!

Soft Foot: This condition involves the

mounting of the motor and/or the driven

equipment to its mounting base. It results

when one of (typically) four mounting feet

is poorly mounted to its base surface. This

can be the result of:

■ A gap between the bottom of the motor/

equipment foot and the base mounting

surface caused by poor machining of

one or both surfaces. In this case, either

the mounting bolt may have too few

shims to fill the gap, or the mounting

bolt may have been tightened down on

too few (or no) shims, forcing the mounting foot down onto the mounting surface. This puts extreme strain on the

mounting foot, which often cracks or

breaks off altogether and makes the situation even worse (three-point mounting).

■ A missing or loose mounting bolt with

various causes like human error, corrosion, fatigue failure, etc. 

In either case, the result is excessive

vibration of the component involved. As

any imbalance in the rotating elements

passes over the “soft foot,” the support structure deflects, adding to the vibration level. 

The next article will continue our investigation of AC induction motor bearing 

failures.

Readers are welcome to send questions,

comments, or suggestions to John Machelor

at:

E-mail: jmachelo@macroint.com or 

macrojmm@aol.com

Phone: (540) 639-4271

Fax: (540) 639-4272

Angular Misalignment

Motor shaft

°

°

Motor shaft

Driven shaft

Driven shaft

Parallel Misalignment

Two common types of misalignment.
6 Energy Matters, July 1999

Performance 

Optimization Tips

Field Measurements 

in Pumping Systems—

Practicalities and Pitfalls

By Don Casada,

Motor Challenge

Program, Oak Ridge

National Laboratory 

Note: This article is

the second in a

series dealing with

practical considerations and pitfalls of field measurements

needed to understand pumping systems.

Pump Head

Head, as a general term, is a measure of

the relative hydraulic energy per unit

weight of the fluid, and is usually

expressed in units of feet in the United

States and meters elsewhere. Although

other energy components, such as heat,

may represent a significant portion of the

overall energy possessed by a fluid in a

pumping system, the portions of the fluid

system energy that are important from a

fluid movement standpoint are pressure,

elevation, and velocity. The total head

associated with these three components, in

respective order, is:

Htot = P

+ z + 

V2

ρ 2g

where Htot is total head, P is gauge

pressure, ρ is fluid density, z is elevation, V is fluid velocity, and g is gravitational constant.

For incompressible fluids, the useful

work per unit weight performed by a pump

is simply the difference between the suction and the discharge heads, or:

Pump head = [(

Pd − Ps

) + (zd − zs) + (

Vd

2 − Vs2

ρ 2g )]

where the subscripts d and s refer to

discharge and suction conditions,

respectively.

In order to understand pump performance in the field, you must account for

these elements of head.

Some practical considerations involving

the pressure component of head were discussed in the May 1999 issue of Energy

Matters. In this issue, the elevation component will be discussed.

Elevation

The elevation head, in the context of

pump measurements, is simply the difference in elevation between the pump suction and discharge reference points, where

pressure measurements are made. Elevation is usually a fairly straightforward term

to measure, and can be done accurately

with nothing more sophisticated than a

pocket tape measure; but there are sometimes complicating factors to be considered. To illustrate, let’s use the example

shown in Figure 1, which shows a pump

with pressure gauges connected by short

instrument tap stubs to the suction and discharge piping (instrument isolation valves

are not shown).

Figure 1. Pump with short pipe stub pressure

taps and local gauges.

The elevation difference between the

discharge and suction reference points—

the pressure gauges—is simply zd– zs. From

a practical standpoint, the elevation difference is usually determined by reference to

some third elevation, such as floor level or

pump datum elevation (defined in Reference 1).

But, what if the pressure gauges are

configured as shown in Figure 2, where an

instrument tube run is used to allow suction and discharge pressure gauges to be

conveniently located next to each other

(e.g., when the gauges or transducers are

located in a common instrument rack)? The

same rules are still applicable, and ideally

the elevation head difference would be

zero—provided the instrument tubing is

completely filled with process fluid. 

But there is a potential pitfall that did

not exist for the arrangement shown in Figure 1. It is associated with an improperly

vented instrument line—a situation that

can easily creep in unnoticed, particularly

when maintenance is performed.

Figure 2. Instrument tubing to provide adjacent

suction and discharge pressure gauges.

Let’s assume the pump develops a problem that requires disassembly to make the

repair. A lockout/tagout procedure is performed, the suction and discharge isolation

valves are closed, and the pump casing

drain plug is opened to drain fluid from the

casing and adjacent pipe sections, which

incidentally includes the instrument tubing. After the maintenance work is completed, the normal procedure would be for

operators to open the suction and discharge valves and complete a system fill

and vent process using system high-point

vents (not shown). After completing the fill

and vent, the system would once again be

available for process service.

It is common operator practice to simply ignore instrument tubing when conducting fill and vent procedures (these

lines “belong” to instrument technicians).

In the case of the system shown in Figure 1,

that is not a practical concern, as the

instrument stubs are short. However, when

the system shown in Figure 2 is filled, the

air pocket left in the suction gauge instrument line from the draining process will be

compressed (assuming the suction pressure

is greater than atmospheric), and the actual

liquid level will be different than the gauge

elevation. 

For moderate- and high-pressure connections, this is usually not an important

concern because the air pocket will be significantly compressed in volume, and the

trapped air will also be more likely to

escape around fittings. Over time, the

escaping air results in the instrument tubing becoming liquid-filled. Further, an error

of a few feet in high-head systems would

be a relatively insignificant factor. But for

low-pressure systems using low-head 

(continued on page 7)

Ps

Pd

zd – zs

Ps Pd zd – zs = 0
Energy Matters, July 1999 7

Letters to the Editor

Energy Matters welcomes

comments from readers by

postal mail or e-mail. Comments should be typewritten and must

include the author’s full name, address, association, and phone number. 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 technical 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.

Is MM+ is Y2K compliant?

Some readers have asked via e-mail, and

we are happy to respond—yes! MotorMaster+ uses full data in all entry fields. Dates

are only used to organize maintenance or

energy action records chronologically or to

determine motor age. Records you have created will not be affected on January 1, 2000.

How have you applied information from this

newsletter on the job? Send us an e-mail at

motorline@energy.wsu.edu.

continued from page 6

pumps, the air will be less likely to be driven from the system, and the error associated with a few feet of compressed air will

be much more significant in calculating

the pump head. It should be noted that the

extent of error attributable to unvented

instrument lines depends on the physical

layout of the tubing run, and it is generally

not practical to adjust for the effect of

unvented lines.

In situations where instrument tubing is

used to make pressure (or flow, for that

matter) measurements, it is helpful to have

a permanently installed vent petcock at the

gauge to ensure the instrument line is completely filled. 

The potential for the instrument line

draining problem can be minimized by a

loop seal or

“pig tail”

between the

pressure

gauge and

the pipe connection, as in

Figure 3. Pig

tails can also

buffer the

pressure

gauge from

high process

temperatures.

The ASME

standard for

pressure

measurements (2) discusses the

importance of ensuring that instrument

lines contain what is intended—whether

gas or liquid. Although it is a lengthy document that is quite involved in some sections, many portions provide useful,

practical guidance for folks involved in

field measurements.

Comments/questions welcome by e-mail:

a85@ornl.gov.

References

1) ANSI/Hydraulic Institute Standard 1.6-1994, Centrifugal Pump Test.

2) ASME/ANSI PTC 19.2-1987, Pressure Measurement.

Correction Note: In the May issue, Don Casada’s equation for hydraulic power was misprinted. The factor

3690 should have read 3960. Energy Matters regrets the

misprint and thanks Mr. Peter Stech of KSB Inc. for

bringing it to our attention.

Guest Column

continued from page 3

requires of an energy efficiency investment.

There are no guarantees that management

will implement energy efficiency projects

even if they make sense from a financial

perspective. Other investments or projects

may have greater financial returns than

energy efficiency projects, capital may be

unavailable, or certain projects may not fit

with a company’s strategic plan. However,

if advocates do not make business sense of

energy efficiency, it may continue to be

perceived by many business people as a 

warm and fuzzy, but costly and unnecessary extravagance.

The most effective way to get management’s attention may be to characterize

energy efficiency as “efficiency” or “productivity,” which have always had positive

connotations in the business community. 

This article is taken from Proceedings from

the 1999 ACEEE Summer Study on Energy

Efficiency in Industry. Washington, D.C.:

American Council for an Energy-Efficient

Economy.

Contact Aimee McKane at (202) 484-0892,

or e-mail atmckane@lbl.gov.

Figure 3. Elevated pressure 

gauge with loop seal.

Water/Wastewater Forum Targets Energy Efficiency

You already know that energy costs

make up a large part of every industrial or

municipal water/wastewater system budget. But did you know that even modest

changes in equipment and operation could

yield large financial rewards? 

Attend the 1999 Energy Efficiency

Forum for the Water & Wastewater Industry, August 29-31, 1999, in San Diego, CA,

to find out about cutting edge ideas to

lower energy costs in water and wastewater operations. Cosponsored by the

DOE’s Motor Challenge Program, the Electric Power Research Institute and WaterWorld Magazine, the forum brings you

workable solutions for improving the

energy efficiency of your industrial and

municipal systems.

Motor Challenge follows up on last

year’s successful “Pump Optimization

Workshop,” which focused specifically on

fresh water and wastewater facilities. This

year’s workshop focuses on plant measurements using software called PSAT—Pump

System Assessment Tool. 

Plan to attend this forum if you:

■ Manage or operate a municipal or

industrial water or wastewater system.

■ Regulate water and wastewater 

operations.

■ Provide engineering consulting services

for water and wastewater systems.

■ Work in the electric power industry.

Take this opportunity to hear case studies describing how utilities have saved

energy and money, and learn about the latest research in energy saving systems and

technologies. See new products that can

help you cut energy costs while maintaining water quality goals. 

For more information, contact Laura

Boland at (918) 831-9179, or visit the Web

site at www.waterworld.com. 
Coming Events 

INFORMATION

CLEARINGHOUSE

Do you have questions about 

using energy-efficient electric

motor systems? Call the OIT Challenge

Programs 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.motor.doe.gov

HOTLINE: (800) 862-2086

DOE Regional Support Office 

Representatives

■ Tim Eastling, Atlanta, GA, 

(404) 347-7141

■ Lili Griffin, Boston, MA, 

(617) 565-9714

■ Julie Nochumsom, 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-10099-590 • July 1999

T OF ENERGY

DEPARTMEN

U

E

N ITE D STAT S OFA ERICA

M

T OF ENERGY

DEPARTMEN

U

E

NI TE D ST AT S OF A ERICA

M

Printed with a renewable-source ink on paper

containing at least 50% wastepaper, including

20% postconsumer waste

COUNCIL OF INDUSTRIAL BOILER OWNERS’ INDUSTRIAL ENERGY SYSTEMS FORUM II 

This forum promotes safe, reliable, and cost-effective practices in design, operation, and

maintenance of industrial energy, steam, and power systems. The forum will address considerations from owners, operators, managers, manufacturers, and developers of industrial

energy systems.

■ July 21-22 in Cleveland, OH

Call Bob Bessette at (703) 250-9042 for more information. 

ENERGY EFFICIENCY FORUM FOR WATER/WASTEWATER FACILITIES

The goal of this forum is to help managers and operations personnel of municipal and

industrial systems find workable energy management solutions.

■ August 29-31 in San Diego, CA

Call Laura Boland at (918) 831-9179 for more information.

UNDERSTANDING PUMP SYSTEMS/PSAT WORKSHOPS

The following sessions present the fundamentals of optimizing industrial and municipal

pump systems. The workshops will present case studies and will focus on the Pump System

Assessment Tool (PSAT).

■ August 29 in San Diego, CA

■ September and October (date TBD) in Sacramento, CA

■ September and October (date/city TBD) in MI

■ September and October (date/city TBD) in CA

■ October 4 and 5 in Westchester or Brooklyn, NY

Call Anna Maksimova at (360) 754-1097, ext.100 for more information.

ADJUSTABLE SPEED DRIVE APPLICATION WORKSHOPS

These workshops address the fundamentals of ASDs and demonstrate the ASDMaster software.

■ September (date TBD) in Reading, PA

■ September (date TBD) in Pittsburgh, PA

Call Anna Maksimova at (360) 754-1097, ext.100 for more information.

FUNDAMENTALS OF COMPRESSED AIR SYSTEMS

These 1-day Compressed Air Systems training seminars are targeted to plant engineers and

maintenance personnel who are responsible for ensuring optimum performance of compressed air systems. 

■ July 13 in Cleveland, OH

■ September 10 in Atlanta, GA

■ September 22 in Salt Lake City, UT

■ September 23 in Knoxville, TN

For information or a registration form, call (800) 862-2086.

U.S. Department of Energy

EE-20, 5G-067

1000 Independence Avenue, SW

Washington, DC 20585

Bulk Rate

U.S. Postage

PAID

Permit No. 258

Golden, Colorado