Positive air pressure for van
Submitted: Monday, Feb 01, 2021 at 06:48
ThreadID:
141028
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16312
Replies:
7
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Daniel G3
Hi I have purchased a continuous cycle Bilge Blower and bilge blower hose to try and create positive air pressure in my caravan to minimise or eliminate dust ingress. When id did some testing with the bilge blower hose attached I found it greatly reduced the amount of air flow from the blower. I am now concerned that when I connect an air filter as
well the unit will not create enough air flow to create positive air pressure.
I know there are commercially available products such as the Carafan, these are out of my current budget.
I do not want to fit a forward facing
snorkel on the van, I was planning to pull air in from a vent located high on the right hand side of the van.
Just concerned about the loss of air flow with the blower just connected to the hose.
Any suggestions or ideas on how to overcome this problem?
Daniel
Reply By: Peter_n_Margaret - Monday, Feb 01, 2021 at 09:56
Monday, Feb 01, 2021 at 09:56
"I do not want to fit a forward facing
snorkel on the van,"
Does not need to be a "snorkel", just a forward facing vent, no fan and no filter, just some S/S fly wire to keep bugs out. Just needs to be configured to avoid water ingress.
The airflow is minimal if you have successfully sealed the van up, which is an essential starting point, in fact if the van is 100% sealed (which is not possible), there will be no airflow at all.
This works a treat. The outlet to the inside is higher than the intake and it also serves as the required top vent for gas.
Ram air vent
Cheers,
Peter
OKA196 motorhome
AnswerID:
634929
Follow Up By: Daniel G3 - Monday, Feb 01, 2021 at 13:14
Monday, Feb 01, 2021 at 13:14
Thanks for the information Peter and I have no doubt that that system would work
well on your vehicle.
My caravan is towed behind a Ford
Ranger and I do have a stone stomper fitted which does minimise some dust. I am concerned that a scupper may still allow dust in. Adding some form of filter even if it is a washing up sponge will minimise the amount of air that gets inside the van.
Thanks for your response
FollowupID:
912353
Follow Up By: Peter_n_Margaret - Monday, Feb 01, 2021 at 13:46
Monday, Feb 01, 2021 at 13:46
I think you will find that the volume of dust at the top front of the van is minimal and as I suggested, the actual air flow is minimal. It is about making sure that those tiny little leaks that you can not find to seal are leaking out, not in.
https://youtu.be/kAVLzfLADPA
Cheers,
Peter
OKA196 motorhome
FollowupID:
912354
Reply By: Darian - Monday, Feb 01, 2021 at 14:02
Monday, Feb 01, 2021 at 14:02
If you
check all of your vans door/window/hatch seals, plus fit a temporary lower door vent cover*, a modest inward air pressure will do the trick.
I chose to fit a Camec scoop over the original factory fitted scupper on the roof’s leading edge...the scoop and the scupper are a ‘system’...they mate, when the scupper is opened, but allow flow through when the scupper is closed...works a treat for inward pressure...and as a result, no dust at all.
*my temporary lower door vent cover has a red flag attached that sticks out of the door frame, as a reminder.
AnswerID:
634932
Follow Up By: Daniel G3 - Monday, Feb 01, 2021 at 16:35
Monday, Feb 01, 2021 at 16:35
Hi Darian
Thanks for the reply I will consider a scupper but would also like to progress with the Bilge blower if I can get it to operate correctly. Just concerned if I purchase a Donaldson filter at $300 and the blower fails to produce enough airflow to create the positive air pressure. Perhaps a combination of the two products will give the best protection from dust ingress
FollowupID:
912356
Follow Up By: Bob Y. - Qld - Tuesday, Feb 02, 2021 at 06:45
Tuesday, Feb 02, 2021 at 06:45
Daniel,
Unless the fitting of a Donaldson filter suits your planned design, it seems a big expense for what will be not a lot of dust anyway. You could peruse the filter aisle at Supercheap, and find a suitable flat filter element you could fit to an inlet vent.
Bob
FollowupID:
912361
Follow Up By: Daniel G3 - Tuesday, Feb 02, 2021 at 07:13
Tuesday, Feb 02, 2021 at 07:13
Thanks Bob that is a great suggestion. Certainly cheaper than the Donaldson unit and if it does not work then I have not wasted a lot of money.
FollowupID:
912362
Reply By: Erad - Tuesday, Feb 02, 2021 at 18:30
Tuesday, Feb 02, 2021 at 18:30
Daniel:
A scupper vent in the caravan roof works quite
well, although being forward facing, if it rains, ..... As for dust entry via the scupper or your bilge fan, you can buy some filter media from an air conditioner supplier and jam it in the intake. We do this with our scupper vent and it works very
well, although at roof level, there isn't very much dust anyway.
Our first trip with our poptop van was a disaster. No foam blocking the lower vent in the door, and the dust was at least 1 cm think. The next trip was to Tiboorburra via
Gladstone in Qld (heading west then south then west etc). After Nocundra, there were
places where I couldn't even see the caravan - the dust was so thick, yet with just the foam in the door, there was very little dust inside the van. That was with no scupper vent in the roof at that time. Subsequently we fitted the vent in the roof and it works
well.
AnswerID:
634948