PS12

Indicator with double Display

In the distance installable, it displays the emissions in mg/Nmc, receiving the 4-20 mA output signal of the dust detectors model:
 
   TD-DIP-4,  TD4

    It calculates the average value of the dust concentration and it shows contemporaneously the average and peak values.

   Two Relays signalise the overcoming of the settled thresholds.

       BROCHURE  (PS12_DEPL.doc)

TD-DIP-4

Suitable for the EMISSION MEASURING
acquired and calculated by a PLC or PC

  -    4-20 mA galvanic insulated output and Relay outlet

  -   Bargraph display with 10 steps for a quick indication of the dust emission 

     BROCHURE  (TD-DIP-4_DEPL1.doc)

 TD-4

Suitable for the EMISSION MEASURING
acquired and calculated by a PLC or PC

  -   4-20 mA galvanic insulated output only

  -   4 LEDs give an approximative display

      BROCHURE  (TD-4_DEPL.doc)
 

ABSTRACT

Since time ago, even the official authorities agree the best way to detect failures in filter plants is to install systems for the continuous monitoring of the dust leakages, rather than the periodical gravimetric measures. This, because a filter failure may happen even just after that the periodic gravimetric sample has been performed.

In Italy, some local authorities dispense from the duty of the periodic gravimetric measures, firms which use systems for the continuous monitoring of the dusts emissions.

 The isokinetic sample will be always kept as reference test for fiscal controls and as reference value for the calibration of other dust monitoring systems

 The major benefit of a continuous monitoring compared to the periodical samples, is to discover a filter failure when the damage and the leakage are still in the very early status. Operating in the proper way on the filter, prevents dust emissions over the admitted limits.

In filters which are cleaned using compressed air jets, the shacking of the filter's cloth causes the emission of the dust, that trend to occlude the tear in the filter's cloth, as well as the emission of the dust deposited near of it.

The actions of the air shots, allow to detect punctures wide even only 1 cm² opened on surfaces hundreds of m² wide.

 ANTI-POLLUTION PREVENTION
 When a dust leakage generates an alarm, it is possible to correlate the alarm with the damaged filter's element (bag or cartridge), which has caused it. This allows to identify the damaged filter's element and to unplug the electrovalve which had had performed its cleaning, until that the ordinary filter's maintenance will be performed and the damaged element will be replaced.
In this way it is possible to continue to let the filter works without to pollute and without stop to work.   

THE PRESENCE OF THE DELTA-P MEASURE 
The measure of the differential pressure of the filter is employed in the clean of filters, in order to use the lower possible cleaning frequency and consequently save energy costs for the production of compressed air.
The aim is also to minimise the mechanical stress of the filter elements, the emission of particulate and to display an alarm when the maximum loss of load (differential pressure) is reached.

But in the facts, it is not possible to use the differential pressure measurement for the detection of broken filtering elements. This is due to the following reasons:

 - the broke or tear don't cause a significant and detectable drop of pressure and it is anyway lower than the drops generated by the ordinary air cleaning jets!
 - During the lifetime of the filter, the value of Delta-P constantly increase, due to the progressive obstruction of the fibres of the filter’s cloth, therefore it is even not possible to establish a permanent set-point value for the alarm.
- Instead, a Delta-P measurer allows to optimize the frequency of the cleaning jets and to stabilize the loss of load until it is possible, stabilizing the drop of pressure also in presence of small tears.