Where our differential pressure transmitters are used:
As the filter becomes increasingly dirty, the ventilation system has to deliver more power to move the required volume of air. This results not only in increasing power consumption, but also in increased energy costs. These hidden costs can be avoided if the filter is changed in time. But when is the right time to change it?
With a differential pressure transmitter, you permanently monitor the degree of contamination of a filter and can thus specifically plan the time of a change. As a result, you save on several fronts: no rising energy costs due to dirty filters and lower material costs (the filter is only changed when necessary). Furthermore, an unwanted shutdown of the plant for maintenance work during business operations can be prevented. The monitoring of the filters by a differential pressure transmitter pays off after a short time.
The air containing wood dust must pass through a filter in the ventilation system that traps the dust particles. The filter generates a resistance to the air flow in the duct – trapping air in front of the filter and lowering the air pressure behind it (see Fig. 2). If too much dust is deposited in front of the filter, less air can pass through. To ensure that all rooms continue to receive an adequate supply of filtered air, the air filters must be cleaned or replaced.
The particles that clog the filter are so fine that the condition of the filter cannot be assessed by service technicians. Fixed maintenance intervals for filter replacement could result in the premature replacement of perfectly serviceable filters, or filters becoming too clogged to filter the required air supply long before they are due to be replaced. The degree of air contamination depends to a great extent on the amount and type of work taking place in the production hall. Fixed intervals for air filter maintenance are therefore not an efficient solution.
Differential pressure transmitters are an effective way to optimise maintenance processes for air filters, reduce operating costs and thus increase efficiency. The transmitter measures the air pressure before and after the filter. If the filter is clogged, the differential pressure increases because less air passes through the filter. The more serious the blockage, the greater the increase in differential pressure. To detect a full filter, the transmitter must be able to measure tiny variations in differential pressures (1 Pascal). If the limit value is exceeded – this must be set beforehand via a relay on the device – a warning message indicates that it is time to change the filter.
However, the warning is not only triggered if the differential pressure is too high. If the differential pressure drops to zero, this means that there is no more resistance in the ventilation duct – the filter is faulty and no longer functioning correctly. Here, too, it is important to replace the filter immediately. If the filter is not replaced promptly, the ventilation system will circulate air contaminated with dust particles back into the production halls.
The filter monitoring system is not only used in wood processing plants but also in other sectors, such as bakeries, the cement and textile industries, and in air-conditioning, heating and ventilation systems. The filter replacement intervals depend on the application. For example, production processes in the cement or textile industries release significant quantities of dust particles into the air, so these filters must be changed more frequently than those in ventilation systems for residential buildings.
halstrup-walcher supplies a wide range of differential pressure transmitters for filter monitoring applications. All these devices are stable measuring systems for extremely low air pressures in the low Pascal range. The portfolio includes various designs with a choice of pressure and electrical connections, interfaces and setting options for parameterisation as well as functions for zero-point adjustment and calibration.
The PU/PI is available with only a few additional functions and is ideal for basic applications. The PS17 offers a wider choice of options and greater flexibility due to its small size. The P26 and P34 transmitters are high-end devices which offer outstanding measurement precision and many adjustable functions, e.g. for volume flow/mass flow measurements. Settings and parameters can be adjusted using a free PC program or via an operating menu (with optional display). In addition to standard devices, halstrup-walcher – as an expert in pressure measurement technology – also offers customerspecific solutions that are precisely matched to the application on site.
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