BS 848-1:1980

Foreword; Cooperating organizations; Methods
Section one. General
1. Scope; 2. References; 3. Definitions
4. Symbols and units
4.1 Symbols; 4.2 Subscripts; 4.3 Multiples and sub-
multiples
5. Instrumentation for measurement of pressure
5.1 Barometers; 5.2 Manometers; 5.3 Damping of
manometers; 5.4 Checking of manometers
6. Determination of average static pressure in an
      airway
6.1 Use of wall tappings; 6.2 Use of wall tappings;
6.4 Position and connections; 6.5 Checks for
compliance; 6.6 Use of pitot-static tube
7. Measurement of temperature
7.1 Thermometers; 7.2 Thermometer location;
7.3 Humidity; 7.4 Influence of air velocity
8. Determination of density
8.1 Density of the air in the test enclosure; 8.2
Average density of the air in an airway section; 8.3
Determination of vapour pressure
9. Measurement of rotational speed
9.1 Fan shaft speed; 9.2 Examples of acceptable
methods
10. Determination of power input
10.1 Measurement accuracy; 10.2 Fan shaft power;
10.3 Electrical instruments; 10.4 Impeller power;
10.5 Transmission systems
11. Measurement of dimensions and determination of
      areas
11.1 Flow measurement devices; 11.2 Tolerance on
dimensions; 11.3 Determination of cross-sectional area
12. Determination of flow rate
12.1 General; 12.2 In-line flowmeters (standard
primary devices); 12.3 Traverse methods
13. Calculation of the results of a test
13.1 General; 13.2 Units; 13.3 Temperature; 13.4
Dynamic pressure and fan dynamic pressure; 13.5 Fan
static pressure and fan total pressure; 13.6 Inlet
volume flow; 13.7 Fan efficiencies (compressible flow);
13.8 Approximation for low pressure fans
14. Conversion rules for spped, air conditions & size
14.1 Direct and indirect tests; 14.2 Conversion of
direct test; 14.3 Conversion of indirect tests; 14.4
Change of size; 14.5 Requirements for conversion
15. Fan characteristics
15.1 General; 15.2 Methods of plotting; 15.3 Constant
speed characteristic;15.4 Inherent speed characteristic
15.5 Adjustable duty fan characteristic; 15.6 Complete
fan characteristic; 15.7 Test for a specified duty
16. Uncertainty of measurement
16.1 Performance errors; 16.2 Uncertainty of measure-
ment; 16.3 Specified uncertainties; 16.4 Uncertainty
of fan performance determination; 16.5 Site tests; 16.6
Precision tests
Section two. Tests with standardized airways
17. Selection of test method
17.1 Classification; 17.2 Installation types; 17.3
Reporting of test; 17.4 User's installations; 17.5
Alternative methods; 17.6 Duct simulation
18. Installation of fan and test airways
18.1 Inlets and outlets; 18.2 Airways; 18.3 Test
enclosure; 18.4 Matching fan and airway; 18.5 Outlet
area
19. Operation of test
19.1 Working fluid; 19.2 Rotational speed; 19.3
Steady operation; 19.4 Ambient conditions; 19.5
Pressure readings; 19.6 Tests for a specified duty;
19.7 Tests for a fan characteristic; 19.8 Operating
range
20. Determination of flow rate by venturi nozzle
20.1 Geometric form; 20.2 Venturi nozzle in free inlet
condition; 20.3 Nozzle performance; 20.4 Uncertainties
21. Determination of flow rate by conical inlet
21.1 Geometric form; 21.2 Screen loading; 21.3 Inlet
zone; 21.4 Conical inlet performance; 21.5
Uncertainties
22. Determinatoin of flow rate by orifice plate
22.1 Installation; 22.2 Orifice plate; 22.3 Ducts;
22.4 Pressure tappings; 22.5 Calculation of mass flow;
22.6 In-duct orifice with D and D/2 taps; 22.7 In-duct
orifice with corner taps; 22.8 Outlet orifice with wall
tappings; 22.9 Inlet orifice with corner taps; 22.10
Expansibility factor; 22.11 Reynolds number
23. Determination of flow rate by pitot-static tube
traverse
23.1 General; 23.2 Pitot-static tube; 23.3 Limits
of air velocity; 23.4 Location of measuring points;
23.5 Determination of flow rate; 23.6 Flow coefficient
23.7 Uncertainty of measurement
24. Common airway sections for ducted fan installations
24.1 Common parts; 24.2 Common part at fan outlet;
24.3 Common part at fan inlet; 24.4 Outlet duct
simulation; 24.5 Inlet duct simulation; 24.6 Loss
allowances for standardized airways
25. Component parts of standardized airways
25.1 Symbols; 25.2 Component parts; 25.3 Flow
measurement devices; 25.4 Meaning of subscripts
26. Standardized inlet side test chambers
26.1 Test chamber; 26.2 Fan under test; 26.3 Pressure
tappings; 26.4 Flow uniformity; 26.5 Flow control;
26.6 Leakage; 26.7 Fan powered exhaust ventilators
27. Standardized test methods with inlet side test
      chambers: type A
27.1 Methods for type A installations; 27.2
Measurements taken during test; 27.3 Calculations;
27.4 Fan performance; 27.5 Use of inlet side chambers
with inlet and outlet duct simulation
28. Standardized test methods with outlet side test
      ducts: type B
28.1 Methods for type B installations; 28.1 Measure-
ments taken during test; 28.3 Calculations; 28.4 Fan
performance
29. Standardized test methods with inlet side test
      ducts: type C
29.1 Methods for type C installations; 29.2 Measure-
ments taken during test; 29.3 Calculations; 29.4 Fan
performance
30. Standardized test methods with inlet and outlet
      test ducts: type D
30.1 Methods for type D installations; 30.2 Measure-
ments taken during test; 30.3 Calculations; 30.4 Fan
performance
Section three. Site tests
31. Introduction; 32. Instructions for site testing
32.1 General conditions; 32.2 Method of varying
operating points
33. Location of measurement planes
33.1 Location of flow measurement plane; 33.2 Location
of pressure measurement plane
34. Measurement of air velocity on site
34.1 Instruments for air velocity measurement; 34.2
Pitot-static tube; 34.3 Anemometer; 34.4 Siting of
measuring points
35. Determination of flow rate on site
35.1 Pitot-static tube; 35.2 Anemometer; 35.3 Deter-
mination of cross-sectional area of airway on site;
35.4 Uncertainty of measurement
36. Determination of fan pressure on site
36.1 General; 36.2 Measurement of static pressure on
site; 36.3 Extract fans; 36.4 Blowing fans; 36.5
Booster fans
37. Determination of power input on site
37.1 Power measurement; 37.2 Transmission systems;
37.3 Other prime movers; 37.4 Special precautions for
site tests
Appendices
A. Tolerances; B. Uncertainty calculations for fan
performance; C. Conversion rules for compressible flow;
D. Friction allowance for straight, smooth ducts; E.
Conversion factors for SI units
Tables
1. Saturation vapour pressures; 2. Uncertainties of
flow rate determination; 3. Ciruclar ducts: measure-
ment positions for 6, 8 and 10 points per diameter by
the log linear rule; 4. Rectangular sections: positions
of measuring points and traverse lines by the log
Tchebycheff rule
Figures
1. Construction of wall pressure tappings; 2. Tapping
connections to obtain average static pressure; 3.
Pressure loss and pressure difference of standard
primary devices; 4. NPL modified ellipsoidal-nosed
standard pitot-static tube; 5. Chart for the deter-
mination of compressibility coefficient kp; 6. Dynamic
viscosity of atmospheric air; 7. Example of a complete,
constant-speed, fan characteristic; 8. Example of an
adjustable-duty fan characteristic; 9. Example of test
for a specified duty; 10. Uncertainty in fan total
pressure from a standardized airway test; 11. Uncertain-
ties in characteristic error and fan total efficiency
from a standardized airway test; 12. Venturi nozzle
geometry; 13. Flow metering installations; 14. Compound
flow coefficients of venturi nozzles; 15. Conical inlet
geometry; 16. Compound flow coefficient of conical
inlets; 17. Orifice plates and assemblies; 18. Flow
coefficients of in-duct orifices with D and D/2 taps;
19. Flow coefficents of in-duct or outlet orifices with
corner taps; 20. Compound flow coefficients of outlet
orifices with wall taps; 21. Flow coefficients of inlet
orifices with corner taps; 22. Expansibility factor
epsilon for orifice plates in atmospheric air; 23.
Location of positions for traverse measurements in
standardized airways; 24. Friction allowance factors for
standardized airways; 25. Inlet side test chamber; 26.
Inlet-chamber methods for type A installations; 27.
Standardized airways for free inlet, ducted outlet, type
B installations; 28. Standardized airways for ducted
inlet, free outlet, type C installations; 29. Standard-
ized airways for ducted inlet, ducted outlet, type D
installations; 30. Locations of flow measurement plane
for site testing; 31. Location of pressure measurement
planes for site testing; 32. Location of velocity
measurements in rectangular sections on site; 33.
Location of velocity measurements in a circular arched
section on site; 34. Application of modified log
Tchebycheff rule for traverse patterns in airway
sections of other than circular and rectangular form;
35. Error diagram; 36. Example of uncertainty in a fan
characteristic; 37. Duct friction allowance

Determination of performance of industrial fans of all types other than for air circulation. Specifies 4 standard installation types and methods of measurement and calculation. Also gives methods of test for determining volume flow rate and for fan pressure under site conditions. Provides estimates of uncertainty of measurement with rules for conversion within specified limits.