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Old 06-17-2011, 11:48 AM   #1
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Death Sentence for a Micropulse sensor:

Unlike those fortunate sensors chosen to report fresh and gray tank quantities, (and seem to last indefinitely), their unfortunate companions condemned to the black tank face an untimely death, usually within a few days. Could it be that despite what Catcon says, they really can't handle solids? Or, could it be the chemicals we add to the black tank? Any new theories would be appreciated.
1) this is the 3rd new trailer with the same problem, so it's not wiring
2) fresh/gray stay accurate
3) yes, I crimp on new connectors, and
4) yes, I use dielectric grease

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Old 06-17-2011, 12:22 PM   #2
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Dunno if it's the same sensor / wiring, but my 12 year old trailer's sensors all work just fine (within the limits of their precision).

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Old 06-17-2011, 12:29 PM   #3
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My gray and black tank sensors seem to be doing fine but the fresh tank sensor is dead. I have a replacement sensor but can't figure out where the sensor is and how to get to it on a 2006 25' Safari. Any guidance would be greatly appreciated.
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Old 06-17-2011, 12:45 PM   #4
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Mine failed once or twice too and is, at present, more or less working. However, it isn't accurate enough to be of much use.

Let's take a minute to understand the engineering problem at work here.

The Catcon sensors are pressure sensors. For a liquid of known density it's easy to determine the liquid depth above the sensor point just by multiplying the pressure by some number.

These are shallow tanks, and there's typically about a 6" working difference in fluid level between when the liquid just reaches the sensor and when the tank is full to its usable capacity. And in order to be of much use indicator has to be correct within 1/4 of a tank or so, a 1.5" difference in liquid depth. That's roughly 0.05 PSI.

It doesn't take much to throw a pressure reading off by that amount. Even a mild amount of debris in the sensor itself would be enough to do it.

I have pretty much come to the conclusion that the problem isn't worth fixing.
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Old 06-17-2011, 02:27 PM   #5
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I gave up on them after replacing my black water tank sensor twice. Didn't cost anything but my time. Micropulse was very helpful and sent a new sensor right away. The fresh water and grey water seem to work just fine. That's how my system is working now. Fresh water, grey water and battery level. The black water is unplugged.
I just look down the toilet to see the level when I flush . Might be a little primitive, but it works for me.
My old 72 had the metel contact sensors that NEVER failed. Maybe those old simple systems were better.
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Old 06-17-2011, 03:27 PM   #6
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Appears to me that each one is unique! I just learned my unit's quirks and live with it.

Black is accurate

Fresh starts off without much change and "catches up" so full is full, 3/4 is about half (at 1/2 I start thinking a shower might be risky without a dump) At 1/4 it's pretty well empty.

Gray is slow to start and really changes fast in the last 1/2 of capacity. I have to keep an eye on this one!

Battery is pretty accurate, but I have a battery monitor system anyway.

Propane is dead accurate for both tanks.

I leave well enough alone after about 4 attempts to calibrate!!
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Old 06-17-2011, 03:32 PM   #7
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My black tank sensor is absolutely reliable. It reads full all the time.

In my opinion, it's just not worth worrying about. I look down the hole when I flush, but I can almost tell the level by the pitch of the sound of flushing. When it get to the high end of the range, it's time to dump the tank.
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Old 06-18-2011, 06:40 AM   #8
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SailorSteve, my last trailer was a 25 FB SE (an early '07), and the fresh tank sensor was accessed from inside; in the area aft of the water pump, the plywood floor will have an opening, allowing access to the fresh tank drain valve, and forward of that, the sensor. It was difficult to reach, so you may have to elongate the opening in the floor.
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Old 06-18-2011, 08:05 AM   #9
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Mine have had their quirks. Fresh water only gets accurate when it's 5 gallons or less from full. Black was fairly decent till the first trip out this year when it immediately showed full after it was about 2 gallons full. Gas is good and the grey water is good. Quite honestly we only camp once a year carrying water so I've lived with the fresh water issue. Black is a no brainer since the visual is always available. Gas is also a no brainer since the tanks also have external gauges. The grey is one that I would take the effort to keep working since an unexpected filling of the grey tank is not a pleasant issue to deal with.

Jack Canavera
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'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700
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Old 06-18-2011, 08:23 AM   #10
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Originally Posted by Jammer View Post
I have pretty much come to the conclusion that the problem isn't worth fixing.
My black tank sensor isn't working - with only two trips in the new trailer. My black tank sensor didn't work in my previous trailer either.

I agree with Jammer.

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Old 06-19-2011, 04:13 PM   #11
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Thanks, everyone, for confirming my "hypothesis" that these sensors just CANNOT withstand the conditions found in the black tank......
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Old 06-19-2011, 04:44 PM   #12
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It seems like a shame this 'system' doesn't often operate properly in a rig you've spent Mega-bucks on!

I would think AS would be aware of such a marginal item and at least look into another system that may be available...

The level monitoring system made by Garnett Tech looks appealing... Sensor Board - For use with all model 709 tank monitor systems It's sensors are attached to the outside of the tank, without any type of 'probe' or 'sensor' entering through the tank wall...Don't know about it's accuracy, but it looks like a better 'mousetrap'...
Ray & Pat; Morada, CA
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Old 06-19-2011, 04:45 PM   #13
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Posts: 456 summary, if they'd redesign those sensors, it'd be a pretty good system; until then, Airstream gets to replace them for me under warranty (5 years).
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Old 06-19-2011, 05:58 PM   #14
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After a slight calibration the sensors in my 2002 ASCL have worked well without any problem for the 10 years I've owned it. I am very conscientious about totally emptying and cleaning the tanks after traveling.

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