ASTM D3796-09

Standard Practice for Calibration of Type S Pitot Tubes

SIGNIFICANCE AND USE
The Type S pitot tube (Fig. 1) is often used to measure the velocity of flowing gas streams in industrial smokestacks and ducts. Before a Type S pitot tube is used for this purpose, its coefficients must be determined by calibration against a standard pitot tube (2).
SCOPE
1.1 This practice covers the determination of Type S pitot tube coefficients in the gas velocity range from 305 to 1524 m/min or 5.08 to 25.4 m/s (1000 to 5000 ft/min). The method applies both to the calibration of isolated Type S pitot tubes (see 5.1), and pitobe assemblies.
1.2 This practice outlines procedures for obtaining Type S pitot tube coefficients by calibration at a single-velocity setting near the midpoint of the normal working range. Type S pitot coefficients obtained by this method will generally be valid to within ±3 % over the normal working range. If a more precise correlation between Type S pitot tube coefficient and velocity is desired, multivelocity calibration technique (Annex A1) should be used. The calibration coefficients determined for the Type S pitot tube by this practice do not apply in field use when the flow is nonaxial to the face of the tube.
1.3 This practice may be used for the calibration of thermal anemometers for gas velocities in excess of 3 m/s (10 ft/s).  
1.4 The values stated in SI units are to be regarded as standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Sep-2004
• ICS: 17.020 - Metrology and measurement in general
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.03 - Ambient Atmospheres and Source Emissions

Relations

• Replaces: ASTM D3796-90(2004) - Standard Practice for Calibration of Type S Pitot Tubes
• Effective Date: 01-Oct-2004
• Replaced By: ASTM D3796-09(2016) - Standard Practice for Calibration of Type S Pitot Tubes
• Effective Date: 01-Sep-2016
• Referred By: ASTM D6331-16 - Standard Test Method for Determination of Mass Concentration of Particulate Matter from Stationary Sources at Low Concentrations (Manual Gravimetric Method)
• Effective Date: 01-Oct-2004
• Referred By: ASTM D6831-11(2018) - Standard Test Method for Sampling and Determining Particulate Matter in Stack Gases Using an In-Stack, Inertial Microbalance
• Effective Date: 01-Oct-2004
• Referred By: ASTM D3685/D3685M-13(2021) - Standard Test Methods for Sampling and Determination of Particulate Matter in Stack Gases
• Effective Date: 01-Oct-2004
• Referred By: ASTM D6784-16 - Standard Test Method for Elemental, Oxidized, Particle-Bound and Total Mercury in Flue Gas Generated from Coal-Fired Stationary Sources (Ontario Hydro Method)
• Effective Date: 01-Oct-2004
• Referred By: ASTM D3154-14(2023) - Standard Test Method for Average Velocity in a Duct (Pitot Tube Method)
• Effective Date: 01-Oct-2004
• Referred By: ASTM D3464-96(2023) - Standard Test Method for Average Velocity in a Duct Using a Thermal Anemometer
• Effective Date: 01-Oct-2004

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D3796 − 09
StandardPractice for
1
Calibration of Type S Pitot Tubes
This standard is issued under the fixed designation D3796; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 Definitions:
3.2.1 isolated Type S pitot tube—any Type S pitot tube that
1.1 This practice covers the determination of Type S pitot
is calibrated or used alone (Fig. 1).
tube coefficients in the gas velocity range from 305 to 1524
3.2.2 normal working velocity range—the range of gas
m/min or 5.08 to 25.4 m/s (1000 to 5000 ft/min). The method
velocities ordinarily encountered in industrial smokestacks and
applies both to the calibration of isolated Type S pitot tubes
ducts: approximately 305 to 1524 m/min or 5.08 to 25.4 m/s
(see 5.1), and pitobe assemblies.
(1000 to 5000 ft/min).
1.2 This practice outlines procedures for obtaining Type S
3.2.3 pitobe assembly—any Type S pitot tube that is cali-
pitot tube coefficients by calibration at a single-velocity setting
brated or used while attached to a conventional isokinetic
near the midpoint of the normal working range. Type S pitot
source-sampling probe (designed in accordance with Martin
coefficients obtained by this method will generally be valid to
3
(1) or allowable modifications thereof; see also Fig. 7).
within 63 % over the normal working range. If a more precise
correlation between Type S pitot tube coefficient and velocity
4. Summary of Practice
is desired, multivelocity calibration technique (Annex A1)
should be used. The calibration coefficients determined for the
4.1 The coefficients of a given Type S pitot tube are
TypeSpitottubebythispracticedonotapplyinfieldusewhen
determined from alternate differential pressure measurements,
the flow is nonaxial to the face of the tube.
made first with a standard pitot tube, and then with the Type S
pitot tube, at a predetermined point in a confined, flowing gas
1.3 This practice may be used for the calibration of thermal
stream. The Type S pitot coefficient is equal to the product of
anemometers for gas velocities in excess of 3 m/s (10 ft/s).
the standard pitot tube coefficient, C (std), and the square root
p
1.4 The values stated in SI units are to be regarded as
of the ratio of the differential pressures indicated by the
standard.
standard and Type S pitot tubes.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Significance and Use
responsibility of the user of this standard to establish appro-
5.1 The Type S pitot tube (Fig. 1) is often used to measure
priate safety and health practices and determine the applica-
the velocity of flowing gas streams in industrial smokestacks
bility of regulatory limitations prior to use.
and ducts. Before a Type S pitot tube is used for this purpose,
2. Referenced Document its coefficients must be determined by calibration against a
2
standard pitot tube (1).
2.1 ASTM Standards:
D1356 Terminology Relating to Sampling and Analysis of
6. Apparatus
Atmospheres
6.1 Flow System—Calibration shall be done in a flow
3. Terminology
system designed in accordance with the criteria illustrated in
3.1 For definitions of terms used in this test method, refer to
Fig. 2 and described in 6.1.1 through 6.1.5.
Terminology D1356.
6.1.1 The flowing gas stream shall be confined within a
definite cross-sectional area; the cross section shall be prefer-
1
This practice is under the jurisdiction of ASTM Committee D22 on Air
ably circular or rectangular (2). For circular cross sections, the
Quality and is the direct responsibility of Subcommittee D22.03 on Ambient
minimum duct diameter shall be 305 mm (12 in.). For
Atmospheres and Source Emissions.
rectangular cross sections, the width shall be at least 254 mm
Current edition approved Oct. 1, 2009. Published October 2009. Originally
approved in 1979. Last previous edition approved in 2004 as D3796 – 90 (2004). (10 in.). Other regular cross-section geometries (for example,
DOI: 10.1520/D3796-09.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3
Standards volume information, refer to the standard’s Document Summary page on The boldface numbers in parentheses refer to the list of references at the end of
the ASTM website. this practice.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D3796 − 09
FIG. 1 Isolated Type-S Pitot Tube
FIG. 2 Pitot Tube Calibration System
he
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:D3796–90 (Reapproved 2004) Designation: D3796 – 09
Standard Practice for
1
Calibration of Type S Pitot Tubes
This standard is issued under the fixed designation D3796; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice covers the determination of Type S pitot tube coefficients in the gas velocity range from 305 to 1524 m/min
or 5.08 to 25.4 m/s [1000(1000 to 5000 ft/min].ft/min). The method applies both to the calibration of isolated Type S pitot tubes
(see 5.1), and pitobe assemblies.
1.2 This practice outlines procedures for obtaining Type S pitot tube coefficients by calibration at a single-velocity setting near
themidpointofthenormalworkingrange.TypeSpitotcoefficientsobtainedbythismethodwillgenerallybevalidtowithin 63%
over the normal working range. If a more precise correlation between Type S pitot tube coefficient and velocity is desired,
multivelocity calibration technique (Annex A1) should be used.
1.3This practice may be used for the calibration of thermal anemometers for gas velocities in excess of 3 m/s [10 ft/s].
1.4) should be used. The calibration coeffıcients determined for the Type S pitot tube by this practice do not apply in field use
when the flow is nonaxial to the face of the tube.
1.3 This practice may be used for the calibration of thermal anemometers for gas velocities in excess of 3 m/s (10 ft/s).
1.4 The values stated in SI units are to be regarded as standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Document
2
2.1 ASTM Standards:
D1356 Terminology Relating to Sampling and Analysis of Atmospheres
3. Terminology
3.1 For definitions of terms used in this test method, refer to Terminology D1356.
3.2 Definitions:
3.2.1 isolated Type S pitot tube—any Type S pitot tube that is calibrated or used alone (Fig. 1).
3.2.2 normal working velocity range—the range of gas velocities ordinarily encountered in industrial smokestacks and ducts:
approximately 305 to 1524 m/min or 5.08 to 25.4 m/s [1000(1000 to 5000 ft/min]. ft/min).
3.2.3 pitobe assembly—any Type S pitot tube that is calibrated or used while attached to a conventional isokinetic
3
source-sampling probe (designed in accordance with Martin (1) or allowable modifications thereof; see also Fig. 7).
4. Summary of Practice
4.1 The coefficients of a given Type S pitot tube are determined from alternate differential pressure measurements, made first
with a standard pitot tube, and then with the Type S pitot tube, at a predetermined point in a confined, flowing gas stream. The
Type S pitot coefficient is equal to the product of the standard pitot tube coefficient, C (std), and the square root of the ratio of
p
the differential pressures indicated by the standard and Type S pitot tubes.
5. Significance and Use
5.1 The Type S pitot tube (Fig. 1) is often used to measure the velocity of flowing gas streams in industrial smokestacks and
ducts. Before aType S pitot tube is used for this purpose, its coefficients must be determined by calibration against a standard pitot
tube (2).
1
This practice is under the jurisdiction of ASTM Committee D22 on Air Quality and is the direct responsibility of Subcommittee D22.01 on Quality Control.
Current edition approved Oct. 1, 2004.2009. Published December 2004.October 2009. Originally approved in 1979. Last previous edition approved in 19982004 as
D3796 - 90 (1998).(2004). DOI: 10.1520/D3796-90R04.10.1520/D3796-09.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The boldface numbers in parentheses refer to the list of references at the end of this practice.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
D3796 – 09
FIG. 1 Isolated Type-S Pitot Tube
6. Apparatus
6.1 Flow System—Calibration shall be done in a flow system designed
...