Sustainable solution
Seawater filters
Seawater is an essential, renewable and ever-present mechanical element for a superyacht. The engines of a superyacht are cooled using seawater, it can be used as a fire extinguisher and be chilled to pass through the onboard air conditioning system. Before seawater can be used in engineering systems, any unwanted materials and pollution in seawater such as plants, sea animals, shells, waste, plastics and wood need to be removed to avoid damage to the piping network of a superyacht. This is done through the use of filters.
These filters are usually made out of metal, which is a very corrosion-sensitive material. Metal filters need to be regularly cleaned and replaced due to their limited lifespan – which can be as little as one year. In turn, the increased production has a negative impact on the environment.
The perfect seawater filter
Plastic is in most cases a very good replacement of steel variations, because of their excellent corrosion resistance in seawater applications. Furthermore it is much lighter and cheaper than steel. Even bronze and cunifer cannot equal their properties. Depending of the particles to be filtered, the maximum allowable pressure loss, capacity and service frequency the largest possible filter surface will be calculated so that a remarkable efficient and light filter will be generated. This results in a very low pressure loss and less service and downtime for the customer.
Polyethylene or HDPE and polypropylene or PP are often chosen for their good resistance to chemicals and seawater.
Very maintenance-friendly
Because the filters are very low weight the cleaning of the strainers is an easier job. No lifting device is necessary because plastic is 10 x lighter than steel! The device can be spared and the job is done quicker. The strainers have a large filter area and are very service friendly because of the smooth surface and scratch resistance of the filters. The result: a efficient removal of solids and unwanted materials out of fluids.
About the material Perfoplast
Perfoplast is a generic name for perforated plastic materials. Many perforations are possible in plastic sheet materials. The most important and most used plastics are HDPE / polyethylene and PP / polypropylene but also PVC. In general the perforations for filters / strainers are mostly round. The smallest diameters that give good perforating results are 2 mm.
Material properties:
- Excellent seawater resistance
- Durable, smooth, shiny, strong, firm
- Chemical resistance
- Anti-fouling
- Scratch-resistant
- No maintenance required
- Good machinability and weldability
- 10 times lighter than steel
- Insulator, not magnetic
- Excellent UV resistance
- Excellent impact strength
Table transmittance:
| Diameter hole (mm) | Pitch/center distance (mm) | Permeability (%) |
|---|---|---|
| 2 | 3 | 40,3 |
| 2 | 3,5 | 29,6 |
| 2 | 4 | 22,7 |
| 3 | 5 | 32,6 |
| 4 | 6 | 40,3 |
| 5 | 8 | 35,4 |
| 6 | 8 | 51,0 |
| 6 | 10 | 22,7 |
| 8 | 10 | 32,6 |
| 8 | 12 | 40,3 |
Sizes
The size of the holes are always indicated in combination with a pattern or pitch. An example of a pattern is the equilateral pitch. This is the most common pattern for filters and strainers. This pitch is designed in an isosceles triangle. The most common is R2T3 or R3T5. The diameter of the holes are 3 mm and the center to center distance is 5 mm.
R = diameter of the hole in mm;
T = pitch or center to center distance in mm.
Applications
The perforated plastic sheets have great application possibilities, like water filters. Filters made of Perfoplast have excellent corrosion resistance in seawater. Furthermore it is much lighter and cheaper than steel.