AMURRAY

AMURRAY

Well Known Member
The inlet hole into the Flowscan 201A-6 is .110 inches in diameter. That is smaller than 1/8 inch. A AN-6 fitting is .300 inches in diameter. It just seems a little choked down.
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My Airflow Performance boost pump pushed 45 US gallons/hr through my Floscan transducer when I did my fuel flow check. Hundreds (thousands?) of RVs are flying with that transducer without problem. Is there something about your aircraft or the way you will operate it that invalidates the good service experience from other RVs?
 
If the device is installed between the electric pump and the mechanical pump, there will be a pressure drop across it when the electric pump is not operating. According to Flowscan specs, that drop will range from .6 psi at 15 gph to 1.4 psi at 40 gph.

This drop in pressure will place the system nearer a vapor lock at the exit port when the electric pump is off and the mechanical pump is sucking fuel through it.

The operating temperature range of Flowscan is -65/100C. That's 212F tops. With cylinder heads running as high as 400F and exhaust ports 1200F, it probably is a good idea not to mount Flowscan in the engine compartment.

I am planning an installation using the 2 electric pumps and Flowscan mounted on the cabin floor with the standard mechanical pump at the engine and running the electric pumps, alternately but continuously. The only thing I did not think of was you can not suck fuel through an electric pump which was pointed out by Dan Rivera at Airflow Performance. A bypass with a check valve will be needed to provide flow if both electric pumps fail. All this to defeat the possibility of a vapor lock.....:)

 
Facet pumps and anti-siphoning valve

I think that Facet market a considerable number of different model fuel pumps and only some have the anti-siphoning valve which would result in a blocked fuel line in the event of pump failure.

I run 4 Facet pumps in series (long story) and usually only use one at a time during cruise to fill a header tank.

Rupert Clarke
RV-9A, NSI/MPS EJ25
 
Hummmmm

This has always been a bone of contention with me. There are several types of senders on the market. Some metal some plastic. All have very small ports except for a few with 1/2 ports. Even those are "necked" down passing the paddle. The only way to do this is a capaticance sensor.....no one makes one for planes. Other fluids yes, but not for planes. Anyway, Placing it before the spider has always been acceptable.
 
I would suggest

David-aviator said:
If the device is installed between the electric pump and the mechanical pump, there will be a pressure drop across it when the electric pump is not operating. According to Flowscan specs, that drop will range from .6 psi at 15 gph to 1.4 psi at 40 gph.

This drop in pressure will place the system nearer a vapor lock at the exit port when the electric pump is off and the mechanical pump is sucking fuel through it.

The operating temperature range of Flowscan is -65/100C. That's 212F tops. With cylinder heads running as high as 400F and exhaust ports 1200F, it probably is a good idea not to mount Flowscan in the engine compartment.

I am planning an installation using the 2 electric pumps and Flowscan mounted on the cabin floor with the standard mechanical pump at the engine and running the electric pumps, alternately but continuously. The only thing I did not think of was you can not suck fuel through an electric pump which was pointed out by Dan Rivera at Airflow Performance. A bypass with a check valve will be needed to provide flow if both electric pumps fail. All this to defeat the possibility of a vapor lock.....:)
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That two independantly wired electric pumps AND a mechanical pump is overkill.

Frank
7a IO360 2* electric pumps..No mechanical pump
 
All the certified STC installs I've seen puts them in the engine compartment, either after the mechanical pump (on carb'd engines) or on the flow divider line (FI). Usually these are wrapped in firesleeving to lower temps.

I think they work just fine, and the engine compartment is where they belong. YMMV.
 
OUCH

frankh said:
That two independantly wired electric pumps AND a mechanical pump is overkill.

Frank
7a IO360 2* electric pumps..No mechanical pump
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Hummmm.......And what do we do on take off..? We turn on a pump. And what happens if that pump fails...?:eek:

Keep the 3 pumps:rolleyes:
 
Wellll...

We are running two pumps so who cares?..I certainly don't!

Now of course this asumes you have plumbed the system so that both pumps can be run independantly.

Frank....700hours on two airplanes without mechanical fuel pumps.
 
Yeah it does

All the fuel has to go through the small hole..Where else can it go?

The reason the small hole is not a problem is that the length of travel through the transducer is very short...I.e if the transducer was replaced with a small tube that was 3 feet long then that would represent a large pressure drop...in other words the pressure drop is directly proportional to length...Conversely as the flowpath (in the transducer) is probably less then half an inch the hole can be pretty small with making a larger pressure drop.

Bottom line these units have many thousands of trouble free hours in all sorts of applications and I have personally never heard of one causing problems.

Frank
 
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