ASHRAE STANDARD Measurement, Testing, Adjusting, and Balancing of Building HVAC Systems

88 Pages·2008·3.86 MB·English

ASHRAE Standard Project Committee 111
Cognizant TC: TC 7.7, Testing and Balancing
SPLS Liaison: H. Michael Newman
Roger Gaylon Richardson, Chair* Frederick A. Lorch*
W. David Bevirt* Thomas A. Lutz
George C. Bozenhard Donald A. Melchiorre
Mark C. Hegberg* Jeffery T. Pearson
Gerald J. Kettler* Michael J. Smith*
Carl N. Lawson* William K. Thomas*
Rodney H. Lewis* Dennis H. Tuttle
*Denotes members of voting status when the document was approved for publication.
ASHRAE STANDARDS COMMITTEE 2007–2008
Stephen D. Kennedy, Chair Nadar R. Jayaraman
Hugh F. Crowther, Vice-Chair Byron W. Jones
Robert G. Baker Jay A. Kohler
Michael F. Beda James D. Lutz
Donald L. Brandt Carol E. Marriott
Steven T. Bushby R. Michael Martin
Paul W. Cabot Merle F. McBride
Kenneth W. Cooper Frank Myers
Samuel D. Cummings, Jr. H. Michael Newman
K. William Dean Lawrence J. Schoen
Robert G. Doerr Bodh R. Subherwal
Roger L. Hedrick Jerry W. White, Jr.
Eli P. Howard, III Bjarne W. Olesen, BOD ExO
Frank E. Jakob Lynn G. Bellenger, CO
Claire B. Ramspeck, Assistant Director of Technology for Standards and Special Projects
SPECIAL NOTE
This American National Standard (ANS) is a national voluntary consensus standard developed under the auspices of the American
Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Consensus is defined by the American National Standards
Institute (ANSI), of which ASHRAE is a member and which has approved this standard as an ANS, as “substantial agreement reached by
directly and materially affected interest categories. This signifies the concurrence of more than a simple majority, but not necessarily unanimity.
Consensus requires that all views and objections be considered, and that an effort be made toward their resolution.” Compliance with this
standard is voluntary until and unless a legal jurisdiction makes compliance mandatory through legislation.
ASHRAE obtains consensus through participation of its national and international members, associated societies, and public review.
ASHRAE Standards are prepared by a Project Committee appointed specifically for the purpose of writing the Standard. The Project
Committee Chair and Vice-Chair must be members of ASHRAE; while other committee members may or may not be ASHRAE members, all
must be technically qualified in the subject area of the Standard. Every effort is made to balance the concerned interests on all Project
Committees.
The Assistant Director of Technology for Standards and Special Projects of ASHRAE should be contacted for:
a. interpretation of the contents of this Standard,
b. participation in the next review of the Standard,
c. offering constructive criticism for improving the Standard, or
d. permission to reprint portions of the Standard.
DISCLAIMER
ASHRAE uses its best efforts to promulgate Standards and Guidelines for the benefit of the public in light of available information and
accepted industry practices. However, ASHRAE does not guarantee, certify, or assure the safety or performance of any products, components,
or systems tested, installed, or operated in accordance with ASHRAE’s Standards or Guidelines or that any tests conducted under its
Standards or Guidelines will be nonhazardous or free from risk.
ASHRAE INDUSTRIAL ADVERTISING POLICY ON STANDARDS
ASHRAE Standards and Guidelines are established to assist industry and the public by offering a uniform method of testing for rating
purposes, by suggesting safe practices in designing and installing equipment, by providing proper definitions of this equipment, and by providing
other information that may serve to guide the industry. The creation of ASHRAE Standards and Guidelines is determined by the need for them,
and conformance to them is completely voluntary.
In referring to this Standard or Guideline and in marking of equipment and in advertising, no claim shall be made, either stated or implied,
that the product has been approved by ASHRAE.
CONTENTS
ANSI/ASHRAE Standard 111-2008
Measurement, Testing, Adjusting, and Balancing of Building HVAC Systems
SECTION PAGE
Foreword...................................................................................................................................................................2
1 Purpose..........................................................................................................................................................2
2 Scope.............................................................................................................................................................2
3 Definitions and Symbols.................................................................................................................................2
4 Instrumentation...............................................................................................................................................3
5 Flow-Measuring and Balancing Devices......................................................................................................15
6 System Effect...............................................................................................................................................19
7 Air System Measurements...........................................................................................................................25
8 Hydronic Measurements...............................................................................................................................36
9 Air Testing, Adjusting, and Balancing...........................................................................................................40
10 Hydronic Testing and Balancing.................................................................................................................47
11 Equipment Field Testing.............................................................................................................................48
12 Reporting Procedures and Forms..............................................................................................................51
13 Commissioning for Test and Balances........................................................................................................57
14 References.................................................................................................................................................58
Informative Appendix A: Bibliography.................................................................................................................58
Informative Appendix B: Sample Specifications.................................................................................................59
Informative Appendix C: System Effect..............................................................................................................60
Informative Appendix D: Air Measurements.......................................................................................................61
Informative Appendix E: Pumps.........................................................................................................................81
NOTE
When addenda, interpretations, or errata to this standard have been approved, they can be downloaded free of
charge from the ASHRAE Web site at http://www.ashrae.org.
© Copyright 2008 American Society of Heating,
Refrigerating and Air-Conditioning Engineers, Inc.
1791 Tullie Circle NE
Atlanta, GA 30329
www.ashrae.org
All rights reserved.
(This foreword is not part of this standard. It is merely 1. PURPOSE
informative and does not contain requirements necessary
To provide uniform procedures for measurement, testing,
for conformance to the standard. It has not been
adjusting, balancing, evaluating, and reporting the perfor-
processed according to the ANSI requirements for a
mance of building heating, ventilating, and air-conditioning
standard and may contain material that has not been
systems in the field.
subject to public review or a consensus process.
Unresolved objectors on informative material are not
2. SCOPE
offered the right to appeal at ASHRAE or ANSI.)
2.1 This standard applies to building heating, ventilating,
FOREWORD
and air-conditioning (HVAC) systems of the air-moving and
ANSI/ASHRAE Standard 111 was first published in hydronic types and their associated heat transfer, distribution,
1988 with the title Practices for Measurement, Testing, refrigeration, electrical power, and control subsystems.
Adjusting, and Balancing of Building Heating, Ventilation,
2.2 This standard includes
Air-Conditioning, and Refrigeration Systems. At the time of
publication, the cognizant Technical Committee was TC 9.7,
a. methods for determining thermodynamic, hydraulic,
Testing and Balancing, which is now designated as Technical
hydronic, mechanical, and electrical conditions;
Committee 7.7. In 1992 the TC recommended that the stan-
b. methods for determining room air-change rates, room
dard be rewritten for testing and balancing in order to
pressurization, and cross contamination of spaces;
update procedures for the industry and to aid design engi-
c. procedures for measuring and adjusting outdoor ventila-
neers in writing a testing and balancing specification that
tion rates to meet specified requirements; and
would encompass the design ramifications of present-day
d. methods for validating collected data while considering
HVAC systems.
system effects.
Field test results are considered essential to designers,
manufacturers, and installers to better enable them to evaluate
2.3 This standard establishes
the results of their design, equipment performance, and instal-
lation techniques under actual operating conditions. This
a. minimum system configuration requirements to ensure
revised standard updates the testing procedures for air,
that the system can be field tested and balanced;
hydronics, and control verification; identifies new instrumen-
b. minimum instrumentation required for field measure-
tation used in today's testing; and incorporates the findings of
ments;
several research projects that have established new means for
c. procedures for obtaining field measurements in HVAC
testing. The standard also suggests how the Test and Balance
testing and balancing and equipment testing; and
Agency can interface with the Commissioning team.
d. formats for recording and reporting results.
This standard covers causes affecting a system's perfor-
mance. Its intent is to convey the message that field testing can
2.4 The field data collected and reported under this standard
be repeated but will not necessarily provide the accuracy of
are intended for use by building designers, operators, and
factory testing. However, when the proper conditions exist—
users, and by manufacturers and installers of HVAC systems.
good engineering practices, realistic ratings, and good crafts-
manship installation—adequate results can be obtained to sat-
3. DEFINITIONS AND SYMBOLS
isfy a given set of design conditions within a reasonable set of
limitations. Testing and balancing provides the means to The following terms are used in this standard as they are
determine and monitor system performance and may be uti- defined below. For definitions of other technical terms, refer
lized repeatedly long after the project is completed. to the ASHRAE Terminology of Heating, Ventilation, Air
Testing and balancing reports provide many benefits that Conditioning, and Refrigeration.
can be used
A factor: the effective area of an air terminal, which is equal
k
a. to assist personnel responsible for the efficient operation to the measured airflow rate divided by the velocity reading of
of HVAC systems; a particular instrument used in a prescribed manner.
b. to provide a record of existing conditions;
fan velocity pressure: the velocity pressure corresponding to
c. to compare periodic tests to original conditions as a way
the average velocity through the fan outlet; the kinetic energy
to determine possible system deterioration or reduced
per unit volume of air exiting the fan.
efficiency;
d. to establish operating conditions whenever modifications (PD): abbreviation for pressure difference and ΔP.
or changes are made in the HVAC system;
sensitivity (instrument): a measure of the smallest incremen-
e. to determine existing conditions for base energy-level cal-
tal change to which an instrument can respond.
culations used in energy conservation programs;
f. to create procedures and reports that can be used to verify static discharge head: the static pressure of a fluid at the outlet
energy conservation results; and of the pumping device, expressed in terms of the height of a
g. to provide a comparison of design versus actual field per- column of the fluid or of the height of some manometric fluid
formance. that it would support.
2 ANSI/ASHRAE Standard 111-2008
static pressure rise: the algebraic difference between the static scale of 0 to 1.0 in of water (0 to 250 Pa) or 0 to 2.0 in. of water
pressure at the fan outlet and the static pressure at the fan inlet. (0 to 500 Pa) connected to a vertical fluid column with scales
of 5 in. of water (1250 Pa) or 10 in. of water (2500 Pa).
static suction lift: the same as the static discharge head,
except that it has a negative value and it is measured at the inlet 4.3.2.2 Recommended Uses. Use with Pitot static tubes
to the pumping device. or static pressure probes.
4.3.2.3 Limitations
4. INSTRUMENTATION
a. Not to be used to measure air velocities less than 600 fpm
4.1 Scope. This section covers the required or recom-
(3.0 m/s). A micromanometer, hook gauge, or another
mended instrumentation needed to obtain the measurements
sensitive instrument shall be used for acceptable accuracy
required for air or fluid system balancing as well as other
in this range.
instruments that are useful or necessary in special situations.
b. In using the manometer, it must be carefully leveled and
For each instrument, this section provides a description,
held in a rigid position so that when “0” pressure is regis-
recommended uses, limitations, accuracy requirements, and
tered, the end of the meniscus arc of the fluid exactly
calibration requirements.
bisects the center of the zero line.
4.2 General. Great care should be taken to follow the man-
ufacturers’ instructions and the instructions herein regarding 4.3.2.4 Calibration Required. Every 12 months, the
safety in the use of these instruments for field measurements. instrument shall be verified with a recently calibrated instru-
This standard does not preclude the use of new instru- ment, and if the reading on the instrument to be verified is not
ments as they are developed and proven to be as accurate as, within 2% of the reading on the reference instrument (recently
or more accurate than, the instruments described herein. calibrated instrument), then the instrument must be calibrated
For detailed instructions on the use, limitations, and accu- before it can be used.
racy of the instruments under field conditions, see Sections 7
4.3.3 Pitot Static Tube
through 11 on system effects, measurements, and testing and
4.3.3.1 Description. A Pitot static tube, used in con-
balancing.
junction with a manometer, provides a basic method of deter-
4.3 Air-Balancing Instruments mining the air velocity within a duct. The typical Pitot static
4.3.1 Inclined Manometer tube is of a double concentric tube construction, consisting of
a 1/8 in. (3.2 mm) O.D. inner tube that is concentrically
4.3.1.1 Description. The inclined manometer is made
located inside a 5/16 in. (7.9 mm) O.D. outer tube. The outer
of a single tube, inclined (usually with a 10:1 slope) to enlarge
static tube has eight equally spaced 0.04 in. (1.02 mm) diam-
the reading. Alcohol or special oils are normally used in place
eter holes around the circumference of the outer tube, located
of water. Such oils have a lower specific gravity than water
2.5 in. (63.5 mm) back from the nose or open end of the Pitot
and, thus, serve to further enlarge the reading. Manometers
tube tip. At the base end, or tube-connection end, the inner
using such fluids have scales calibrated in inches of water
tube is open ended, as is the head. The outer tube has a side
(Pascals) corresponding to the pressure indicated on the oil of
outlet tube connector perpendicular to the outer tube, directly
a known specific gravity.
parallel with and in the same direction as the head end of the
4.3.1.2 Recommended Uses. Use with Pitot static tubes
Pitot static tube.
or static pressure probes.
4.3.3.2 Recommended Uses
4.3.1.3 Limitations
a. Use to measure airstream “total pressure” by connecting
a. Not to be used to measure air velocities less than 600 fpm
the inner tube outlet connector to one side of a manometer
(3.0 m/s). A micromanometer, hook gauge, or another
or draft gauge.
sensitive instrument shall be used for acceptable accuracy
in this range. b. Use to measure airstream “static pressure” by connecting
b. In using the manometer, it must be carefully leveled and the outer tube side outlet connector to one side of a
held in a rigid position so that when “0” pressure is regis- manometer or draft gauge.
tered, the end of the meniscus arc of the fluid exactly c. Use to measure airstream “velocity pressure” by connect-
bisects the center of the zero line. ing both the inner and outer tube connectors to opposite
sides of a manometer or draft gauge.
4.3.1.4 Calibration Required. Every 12 months, the d. This instrument, when used with a manometer or micro-
instrument shall be verified with a recently calibrated instru- manometer, is a reliable and rugged instrument. Its use is
ment, and if the reading on the instrument to be verified is not preferred over any other method for the field measure-
within 2% of the reading on the reference instrument (recently ment of air velocity, system total air, outdoor air, return
calibrated instrument), then the instrument must be calibrated air quantities, fan static pressure, fan total pressure, and
before it can be used. fan outlet velocity pressures, where such measured quan-
4.3.2 Combination Vertical-Inclined Manometer tities may be required.
4.3.2.1 Description. The combination vertical-inclined e. The following instruments may be used with the Pitot
manometer is constructed of an inclined fluid column with a static tube:
ANSI/ASHRAE Standard 111-2008 3
1. Micromanometer—very low pressure differential, less (Eddy-current) type or solid-state instruments with digital
than 1.0 in. of water (250 Pa) readout. Instrument accuracy shall be within ±1% of full-dial
2. Inclined manometer—moderate pressure differential, scale or range.
0 to 10 in. of water (0 to 2500 Pa) 4.3.4.2 Recommended Uses. Use to determine the
3. U-tube manometer—medium pressure differential, speed of any shaft having a countersunk end.
greater than 10 in. of water (2500 Pa)
4.3.4.3 Limitations. The shaft end must be accessible
4. Diaphragm-type pressure gauge and countersunk.
5. Electronic differential pressure meters
4.3.4.4 Accuracy of Field Measurements. Within one-
half of a scale division mark.
4.3.3.3 Limitations
4.3.4.5 Calibration Required. Check against readings
a. The accuracy depends upon uniformity of flow and com- made with a recently calibrated chronometric tachometer on
pleteness of traverse. each project. If the reading is not within ±2% of the recently cal-
b. A reasonably large space is required adjacent to the duct ibrated tachometer, have the instrument tested for calibration.
penetrations for maneuvering the instrument. 4.3.5 Clamp-On Voltammeter
c. Care must be taken to avoid pinching instrument tubing. 4.3.5.1 Description. The clamp-on type voltammeter
d. Because of the distance between the impact and static has trigger-operated, clamp-on transformer jaws that permit
holes, the Pitot static tube cannot be used to measure flow current readings without interrupting electrical service. Most
through orifice-type openings. voltammeters have several scale ranges in amperes and volts.
e. The Pitot static tube is susceptible to plugging in air- Two voltage test leads are furnished, which may quickly be
streams with heavy dust or moisture loadings. connected to the bottom of the voltammeter opposite the end
f. Acceptance of the standard Pitot static tube is due to its used for measuring current. Some of the voltammeter models
accuracy in the correct determination of the static pres- are furnished with a built-in ohmmeter. Instrument accuracy
sure. The total pressure is not affected by yaw or angular- is within ±3% of full scale.
ity up to approximately 8° on either side of parallel flow. 4.3.5.2 Recommended Uses. Use to measure operating
The static pressure, however, is extremely sensitive to voltages and currents of electric motors and of electric-resis-
direction of flow. tance heating coils.
4.3.5.3 Limitations
4.3.3.4 Accuracy of Field Measurement. Rigorous
error analysis shows that flow rate determinations by the Pitot
a. The proper range must be selected. When in doubt, begin
static tube and manometer combination method can range
with the highest range for both voltage and current scales.
from 5% to 10% error. Experience shows that qualified tech-
It is desirable for readings to occur about midscale. The
nicians can obtain measurements that range within 5% and
accuracy of reading low currents can be improved by
10% accuracy of actual flow under good field conditions. It
looping the conductor wire around the jaw once and
has also been determined that suitable traverse conditions do
dividing the current reading by two (2).
not always exist, and measurements can then exceed a ±10%
b. Depending upon the conditions at the point of measure-
error rate.
ment and the size of the voltammeter, access for measure-
4.3.3.5 Calibration Required. Every 12 months, the ment may be restrictive. Caution is required, particularly
instrument shall be verified with a recently calibrated instru- when taking measurements under confined conditions.
ment, and if the reading on the instrument to be verified is not c. To avoid distortion of current readings by other fields,
within 2% of the reading on the reference instrument (recently move the meter along the wire to verify that the reading
calibrated instrument), then the instrument must be calibrated remains constant.
before it can be used.
4.3.5.4 Accuracy of Field Measurements. ±3% of full
4.3.4 Chronometric Tachometer
scale.
4.3.4.1 Description. The chronometric tachometer is a
4.3.5.5 Calibration Required. Check against readings
hand-held instrument that combines an accurate timer and a
made with a recently calibrated clamp-on volt-ammeter on each
revolution counter into one instrument. After the instrument
project. If the reading is not within ± 2% of the recently cali-
tip is placed on the rotating shaft, the stopwatch button is
brated instrument, have the instrument tested for calibration.
depressed, which simultaneously activates the counter and the
stop watch. After the timer has run for an accurately timed 4.3.6 Deflecting Vane Anemometer
interval of 3 or 6 s, the instrument stops accumulating revolu- 4.3.6.1 Description. The deflecting vane anemometer
tions, even though it is still in contact with the rotating shaft. consists of a pivoted vane enclosed in a case. Air exerts a pres-
The scale is calibrated so that, with the 3 or 6 s stopwatch sure upon the vane as it passes through the instrument from an
mechanism used in the instrument, the readings are read upstream to a downstream opening. The movement of the
directly in rpm. Instrument accuracy shall be within ±0.5% of vane is resisted by a hairspring. The instrument gives instan-
the scale range. taneous readings of directional velocities on an indicating
There are hand tachometers capable of producing instan- scale. The instrument is supplied with various types of remote
taneous rpm measurement readings, such as the dial-face and direct-connected measuring tips, or jets.
4 ANSI/ASHRAE Standard 111-2008
4.3.6.2 Recommended Uses b. The air terminal manufacturer’s specified A factor for the
k
terminal must be used in computing air quantities.
a. This instrument may be used for measurement of air c. Total inlet area of the instrument must be in the measured
quantities through both supply and return air terminals airstream.
using the proper air-terminal factor, Ak (effective area), d. It is not suitable for measurement in ducts.
for airflow calculation. e. It is fragile and cannot be used in dusty or corrosive air.
b. This instrument may also be used for indicating low f. Since the instrument has a turbine wheel of very low iner-
velocities (100 to 300 fpm, 0.5 to 1.5 m/s) where the tia, caution is advised as to reliability of readings in non-
instrument case itself with the appropriate probe attached uniform, turbulent, or stratified airstreams. This is likely
is placed in the airstream, as within a hood or booth. to occur downstream of dampers, face and bypass coils,
or any device that causes turbulence in the airstream
4.3.6.3 Limitations
being measured.
g. The instrument is not direct reading and, therefore, must
a. The instrument shall not be used in extremely hot, cold,
be timed manually.
or contaminated air.
h. At low velocities, the friction drag of the mechanism is
b. The instrument is affected by static electricity.
considerable. In order to compensate for this, a gear is
c. The instrument duct probe is sensitive to the presence and
commonly used. For this reason, the correction is additive
proximity of duct walls and tends to read high on the suc-
at the lower range and subtractive at the upper range, with
tion side and low on the discharge side of a fan.
the least correction in the middle of the range. Most of
d. The accuracy of the instrument is affected by position.
these instruments are not sensitive enough for use below
200 fpm (1.0 m/s), although ball-bearing models claim
4.3.6.4 Accuracy of Field Measurements. Accuracy is
ranges down to 30 fpm (0.15 m/s). The useful range is
within ±10% when the instrument is within calibration and
from 200 to 2000 fpm (1.0 to 10.0 m/s).
used in accordance with the manufacturer’s recommenda-
tions. Terminal A factors are a function of duct and damper
k 4.3.7.1.4 Accuracy of Field Measurements
conditions which affect the velocity immediately before the
terminal. Use of this instrument with conditions not identical a. Smooth flow ±5% of reading above 200 fpm (1.0 m/s);
to the terminal manufacturer’s test conditions produces mea- not recommended for velocities below 200 fpm (1.0 m/s)
surement error. The instrument must be calibrated in the field b. Nonuniform flow ±30%
for correction factor by Pitot-tube traverse within the limita-
c. The instrument must be calibrated in the field for a cor-
tions of the system.
rection factor by Pitot-tube traverse within the limitations
4.3.6.5 Calibration Required. Check against readings of the system.
made with a recently calibrated deflecting vane anemometer
4.3.7.1.5 Calibration Required. The instrument
on each project. If the reading is not within ±2% of the
shall be calibrated by the manufacturer or other agency every
recently calibrated instrument, have the instrument tested for
six (6) months, depending on usage. Check against readings
calibration.
made with a recently calibrated instrument on each project. If
4.3.7 Revolving Vane or Propeller Anemometer the reading is not within ±2% of the recently calibrated instru-
4.3.7.1 Mechanical Type ment, have the instrument tested for calibration.
4.3.7.1.1 Description. The mechanical propeller or 4.3.7.2 Direct Reading Digital Type
revolving vane anemometer consists of a light, wind-driven 4.3.7.2.1 Description. This instrument is the same as
wheel connected through a gear train to a set of recording the mechanical type in most respects, except that it uses a
dials that read the linear feet (meters) of air passing through powered electronic circuit to convert a pulse generated by the
the wheel in a measured length of time. The instrument is rotating vane into a small electric current to give a meter read-
made in various sizes, but 3, 4, and 5 in. (75, 100, and 125 ing calibrated directly in air velocity units. Generally, these
mm) are the most common. Each instrument requires individ- instruments have microprocessor software to compensate for
ual calibration. The required instrument accuracy of calibra- any nonlinearity.
tion is 1%–3% of scale (using a corrective chart). 4.3.7.2.2 Recommended Uses
4.3.7.1.2 Recommended Uses
a. Use to measure supply, return, and exhaust air quantities
a. Use to measure supply, return, and exhaust air quantities at registers and grilles.
at registers and grilles. b. Use to measure air quantities at the faces of return air
b. Use to measure air quantities at the faces of return air dampers or openings or of total air across the filter or coil
dampers or openings, total air across the filter or coil face face areas, etc.
areas, etc.
4.3.7.2.3 Limitations
4.3.7.1.3 Limitations
a. The air terminal manufacturer’s specified A factor (effec-
k
a. Each reading from this instrument must be corrected by tive area) for the terminal must be used in computing air
its calibration chart. quantities.
ANSI/ASHRAE Standard 111-2008 5
b. The total inlet area of the instrument must be placed in the 4.3.8.3 Limitations
measured airstream.
c. It is not suitable for measurement in ducts. a. The probe that is used with this instrument is very direc-
d. It is fragile and cannot be used in dusty or corrosive air. tional for velocity readings and must be located at the
exact point on the diffuser or grille as specified by the
e. Since the instrument has a turbine wheel of very low iner-
terminal-unit manufacturer.
tia, caution is advised as to reliability of readings in non-
b. Probes are subject to fouling by dust and corrosive air.
uniform, turbulent, or stratified airstreams. This is likely
to occur downstream of dampers, face and bypass coils, c. The instrument probe must be used in the direction of
calibration.
or any device that causes turbulence in the airstream
being measured. d. In general, these instruments should not be used in flam-
mable or explosive atmospheres. However, there are spe-
f. At low velocities, the friction drag of the mechanism is
cial thermal anemometer probes available for use in these
considerable. In order to compensate for this, a gear is
environments.
commonly used. For this reason, the correction is additive
at the lower range and subtractive at the upper range, with 4.3.8.4 Accuracy of Field Measurements. Accuracy is
the least correction in the middle of the range. Most of ±10% above 100 fpm (0.5 m/s). The instrument must be cal-
these instruments are not sensitive enough for use below ibrated in the field for the correction factor by Pitot-tube tra-
200 fpm (1.0 m/s), although ball-bearing models claim verse within the limitations of the system.
ranges down to 30 fpm (0.15 m/s). The useful range is 4.3.8.5 Calibration Required. By the manufacturer or
from 100 to 5000 fpm (0.51 to 25.4 m/s). other agency every six (6) months. In addition, check the
instrument against readings made with a recently calibrated
4.3.7.2.4 Accuracy of Field Measurements instrument on each project. If the reading is not within ± 2%
of the recently calibrated instrument, have the instrument
a. For smooth flow: ±5% of reading above 200 fpm (1.0 m/s);
tested for calibration.
Not recommended for velocities below 50 fpm (1.0 m/s).
4.3.9 Mercury Thermometers
b. For nonuniform flow: ±30%
4.3.9.1 Description. Mercury-filled glass-tube ther-
c. For volume measurements, a correction factor must be
mometers have a useful temperature range of –38°F to 950°F
established in the field by Pitot-tube traverse (the average
(–36°C to 510°C). They are available in a variety of tempera-
velocity of the traverse must be > 1200 fpm for accuracy).
ture ranges, scale graduations, and lengths. The required
instrument test accuracy minimum must be within a scale
4.3.7.2.5 Calibration Required. By the manufac-
division mark.
turer or other agency every six (6) months, depending on
usage. Check against readings made with a recently calibrated 4.3.9.2 Recommended Uses
instrument on each project. If the reading is not within ±2% of
a. The complete-stem-immersion calibrated thermometer
the recently calibrated instrument, have the instrument tested
must be used with the stem completely immersed in the
for calibration.
fluid in which the temperature is to be measured.
4.3.8 Thermal Anemometer
b. Thermometers calibrated for partial stem immersion are
4.3.8.1 Description. The operation of this instrument
more commonly used. They are used in conjunction with
depends on the principle that the resistance of a heated wire thermometer test wells specifically designed to receive
will change with its temperature. Incorporated with the instru- them. No emergent stem correction is required for the
ment is a probe that is provided with a special type of wire ele- partial-stem-immersion type.
ment energized by batteries contained in the instrument case.
As air flows over the element in the probe, the temperature of 4.3.9.3 Limitations
the element is changed from that which exists in still air. The
resistance change is indicated as a velocity on the indicating a. Radiation effects—When the temperature of the sur-
scale of the instrument. Similar instruments are available rounding surfaces are substantially different from the
using a heated thermocouple or heated thermistor instead of a measured fluid, there is a considerable radiation effect
hot wire. They have similar characteristics regarding uses, upon the thermometer reading if the thermometer is left
limitations, and accuracy to the thermal anemometer. unshielded or otherwise unprotected. Proper shielding or
Some instruments are also provided with temperature aspiration of the thermometer bulb and stem can mini-
scales that can be utilized simply by setting the proper selector mize these radiation effects.
button. Some instruments can measure static pressure with b. Time is required for the thermometer to reach the temper-
provided accessories. ature of the fluid being measured.
4.3.8.2 Recommended Uses c. Mercury may separate in the tube.
4.3.9.4 Accuracy of Field Measurements. Within one-
a. Use to measure very low air velocities, such as room air
half of a scale division mark.
currents and airflow in hoods (10 to 600 fpm; 0.05 to
3.0 m/s). 4.3.10 Dial Thermometers
b. Use for measurements at grilles and diffusers. 4.3.10.1 Description. Dial thermometers are of two
c. Use for velocity measurements within ducts. general types: the stem type and the flexible-capillary type.
6 ANSI/ASHRAE Standard 111-2008
They are constructed with various sizes of dial heads, 1-3/4 to 4.3.11.2 Recommended Uses. Suitable for all TAB
5 in. (45 to 125 mm), with stainless-steel encapsulated tem- temperature measurements, including air and other gases, liq-
perature sensing elements. Hermetically sealed, they are rust, uids, and surfaces of pipes and other components with the
dust, and leak proof, and are actuated by sensitive bimetallic appropriate probe. The manufacturers’ directions must be fol-
helix coils. Some can be field calibrated. Sensing elements lowed regarding proper use of probe and maximum allowable
range in length from 2-1/2 to 24 in. (60 to 600 mm) and are temperature for the probe and/or thermometer. Equipment is
available in many temperature ranges, with or without ther- available to measure from –380°F to 2250°F (–230°C to
mometer wells. 1230°C). Common ranges used are +14°F to +248°F (–10°C
The advantage of dial thermometers is that they are more to 120°C).
rugged and more easily read than mercury thermometers.
4.3.11.3 Limitations
Small dial thermometers of this type usually use a bimetallic
temperature-sensing element in the stem. Temperature changes a. Batteries must be recharged or changed when required.
cause a change in the twist of the element, and this movement
b. In piping applications, it should be remembered that the
is transmitted to the pointer by a mechanical linkage.
surface temperature of the pipe is not equal to the fluid
The flexible capillary-type dial thermometer has a rather
temperature and that a relative comparison is more reli-
large temperature-sensing bulb, which is connected to the
able than an absolute reliance on readings at a single cir-
instrument with a capillary tube. The instrument contains a
cuit or terminal unit.
Bourdon tube, the same as in pressure gauges. The temperature-
c. Measurement must be taken at least as long as the
sensing system, consisting of the bulb, capillary tube, and Bour-
response time.
don tube, is charged with either liquid or gas. Temperature
changes at the bulb cause the contained liquid or gas to expand
4.3.11.4 Accuracy of Field Measurements. When
or contract, resulting in changes in the pressure exerted within
properly used, the instrument accuracy shall be attainable in
the Bourdon tube. This causes the pointer to move over a grad-
the field.
uated scale, as in a pressure gauge, except that the thermometer
4.3.11.5 Calibration Required. Every twelve months.
dial is graduated in degrees. The advantage of this type of ther-
In addition, check the thermometer against readings made
mometer is that it can be used to read the temperature in a remote
with a recently calibrated instrument on each project. If the
location. When a dial thermometer is used, the stem or bulb
reading is not within ±2% of the recently calibrated instru-
must be immersed a sufficient distance to allow this part of the
ment, have the instrument tested for calibration.
thermometer to reach the temperature being measured.
4.3.10.2 Recommended Uses. Dial thermometers are 4.4 Fluid Systems Measuring Instruments
suitable for checking both air and water temperature in ducts
4.4.1 Pyrometers
and pipe thermometer wells.
4.4.1.1 Description. Pyrometers normally used in
4.3.10.3 Limitations. Dial thermometers have a relatively
measurements of surface temperatures in heating and air-
long time lag, so enough time must be allowed for the thermom-
conditioning applications use a thermocouple as a sensing
eter to reach equilibrium and the pointer to come to rest.
device and a millivoltmeter (or potentiometer) with a scale
4.3.10.4 Accuracy of Field Measurements. Within calibrated for reading temperatures directly. A variety of
one-half of a scale division mark. types, shapes, and scale ranges are available. The required
4.3.10.5 Calibration Required. Check against read- instrument test accuracy is ±1% of full scale.
ings made with a recently calibrated instrument on each proj-
4.4.1.2 Recommended Uses
ect. If the reading is not within ±2% of the recently calibrated
instrument, have the instrument tested for calibration. a. Use to balance water circuits thermally whenever balanc-
4.3.11 Digital Electronic Thermometer ing by flow measurements are not practical.
4.3.11.1 Description. There are four basic types of elec- b. Use to evaluate some types of boilers, furnaces, ovens,
tronic thermometers: thermocouple, thermistor, RTD (resis- etc., where temperatures are over 100°F (40°C).
tance temperature detector), and diode sensors. They consist of
a portable, hand-held, battery-powered, digital thermometer 4.4.1.3 Limitations. In piping applications, it should be
connected by a short cable to a variety of interchangeable remembered that the surface temperature of the conduit is not
probes. The probes are designed for sensing the temperature of equal to the fluid temperature and that a relative comparison
air or other gases, of liquids by immersion in liquids, or of the is more reliable than an absolute reliance on readings at a sin-
surfaces of solids by contact with a solid surface. Some instru- gle circuit or terminal unit.
ments have a calibration reference that allows calibrating out 4.4.1.4 Accuracy of Field Measurements. Within one-
offsets introduced by mechanical shocks, ambient temperature half of a scale division mark.
variations, or component drift. Some instruments have F/C
4.4.1.5 Calibration Required. Every twelve months.
switching and 0.1/1.0 resolution switching. Response times are
4.4.2 Mercury U-Tube or Well-Type Manometer
1 to 10 s for liquids and solids, and 5 to 50 s for gases. Instru-
ment accuracy shall be ±0.5°F (±0.3°C) where the temperature 4.4.2.1 Description. The manometer is a simple and
is below 700°F (350°C) and ±1.5°F (±0.8°C) for temperatures useful means of measuring partial vacuum and pressure, both
of 700°F (350°C) and above. The lower range instruments shall for air and hydronic systems. In its simplest form, the manom-
be used for all measurements within their range. eter consists of a U-shaped glass tube partially filled with liq-
ANSI/ASHRAE Standard 111-2008 7
uid. A difference in height of the two fluid columns denotes a 4.4.3.5 Calibration Required. The gauge shall be cali-
difference in pressure in the two legs. brated against a dead-weight tester every 24 months. Also,
4.4.2.2 Recommended Uses check it against a recently calibrated test gauge on each project.
4.4.4 Differential Pressure Gauge
a. Use to measure pressure changes through coils, heat
4.4.4.1 Description. The differential pressure gauge is a
exchangers, and orifices.
dual inlet, “Grade A,” dual Bourdon tube pressure gauge with
b. Use to measure pressure changes across water circulators.
a single indicating pointer on the dial face that indicates the
c. Use to measuring gas pressures. pressure differential existing between the two measured pres-
sures. It can be calibrated in psi (kPa), inches of water (Pa), or
4.4.2.3 Limitations
inches of mercury (kPa). The required instrument accuracy
minimum is ±1% of full scale.
a. Manometer tubes shall be cleaned to ensure accuracy and
4.4.4.2 Recommended Uses
shall be filled with the correct fluid.
b. Use collecting safety reservoirs on each side of a mercury
a. This instrument, when furnished in one of the lower dif-
manometer to prevent blowing out mercury into the water
ferential pressure ranges and calibrated in inches of mer-
system, which can cause rapid deterioration of any copper
cury (kPa) or in inches of water (Pa), can be used with
it touches in the system.
water-hose flexible connectors for water distribution bal-
c. Mercury shall not be used for readings less than 1.0 in. of
ancing in much the same manner that the mercury U-tube
water (250 Pa). Corrections to direct readings are neces-
manometer is used.
sary to allow for the weight of the column of system fluid
b. This instrument, when furnished in one of the higher dif-
equal in height to the distance between manometer leg
ferential pressure ranges, can be used in place of the two
readings.
combination-type high pressure gauges mounted on the
d. Mercury shall not be used where it may become a con-
mercury U-tube manometer board.
taminant if the instrument becomes damaged.
4.4.4.3 Limitations. Some applications require use of a
4.4.3 Calibrated Pressure Gauge
snubber or needle valve. A three-valve cluster for shutoff and
4.4.3.1 Description. Test gauge shall be of a minimum bypass is necessary to prevent over-pressure damage when
“Grade A” quality and have Bourdon tube assemblies made of used as a portable test gauge.
stainless steel, alloy steel, monel, or bronze, and a nonreflect-
4.4.4.4 Accuracy of Field Measurements. Within one-
ing white face with black letter graduations conforming to
half of a scale division mark.
ANSI/ASME Standard B40.1-1985, Gauges: Pressure Indi-
cating Dial Type-Elastic Element.1 Test gauges are usually 4.4.4.5 Calibration Required. By a test agency every
24 months. Also, check the gauge against readings made with
3.5 to 6 in. (90 to 150 mm) in diameter with bottom or back
a recently calibrated instrument on each project. If the reading
connections. Many dials are available with pressure, vacuum,
is not within ±2% of the recently calibrated instrument, have
or compound ranges. Instrument minimum accuracy shall be
the instrument tested for calibration.
within 1% of full scale.
4.4.5 Differential Pressure Manifold Gauge
4.4.3.2 Recommended Uses. Use primarily for check-
ing pump pressures, coil, chiller, and condenser pressure 4.4.5.1 Description. This is a single-port, “Grade A,”
drops and pressure drops across orifice plates, venturis, and Bourdon-tube, calibrated test gauge (See Section 5.4c) with
other flow-calibrated devices.” an appropriate range for the differential pressure to be mea-
4.4.3.3 Limitations sured, attached to the bull of a tee. Each branch is fitted with
a tight shutoff ball valve and a length of hose, terminating in
a. Pressure ranges shall be such that the anticipated working a union and nipple for attachment to a conventional gauge port
pressure range is in the middle two-thirds of the scale at each measuring point.
range, and the gauge shall not be exposed to pressures 4.4.5.2 Recommended Uses
greater than the maximum dial reading. Similarly, where
there is exposure to vacuum, use a compound gauge. a. This instrument assembly is used to indicate the pressure
b. Reduce or eliminate pressure pulsations by installing a at each point by alternating valve opening and closing.
snubber or needle valve in the water line. b. By using the same gauge, the error from using two sepa-
c. Eliminate vibration by avoiding mounting on vibrating rate permanently mounted gauges, which are subject to
equipment or piping. Wall mounting is preferred. Another possible vibration damage and differences in calibration,
alternative is to install pressure/temperature test ports that can be eliminated.
can be used with a portable stem probe and gauge (or
thermometer) through an elastic, durable, self-sealing 4.4.5.3 Calibration Required. The instrument shall be
material. The test port shall be capped when not in use for verified with a recently calibrated instrument and, if the read-
additional sealing security. ing on the instrument to be verified is not within 2% of the
reading on the reference instrument (recently calibrated
4.4.3.4 Accuracy of Field Measurements. Within one- instrument), then the instrument must be calibrated before it
half of a scale division mark. can be used.
8 ANSI/ASHRAE Standard 111-2008
4.5 Other Measuring Instruments for Certain Situations the frequency of the rotating machine, the machine will
(Air or Fluid Systems) appear to stand still. This unit need not be in contact with the
machine when it is being used. The instrument accuracy is
a. revolution counter and timing device generally within 1.5% of the indicated value and within 1% if
b. electronic tachometers (stroboscope and photoelectric) a magnetic pickup is used.
c. dual-function tachometer The solid-state photoelectric tachometer is an optional
d. U-tube manometer (low-density fluid) instrument that is pointed at the device to be measured and the
e. diaphragm-type differential-pressure gauges rpm is directly read on the dial face. A reflective paint or mate-
f. smoke devices rial must be spotted on the rotating device, which is actually
g. sling psychrometer counted and electronically integrated over time to give an
h. flow-measuring hoods instantaneous rpm reading. The instruments usually have
i. micromanometer (hook gauge) several ranges, and no electrical or physical contact with the
j. double-reverse tube device is necessary. Accuracy is within ±1% of the dial scale
k. clamp-on AC power meter reading when properly calibrated.
l. recording instruments 4.5.2.2 Recommended Uses. Use to measure rotational
m. humidity-measuring devices speeds when instrument contact with the rotating equipment
n. barometer is not feasible.
o. electronic digital flow and differential-pressure meter 4.5.2.3 Limitations. Care must be taken to avoid read-
p. ultra-sonic flowmeters ing multiples of the actual rpm when using the stroboscope.
q. turbine flowmeters Readings must be started at the lower end of the scale.
r. variable-area flowmeters 4.5.2.4 Accuracy of Field Measurements. Within one-
half of a scale division.
4.5.1 Revolution Counter (Odometer) and
4.5.2.5 Calibration Required. The instrument is self
Timing Device
calibrating to an extent but shall be checked every 24 months.
4.5.1.1 Description. The revolution counter is a small
Also, check it against readings made with a recently cali-
hand-held counting device that is pressed to the center of a
brated instrument on each project. If the reading is not within
rotating shaft for a period of 30 to 60 s. Reasonable accuracy
±2% of the recently calibrated instrument, have the instru-
can be obtained by using a good watch with a sweep second
ment tested for calibration.
hand or a digital watch if a stopwatch is not available.
4.5.3 Dual-Function Tachometer
4.5.1.2 Recommended Uses. Use to determine shaft
4.5.3.1 Description. The dual-function tachometer pro-
speed on any shaft having an accessible shaft end with a coun-
vides both optical and contact measurements of rotation and
tersink.
linear motions. Many allow a choice of ranges, depending on
4.5.1.3 Limitations the application. A digital display always indicates the unit of
measurement to identify the operating range. A memory but-
a. Not to be used on shafts with flat ends without the correct
ton may be used to recall the last, maximum, minimum, and
adaptor. (Slip and inaccurate readings are inevitable.)
average readings. Compact size and light weight make for
b. Some types of these devices feature a clutch engagement
easy operation.
in which a certain amount of force is required to activate
4.5.3.2 Recommended Uses. Use to measure rotation
the recording mechanism.
speeds by direct contact or by counting the speed of a reflec-
c. The instrument must be used with and coordinated with
tive mark.
an accurate timepiece.
4.5.3.3 Limitations. Battery operated.
d. This instrument cannot normally be reset to zero; the
shaft speed measured is the difference between the initial 4.5.3.4 Accuracy of Field Measurements. Within one-
and final instrument readings divided by the time interval. half of a scale division.
4.5.3.5 Calibration Required. Instrument is self cali-
4.5.1.4 Accuracy of Field Measurement. ±2%, when brating to an extent but shall be checked every 24 months. In
used properly. addition, check it against readings made with a recently cali-
4.5.1.5 Calibration Required. Check the instrument brated instrument on each project. If the reading is not within
against readings made with a recently calibrated instrument ±2% of the recently calibrated instrument, have the instru-
on each project. If the reading is not within ±2% of the ment tested for calibration.
recently calibrated instrument, have the instrument tested for 4.5.4 Low Density Fluid U-Tube Manometer
calibration. 4.5.4.1 Description. The manometer is a simple and use-
4.5.2 Electronic Tachometer (Stroboscope and ful means of measuring partial vacuum and pressure. In its sim-
Photoelectric) plest form, the manometer consists of a U-shaped glass tube
4.5.2.1 Description. The stroboscope has a controlled partially filled with liquid; a difference in height of the two fluid
high-speed electronic flashing light. The frequency of the columns denotes a pressure difference in the two legs.
flashing light is electronically controlled and adjustable. 4.5.4.2 Recommended Uses. Use for air and gas
When the frequency of the flashing light is adjusted to equal streams (with water or oil in the instrument).
ANSI/ASHRAE Standard 111-2008 9