Hello Ltd. Hungary | Address: 46-48 Bekesi ut. Bekescsaba, Hungary 5600 | Tel: +36704292951 | Email: info@porosimeter.hu

Here is the Porozit N !
Same price — more accuracy


dhv When we have started to produce porosimeters our primary goal was to facilitate the safe flight, to separate the flyable and not flyable paragliders in terms of porosity. Our device could reliably determine the threshold which is 18 seconds (defined by the JDC and paraglider producers). We have already achieved this goal with our first Porozit at 2008.

New Demands

Nowdays there's a demand of paraglider owners to more accurately know the porosity of paragliders whit porosity thresholds of more than 200 seconds. At this measuring limit we need to pay more attention to the amount of false air leaking in between the measurement device and the material of the glider.

dhv When magnified, a paraglider's material shows not a smooth, but a striated surface. The level of striation depends on the material structure, the weaving technique and the thickness of the applied barrier layer. The amount of false air of a low-porosity material is negligible. For high-porosity materials however, it’s amount can reach a more significant level, which can even surpass the amount of influx air during a measurement of the material, since the material itself has a good quality and low air throughput.

Our solution

We’ve met the challenge: our new Porozit N has a new high-walled rubber cover, which by itself already allows to get higher accuracy for measuring high-porosity materials. This rubber cover is more durable and resistant to wear and abrasion, and fits more accurately
(We have produced our porosimeters with these rubber covers exclusively since July of 2013.)

dhv Additionally, we have replaced the ferrite magnets with neodymium magnets. With these magnets we have increased the cohesive force by multitudes even for the normal strength model. There are two model options: the medium strength model uses 7 pieces of neodymium magnets and the extra strength model uses 8 pieces of neodymium magnets.These magnets have greater endurance, and they have an extended lifetime of their magnetic properties.
(We have produced all of our devices with these magnets since July of 2013.)

We’ve also modified the software of the digital gauges. Not it’s easier to monitor how many times the meter has passed a thousand seconds.

Attention!!

There are many properties of a paraglider apart from porosity of the material which determine whether it’s flight safe or not. Tensile strength of the material, elongation, contraction and the changes of the length of the lines, and last but not least the damages (wear and tear) should also be taken into account. Pay attention to your paraglider. csik

Generally about the measuring of porosity:

Nowadays there are great emphasis on the porosity tests of paragliders worldwide. dhv Why is useful to measuring the porosity of a glider?

It’s show deterioration over time, and below a limit it warns the owner of the glider, the paraglider is not suitable for flight. We can gauge an important property of our glide without any damage. We can find some porosimeter on the market, but none of them is perfect. A real instrument has a lots of criterions, and these meters are really expensive. Even if there were any producer, they would have to provide laboratory conditions for the measuring (humidity, temperature etc.)

But exactly we don’t need to measuring in that accuracy. The new paragliders have 300-1000 sec (JDC) porosity depending their main materials. These values of a glider decreases over time, and at the end it won’t be suitable for flight. The paraglider producers aren’t at the same opinion about what is the limit while a glider is able to safety flight. There are producers who determined in 15 sec (JDC) their glider, while others think their paragliders able to flight safely with 5 sec (JDC). The general accepted limit is minimum 10 sec (JDC) of porosity.

dhv We suggest this minimum limit in 18 sec (JDC). But need to know about it, the humidity of the air, and the temperature is greatly influence the results. And of course the porosimeter has a failure rate which is +- 3% , but with this failure rate is nearly nothing, because if the safety minimum value is 18 sec (JDC) the failure rate number is just +- 0.54 sec. Which is nearly nothing.

In additon very important to check the susceptibility to secedes. Good case if our paraglider are corresponded, we get away this with few 1mm holes. It’s impossible to measuring exactly the changes of th flight properties because the stretches of the material, but if our paraglider passed that two test (porosity and secede) and we measured the length of the lines, we can’t think just the changes of the shape of the canopy. It rarely occurs, because the ribs of the paraglider are very strong. These ribs limit the stretches of the upper wing.

SUGGESTIONS:
- Just measuring the porosity of the upper wing of the canopy !
- Not measuring porosity before the “A” (forward) risers
- More worse the porosity of a paraglider, than repeat the measuring more, therefore we will get more accurate picture of the paraglider !
- Measuring the porosity symmetrical (left and right sides of the paraglider)
- Expect the worst results at the middle and at the front of the canopy.
- If our paraglider results are limiting case, measure the porosity another day, and if we measure the same,
DON’T FLY WITH IT !!

For more information, check our youtube videos: http://www.youtube.com/user/helloporozit/
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Porosity examination of paragliders

,During the condition analysis of the gliders need exists to measuring the porosity of a glider, and we see the annual impairment of our glider. Overtime two kind of measuring method be formed in the same time. It’s not easy to compare these. One of them is the Kretschmer-TextileClock which was used earlier but it wasn’t improve exactly for paragliders. The other method is the JDC measuring where we can use two measuring instruments: The JDC porosimeter (1200 euro) and our HELLO porosimeter (645 euro).

Kretschmer measuring method:

dhv The meter presses with a spring 0,7 liter air through the material which is fixed and clamped properly to the meter. The surface of the hole is 50 ccm. The meter counts how much time does it take to pressed through the material that amount of air in tenth of a seconds. The force of the spring changes in the time.

Advantages: There aren’t fake air, because the material can mount on the meter with a bayonet lock properly.
Disadvantages: Because the shape of the meter, we can’t measure the glider anywhere. This meter is not so popular and very expensive.

JDC - measuring method:

dhv We mount the material with a magnet cap, which hole is 37.5 ccm and it wicks 0.25 liter of air with 10 mbar vacuum. The wicking force are generated by the gravitation. The meter counts the seconds of the measurments process.

Advantages: Easy to measuring the entire surface of the glider. This method is the most common at the technical testing.
Disadvantages: If we are careless, air could escape between the cap and the material. But the Hello porosimeter is nearly impossible, because between the measuring instrument and cap, have a slut mounting. Therefore you can’t mount it wrongly.

The Hello porosimeter has other advantages as well: the beginning and the end of the measuring process are indicated by beep. The magnetic cap is strengthened, the rubber sealing rings fit into each other. The process of the measuring are linear thanks to the rubber bellow which contains caoutchouc. Last but not least the price of it is very affordable. The ratio between the two instruments is 37.3.

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The material of paragliders

dhv The producers of the paragliders material are presented high demands by the producers and designers. They expect better and better properties by the producers of the materials. Which are those properties what they have to consider during the manufacturing process.

1. Be high the tensile strength
2. Not stretch
3. Be light
4. Be minimum of the air permeability
5. Be flexible, become durable after several fold
6. Become resistant to UV ray

dhv It's not easy to meet these expectation, because if they want to improve one of the properties of the material they deteriorate another property. Let’s see these properties of a paraglider why are so important. The canopy of the gliders aren’t just static load is applied, also dynamic load is applied during an emergency or dynamic maneuver. That why the materials were designed for these load. In addition the thicker fiber - which were be interwoven in the material - are functioning to prevent the tears spreading. Because the wing profile it’s the most important the flight characteristics as regards, important that profile are not change during use and not deform. In so far as the material of the glider is able to stretch, it’s not warrantable the flight characteristics. Not easy to start wiht those paragliders which made by heavy materials in low wind, and moreover our pack what we have to carry will be larger and heavier also. But most of these gliders are more durable than the light ones.

Overpressure dominates into the cells, which are maintained by velocity due to wind pressure. The course of time the velocity of the paragliders were increasing, therefore the pressure of the cells were increasing as well. The escaping air between the pores of the material reduces the flow around the wing profile (decreasing the glide ratio), in extremis this escaping air could eliminate the lift force (deep stall). For these reasons it’s very important the material of the glider keeps the air inside the cells, and not be permeable.
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The paragliders are used in different extreme weather conditions, in frosty alpine mountains, and burning deserts sun. The material has to be durable for these extreme environmental impacts. It’s not allow the material will be brusque or brittle in cold or be soft when it’s hot.

The material of the gliders is consists of long-stranded molecules which were destructived by the UV rays. How quick, it’s depending on the material and how we use the our glider. In the producing process the base material is mixed with certain chemicals which damage caused by UV radiation can be extended.