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Vacuume pressure warning light

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cfi(at)conwaycorp.net
Guest

Posted: Fri Jul 27, 2007 3:40 pm Post subject: Vacuume pressure warning light

I would like to add a vacuum pressure warning light to my ship's  panel.  What do you guys recommend?  Is there a particular  vacuum pressure switch that I can connect to my vac line that will  illuminate a panel lamp in the event the vacuum pressure slides to  an unsafe level - or is there another (better) way to do this?

  

 Michael H.

  

  

                    

                

  

 

   [quote][b]

rhdudley1(at)bellsouth.ne
Guest

Posted: Fri Jul 27, 2007 4:11 pm Post subject: Vacuume pressure warning light

Michael,

 I purchased a vacuum switch from Precise Flight, Inc several years ago. I just looked at their website and could not find that switch. You might contact them to see if they still sell the switch. It was part of a vacuum backup system that used manifold pressure. But they sold the switch separately. They may have discontinued it because of the move toward all electrical panels.

 Regards,

 

 Richard Dudley

 RV-6A flying

 

 Michael Hinchcliff wrote:

 [quote]   My VistaPrint Electronic Business Card                       v\:* { 	BEHAVIOR: url(#default#VML) } o\:* { 	BEHAVIOR: url(#default#VML) } w\:* { 	BEHAVIOR: url(#default#VML) } .shape { 	BEHAVIOR: url(#default#VML) }  <![endif]-->     Hinchcliff   Normal   Hinchcliff   2   0   2007-03-11T21:17:00Z   2007-03-11T21:18:00Z   1   20   116       1   1   135   11.8122   <![endif]-->     Clean      false   false   false   MicrosoftInternetExplorer4   <![endif]-->     <![endif]-->          /* Style Definitions */  table.MsoNormalTable 	{mso-style-name:"Table Normal"; 	mso-tstyle-rowband-size:0; 	mso-tstyle-colband-size:0; 	mso-style-noshow:yes; 	mso-style-parent:""; 	mso-padding-alt:0in 5.4pt 0in 5.4pt; 	mso-para-margin:0in; 	mso-para-margin-bottom:.0001pt; 	mso-pagination:widow-orphan; 	font-size:10.0pt; 	font-family:"Times New Roman"; 	mso-ansi-language:#0400; 	mso-fareast-language:#0400; 	mso-bidi-language:#0400;}  <![endif]-->   I would like to add a vacuum pressure warning light to my ship's panel.  What do you guys recommend?  Is there a particular vacuum pressure switch that I can connect to my vac line that will illuminate a panel lamp in the event the vacuum pressure slides to an unsafe level - or is there another (better) way to do this?

    

   Michael H.

    

      

                                  

                                          

                            

    

    	  Quote: 	
		  



 href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matronics.com/Navigator?AeroElectric-List



	
 [b]

rd2(at)evenlink.com
Guest

Posted: Fri Jul 27, 2007 4:53 pm Post subject: Vacuume pressure warning light

Michael-



This switch, along with a blinking LED, should work fine:



http://www.surpluscenter.com/item.asp?UID 05081210041966&item=11-2344&catn

ame



The chamber is SS.



The problem is, it would need a field approval for certified aircraft - and

local FSDO's may not be very sympathetic to messing with the vac system.

I'd like to get my hnads on such a field approval for my own installation.

Anyone?



Best 

Rumen

_____________________Original message __________________________

                  (received from Michael Hinchcliff; Date: 06:32 PM

7/27/2007 -0500)

________________________________________________________________



I would like to add a vacuum pressure warning light to my ship's panel.

What do you guys recommend?  Is there a particular vacuum pressure switch

that I can connect to my vac line that will illuminate a panel lamp in the

event the vacuum pressure slides to an unsafe level - or is there another

(better) way to do this?

  

Michael H.

Ivor Phillips

Joined: 16 Jan 2006
Posts: 253
Location: London UK

Posted: Sat Jul 28, 2007 1:55 am Post subject: Vacuume pressure warning light

I have used a XV600 vacuum switch with three terminals, One  N/C and one N/O so I can have both a vacuum low warning light and a engine tach time from the one instrument, You can adjust the switch to suit your installation ,  

http://www.valvesystems.co.uk/catalog/Type-XV600-Vacuum-Switches-p-1-c-50.html  

   

regards  

Ivor Phillips  

   

--

cfi(at)conwaycorp.net
Guest

Posted: Sat Jul 28, 2007 4:20 am Post subject: Vacuume pressure warning light

Yes, this should work nicely.  Thank you!



---

rd2(at)evenlink.com
Guest

Posted: Sat Jul 28, 2007 4:34 am Post subject: Vacuume pressure warning light

You are welcome.

Rumen

do not archive

_____________________Original message __________________________

                  (received from Michael Hinchcliff; Date: 07:14 AM

7/28/2007 -0500)

________________________________________________________________


<cfi(at)conwaycorp.net>



Yes, this should work nicely.  Thank you!



---

cfi(at)conwaycorp.net
Guest

Posted: Sat Jul 28, 2007 5:19 am Post subject: Vacuume pressure warning light

Ivor, I'm sure this would have worked fine,  but I'm in the U.S.  Thanks for sharing.  

  

 Do not archive.

 [quote]   ---

klehman(at)albedo.net
Guest

Posted: Sat Jul 28, 2007 9:16 am Post subject: Vacuume pressure warning light

Does this mean that you guys are running more than 6" vacuum in order to 

put the warning light out?? I had thought that 5" was about normal??



I'm using a solid state sensor to feed my EIS but have only set the 

regulator for about 5". However sometime after a hundred hours or so my 

imported horizon became somewhat erratic and unreliable.



Ken



" New WASCO model 414-0005. Compact size vacuum switch. Single pole 

contacts open at 6" Hg., close at 3" Hg. Factory setting non-adjustable. 

Contacts rated to 5 Amps at 230 volt AC. Spade terminals 1/4". Port 1/8" 

NPT. 30" Hg. max. Shpg. 1/4 lb.



rd2(at)evenlink.com wrote:



 	  Quote: 	
		  



Michael-



This switch, along with a blinking LED, should work fine:



http://www.surpluscenter.com/item.asp?UID 05081210041966&item=11-2344&catn

ame



The chamber is SS.



The problem is, it would need a field approval for certified aircraft - and

local FSDO's may not be very sympathetic to messing with the vac system.

I'd like to get my hnads on such a field approval for my own installation.

Anyone?



Best 

Rumen

_____________________Original message __________________________

                  (received from Michael Hinchcliff; Date: 06:32 PM

7/27/2007 -0500)

________________________________________________________________



I would like to add a vacuum pressure warning light to my ship's panel.

What do you guys recommend?  Is there a particular vacuum pressure switch

that I can connect to my vac line that will illuminate a panel lamp in the

event the vacuum pressure slides to an unsafe level - or is there another

(better) way to do this?

  

Michael H.

cfi(at)conwaycorp.net
Guest

Posted: Sat Jul 28, 2007 11:13 am Post subject: Vacuume pressure warning light

Yes, 5 in Hg is normal.  I'm going to wire this so the light illuminates 

when the pressure falls above the 6 inch Hg range (i.e. vac failure).  If it 

does not work out, I'll be out just 8 bucks.



---

klehman(at)albedo.net
Guest

Posted: Sat Jul 28, 2007 12:04 pm Post subject: Vacuume pressure warning light

Hmmm I don't think that will work Michael.  If I read this correctly, it 

seems to me that switch will do nothing at all unless it has more than 

6" of vacuum applied at every startup. After that then the contacts 

would close at shutdown or whenever vacuum fell to less than 3".

Ken



Michael Hinchcliff wrote:



[quote] 

 <cfi(at)conwaycorp.net>



 Yes, 5 in Hg is normal.  I'm going to wire this so the light 

 illuminates when the pressure falls above the 6 inch Hg range (i.e. 

 vac failure).  If it does not work out, I'll be out just 8 bucks.



 ---

cfi(at)conwaycorp.net
Guest

Posted: Sat Jul 28, 2007 1:38 pm Post subject: Vacuume pressure warning light

Hello, Ken. Since the vacuum system will always initialize at atmospheric 

pressure (29.92” Hg give or take) at each startup and then work it's way 

down to 5" Hg after startup, the switch should work fine according to my 

interpretation of the description, "Contact open at 6" Hg., close at 3" Hg". 

I interpret that the contactor will be disengaged (i.e. light off) while 

between 3-6" Hg, which is what I'm looking for.  Please let me know if you 

think I am overlooking something here.



---

Bob McC

Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON

Posted: Sat Jul 28, 2007 3:06 pm Post subject: Vacuume pressure warning light

Michael;

The system starts out at give or take 29.92 inches of positive pressure,

then gets "sucked" down to "zero" positive pressure by the vacuum pump, then

gets sucked down further until 1" of vacuum (or negative pressure) is

created, then 2" of vacuum etc until finally you have, give or take, 5" of

vacuum. It will, in theory, never reach 6" of vacuum unless your vacuum

regulator fails and allows the pump to create "extra" vacuum if it's

capable. Your switch will therefore switch on as it passes 3" of vacuum, but

it will be "ON" at the normal vacuum of 5", it will never reach 6" to turn

"OFF", just the opposite of what you describe. (ON between 3 and 6, not OFF)



Bob McC



---

_________________
Bob McC
Falco #908
(just starting)

khorton01(at)rogers.com
Guest

Posted: Sat Jul 28, 2007 3:35 pm Post subject: Vacuume pressure warning light

This switch almost certainly works on gauge pressure, rather than  

absolute pressure.  Gauge pressure is the difference between the  

pressure of interest and ambient pressure.  The vacuum system will  

have a gauge pressure of zero prior to engine start, and the vacuum  

will increase to a gauge pressure of about 5" Hg once the engine is  

running (i.e. the absolute pressure in the vacuum system will be 5"  

Hg lower than ambient pressure).  If the spec sheet values are  

accurate, the contacts would remain closed unless the vacuum ever got  

greater than 6" Hg, which should only happen if the regulator fails.



I don't think this switch will work for you.  But, all you risk is $8  

and a bit of time and energy.



Kevin Horton

On 28 Jul 2007, at 17:31, Michael Hinchcliff wrote:



[quote] 

 <cfi(at)conwaycorp.net>



 Hello, Ken. Since the vacuum system will always initialize at  

 atmospheric pressure (29.92” Hg give or take) at each startup and  

 then work it's way down to 5" Hg after startup, the switch should  

 work fine according to my interpretation of the description,  

 "Contact open at 6" Hg., close at 3" Hg". I interpret that the  

 contactor will be disengaged (i.e. light off) while between 3-6"  

 Hg, which is what I'm looking for.  Please let me know if you think  

 I am overlooking something here.



 ---

Bob McC

Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON

Posted: Sat Jul 28, 2007 4:02 pm Post subject: Vacuume pressure warning light

Please forget this post. My mind was completely somewhere else and this

description is obvious nonsense. Sorry.



Bob McC

---

_________________
Bob McC
Falco #908
(just starting)

klehman(at)albedo.net
Guest

Posted: Sat Jul 28, 2007 4:08 pm Post subject: Vacuume pressure warning light

Michael



Since it is called a vacuum switch, I'm guessing it is referenced to 

atmospheric and the switch points are 3" and 6" below ambient 

atmospheric pressure.  The 30" max vacuum in the specification tends to 

confirm that to me but I could be wrong about that.



Ken



Michael Hinchcliff wrote:



[quote] 

 <cfi(at)conwaycorp.net>



 Hello, Ken. Since the vacuum system will always initialize at 

 atmospheric pressure (29.92” Hg give or take) at each startup and then 

 work it's way down to 5" Hg after startup, the switch should work fine 

 according to my interpretation of the description, "Contact open at 6" 

 Hg., close at 3" Hg". I interpret that the contactor will be 

 disengaged (i.e. light off) while between 3-6" Hg, which is what I'm 

 looking for.  Please let me know if you think I am overlooking 

 something here.



 ---

cfi(at)conwaycorp.net
Guest

Posted: Sat Jul 28, 2007 4:32 pm Post subject: Vacuume pressure warning light

Bob, you are right.  Our vacuum systems require negative 3-5" Hg of vacuum 

pressure as a opposed to a mere "reduced" pressure that I was thinking of. 

I confirmed this in the EA-AC-65-15A - A&P Mechanic's airframe handbook. 

Hence we have VACUUM switch and not a PRESSURE switch. Thank you for the 

clarification.



So, with that said, could a transistor or switch not be used to turn the 

light off when the vacuum switch engages between 3-5 in Hg?



Michael





---

cfi(at)conwaycorp.net
Guest

Posted: Sat Jul 28, 2007 4:39 pm Post subject: Vacuume pressure warning light

Ok, now that we're all totally confused, I'm going to go ahead and order the 

$8 switch and see if/how it can be implemented.  This should make for a good 

educational test bed. Stay tuned.



---

Melvinke(at)coho.net
Guest

Posted: Sat Jul 28, 2007 5:55 pm Post subject: Vacuume pressure warning light

At start up, the vacuum pump will pull at least 6"Hg, settling down to

around 5 as the gyros spool up. This will result in the switch passing to

"OFF", and remaining thus until the vacuum falls below 3" upon pump failure

or switch-off.

Kenneth Melvin

RV9A

arrow54t(at)yahoo.com
Guest

Posted: Sat Jul 28, 2007 8:13 pm Post subject: Vacuume pressure warning light

I have installed this pressure/vacuum switch in my Lancair.  I connected an LED indicator light.  Works great in the SUMMER.  In the WINTER, the vacuum pump doesn't pull enough vacuum on startup(cold), to open the contacts which causes the LED to stay lighted.  Sometimes, the light will go out during flight.  On warm starts in the winter, the light usually goes out.  I connected the switch to the gauge port on one of the vacuum instruments.  Maybe another location would yield better results.

  

 Mike Salzman

 Fairfield, CA

 LNCE

 ---

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