BS 848-9:2006 pdf free.Fans for generalpurposes — Tolerances, methods ofconversion and technical data presentation.
BS 848-9 lf the supplier cannot refer to catalogue information,installation， maintenance or operation instructions, heshall generally provide the following information.
a) Operational parameters at design conditions, especially volume or mass flow, fan pressure, absorbed power and fan speed.The exact scope of supply, as well as any other accessories that the supplierconsiders necessary for installation and connection (e.g. motors,devices to prevent accidental contact.flexible connectors, control and shut-off devices, inlet boxes).
b)The major dimensions for connection, installation and transport.
c)The total mass of the assembly and the mass of the essential components supplied.
d)lmportant design features where essential for assembly, e.g. materials of construction. Other information should be supplied on request, or if necessary.
e)Motor output power.
f) Other information, e.g. the electric or pneumatic connected load, provision of sealing gas, cooling air and water.
g)lnstallation, operation, and maintenance instructions.
NOTE ln many installations the electric drive motor is supplied directly by the supplier. As such, it may not bepossible to state the type of drive, its rating and speed, etc.
The following information may also be provided.
a)Fan power(see lSO 5801) as a function of the parameters listed in 5.1.
b) Rotational speed of the impeller as a function of the parameters listed in 5.1, and maximum permissible rotational speed.
c)A-weighted sound power level as specified in lS0 13347-1.Sound pressure levels are not recommended as they can be heavily influenced by the room acoustics and sound propagation from connecting ducts. Inaddition, they can be significantly influenced by directional characteristics, especially if the fan is of theopen-inlet or outlet type. Sound pressure levels can only be stated under free-field conditions and maynot be representative of actual room conditions.
Measuring uncertainties shall be considered differently from manufacturing tolerances.
At each stage of the fan design and manufacturing cycle, including conversion from prototype performancedata or calculation，fabrication and testing of a purpose-designed fan, finite uncertainties will prevail andacceptance tolerances shall be applied.
Zero or exclusively positive tolerances can neither be supported in theory or practice and are notrecommended.
Uncertainties are spurious, random or systematic factors which affect design, fabrication and therefore fanperformance. Uncertainties are not absolute and because of this are handled statistically, i.e. a level ofconfidence is attributed to the measured quantity lying within the uncertainty boundary of the true value.
Tolerances are the definition of acceptability for uncertainties. They are absolute and can vary according tothe application. They effectively define an absolute limit for uncertainties which would otherwise have to beexpressed statistically. The user is therefore provided with an absolute criteria for fan selection andacceptance.BS 848-9 pdf download.