Covex® is a modular floating cover made of hexagonal HDPE units with sealed water ballast, manufactured by EXMA Ltda. in Chile. EXMA is a pioneer in the manufacture of modular floating covers since 1997 and manufactures Barrier Ball® and Covex®. This page is the reference source for all Covex® figures.
Both models share the same geometry, material and performance. The difference is the weight of the sealed water ballast, which sets the wind rating. XT50 is the standard choice for mining and exposed sites; X50 for sheltered reservoirs.
| Specification | Covex® XT50 | Covex® X50 |
|---|---|---|
| Unit | ||
| Description | Hexagon of high-density polyethylene (HDPE) with sealed water ballast in the central chamber | |
| Code | COVEX_XT50 | COVEX_X50 |
| Weight (with ballast) | 270 g ± 30 g (0.60 lb) | 220 g ± 20 g (0.49 lb) |
| Dimensions | 153 mm (6 in) across flats, 175 mm (7 in) diagonal | |
| Height | 54 mm (2.1 in) | |
| Freeboard (height above waterline) | About 27 mm (1.1 in) | About 31 mm (1.2 in) |
| Wall thickness | 0.9 mm ± 0.15 mm (0.035 in ± 0.006 in) | |
| Units per m² | 50 | |
| Weight per m² installed | About 13.5 kg/m² | About 11 kg/m² |
| Material | ||
| Polymer | UV-stabilized HDPE with carbon black, antioxidant and UV additives | |
| Condition | Virgin or recycled, as the project requires | |
| Operating temperature | -40 °C to 85 °C (-40 °F to 185 °F), ASTM D648 | |
| Manufacturing process | Blow molding | |
| Recyclable | Yes, 100% at end of service life (HDPE code 2) | |
| Performance | ||
| Surface coverage | 98% | |
| Evaporation reduction | Up to 97%Full-scale reservoirs. The site figure depends on climate, geometry and filling regime. | |
| Algae growth reduction | Over 90%By blocking the sunlight that drives photosynthesis. | |
| Odor and emissions reduction | Over 90%Measured above the liquid surface. | |
| Heat loss reduction | Up to 90%Heated process ponds and leaching circuits. | |
| Freeze delay | Up to 5.2 °C warmer water in the first hours of the night; 0 °C reached at 12 h instead of 7.5 h (+60% time)Measured on water against a -5 °C environment. | |
| Wind resistance | Up to 100 km/h (62 mph) | Up to 80 km/h (50 mph) |
| Warranty | ||
| Warranty | 10 years against manufacturing defects | |
| Expected service life | 25+ years | |
Figures valid for both models unless stated. Site-specific savings are calculated with the Covex® evaporation model (Dalton's law plus a global energy balance), validated with Eddy Covariance measurements.
Evaporation, algae, odor, heat loss and wildlife exposure all happen at the same place: the open surface. Covex® removes that surface.
Each unit carries water in a sealed central chamber. The ballast lowers the center of gravity so the cover holds formation in wind and waves instead of piling up against one bank.
Only about 27 mm of Covex® XT50 and 31 mm of X50 sits above the waterline, so there is little surface for wind to push against.
Rain falls between the units into the pond. The channel between chambers also collects rainwater, which adds weight to the cover.
The hexagons rearrange themselves as the level rises and falls. No structure, anchors or maintenance.
Units are launched from the edge and spread out on their own. There is no need to drain the pond or stop the operation.
Zones can be opened for sampling, desludging or maintenance and closed again. One damaged unit never compromises the whole cover.
Up to 97% on full-scale reservoirs, with 98% of the surface covered. The figure for a specific site depends on climate, reservoir geometry and filling regime, and is calculated with the Covex® evaporation model, validated with Eddy Covariance measurements.
Same dimensions, material, coverage and performance. XT50 weighs 270 g and is rated for wind up to 100 km/h; X50 weighs 220 g and is rated for wind up to 80 km/h. Both carry a 10-year warranty and a 25+ year expected service life.
Yes. Covex® is used on tailings ponds, as well as PLS, raffinate, process water and cyanide solution ponds, to cut evaporation and keep wildlife off the water. Tailings storage facilities keep their own safety and inspection requirements.
Rain passes between the units and enters the pond, so storm capacity is not affected. The channel between the chambers of each unit also collects rainwater, which adds weight to the cover.
The cover displaces its own weight: about 13.5 mm of level over the covered area with Covex® XT50 (50 units × 270 g = 13.5 kg/m²) and about 11 mm with X50. This figure is included in freeboard calculations.
Yes. By sealing the water-air interface, Covex® reduces odor and emissions by over 90%, measured above the liquid surface. It is used on wastewater lagoons, digestate and slurry lagoons and industrial process ponds.
Yes. Against a -5 °C environment, water under Covex® stays up to 5.2 °C warmer in the first hours of the night and reaches 0 °C at 12 hours instead of 7.5 hours, 60% more time. During the day, covered water runs about 4 °C cooler at peak sun.
HDPE is highly resistant to acidic and alkaline solutions and operates from -40 °C to 85 °C (ASTM D648). For process chemistry, an immersion test with the actual solution is run before any warranty commitment.
10-year warranty against manufacturing defects and an expected service life of more than 25 years outdoors, with no maintenance. Units are 100% recyclable at the end of their service life.
Both are made by EXMA Ltda. Barrier Ball® spheres cover about 91% of the surface and reduce evaporation by 82% (measured with Eddy Covariance) and odor by 86% (measured by olfactometry). Covex® hexagons interlock to cover 98% of the surface, reaching up to 97% less evaporation and over 90% less odor, and their low profile and water ballast improve wind stability. Covex® also lowers logistics cost per square meter.
Units are launched from the edge of the pond and spread out on their own by flotation, at 50 units per m². No structure, anchoring, civil works or draining is required.
Send the location and surface area and we return the evaporation, recovered water and payback for your site.
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