EPDM tube diffusers

In depth subjects relating to Airlift.
manu
Posts: 16
Joined: 15 Jul 2019, 14:40

Re: EPDM tube diffusers

Post by manu » 21 Jul 2019, 12:04

Thanks guys.
So I purchased a pump from Gast (Gast 1531)
https://gastmfg.com/products/compressor ... unted/1531
which can support a flow up to 2.1 m3/hr and upto 15psi(330 mBar).
My understanding is, with a higher diameter pipe it needs a higher airflow to work properly. I also can not go over depth of 2 meter ,20.000 liter is enough as the pond only has 40.000-50.000 Liters of water and it is natural pool in tropical weather.
I thought about drilling holes in PVC ,but considering the work involved perhaps a disc or tube membrane diffuser seemed a better option.
Frank ,what is the relation ship between airflow and tube diameter? I am thinking there should be a diameter after which the pump become less efficient for a given airflow rate? or otherwise I am not limited by diameter of the pvc tube or pressure to open the epdm,but by flow rate of the air with the pump I purchased in a hurry.

Frank
Posts: 52
Joined: 24 Apr 2016, 22:04
Location: Ceylon

Re: EPDM tube diffusers

Post by Frank » 21 Jul 2019, 22:07

The Gast 1531 seems not to be the best, because the air pump is not efficient. Why that one?

You could use a 160 mm airlift supporting up to 40.000 l/h.

Regards,
Frank

manu
Posts: 16
Joined: 15 Jul 2019, 14:40

Re: EPDM tube diffusers

Post by manu » 21 Jul 2019, 22:32

I know it’s not efficient , noisy and more expensive but other options are not available in India.
Also diaphragm pumps like secoh may not survive the hot humid weather of tropics as well as they do in Europe.
Now if I try to explain with what I learned from this forum.
From here
viewtopic.php?f=118&t=15803&p=253571#p253571
An SLL-40 through 165mm diameter tube of 175 cm height can deliver 22.500 Litter/hour.
From here
http://secoh.com.pl/produkty/dmuchawy/secoh-sll-20
A secoh SLL-40 can deliver 36LPM air at 200 mBar (0.2Bar).
A water column of 175cm exerts a pressure of 0.17 Bar or 170 mBar. Plus if I use a EPDM disk perhaps It will need 20-30 mBar to make it work ,making total pressure head of 200 mBar.
Now none of the linear pump models recommend to make them work at maximum pressure they support.
Now if you consider Gast1531 it can deliver 34lpm(1.25cfm) but the peak pressure is 1000 mBar,which is an overkill ,but perhaps it will give more longevity to the pump.
Also rotary vane pumps are more robustly made and has more life than diaphragm pump such as Secoh SLL or JDK. Of course the drawback is power consumption, as documented everywhere.

But as the test result indicate SLL-40 only using 28Watts of peak rated wattage of 36W for that Model working on almost maximum pressure it can deliver at 175cm. So perhaps Gast1531 will not consume 70 Watts peak rated when it is working only at its 1/5th rated pressure.

The test result also shows SLL-40 deliver 24.000liter/hr water through a 110mm diameter pipe of 175 cm length using pressure chamber.
whereas SLL-40 can only deliver 22.500/hr through 165mm diameter pipe of 175 cm using a membrane diffuser with comparable power usage.

Not a huge loss but flow did not go up (as expected with a larger diameter pipe).

Now if we compare SLL50 delivers 44 LPM of air at 200mBar. 200mBar is where most linear pumps pressure rating runs. Low quality pumps may not even go there for their published air flow rate. This pressure is purely developed by the rubber membrane( diaphragm) that will loosen up and won’t be able to provide that pressure support over time( make sense). So depending on how old the pumps were at the time of the testing below the observed result may change.
NOW MY ATTEMPT for some interpretation of test results available.
Membrane disk Airlift made by Gino (24cm disk) with 250mm to 160mm reduction:

Pump------Diameter rising pipe--------Length rising pipe--------Litres per hour--------consumption-------watt/m³
SLL50---------------160----------------------------175----------------------25.000----------------35 watt-----------1,4 watt

Disk Airlift made by Guyke with 160mm to 110mm reduction:

Pump------Diameter rising pipe--------Length rising pipe--------Litres per hour-------consumption-------watt/m³
SLL50---------------110---------------------------205----------------------23.000----------------36 watt---------1,56 watt

Disk Airlift made by Guyke with 250mm to 110mm reduction:


Pump------Diameter rising pipe--------Length rising pipe--------Litres per hour-------consumption-------watt/m³
SLL50---------------110---------------------------205-----------------------23.000---------------40 watt---------1,73 watt

with the length of rising pipe increasing from 175 to 205 there is an increase in pressure load to 200m Bar just from water pressure plus pressure to over come EPDM membrane opening (20-30mBar). From the plots on SLL-50 for a total pressure of 225mBar air flow drops to 40lpm from 44

Inference from above data the reduction pipe has no influence on water output as 250---->110 and 160--->110 reductions has not changed output.
SLL-40 at 200mBar can deliver 36lpm of airflow based on data from http://secoh.com.pl/produkty/dmuchawy/secoh-sll-20
Now comparing pressure chamber to disk diffuser
Pressure chamber Airlift:

Pump------Diameter rising pipe--------Length rising pipe--------Litres per hour-------consumption-------watt/m³

SLL40----------------110---------------------------170---------------------24.000---------------32 watt------------1,3 watt

Membrane disk Airlift made by Gino (24cm disk) with 250mm to 160mm reduction:

Pump------Diameter rising pipe--------Length rising pipe--------Litres per hour--------consumption-------watt/m³
SLL40---------------160----------------------------175----------------------22.500----------------28 watt----------1,24 watt

increasing diameter of riser pipe from 110 to 160 mm reduced the flow at almost similar length for rising pipe.
Now if we look at the available data there is a connection of airflow with diameter of rising pipe.
SLL50 at 44lpm deliver 25.000 litter through 160 mm diameter pipe
SLL50 at 40lpm deliver 23.000 litter through 110mm diameter pipe
SLL40 at 36lpm deliver 24.000 litter through 110 mm diameter pipe
SLL40 AT 36LPM deliver 22.500litter through 160mm diameter pipe
What is your inference?
Please provide your valuable inputs as most of you have practical experiences and can validate my observations.
Last edited by manu on 23 Jul 2019, 01:39, edited 1 time in total.

Frank
Posts: 52
Joined: 24 Apr 2016, 22:04
Location: Ceylon

Re: EPDM tube diffusers

Post by Frank » 23 Jul 2019, 00:07

My interference is to do own tests. :wink:

Best regards,
Frank

manu
Posts: 16
Joined: 15 Jul 2019, 14:40

Re: EPDM tube diffusers

Post by manu » 23 Jul 2019, 01:40

Frank wrote:
23 Jul 2019, 00:07
My interference is to do own tests. :wink:

Best regards,
Frank
Well,That is one way. But the wise way is to learn what Others have done and failed too. ;cool;

Frank
Posts: 52
Joined: 24 Apr 2016, 22:04
Location: Ceylon

Re: EPDM tube diffusers

Post by Frank » 23 Jul 2019, 08:44

The results are partly contradictory.

manu
Posts: 16
Joined: 15 Jul 2019, 14:40

Re: EPDM tube diffusers

Post by manu » 23 Jul 2019, 12:27

Frank wrote:
23 Jul 2019, 08:44
The results are partly contradictory.
Looks like it. is it because it was done at different times with different air pumps ( same model)? Perhaps pssymon may know?

User avatar
Pssymon
Posts: 171
Joined: 11 Dec 2015, 00:12
Location: The Netherlands

Re: EPDM tube diffusers

Post by Pssymon » 25 Jul 2019, 01:23

I'll get back to this topic asap. I've been reading but I want to give a proper response. It's easy to make mistakes with a quick reply.

manu
Posts: 16
Joined: 15 Jul 2019, 14:40

Re: EPDM tube diffusers

Post by manu » 04 Aug 2019, 03:17

Any updates Pssymon?

User avatar
Pssymon
Posts: 171
Joined: 11 Dec 2015, 00:12
Location: The Netherlands

Re: EPDM tube diffusers

Post by Pssymon » 08 Aug 2019, 21:49

I completely forgot :? Probably because of the spam situation. I will get back to this topic as soon as possible. I'll leave the tab open. I'm a bit busy, apologies!

User avatar
Pssymon
Posts: 171
Joined: 11 Dec 2015, 00:12
Location: The Netherlands

Re: EPDM tube diffusers

Post by Pssymon » 21 Sep 2019, 21:10

manu wrote:
21 Jul 2019, 22:32
I know it’s not efficient , noisy and more expensive but other options are not available in India.
Also diaphragm pumps like secoh may not survive the hot humid weather of tropics as well as they do in Europe.
Now if I try to explain with what I learned from this forum.
From here
viewtopic.php?f=118&t=15803&p=253571#p253571
An SLL-40 through 165mm diameter tube of 175 cm height can deliver 22.500 Litter/hour.
From here
http://secoh.com.pl/produkty/dmuchawy/secoh-sll-20
A secoh SLL-40 can deliver 36LPM air at 200 mBar (0.2Bar).
A water column of 175cm exerts a pressure of 0.17 Bar or 170 mBar. Plus if I use a EPDM disk perhaps It will need 20-30 mBar to make it work ,making total pressure head of 200 mBar.
Now none of the linear pump models recommend to make them work at maximum pressure they support.
Now if you consider Gast1531 it can deliver 34lpm(1.25cfm) but the peak pressure is 1000 mBar,which is an overkill ,but perhaps it will give more longevity to the pump.
Also rotary vane pumps are more robustly made and has more life than diaphragm pump such as Secoh SLL or JDK. Of course the drawback is power consumption, as documented everywhere.

But as the test result indicate SLL-40 only using 28Watts of peak rated wattage of 36W for that Model working on almost maximum pressure it can deliver at 175cm. So perhaps Gast1531 will not consume 70 Watts peak rated when it is working only at its 1/5th rated pressure.

The test result also shows SLL-40 deliver 24.000liter/hr water through a 110mm diameter pipe of 175 cm length using pressure chamber.
whereas SLL-40 can only deliver 22.500/hr through 165mm diameter pipe of 175 cm using a membrane diffuser with comparable power usage.

Not a huge loss but flow did not go up (as expected with a larger diameter pipe).

Now if we compare SLL50 delivers 44 LPM of air at 200mBar. 200mBar is where most linear pumps pressure rating runs. Low quality pumps may not even go there for their published air flow rate. This pressure is purely developed by the rubber membrane( diaphragm) that will loosen up and won’t be able to provide that pressure support over time( make sense). So depending on how old the pumps were at the time of the testing below the observed result may change.
NOW MY ATTEMPT for some interpretation of test results available.
Membrane disk Airlift made by Gino (24cm disk) with 250mm to 160mm reduction:

Pump------Diameter rising pipe--------Length rising pipe--------Litres per hour--------consumption-------watt/m³
SLL50---------------160----------------------------175----------------------25.000----------------35 watt-----------1,4 watt

Disk Airlift made by Guyke with 160mm to 110mm reduction:

Pump------Diameter rising pipe--------Length rising pipe--------Litres per hour-------consumption-------watt/m³
SLL50---------------110---------------------------205----------------------23.000----------------36 watt---------1,56 watt

Disk Airlift made by Guyke with 250mm to 110mm reduction:


Pump------Diameter rising pipe--------Length rising pipe--------Litres per hour-------consumption-------watt/m³
SLL50---------------110---------------------------205-----------------------23.000---------------40 watt---------1,73 watt

with the length of rising pipe increasing from 175 to 205 there is an increase in pressure load to 200m Bar just from water pressure plus pressure to over come EPDM membrane opening (20-30mBar). From the plots on SLL-50 for a total pressure of 225mBar air flow drops to 40lpm from 44

Inference from above data the reduction pipe has no influence on water output as 250---->110 and 160--->110 reductions has not changed output.
SLL-40 at 200mBar can deliver 36lpm of airflow based on data from http://secoh.com.pl/produkty/dmuchawy/secoh-sll-20
Now comparing pressure chamber to disk diffuser
Pressure chamber Airlift:

Pump------Diameter rising pipe--------Length rising pipe--------Litres per hour-------consumption-------watt/m³

SLL40----------------110---------------------------170---------------------24.000---------------32 watt------------1,3 watt

Membrane disk Airlift made by Gino (24cm disk) with 250mm to 160mm reduction:

Pump------Diameter rising pipe--------Length rising pipe--------Litres per hour--------consumption-------watt/m³
SLL40---------------160----------------------------175----------------------22.500----------------28 watt----------1,24 watt

increasing diameter of riser pipe from 110 to 160 mm reduced the flow at almost similar length for rising pipe.
Now if we look at the available data there is a connection of airflow with diameter of rising pipe.
SLL50 at 44lpm deliver 25.000 litter through 160 mm diameter pipe
SLL50 at 40lpm deliver 23.000 litter through 110mm diameter pipe
SLL40 at 36lpm deliver 24.000 litter through 110 mm diameter pipe
SLL40 AT 36LPM deliver 22.500litter through 160mm diameter pipe
What is your inference?
Please provide your valuable inputs as most of you have practical experiences and can validate my observations.
Very sorry about the late reply!
I read everything carefully. What I can say:

The test results we provide have all been submitted by Marc while working with Guyke and Gino. Some were tested on the same day in Marc's test setup as seen in these videos:




I think the membrane results have been submitted by either Guyke and/or Gino, seperately from that day. Your observation is something I noticed as well. Sometimes flow results are the opposite of what you would expect. In some cases this may be due to older pumps, I can't say for certain.

Testing these setups can be challenging as you need to make sure the proper depth for the airlift can be reached and that there are no bottlenecks in your system that cause drag. The results we published are somewhat limited and outdated. This is something that has been bothering me as well. I am preparing to build a proper (and I do mean proper) test setup that will be adjustable to account for most variables in testing and real life results (while running a filter which causes drag for example). I will oversize transits and use an oversized collector or collector chamber so any type of airlift can be connected and tested properly. I am currently making preparations. When my build is finished this problem will be in the past, as the results will be shared by me personally and I will be able to test any suggestion made on the site.

Meanwhile, my advice is to look at the numbers we shared. If you want to use a membrane airlift, or multiple, look at the results Frank shared as he has good experience with this. Alternatively, the 145cm and 170cm pressure chamber airlifts have been tried and tested and will definitely get you good results very close to what has been tested by Marc. Since you are using quite a heavy air pump, consider simply splitting the flow. You should be able to run two 110mm pressure chamber airlifts on that single pump. That could be something to consider.

Reading your other topic, you seem to have changed your mind somewhat on what you want to do.
You say you want 8000 liters of flow at a height of 30cm.

It may be possible, but then I would try the 'brute force' approach. Simply adding a bigger pump will up your flowrate on any airlift (up to a limit).
Have a look at this video where Marc is using a 250W compressor on a 110mm airlift:


However, this is what you can expect under normal circumstances:


From what I've gathered, if you really want to try and use an airlift with some discharge head in your system, the way to go is smaller diameter (110mm or even less) and a relatively strong pump. In this case I would definitely only use one airlift. I am unsure on how membrane airlifts perform with discharge head. This is something Frank could maybe shed some light on.

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