Closed loop water circuits used as part of building heating and cooling systems typically become contaminated during fabrication with materials such as mill scale, jointing compound and building debris and on an on-going basis with suspended solids from corroding pipe work and bio-films.  If these materials are allowed to remain in the system they are likely to cause component blockage and damage to control valves and small bore heat exchangers.

Side Stream filters specifically designed for hot and cold water systems

The presence of these contaminants may also initiate further corrosion and the proliferation of micro-organisms such as Pseudomonads, which when chemically treated, can add to the quantity of recirculating particulate matter.  This issue has become a greater problem as the drive to install systems that are more energy efficient has resulted in smaller orifices in control valves and lower flow rates in terminal units.

It is with these challenges in mind that the Building Services Research and Information Association (BSRIA publication BG 29/2012: Pre-commission Cleaning of Pipework Systems) has recommended the use of Side Stream filters for both the initial clean-up and also for the on-going maintenance of pipework systems. Therefore it is not surprising that Amazon Filters’ Side Stream Filtration is being installed in an increasing number of Low Temperature Hot Water Systems (LTHW), Chilled Water Systems (CHW) and Condenser Systems.

Typically Amazon supplies SupaGard filters for these applications. SupaGard filters are available with a wide range of micron ratings (removal efficiencies), so finer filters can be used over time so as to achieve a progressive clean-up of the circulating water (i.e. 20μm rated filter initially, then reduced to 10μm later and possibly 5μm after further clean-up is achieved). When blocked, the filters are easily and inexpensively replaced.

Amazon also suppliers different filter cartridge designs for its SupaGard filters to ensure the filter performance and price are optimised for the different applications. For Chilled Water Systems, typically operating at approximately 6°C, a more simple, low cost ‘double open ended’ design can be used. This has a basic polypropylene core and the cartridge is sealed into the housing using a knife edge sealing mechanism. This design is adequate for systems which do not see significant temperature changes that could compromise the cartridge to housing seal and allow by-pass of contaminants. A similar design is used for Condenser Systems.

SupaSpun II Markings

Photo shows: Amazon Filters double open ended knife edge seal cartridge

For Low Temperature Hot Water Systems (LTHW), typically operating in the region of 80°C, two changes to cartridge design are incorporated. The simple polypropylene core is replaced with glass filled polypropylene core which offers greater mechanical strength at elevated temperatures. Also the general cartridge design is changed from double open ended to single open ended with a positive double o ring sealing mechanism that retains its integrity even if significant temperature changes are experienced.  This ensures the filter provides protection against contamination even under more arduous process conditions.

SupaSpun II Cutout copy

Photo shows: The difference in appearance of Side Stream Filters for hot and cold water systems

The difference in design also prevents a ‘low temperature’ filter being used in a ‘high temperature‘ system ensuring the system is operated correctly and the building temperature control equipment is not compromised by filter installation errors.

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This entry was posted on 6th Feb 2014