 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
tonyrenshaw268(at)gmail.c
Guest
|
 Posted: Thu Jul 01, 2010 10:03 pm Post subject: Pierburg Output Fuel Pressure |
 |
|
Gidday,
I have a VDO pressure switch set to close at PSI < 2, and am wondering if I can use this in my Europa designed Fuel System for my 914. I am thinking of putting it after my primary pump, before it feeds into the common manifold, and have it automatically switch on the 2nd pump, whilst illuminating a low fuel pressure light. Whenever the 2nd pump is operating, either manually or automatically I am after a light to tell me so on the dash, which shouldn't be too hard. My research suggests that the Pierburg outputs at 1 bar, which is 14 PSI, so this switch will work as good as any, albeit at that low warning it probably won't precede the engine burping and protesting. So, is it worthy of putting into the system or should I change it for something set to a more appropriate value, and what would that be ideally?
Reg
Tony Renshaw
Sydney Ausie
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
 |
rparigoris
Joined: 24 Nov 2009
Posts: 797
|
| Posted: Fri Jul 02, 2010 5:57 am Post subject: Re: Pierburg Output Fuel Pressure |
|
|
Hi Tony
If you were to have such a circuit, you would want to have it turn on second pump when it falls below ~ 2 PSI differential pressure (fuel pressure going to carb less the airbox pressure).
I have series with bypass laid out fuel system and to me it makes sense to have second pump running when having fuel pressure going low would be a bad thing, like during take offs and landings. This may not be the thing to do if you have parallel pumps because you can blow over the ~ 5 PSI differential.
UMA can provide an output from their differential gauge to drive a LED to indicate below ~ 2 or above ~ 5. You could probably modify signal or have them do it to only provide below 2 and use that to turn on second pump. Their gauge is driven by a differential pressure sender.
I will have a LED in my gauge to indicate above ~ 5 and below ~ 2.
Ron Parigoris
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
frans(at)privatepilots.nl
Guest
|
| Posted: Tue Jul 06, 2010 10:24 am Post subject: Pierburg Output Fuel Pressure |
|
|
On 07/02/2010 03:57 PM, rparigoris wrote:
| Quote: | If you were to have such a circuit, you would want to have it turn on
second pump when it falls below ~ 2 PSI differential pressure (fuel
pressure going to carb less the airbox pressure).
|
I agree you should have a differential fuel pressure switch. The Rotax
maintains a specific fuel pressure OVER the airbox pressure (which
varies with power setting and altitude).
| Quote: | not be the thing to do if you have parallel pumps because you can
blow over the ~ 5 PSI differential.
|
I have the serial pump layout, but with a full tank and both fuel pumps
on, the differential pressure raises to 6 psi while the engine is
running on low power. I was concerned that this higher fuel pressure
would choke the engine during the approach, when both fuel pumps are on
and the power setting is low, but I have not experienced any problems
with it.
Yet I would like to know whether this is normal. During flight, with one
pump on, the differential pressure is always around 4.5, regardless of
power setting. Interestingly, the fuel pump connected to the Andair
gascolator provides a lower pressure than the fuel pump connected to the
disposable fuel filter.
Frans
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
rparigoris
Joined: 24 Nov 2009
Posts: 797
|
| Posted: Tue Jul 06, 2010 11:35 am Post subject: Pierburg Output Fuel Pressure |
|
|
Hi Frans
Just a few ideas:
**Differential pressure gauge may not be speaking absolute truth
**The fuel pressure regulator is adjustable, you could lower a pound
**You may have more of a restriction on the return line than is desirable, make sure fittings you are using are of large bore varient. Supplied with my kit were both large and smaller bore (more restricting). Also look for kinks or pinches. Rotax tells you max. restriction they want, worth measuring. Measure and or fix restriction before you adjust regulator.
**Fuel pressure needs to be higher than airbox pressure or it won't flow into carb bowl. Too high and it could overcome needle valve and leak. That said there are plenty of 914s flying with parallel fuel systems that blow way higher than 5 PSI and pilots say seems fine. 6 PSI is not very high, but if it were I, would get it down a little if could.
**Perhaps you can check gauge/sender calibration?
Ron Parigoris
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
g-iani(at)ntlworld.com
Guest
|
| Posted: Wed Jul 07, 2010 12:37 am Post subject: Pierburg Output Fuel Pressure |
|
|
Ron
Where does the information that the parallel system blows over 2.8psi come from. From memory one of the books says it should be 1.8psi from either pump and 2.8 with them both on.
This is exactly what my IES tells me is happening in G-IANI. We use this fact to check that both filters are not blocked at every engine start.
Ian Rickard G-IANI XS Trigear, 300hours
Europa Club Mods Specialist
e-mail g-iani(at)ntlworld.com
From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of rparigor(at)suffolk.lib.ny.us
Sent: 06 July 2010 20:32
To: Europa
Subject: Re: Re: Pierburg Output Fuel Pressure
Hi Frans
Just a few ideas:
Differential pressure gauge may not be speaking absolute truth
The fuel pressure regulator is adjustable, you could lower a pound
You may have more of a restriction on the return line than is desirable, make sure fittings you are using are of large bore varient. supplied with my kit were both large and smaller bore (more restricting). also look for kinks or pinches. Rotax tells you max. restriction they want, worth measuring. Measure and or fix restriction before you adjust regulator.
Fuel pressure needs to be higher than airbox pressure or it won't flow into carb bowl. Too high and it could overcome needle valve and leak. That said there are plenty of 914s flying with parallel fuel systems that blow way higher than 5 PSI and pilots sday seems fine. 6 PSI is not very high, but if it were i I would get it down a little if i could. Perhaps you can check gauge/sender calibration?
Ron P.
> --> Europa-List message posted by: Frans Veldman <frans(at)privatepilots.nl>
>
> On 07/02/2010 03:57 PM, rparigoris wrote:
>
>> If you were to have such a circuit, you would want to have it turn on
>> second pump when it falls below ~ 2 PSI differential pressure (fuel
>> pressure going to carb less the airbox pressure).
>
> I agree you should have a differential fuel pressure switch. The Rotax
> maintains a specific fuel pressure OVER the airbox pressure (which
> varies with power setting and altitude).
>
>> not be the thing to do if you have parallel pumps because you can
>> blow over the ~ 5 PSI differential.
>
> I have the serial pump layout, but with a full tank and both fuel pumps
> on, the differential pressure raises to 6 psi while the engine is
> running on low power. I was concerned that this higher fuel pressure
> would choke the engine during the approach, when both fuel pumps are on
> and the power setting is low, but I have not experienced any problems
> with it.
> Yet I would like to know whether this is normal. During flight, with one
> pump on, the differential pressure is always around 4.5, regardless of
> power setting. Interestingly, the fuel pump connected to the Andair
> gascolator provides a lower pressure than the fuel pump connected to the
> disposable fuel filter.
>
> Frans
>
>
> --> http://www.matronics.com/contribution
>
>
>
> | Quote: | | http://www.matronics.com/Navigator?Europa-List |
0123456789
[quote][b]
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
rparigoris
Joined: 24 Nov 2009
Posts: 797
|
| Posted: Wed Jul 07, 2010 5:42 am Post subject: Pierburg Output Fuel Pressure |
|
|
Hi IanMy statement was based on Europas comment when they implimented series with bypass and offering a differential gauge that having parallel pumps running can overwhelm fuel pressure regulators ability to get fuel out of its exiting orifice and blow above high side of 5PSI. John Hurst also mentioned parallel with both pumps running would go above 5 PSI. (I purchased my UMA gauge from him). Through the years I either read or talked to folks that the same was mentioned. Some folks said they ran 2 parallel pumps for take off and landings without problems. Running parallel increases flow when second pump is turned on but pressure is about the same. Running second pump in series increases flow only a slight bit but can increase pressure. I tested my series with bypass set up on bench and when challenged with restriction on intake or output second pump helps a lot: http://contrails.free.fr/engine_914_fuel_syst_test_en.php Ron Parigoris [quote][b]
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
