Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Drop-out relay

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

jonlaury(at)impulse.net
Guest

Posted: Tue Jul 18, 2006 8:03 am Post subject: Drop-out relay

I have a fuel transfer pump that I want to drop-out  when it goes dry. Suggestions?

  

 Thanks,

 John

nuckollsr(at)cox.net
Guest

Posted: Tue Jul 18, 2006 8:31 am Post subject: Drop-out relay

At 08:36 AM 7/18/2006 -0700, you wrote:



 	  Quote: 	
		  I have a fuel transfer pump that I want to drop-out when it goes dry. 

Suggestions?



Thanks,

John


	


  How can you SENSE that it's dry? Output pressure? Current flow?

  liquid level at the inlet?

        Bob . . .

      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

klwerner(at)comcast.net
Guest

Posted: Tue Jul 18, 2006 8:36 am Post subject: Drop-out relay

How about a Fuel Pressure Switch  (normally open if no pressure is present). 

 Hit the Transfer Start Button, pump  until pressure goes away and then switch opens circuit to  pump.

  

 do not archive

 [quote]   ---

BRogers(at)fdic.gov
Guest

Posted: Tue Jul 18, 2006 8:58 am Post subject: Drop-out relay

Check out the product(s) at this web page.  It might just be what you are looking for.  

   

http://www.ppavionics.com/XFR.htm  

   

         

  

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of John Burnaby

 Sent: Tuesday, July 18, 2006 10:36 AM

 To: aeroelectric-list(at)matronics.com

 Subject: AeroElectric-List: Drop-out relay  

  

     

I have a fuel transfer pump that I want to drop-out when it goes dry. Suggestions?  

    

   

    

Thanks,  

    

John

frank.hinde(at)hp.com
Guest

Posted: Tue Jul 18, 2006 9:08 am Post subject: Drop-out relay

Here it is...



Frank



http://www.ppavionics.com/XFR.htm

--

frank.hinde(at)hp.com
Guest

Posted: Tue Jul 18, 2006 9:10 am Post subject: Drop-out relay

A while back there was a device that did light a warning light when the

current flow dropped, indicating a dry pump...Can't remember where it

came from though.



Typically it is a bad idea to run a pump dry but the facets apparently

are completely unphased by running dry.



The light could be used to switch a relay instead to drop the pump off

line.



Frank 



--

jonlaury(at)impulse.net
Guest

Posted: Wed Jul 19, 2006 7:06 am Post subject: Drop-out relay

Thanks all for your suggestions. 

 At the moment, I have no means of determining  "dryness".

  I'm open to the simplest solution that's cost  effective. The XFR fuel controller switch would fit the job, if a little pricey.  I like the idea of a fuel pressure switch controlling a pump relay, but when  there's no pressure (switch open) how does the pump start? How much pressure is  req'd to close the switch? There's not much pressure developed in the transfer  line.

  

 I'm using one of the Facet cube-shaped pumps.  

  

  

 John

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Wed Jul 19, 2006 7:40 am Post subject: Drop-out relay

On Jul 19, 2006, at 10:34 AM, John Burnaby wrote:



 	  Quote: 	
		   Thanks all for your suggestions.

 At the moment, I have no means of determining "dryness".

  I'm open to the simplest solution that's cost effective. The XFR  

 fuel controller switch would fit the job, if a little pricey. I  

 like the idea of a fuel pressure switch controlling a pump relay,  

 but when there's no pressure (switch open) how does the pump start?  

 How much pressure is req'd to close the switch? There's not much  

 pressure developed in the transfer line.


	


The pressure switch must be the normally open type, i.e. the pressure  

switch contacts are open when there is no pressure. Put a momentary  

contact switch in parallel with the pressure switch. When you press  

the momentary contact switch and hold it for long enough that the  

pump starts running, the pressure will activate the pressure switch  

which will then keep the pump running until the tank runs dry. You  

will need to hold the momentary switch on every time you want to  

start the pump.



Make sure that the contacts in the pressure switch are rated to  

handle the running current of the pump. The momentary contact switch  

will handle the starting current for the pump.



Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

_________________
Brian Lloyd
brian-yak at lloyd dot com
+1.916.367.2131 (voice) +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery

mark.steitle(at)austin.ut
Guest

Posted: Wed Jul 19, 2006 7:43 am Post subject: Drop-out relay

John,  

Have you considered using a GEMS sensor connected into the line coming from the pump?  The ELS-900 is smaller than the ELS-1100, and might be a better choice for your application.  Seems simple enough to implement using a tee fitting.  The GEMS sensor is solid state and uses a prism to detect the presence/absence of liquid.  That could control a relay which would control the pump.  You can pick up these sensors off ebay for under $10/ea.    

   

Mark S.  

         

  

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of John Burnaby

 Sent: Wednesday, July 19, 2006 9:35 AM

 To: aeroelectric-list(at)matronics.com

 Subject: Re: AeroElectric-List: Drop-out relay  

  

     

Thanks all for your suggestions.   

    

At the moment, I have no means of determining "dryness".  

    

 I'm open to the simplest solution that's cost effective. The XFR fuel controller switch would fit the job, if a little pricey. I like the idea of a fuel pressure switch controlling a pump relay, but when there's no pressure (switch open) how does the pump start? How much pressure is req'd to close the switch? There's not much pressure developed in the transfer line.  

    

   

    

I'm using one of the Facet cube-shaped pumps.   

    

   

    

   

    

John

GEMS_ELS-1100_Fuel_probe.jpg

Description:

Filesize:

12.86 KB

Viewed:

308 Time(s)

klwerner(at)comcast.net
Guest

Posted: Wed Jul 19, 2006 7:48 am Post subject: Drop-out relay

John,

  

 1. Perhaps you try a pressure  switch as used to activate the brake lights, -low oil  pressure, etc.

  

 2. To create some pressure in the  transfer line you will need a restricting orifice downstream from the transfer  pump, so some experimentation will be needed.

  

 3. The transfer starts by the Pilot  pushing a button for a few seconds or until the pressure is high enough to  activate the switch which will then hold the relay open all by itself, . . . and  when the transfer tank is getting low and the  pump starts sucking air, the pressure will drop below what is needed  by the switch to hold the relay  open, which will then drop out shutting of the pump. 

  

 Relatively simple and cheap too (some  thinking and tinkering required)

  

 do not archive

 [quote]   ---

Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Wed Jul 19, 2006 8:43 am Post subject: Drop-out relay

In a message dated 7/19/06 10:08:58 AM Central Daylight Time, jonlaury(at)impulse.net writes:

 

  	  Quote: 	
		  I like the idea of a fuel pressure switch controlling a pump relay, but when there's no pressure (switch open) how does the pump start? 	


 

 >>>>

 

 You could wire your start button in parallel with the NC pressure switch contacts- make the "Pump On" button a momentary button and hold it in until the pressure builds enough to close the contacts, then release the button.  The pressure switch contacts will hold the pump on until the fuel is gone and the pressure drops, turning the pump off.  An indicator light connected to the input side of the pump motor would be useful here to tell you the pressure switch is closed and the pump is operating.  It will turn off once the pressure drops and the pump stops.

 

 Mark

_________________
From The PossumWorks...

Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Wed Jul 19, 2006 8:45 am Post subject: Drop-out relay

In a message dated 7/19/06 10:42:06 AM Central Daylight Time, brian-yak(at)lloyd.com writes:

 

  	  Quote: 	
		  The pressure switch must be the normally open type 	


 

 >>>

 Duh- I knew this but my fingers obviously didn't-  Brian is right, natcherly!

 

 Mark - do not archive

_________________
From The PossumWorks...

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

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