BVM UAT HELP
 

Hi Guys,

I am aware that the BVM UAT should be positioned at around 45 degrees so that any bubbles might find their way to the top of the tank. However, would it matter if the UAT is placed upright?
In such a case would it affect the fuel draw to the pump?
Another question please. The UAT has a 6mm pipe to the pump. My pump takes 4mm. Is there a reducer available?

Anybody would like to take a shot at these questions?

Thank you

Regards

Reuben

RE: BVM UAT HELP
 

No
flew my F15 with one vertical 75 flights no flame outs
never drained the fuel system always left the uat full
brian

RE: BVM UAT HELP
 

i use them from flat to almost upright, without any single problem. Important is to follow the instruction, to clear the uat from air, and to keep the bubbles as small as possible. A good idea, (what i do normally) is the run the pump with the test function (on JC turbine) or with a 2 V battery to check the bubble free operation of the fuel circuit..

for the pump is important to keep the pipe lenght befoer the pump as short as possible, in other work to place the UAT closer as possible ans the tank and the pump closer to the UAT keeping the pipes short.

Yes, adapter exist, from festo. 6-4 mm
i use a short festo 6 mm pipe from the UAT, short before pump adapter 6-4 and in the pump with 4.

RE: BVM UAT HELP
 

I have only had about 10 flights on my Roo with an upright UAT but so far it is absolutely fine.

For the line, I used a 6mm-4mm Festo reducer. Some say that under suction they may let air in but I haven't had any problems (yet).

RE: BVM UAT HELP
 

Reuben,

The jetcat manual shows how to hook up a UAT to your pump. If you don't have a jetcat Dreamworksrc carries a reducer here

http://dreamworksrc.com/catalog/prod...roducts_id=470

Current price of $5.25. I'd buy a few since you're likely to have more than one jet.:D

I've seen many people mount their UAT upright. I like to follow instructions when ever I can![X(]:D

Raf

RE: BVM UAT HELP
 

In fact the set up instructions for the Bobcat show the UAT is upright.

RE: BVM UAT HELP
 

As long as air bubbles stay away from the bag, they seem to work in almost any orientation....The 45 degree set is probably a little easier to bleed the air out though...

A barbed reducer ( http://s43500.sites99.storefront-hos...ail.aspx?ID=48 ) would be much more effective and bubble proof on the suction side of the pump...besides that, they are cheaper!

RE: BVM UAT HELP
 

I have used the UAT in the vert position with no problems. If you can, fill the UAT for the first time thru the center cap fitting, this fills the filter media from the inside out purging the air. Run the motor and shake the jet to be sure there are no more air bubbles otherwise it will ruin your day.Also leave the UAT full for the next flying session.

V..

RE: BVM UAT HELP
 

Interesting replies guys...thanks....Wayne that reducer from GNM is very cool....pity I have just received some stuff from Dreamworks already... I guess I have to re-order again from across the pond :D

Thanks again

Reuben

RE: BVM UAT HELP
 

4 mm pump inlet, 6 mm tubing. Hmmmmm....I wonder how you do this.........

Q. What is the ID of 6 mm tubing?
A. 4 mm!

Without any further headscratching, here's how you hook 6 mm line to the 4 mm pump fitting.....

1. Slide a piece of 4 mm tubing over the pump inlet barbed fitting.
2. Using a sharp exacto or razor blade, cut the 4 mm tubing off FLUSH with the end of the barbed fitting.
3. Slide the 6mm tubing over the 4 mm tubing you just placed on the barbed pump inlet fitting.
4. Safety wire the 6 mm tubing to the pump inlet barbed fitting, to keep it from leaking.
The point of this exercise is to supply the pump with as much fuel as it can ever use. There is no reason or sense in reducing the available fuel to the pump by aa reduction of the supply line cross section. Let the pump work as easily as possible. Remember that the fuel supply is on the SUCTION side of the fuel system.
It's easier to drink through a regular straw than through a cocktail stirring thingie.

Harley Condra
BVM REP
JetCat REP

RE: BVM UAT HELP
 

You don't need a reducer!

Put a short length of 4 mm. line on the pump inlet nipple. It should be no longer than the nipple. Then slide the 6 mm. line over that. It provides a nice snug fit. Safety wire it just like all of your fuel fittings.

I've never had a problem with this set-up in hundreds of flights. Frankly I thought that's the way everyone did it, since that is what was in the Ram instruction manual.

Joe

RE: BVM UAT HELP
 

joeflyer,
HA HA... beat you to it.:D

Harley

RE: BVM UAT HELP
 

Harley,
Guess you can type faster than I can.

Joe

RE: BVM UAT HELP
 

Joe, Harley you two beat me to it. the tubing idea is just right and cheap too, I had a bunch and more flights this way too, Zero leaks.

RE: BVM UAT HELP
 

Just remember when safety wiring to wrap twice before twisting...

Bob

RE: BVM UAT HELP
 

So why are the solenoids designed for 4mm hose?

The 6mm UAT to 4mm solenoid fitting is, IMHO, a complete pain in the ass. Why can't BVM make the UAT with a 4mm nipple. Or, if the fuel line cross section is that important, why can't Jetcat (and others) make the solenoids with 6mm fittings?

Considering the price of the UAT, it seems a pretty stupid design decision.

RE: BVM UAT HELP
 

Sic,
These fuel pumps push a lot better than they pull. It is a good idea to have everything on the suction side 6 mm. to minimize flow restriction and make life easier for the pump.

Typically the UAT goes directly to the pump, which is why BVM made that line 6 mm. The solenoids are on the pressure side of the pump, which is why they have 4 mm. fittings. The design flaw, as I see it, is the pump manufacturers not having a 6 mm. fitting on the pump suction side.

Joe

RE: BVM UAT HELP
 

Sic,
The original RAM 750 pump (circa 1999) had Festo fittings instead of barbed fittings.
The pump inlet fitting WAS 6 mm, and the outlet was 4 mm.
When Hausel came out with their pump, everyone including RAM jumped on the bandwagon with them. Considering the price of the pump, it's cheaper to buy them O.P. than to make them in house.

Attached are a couple of photos of the original RAM pump and it's new home on my "Montana Modeler" fuel can....14 gallons, from Pep Boys Auto Parts....around $100.00 before conversion. On 4.8 volts, it fills a KingCat about a minute slower than the original pump on 7.2 volts (the type Jersey Modeler uses, and creates far less static imbalance as well).
When I switched to the old RAM pump, 90% of the static charge imbalance problem went away.
No flaming intended......
As you can see, the pump has a 6 mm inlet fitting. I wish they were still made this way too.

Harley Condra
BVM REP
JetCat REP

RE: BVM UAT HELP
 

Q: what are the inlets of your fuel pumps?
A: 4mm you need to use 6mm Festo:D

RE: BVM UAT HELP
 

Hey wait a minute....is there more than one way to skin a cat???!!! Yes, there is!!:D

Raf

RE: BVM UAT HELP
 

Well, there are many ways to skin a cat but there is one "CORRECT WAY" to skin her:):)

RE: BVM UAT HELP
 

Oh yes, you're right, again:eek: But the right way is my way!!! Ha ha!!![X(]:D

RE: BVM UAT HELP
 

Can't argue with a Doctor with a needle in his hands:):)

Raf, going to Tam's, need anything?????????? Like a new jet????:):)

RE: BVM UAT HELP
 

Ehab,

Could you drop off some money at Tam's for me????:):)

Raf

RE: BVM UAT HELP
 

Digitech,
What he means is that the pump has barbed fittings made to accommodate 4 mm. tubing, which I believe is 4 mm. o.d. and 2 mm. i.d. What would make more sense is to have the pump inlet sized to accommodate 6 mm. tubing and the outlet to accommodate 4 mm. tubing.

Joe