Crud the prefilter misses becomes boiler scale and turbine deposits.
Iron, copper and silica in condensate lead to scaling and corrosion in boiler tubes, lost thermal efficiency, and plating on turbine blades. A prefilter that bypasses at the seal, or blinds early, passes that load downstream or forces a change-out outside the outage plan.
Where does the prefilter sit?
Condensate return
Condensate returning from the turbine carries suspended solids generated by high steam and condensate velocities.
Prefilter vessel
Long cartridge elements, 60 to 70 inch, in the vessel ahead of the condensate polishing unit.
Polisher and boiler
The polishing unit, then the boiler and turbine, in sub-critical and super-critical units where condensate quality is watched closely.
Which CPU prefilter fits your vessel?
| Parameter | Clarywound CPU | Clarypleat CPU |
|---|---|---|
| Construction | Polypropylene yarn wound on a stainless steel core | Pleated polypropylene media, core and support layers |
| End caps and support | Stainless steel end caps, SS 304 support | Polypropylene |
| O-ring | Silicone | Buna-N |
| Filtration rating | 1, 5, 10 micron nominal | 1, 5, 10 micron absolute |
| Length | 60 to 70 inch | 60 and 70 inch |
| Outer diameter | 54 mm standard, others on request | 70 mm standard |
| Maximum temperature | 82 C | 82 C |
| Maximum forward differential pressure | 3.0 bar at 65 C | 3.0 bar at 65 C |
| Maximum reverse differential pressure | Not stated | 2.0 bar at 20 C |
| Design flow per element | 2.2 to 2.8 m3/hr | 3.5 to 4.5 m3/hr |
| Connections | M33 x 1.5, M33 x 2 inch, G 1 inch, 13/16 inch BSW; bottom thread M6, M8, M10 | Code T (stud nut or internal thread), Code 6 (222 with fin) |
Datasheet values from the two product pages. Confirm against the current catalogue and your vessel drawing before specification.
What you can check today
Stated limits on both elements
A maximum of 82 C and 3.0 bar forward differential pressure at 65 C, published for both CPU prefilters, with a design flow per element.
Additive-free construction
Clarypleat CPU is thermally welded throughout, with no additives. Clarywound CPU is free from resin binders, lubricants, antistatic and release agents.
Sealing support
Technical assistance at installation to confirm positive sealing and prevent bypass in your existing vessels.
What is not here yet
Station results for these elements are not yet published here. We will measure element life on your condensate in a trial and give you the result in writing.
Industries and products for condensate duty
Power and Energy
Boiler feed, cooling tower and steam filtration around the CPU.
Read the industry pageCondensate polishing prefiltration: direct answers
What is condensate crud and where does it come from?
Crud is the suspended solids carried in condensate, generated by the high velocities of steam and condensate through the cycle. It includes iron, copper and silica. The prefilter's job is to take it out before the condensate polishing unit, so it does not reach the boiler or the turbine.
Nominal or absolute rating for a CPU prefilter?
Clarywound CPU is a depth element rated nominal at 1, 5 or 10 micron. Clarypleat CPU is a pleated element rated absolute at 1, 5 or 10 micron, with a larger surface area and a higher design flow per element. If your chemistry programme sets an absolute limit on particles reaching the polisher, start from the pleated element; if the load is heavy and depth capacity matters more, start from the wound one. We confirm with your data.
Will these elements fit our existing prefilter vessels?
Clarywound CPU is designed for pre-existing housings and comes with a range of thread connections; Clarypleat CPU comes in Code T and Code 6 fittings. Send the vessel drawing or a photograph of the current element's end fitting and we will confirm the match.
Can you deliver a year's elements on a schedule?
Yes. We offer scheduled deliveries against your annual element requirement, so the elements for each planned outage are on site before it starts.
Send us your vessel and your outage date.
Element count, length, end fitting, condensate flow, and how long elements last today. We will recommend the element and the trial that proves its life before your next outage.