Will this gauge be ok?

MotownSteamer

As many of you know, I've posted my "issues" this week trying to build my control/gauge manifold and already wrecked a Wika 0-20 oz gauge. Today the new 0-3 psi gauge arrived and I finished the job. I cycled the system (two-pipe vapor/vacuum) for about an hour. Low and behold, it looks like it's operating below 4 oz! I shut it down to see how long/how much vacuum would register on the new gauge (by pulling PAST zero of course). Compare with the compound gauge to the left. Can the gauge handle going this far past zero? Any one had a couple years under their belt exercising these expensive little buggers? Would a snubber eliminate the pull from the vacuum or can I install an inline check valve? I'm tired of scampering into the boiler room wringing my hands.

Charlie from wmass

You can leave the gauge off

It only needs turned on when you are looking at it.

Charlie from wmass

You can leave the gauge off

It only needs turned on when you are looking at it.

MotownSteamer

Well.....

I didn't think of that but it is a nice benefit of having the lever valves. But if I throw the lever on and off it's still going to read pressure or vacuum depending on where it is in the cycle.



Nick Z, are you out there? You had a post recently about your 0-3 going into vacuum. How far and is it still alive?

MotownSteamer

the answer is NO

the gauge will not be ok getting sucked into that much vacuum. Look; this is a photo of the needle being stuck well below zero after re-firing the boiler. The calibration screw got it back to zero, thank goodness, but it took a considerable turn to +. I put the gauge back on and it is responding to pressure ok. Glad I put the lever valves on.



So now I need to know if snubbers will protect against the vacuum or will a check valve. Or do I just leave the lever off until I decide I want to check it from time to time? This is turning into an expensive experiment.....

crash2009

What do you have for main vents?

  Don't they release the vacuum at the end of the cycle?  I wonder if my Hoffman 75's are extending the life of my gauges.

MotownSteamer

The vent is a

Barnes and Jones Quick Vent...just one of 'em. We discussed it a few threads ago, but afterwards someone reminded me a vapor/vacuum system is supposed to go into a vacuum. That's why the steam is made so quickly on the next cycle. I think my system is working correctly, great in fact. The problem is I'm trying to make a gauge do something it wasn't built to do. I have a true compound gauge on the boiler too; it's working great. It just doesn't measure these low pressures.



I just researched snubbers; they are designed for 5 psi and greater. I think a check valve is the only way to eliminate the effect of the vacuum.

crash2009

inline check valve

Have you looked into these?  http://www.generant.com/ICV.shtml



Also you could give these guys a call, they might have exactly what you need.  1-888-snubber  Maybe a combination inline valve/snubber



Let us know what you find.

MotownSteamer

Will do

Ok, I'll check it out. Thanks

PMJ

Gauges

I have a compund gauge on my boiler right next to the vaporstat just like this. The range is +30/-30 inches of water. I never see any pressure there and I know the system goes below to about 40 inches of vacuum on cold days between cycles but that hasn't damaged the gauge.

Hap_Hazzard

Maybe you need a vacuum-pressure gauge?

There are gauges that measure both pressure and vacuum, like the Ashcroft Type 1490. They make one that goes from -30–30 in. H₂O. That's about -1–1 psi. This is a diaphragm gauge. They're similar to a capsule gauge, but, as I understand it, the diaphragm has a flat surface so it returns to its resting position when there's no pressure acting on it. A well-made capsule should too, but these Wika gauges aren't that well made.



I'm still puzzled about why the other gauge got wrecked by a vacuum. A capsule or bellows should be able to collapse completely and still be able to spring back at least most of the way. The only limit should be the plasticity of the material. The only thing I can imagine is that the lever that transfers the capsule's motion to the gauge movement slipped off the tab that sticks out from the capsule.



As you can see in the attached image, the lever is pretty far from being centered on this tab in my gauge. If the capsule should happen to collapse more on one side at first, that could cock that tab one way or the other, and if it shifted to the right (in the picture), the lever could easily slip off.



Have you taken a look inside the old gauge? If you still have it, and they're not giving you a replacement, you might want to open it up and see if you can fix it. It's not hard to do. Just pop off the lens and take the screws out of the back and it will slide right out of its case through the front.

MotownSteamer

thanks for the insight.....

I'm not sure how/why the old gauge got damaged. Maybe it wasn't damaged and was just hung up like you describe. We'll never know. I have the temper of a three year old girl. When the calibration screw wouldn't work, I tried to disassemble. I had difficulty just doing that , so I crushed it with my channel locks. Honest? Yes. Proud? Noooooo.......

Hap_Hazzard

Aside from being curiously satisfying...

That might just have inspired enough fear in the new gauge to keep it in line. :-D

Jean-David Beyer

That might just have inspired enough fear in the new gauge to keep it in line.

Yes; keep tho old one on a self near the new one as a constant reminder to the new one. Never underestimate the psychology of inanimate objects.



I woman I knew had a sports car that would frequently not start. It had an aluminum cylinder head. I got tired of changing the spark plugs on her car, so I bought her a torque wrench and a spark-plug size socket and taught her to change her own plugs. And she could do that, but she had to change them too often. We tried psychology on the engine. She always carried a box of new plugs, and kept the torque wrench in the trunk. It started all the time after that, needing new plugs only at the normal interval. I guess the car wanted the assurance to know that new plugs were available at a monemt's notice. Psychology is a wonderful thing.