Low Vac. Alarm How to ?

I want to make a low vac light and can not seem to find a switch. I looked at Digikey but I am not sure what I need. I want something adjustable in the 4 to 6 In Vac range so I can hook it up through my 5 volt circuit on a extra channel of my EIS 4000. Any help would be welcome .

Thanks,
BJB

Wonder if Precise Flight would sell you theirs. They include one as part of their standby vac kits. Just an idea if nothing good "homebrew" turns up.

Years ago, I wanted the exact same thing for my Grumman. I seem to remember that I got it from one of the instrument shops in Wichita - I literally just started calling them from their adds in TAP, and sure enough, someone had one for a remarkably low price. No way I can remember who it was, but that's how I had to do it...

Paul

Why not just order the Vacuum/Pressure sensor, VP15-01, from GRT for $60.00 (last years price), and use the internal alarm on the EIS 4000?

Yeah, I know I'm a smart a$$ at times

I also know it's not obvious on the website, I had to specifically ask when I bought mine. Sandy can help!

Geez, I hope they're still available

Low Vacuun

You might entertain a gauge rather than a warning light. The gauge will warn you, visually of any impending failures far before they may occur. The gauge will display, in conjunction with your tach, if the pump is healthy, i.e. speed required to achieve normal vacuum. In addition, a flickering needle is also an indication of impending pump or vac. system malidies. The warning lamp is either on of off, and gives one little indication of the health of the system untill it's too late. Two vac failures in IFR convinced me that the needle was a better visual aid, in addition to being less expensive than an electrical sensor.
T88

You're right, T88, a gauge IS better than a light alone! As a matter of fact, I think that on certified systems, a gauge is required (but I could be remembering that wrong). Unfortunately, in the Grumman, it was way over on the right side of the panel, well out of a normal instrument scan, that's why I added a light, right next to my attitude gyro. It was after that when the new gyros with built in low vacumn flags started appearing....now those are a great idea!

Paul

Stewart Warner has em...

http://www.stewartwarner.com/Catalog/swvac.html

They make good stuff. Lowest setpoint is 4" hg, though..
John

I have a C-150. The gauge is standard, but like the Grumman, way over on the right. I had an instrument shop put in an alarm light right next to the artificial Horizon. It comes on at idle, so it is an easy thing to check before flight. I hope I never need it, but it brings a lot of peace of mind for about $100.00 and a spliced vacuum line. That said, my RV-7A has no vacuum at all!

Gauge is too subtle

I HATE VACUUM PUMPS - they are killers but I personally find it hard to live without them. I have a gauge stuck where I could fit it in (similar to the placement in my old beloved Archer II) and there is absolutely no way it would help me in case of a real failure - I WOULD NEVER SEE IT! I love the digital readout on my Tru Trak Pictorial Pilot that I stuck in the hole originally occupied by my old turn coordinator but ... I have rolled up on a wing tip and made some tight turns and seen the display go meaningless until I rolled out on a new heading. In other words if I had a vacuum pump failure without timely and unavoidable alarming it is concievable that I would get into a tight graveyard spiral with no functional partial panel to get out of it with. I'm working on other things at the moment but if the thread produces a simple pressure switch activated warning light I would buy it and put it in.

Bob Axsom

Low Vac Light

Thanks for all of the good information. I have a gauge but I think a switch that hooks to the big red light on my EIS would get my attention ASAP. I think of it as on idiot light in a car, a warning that something is wrong and must be checked. I was even thinking of a vac. on/off switch. That might work because once the pump quits it never comes back.