Air suction analysis

[roidan]

here is the air suction of my beckett injector, running in dual beckett mode with mx100

30litres of air / min

which means 1800 litres/hr on each beckett injector

1800 l/hr x 2 (dual beckett mode)

= 3600 l/hr of air

1800 l/hr x 4 (quattro mode)

= 7200 l/hr of air

phew......

[roidan]

AP 850 600l/hr

BBK 200 1000l/hr

AP 902 1200l/hr

AP 702 1400l/hr

BBK 250 1500l/hr

AP 1003 1800l/hr

BBK 300 2000l/hr

AP 703 2100/hr

AP 1004 2400l/hr

BBK 400 2500l/hr

BBK 500 3000l/hr

AP 1006 3600l/hr = Roidan's Quattro in dual-mode 3600l/hr

BBK 650 4000l/hr

Roidan's Quattro in quattro mode 7200l/hr

just air suction comparison, BBK and deltec air flow taken from manufacturer's catalogue

[Achilles Tang]

Wow! You got an airflow meter!!!

How was this test done? The 4 airlines were connected to this meter?

[roidan]

ya...flown in from the states...hehe

i am running in dual beckett mode currently mah...

so i see 1800l/hr of air ###### in through each injector

so dual beckett mode is 1800l/hr x 2 lor

each airline to each flowmeter

but hor..must remember this flow is achieved from mx100 pushing through 2 injectors....and even if use the same mx100 to push through another dual beckett skimmer...air flow suction may differ alot also...do to tonnes of factors in the skimmer design...like size of downtubes..size of chamber...size of beckett housings....tooo many factors to consider that will affect airflow despite a same pump pushing through them...

well, as you can see from the list....it is of no coincidence that that higher range skimmers from deltec or BBK suck in more air than their lower models...hehe

more air flow means more expensive, along with other factors of coz....

[AlfaRomeo]

Wow! You have the max air-flow compared to anything out there. Almost double the BBK650. Congrats!

I think if yours is a commercial product, it would at least cost $20k! cool!

[roidan]

no lah..since i am running in dual beckett mode now....it still sucks less air than the BBK 650 (my 3600l/hr vs 4000l/hr)

so the BBK still rules over me in terms of air suction, for model 650 at least

which the external model costs just under EURO 5k according to their catalogue

i think it's time to roll in the RK2s for comparison

[AlfaRomeo]

Where did you get the airflow meter from? how the much? hehehehe

[roidan]

a non-SRC reefer counterpart got it for me...

how much? not sure, he hasn't billed me yet

but i am sure $100 still got change..hehe

[roidan]

anyway, upon viewing the list....i would like to think that the BBK300 is quite a value for money needlewheel because the AP1003 is more expensive

for BBK300 users out there....enjoy your skimmers, you have just edged AP1003 triple 1260 powered needlewheels by 200 l/hr

[Achilles Tang]

Do you figure out the airflow by opening the air valve completely or do you tune for an optimum bubble size and then measure the airflow?

They both should give different readings.

Free can borrow or not?

[roidan]

i measure mine at operating position....

which makes me wonder also if the manufacturers give their air flow numbers at operating or full open.....

but with the logic that not every user will dial in their airflow valves the same, probably the manufacturers' figures are at full open position so there will not be any discrepancy in air flow and they get sued for providing misleading figures...

borrow ah...if i pass by toa payoh next time i call you lor..if u are at home then i run up with the meter lend you but i dunno which block you stay, only know you stay toa payoh...

i think those who DIY skimmers should get their hands on a flowmeter so that they know if their air flow is far off from those manufactured ones...if you are close means the design is sound and ok....if far off from the figures means there is something wrong with the design and you can R&D till you get near the ballpark figures

[Achilles Tang]

Actually, those who DIYed with beckett heads need not worry much about variations as it is a fixed designed super venturi.

It's those with DIY needlewheels or modified impellers.

The variations for all skimmers in terms of airflow is in the pump strength and head pressure.

[roidan]

i beg to differ boss..hehe

the design of the beckett skimmer itself does play an important role in the airflow....like i said earlier..the sizes of the pipes..the chambers...the back pressure due to the design and other factors...

just take the below factor for an example

One of the design parameters of this type of skimmer is the length of the injection tube. You can mount the Beckett injector directly on top of the skimmer box, which amounts to having a zero-length injection tube, or you can have a length of rigid PVC or acrylic tubing between the Beckett and the skimmer box. I found that the length of the injector tube significantly affects the amount of air that the skimmer draws. To my surprise, increasing the injector tube length increased the air flow

http://www-2.cs.cmu.edu/~cap/raid/skimmers/thoughts/

just take for example the design of downtubes for example....2 similar lengths...one larger diameter, one more narrow.....the rest of the skimmers are identical..but you can have vastly different airflow through them as the diameter of the downtubes affect water flow thru the tubes..which incidentally affects the air suction induced by the water flow and also the diameter of downtubes will have different back pressure on the same pump used...

so there are really a lot of factors to consider...

[Achilles Tang]

Hmmm.... so it seems.

I only concentrated on the venturi part where air and water is mixed.

But again because different skimmers have different heights, it's really quite variable, isn't it?

A 3m tall skimmer will draw air differently from a 1m tall one. And a 1m tall skimmer may draw in a lot more air if run on an MX-100 right?

[roidan]

yeah....

in a way you are not wrong also...just isolating the beckett venturi and surrounding air for analysis, all beckett injectors will draw in a similar fashion...but it's all these design parameters in the skimmer itself that will either aid the beckett injector from drawing air the way it should and could or the design may end up bottle-necking the beckett injector from performing the way it should...

thus a poorly designed beckett skimmer is actually handicapping the potential of the beckett venturi despite the same beckett injector used in thousands of beckett skimmers everywhere.

a 3m high beckett theoretically speaking will have more head pressure for the pump to work on than the 1m high one...so the 1m high one theoretically should push more.....BUT that's provided other variables are kept constant...both same size downtubes...both same injector housing...and so on...

but it won't be surprising if, even using the same pump, a well designed 3m high version will suck in more air than the 1m high poorly designed version which handicaps the beckett venturi.....but of coz this is only in terms of air suction

in terms of reaction time...the 3m high version will win hands down..hehe

[Achilles Tang]

How many people can have a 3m high skimmer?

[roidan]

maybe those staying in landed property can house one in their backyards...lol

kidding lah..jokes aside...

we should liken the beckett injector like a Mercedes-McLaren engine....every thought and design of the car must be carefully mapped out to bring out the potential of the engine as well as for the engine to serve to its full potential for the car..

if any parts of the car (skimmer) like suspension (downpipes), brakes(housing) cannot fully complement the engine, you will end up with a very problematic car (skimmer).....hehe

also the same engine (beckett) use in different cars (designs), you will get different performance also

so beckett users do not lose heart...if you have a well designed one...the skimmer will serve you very well

[weisoon]

Where did you get the airflow meter from? how the much? hehehehe

Alfa, can get in Singapore...ex stock. Model RMA23SSV measures 5-50 l/min air size 4.5" with 1/8" NPT fitting.

[AlfaRomeo]

The only inherent problem with the beckett is that the bubbles produced cannot be as fine and at the same time in a very dense fashion as from a high performance pump/impeller like the Bubbleking.

Afterall, the beckett injector was designed as a foam head used in fountains and not purpose built.

Also, due to the high flowrates required for the injector, traditionally, dwell time suffers (when compared with similar sized needlewheel skimmers). This 'flaw' is resolved by the newer generation recirculating becketts which uses a separate feed pump to deliver tank water for processing at a slower flowrate (more dwell time)...

More and more skimmer manufacturers will move over to recirculating models as it has tremendously advantages when compared to the 'Straight thru processing' becketts.

[AlfaRomeo]

Alfa, can get in Singapore...ex stock. Model RMA23SSV measures 5-50 l/min air size 4.5" with 1/8" NPT fitting.

Thanks Weisoon!

[roidan]

yeah lor....

alot of designs coming up and will continue to do so even after we leave this world..

probably we may hear purpose-built iwaki needlewheel impellers or needlewheel impeller tunze streams (housed near the base of the skimmer) which run super low wattage with high flow to chop the bubbles fine fine?

anyway, there are ingenious ways to make the beckett bubbles finer but even as we say for the conventional beckett bubbles, their bubbles are not pretty far off compared to needlewheels seriously.....to scrutinise every single bubble is akinned to comparing noise levels from a canon 300d and a nikon d70...

inspecting pixel by pixel, yes, you can see the differences in noise level....but when you wake up to the practical world of printing in 4R to even 8R or A4 size...you will not be able to tell the pictures apart seriously....

so sometimes we may get carried away at the micro level and forgot to appreciate our systems at the macro level

[roidan]

and also not to deviate from the purpose of this thread which is to document who is the best SUCKER

at this very moment....the BBK 650 wins

[AlfaRomeo]

Roidan, the whole point of smaller bubbles is contact area between air and water. The finer the bubbles , the more contact area. So a 2ft tall skimmer with bubbles of 1mm size is equivalent to a 0.5ft tall skimmer with 0.5mm bubbles.

Better still to have 2ft tall skimmer with 0.5mm bubbles giving at least 4x the contact area thus 4x the efficiency?

I think its the micro level of the things we do/have that influences the macro functionalities. Its called efficiency.

[alanseah]

well BK 650 is just one of the top range u see RE selling only.. there are even more custom make BK which U never get to see..

BK like those as high as roidan skimmer.. and you should guess how the air ###### will be like... with RD pump use...

Roidan the way you compare very hard to come to an end.. why not just compare apple with apple.. e.g. given this litre/h that pump can push it can suck how much air..

e.g. RD 12m3 to MX100

[roidan]

alfa...all these i think is quite common knowledge lah...

just like the theory of fluidised reactors....many small surface areas is better than a whole big clump of media sitting in a media bag...duh and i dun think we need to dwell into calculating the surface areas of the bubble spheres to know that

well...maybe some of us are not satisfied with the size of our bubbles till maybe they get to nano-scale? since nano-technology is the IN-thing nowadays...

like i said, this thread is just to document who is the best sucker....perhaps we can start another thread to document bubble sizes...price...wattage..efficiency...and so on

that's why there is never a conclusion which skimmer is absolutely better.....

really too many categories to compare ...size for size...wattage for wattage...bubble size for bubble size....efficiency for efficiency...price for price...and so on....

in my opinion the best skimmer for oneself is one that fits the budget and performs satisfactorily to one's own expectations

anyway, the collated airflow comparison done by me should help those deciding between H&S/deltec and bubblekings in a little way i hope