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| EN
EIOM v2018.04
8. AIR FILTER SECTION
The air filters in a ventilation system prevent dust and other impurities reaching the premises. They also protect sensitive components in the air
handling unit, such as air heaters, coolers and heat exchangers from contamination.
Changing of filter should be primarily based on clogging, indicated by final pressure drop. Both visual inspection and monitoring of pressure drop
is recommended.
Pressure drop indication:
Differential pressure switch or transmitter can be used for monitoring of filter contamination.
Pressure difference before and after the filter is generated, when filter performance of ventilation device changes.
Figure 8.1- Differential pressure switch / transmitter and pressure tubes mounting scheme with filter:
1 – Differential pressure switch / transmitter; 2 – Filter; 3 – Air flow before filter; 4 – Air flow after filter;
Differential pressure switch (digital output signal):
Figure 8.2 - Differential pressure switch
Figure 8.3 - Differential pressure switch wiring diagram:
1 – Cover; 2 – Differential pressure selection wheel; 3 – Cable gland;
4 – Pressure tubes;
NO – normally open; NC – normally closed; COM – common;
Differential pressure transmitter (analogue output signal):
The SPS series transmitters provide an analogue / digital output and eight selectable measuring windows. They are equipped with Modbus RTU
communication. These make the units suitable for a wide range of applications. The SPS transmitters are calibrated and temperature & pressure
compensated. They feature a high degree of reliability and accuracy.
Figure 8.4 - Differential pressure transmitter:
Figure 8.5 - Differential pressure transmitter wiring diagram:
1 – Cover; 2 – Pressure tubes; 3 – Cable gland;
1 – Power supply (13-26VAC/ 18-34VDC); 2 – Modbus RTU; 3 –
Analogue output;
NOTE: For more information, control, maintenance, diagnostics and troubleshooting refer to differential pressure switch / transmitter
technical specification.
