Dirt Separators

Dirt, magnetite & Sludge is formed over time in the heating and cooling systems. Dirt & magnetite will circulate a piped water system while they are in use, this can block heat exchangers – particularly more modern low water content heat exchangers; heat emitters and under floor heating pipes become partially blocked and the heat output is reduced.

A common way of reducing particles in piped water systems is to incorporate a filter or a strainer. There is always a compromise when using strainers – large mesh sizes allow larger particles to pass through, while a finer mesh will collect a large volume of particles rapidly, potentially leading to obstruction of the waterway. To prevent problems, and ensure that system performance does not suffer, strainers are provided with apertures that allow all the by-products of corrosion to pass through, so they don't block the filter. Specialised magnetic dirt separators remove particles down to 0.5μm (compared to strainers that typically only remove down to 1,600μm).

Magvent CVDInline Magnetic Dirt Separator:

Manufacturer & BSRIA tests have shown that, during the normal commissioning period, the separator will remove approximately 96% of all circulating material, which can then be ‘blown down’ through the valve at the base of the separator.

In operation a dirt separator would normally be blown down at building handover and quarterly thereafter. Maintenance is typically then no more than five minutes in a year.   Dirt separators can remove any dirt particle, not just magnetic dirt, provided that the particle is heavier than water. As with the deaerator, dirt separators require a still water zone to remove all dirt particles that are heavier than water. Fitting dirt separators into existing systems has reportedly shown impressive reductions in solid matter. One particular independent test saw the dirt content reduced from 620 g/m3 (sized 5 to 10μm) to less than 1 g/m3 of all particulates larger than 0.45μm following the installation of a dirt separator, over a seven-week period.

Case study: example of reduced maintenance through dirt and air removal – Sheffield UK

This was undertaken in a department Store built in the 1990s using two-pipe heating systems. An investigation was undertaken comparing the use of air and dirt separators in three similar buildings – one fitted with a combined air and dirt separator; one with a dirt separator; and one with standard strainers

Graph showing cost reduction in % rather than nothing installed.

Maintenance Cost Reduction

Fig. 6: Case study one – impact of deaerators and dirt separators on maintenance costs

The cost of maintenance in the three buildings was recorded and the normalised values are shown in Figure 6. The system with the combined dirt and air separator required far less maintenance to ensure effective operation of the systems by reducing the dissolved air as well reducing the amount of ‘dirt’ in the system by 27 per cent compared to the previous year. By comparison, the system that used dirt separators reduced maintenance by 17 per cent.

Air and Dirt Separators Clients 1
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