Sensor type filter monitor can only function if the air flow through the filter is being measured or calculated.

The airflow utilized by the filter monitor differs if the AHU is recirculation capable or not:


Filter type

Filter air flow

(No recirculation)

Filter air flow

(With recirculation)

Supply air pre filter

Supply air fan flow

Exchanger supply air flow

Supply air filter

Supply air fan flow

Exchanger supply air flow

Supply air end filter

Supply air fan flow

Supply air fan flow

Extract air pre filter

Extract air fan flow

Calculated extract air flow

Extract air filter

Extract air fan flow

Calculated extract air flow


  • Supply air fan flow = direct measurement over supply air fan
  • Extract air fan flow = direct measurement over extract air fan
  • Exchanger supply air flow = direct measurement over exchanger (supply air)
  • Calculated extract air flow = [Extract air fan flow] + [Supply air fan flow] – [Exchanger Supply air flow]


The alarm limit is determined by the linear dependency curve of the pressure drop at airflow through the filter. The low point of the curve starts at "0" (both pressure drop and air flow).

The high point can be adjusted manually or set by the filter calibration function.


Filter condition is determined by its working point relative to the filter alarm limit curve:

 

  1. Pressure drop of the filter is lower than the alarm limit - filter is OK.
  2. Pressure drop of the filter is higher than the alarm limit - filter is dirty and should be replaced.
  3. The readings of the filter pressure drop are unreliable at low airflow - filter alarm is blocked.




Each of the filters share the similar setup steps as shown in the example:


Configuration and settings for sensor type filter monitoring






Variable

Available options & Selection

Note





Activate filter monitoring function




Configuration > Functions > Function activation




Filter monitoring

| Yes | No |






Configuration of filter monitoring function




Configuration > Functions > Filter monitoring







Supply air filter

| No | Sensor | Guard |

Selecting monitor type for appropriate filters




Filter classification

| - | G2..G4 | M5..M6 | F7..F9 | HEPA | Carbon filter |

Select filter classification if calibration will be used to determine the final pressure drop







Min limit reference flow alarm interlock

[20] %

Filter alarms stays disabled until airflow through filter is at least 20% of the alarm limit flow








Configure input




Configuration > I/O allocation settings > Analog inputs >




Pressure filter supply air

Any available I/O









Operational settings




Data & Settings > Filter monitoring > Supply air filter > Manual alarm limit




Final pressure drop at filter air flow

[150] Pa

Set Pressure drop / Air flow at which filter is considered dirty




Filter air flow

[2000] m3/h




Data & Settings > Filter monitoring > Supply air filter




Reference flow

Supply air fan flow |

Exchanger supply air flow

Indication of the airflow which is passing through the filter




Final pressure drop at filter airflow

150 Pa

Indication of alarm limit

(set manually or calibrated)




Filter air flow

2000 m3/h





Overview




Data & Settings > Operation overview > Filter monitoring




Pressure filter supply air

_ Pa

Actually measured pressure drop of the filter







Calculated filter alarm limit

_ Pa

Maximal acceptable filter pressure at actual air flow





Chapter info                              

Last reviewed: 09/14/2021

Access version: 4.6-1-00 (3068)