What is the difference between a pressure-dependent and a pressure-independent flow controller?
A pressure-dependent product provides a certain flow at a given pressure. The flow changes as the pressure varies: the flow increases as the pressure increases and visa versa.
A pressure-independent product always gives the same flow throughout a given pressure range. The flow is always the sameat differing within the pressure range, both when the pressure is rising and when it is falling.
What is the difference between a pressure-independent flow controller and a pressure-reducing valve?
A pressure-independent flow controller ensures a constant flow rate at all times, regardless of the water pressure or any fluctuations in that pressure.
A pressure-reducing valve is a device that protects the system in which it is installedfrom excessive static pressure by lowering this excessive static pressure to a pre-set value. It is, in other words, a safety measure designed to prevent excessive static pressure within the system.
The systemic pressure downstream from the pressure-reducing valve – and therefore the flow – can vary considerably, however, depending on factors such as the pressure-reducing valve itself and the pipe configuration (length, diameter, bends, auxiliary equipment, friction losses).
A Pressure-reducing valve, in other words, reduces the pressurein the system after the pressure-reducing valve, as a means to reduce the flow from the subsequent draw-off points. In a cabin, for example, the pressure immediately after the pressure-reducing valve can be 300kPa, whereas the pressure at the furthest draw-off point, if there are several, may be only 200kPa. The effect of a pressure-reducing valve (a reduction in flow rate) can also be achieved by means of a pressure-independent flow controller. For this reason, there is often confusion regarding the application of these two devices.
There are, however, important differences between the two. When a pressure-reducing valve is installed (as opposed to a pressure-independent flow controller), it is so that:
- the flow at the draw-off point will vary (because compensation for changes in pressure does not occur quickly and accurately enough);
- limitation/levelling of the flow will only occur at higher pressure (3 to 6 bar);
- temperature fluctuations can result in mixer taps (as a result of differences in flow rate, which in turn may be caused by differences and fluctuations in pressure ‘upstream’ from the points where the cold and hot tap water enter the mixing tap);
- variation in flow is possible between two identical draw-off points (because the pressure at the individual draw-off points is not identical).
As a pressure-independent flow controller:
- ensures a constant flow rate at all times
- is effective with pressure starting at 1.5 bar
- provides a solution to temperature fluctuations at mixer taps and
- ensures that identical draw-off points deliver an identical flow.
In addition, our pressure-independent flow controllers conserve water and energy and reduces CO2 emissions – benefits that a pressure-reducing valve can’t provide. In fact, a pressure-reducing valve actually wastes energy of lowering the pressure.
How often will I need to clean a flow controller?
Marine Flow products are maintenance-free, but take into account the following:
Possible residue that originates from the water system and that exceeds the maximum particle size for the product (see product data sheet) will collect on the meshes inside the product. This needs to be removed by removing the entire product from the piping. Hold the product upside down, submerge in cleam water and shake until dirt falls out. Rinse witch clean water prior to re-installation. Keep the product clean for optimal functionality.
Does the flow controller increase the chances of Legionella in a water system?
In the development of our flow controller, much attention has been paid to the prevention of growth of Legionella bacteria and to the formation of biofilm on the surface, for example by design (high flow velocity and turbulence) and the choise of materials (high-quality engineering plastic and stainless steel). The materials used are resistant to high temperatures, which means that thermal disinfection of an installation will not normally have a negative effect on the product.
The use of certified Marine Flow products is suitable for drinking water purposes and meet the most demanding European certification schemes in this area (e.g. Kiwa Water MArk). Thus, the use of Marine Flow products has demonstrably no negative influence on the drinking quality.
It is important to emphasize that Marine Flow products were not designed with the aim of eliminating or preventing Legionella contamination. The high temperature tolerance, the choise of materials and the turbulence of the water inside our flow controllers do however make the products safe for use in drinking water and permit thermal disinfection at high temperatures. Aerosols are also barely released when the MF Tap is used. Splashes of water from the sink or washbasin are eliminated or hardly occur any more.
Are the Marine Flow products negatively affected by limescale?
Marine Flow products are relatively unaffected by limescale deposits for the following reasons:
- Firstly, the materials used in the flow controllers do not actively react with the lime that is present in water;
- Secondly, the interior of Marine Flow products (with the exception of the mouth of the MF Tap*) remain permanently underwater. As a result, there is no evaporation and no limescale deposits will from there;
- Thirdly, the speed of the laminar flow in the integrated flow controller is very high and there is therefore so much turbulence that deposition cannot take place. Should a deposit nevertheless start to be formed in exceptional situations, it will be flushed away the next time the device is used.
* Evaporation of water only occurs from the stainless steel mesh at the mouth of the MF Tap. This can result in scale formation. The limescale does not however adhere to the surface of the product (psuedo-cohesion) and it can therefore be cleaned off easily without damaging the product. The surface of the products is extremely smooth and any limescale left behind will therefore come of easily after being soaked for a little while in cleaning vinegar.
How does the flow controller deal with dirt residues in the pipes?
Marine Flow products function best in a clean water system. Any residue dirt particles from the water installation of 400µm or larger will accumulate outside the product; particles smaller than 400µm will be flushed through the product. For every Marine Flow product counts: whatever gets in, will also get out again.
Marine Flow products function best when they are clean. Dirt residues taht accumulate on the product’s upper dirt collector filter must therefore be removed by removing the whole product from the pipe. The product can be cleaned by holding it upside-down and immersing it in clean water, then shaking it back and forth until the dirt falls out. Then rinse it with clean water before re-installing it.
How can i use the flow controller to minimise fluctuations in the temperature of water from a mixer tap?
Install the flow controller at the hot ánd cold (thermostatic) mixer inlets.
By providing an accurate and rapid mechanism for keeping both the hot and cold flows in the thermostatic tap constant, Marine Flow ensures that pressure differences are no longer translated into flow differences at the inlets to a thermostatic tap. The result is that the temperature deviations are mostly minimized to an imperceptible level. In the case of non-thermostatic mixers, accurate flow control on both inlets yields not only a more constant outflow temperature but also better – in this case manual – control of the mixed water temperature.
What sets Marine Flow products apart from the rest?
Marine Flow stands out as the sole patented flow controller that operates independently of pressure. It holds the unique distinction of being the only product with a BRL-K635 certification, further highlighting its exclusive and innovative features.
