Honeywell F-BO-AFE70 Series Installation, Connection, Commissioning, Maintenance

Contents

Honeywell F-BO-AFE70 Series Installation, Connection, Commissioning, Maintenance Manual pdf 16 page image

Chapter 4 • Pneumatic components – dimensioning User Manual Series F-BO-AFE70There is a tool based on a spreadsheet which makes this dimensioning easier. In order to use it,you need the following parameters:- Ambient temperature- Number of aspiration holes- Diameter of aspiration holes- Air vessel overpressure- Actual input overpressureThe compressed air must always be clean and free from oil and water or other contamination. Ifcompressed air is used which is not sufficiently purified, these contaminations can result in mal-functions of the Purging unit or of the aspirating smoke detector. For example, the valve pistonsystem of the Purging unit can ice up or the measuring device of the aspirating smoke detectorcan become oily, and therefore can become useless or can even be destroyed. This can also leadto false alarms or increased contamination of the aspirating smoke detector as a result of particlesin the compressed air, which are again drawn in by the evaluation unit of the aspirating smokedetector after a Purging process.Metal shavings, other foreign particles or liquids in compressed-air lines must not get into thePurging unit because otherwise the Purging unit can be damaged.As recommended value for the purity of compressed air, Class 2 according to ISO8573-1:2010should be used, which for oil permits a limit value of max. 0.1mg/m³ of compressed air. Thisvalue also makes sense with regard to the durability of the compressed-air lines.During the Purging process the Automatic Purging Units Series F-BO-AFE70 briefly need a verylarge amount of air which is withdrawn from the compressed-air vessel of the compressed-air sup-ply. The air output capacity of a compressor is only of secondary importance for the dimensioningof the compressed-air supply of the Purging unit because usually the time between two Purgingprocesses is very long and therefore the compressor has sufficient time for charging the com-pressed-air vessel. Therefore, only the dimensioning of the compressed-air vessel is dealt withbelow.Fig. 3: Typical construction of a compressed-air system for providing the required compressed-airvolume of an Automatic Purging Unit Series F-BO-AFE70, and explanation of the terms used inthis chapter and by the calculation tool.A … Air vessel overpressure: This is the pressure that prevails in the compressed-air vessel – aswell as the reference value that has been set on the compressor and at which the compressorshould turn itself on again.B … Input overpressure: This is the pressure at the Purging unit's input (compressed-air connec-tion) that results from the number and size of aspiration holes, from the flow rate of thesolenoid valve that has been installed in the Purging unit, as well as from the pressurelosses in the compressed-air supply pipe.C … Pressure regulator (option): The pressure regulator SHOULD be used whenever the avail-able air vessel overpressure is markedly higher than the recommended input overpressure,and MUST be used whenever the air vessel overpressure is higher than the maximum inputoverpressure of the F-BO-AFE70 used.If several Purging units are supplied by the same compressed-air vessel, it is also possibleto use one pressure regulator for several Purging units. But in this case, please note themaximum possible flow rate of the pressure regulator.Tables 6 and 7 contain approximate values for the calculation of the minimum size of the com-pressed-air vessel of the compressed-air system, depending on the air vessel overpressure and thechosen input overpressure of the respective Purging unit. The result of the table is given in litresper second of operation of the solenoid valve, and therefore it still has to be multiplied by theI56-4252-010D200-104-0016