Flowscan fuel flow unit. Should I be concerned?

AMURRAY · #1 07-19-2008, 01:13 AM

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.

Kevin Horton · #2 07-19-2008, 04:09 AM

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?

David-aviator · #3 07-19-2008, 07:02 AM

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.....

clarkefarm · #4 07-19-2008, 11:29 AM

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

Sticky1 · #5 07-19-2008, 02:06 PM

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.

frankh · #6 07-19-2008, 02:09 PM

Quote:

Originally Posted by David-aviator

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.....

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

Frank
7a IO360 2* electric pumps..No mechanical pump

osxuser · #7 07-20-2008, 09:00 AM

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.

Sticky1 · #8 07-20-2008, 05:32 PM

Quote:

Originally Posted by frankh

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

Frank
7a IO360 2* electric pumps..No mechanical pump

Hummmm.......And what do we do on take off..? We turn on a pump. And what happens if that pump fails...?

Keep the 3 pumps

frankh · #9 07-20-2008, 06:25 PM

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.

Tony Spicer · #10 07-21-2008, 04:42 AM

Quote:

Originally Posted by AMURRAY

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.

Floscan specs here:

http://www.floscan.com/html/blue/aviation.php

My read is that not all the fuel goes thru the small hole.

Tony