Sun Mar 21 2021

Sterilizer troubleshooting

Been doing service on sterilizers for 37 years but have finally run into a problem I cant figure out. About to lose my mind. Its basically a Steris 20x20 with vacuum pump as only unusual aspect. Gasket gradually pushes out 30 seconds after cycle complete/door open. 2 machines side by side doing same exact freakin thing. Ive replaced S35 multiple times. I can not detect any steam passing through to gasket channel. Ive replaced all check valves on bottom end. The entire bottom end plumbing schematic is ridiculous honestly. Steris has their proprietary manifolds and every other aspect of the design is based upon the these manifolds instead of common sense. Backwards logic. Anyway Ive rebuilt S35, S37, check valves 4,6,8,14 (gasket condensate exhaust). Ive increased the rate of condensate bleed to max thinking perhaps water in steam creating pressure behind gasket as it burns off. I have not replaced the gaskets primarily because if I detach the line from S35 it doesnt pop out. Theres one unusual aspect to the facility that could contribute. Steam lines, although new, constantly muck up steam strainers, screened traps, etc. Ive have to remove all the washers off of steam returns because there is back pressure which causes the thermo dynamic traps to lock up constantly. Hydraulic lock or similar. Their returns and supply lines are full of the crap. So its safe to say the steam is wet. $100 to first person that can accurate diagnose!! Montaquip@gmail.com

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Mon Mar 22 2021Reply from Neil Blagman
Neil Blagman

It's been a long time since I've been down this road but it sounds to me like you've got some crud in the door channel drain line that's hanging on to some condensed water that is subsequently turning back to steam once S35 closes at the end of the cycle.  try disconnecting the line at the manifold and blowing it out with compressed air from the bottom of the door groove and see if it helps.


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Mon Mar 22 2021Reply from Bob@montaquip
avatar placemark

Thank you for your response. That's a good suggestion, I will try tomorrow. I can watch the gasket condensate drain line operate as it's clear plastic. Lots of liquid. As I said I opened needle valve wide open and made sure ck 6 port was clear, but I never considered a partial blockage prior (Unfortunately). I'm leaning towards condensate burn off as the cause. Unfortunately with the facility steam issues I'm not starting with a clean slate. As none of the return lines function properly, I suspect super wet steam (it's a lab, not SPS) which may explain side by side malfunctions. I'll let you know. I meet with boiler plant people tomorrow. Thanks 


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Mon Mar 22 2021Reply from Bob@montaquip
avatar placemark

Here's the muck that is clogging there steam strainers and rendering their returns lines useless. The red orange bulky substance in strainers and the gray fine material in machine piping. I didn't have a magnet but I believe it's iron oxide (red) and iron (dark gray)

I've been battling the steam issues for a couple years, unfortunately nobody wants to hear my thoughts on steam quality.  


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Tue Mar 23 2021Reply from Chris35
avatar placemark

Make sure the 1/4" check valve (CK14) that ties into the tee at the top of the diffuser is good. I've had several of these be bad right out of the box or shortly after installing. Also check its orientation, the flex copper can easily bend causing the check to be at an incline which could hold it open. I would also replace the S35 seat. It has an oring seal between the removable seat and the valve body that can leak and cause this kind of gasket creep. You say if you disconnect the S35 line it doesn't happen, does steam build up on that line coming from the manifold? What kind of vacuum are you getting to the gasket on retract? I've only dealt with vac pumps on the larger units, but on those when the S3 seat gets pitted out, the gasket won't retract fully or pull all the steam / water from the circuit because its pulling from the less resistive chamber atmosphere through the leaking S3. Chamber vacuum will still be great during cycles and the leak test will be good thanks to CK8. I would think the steam supply strainer would be clogging up as well as the jacket trap strainer if you had that much muck getting to the unit, how do they look? If they aren't already, see if you can get the supply taps that feed the machines from the main steam supply line tapped off the top of the pipe so the steam has to go up before coming down to the machine, this can go a long way with helping dirty or wet steam.

edit: One more thing, keep the bleed set to 3/4 - 1 turn open from seated, its not in play with S37 open so cranking it open is just higher risk for "door unsealed" alarms.

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Wed Mar 24 2021Reply from Bob@montaquip
avatar placemark

Thank you for your responses and suggestions.  
 

Under the heading of "even a blind squirrel finds a nut sometimes "- In the end I decided to try to solve from a different direction. I eliminated  the symptom rather than problem I guess (yes I know its a sin, but perhaps forgivable with poor designs). But I still count it as a win. I removed check valve 6 in the exhaust manifold and gasket stopped popping out on both machines. Since these units have vacuum pumps, there was an additional spring loaded check valve at the end of the gasket discharge line just before it enters the mixing tube -- that basically performs the same function. I may double up on that check in future but right now I'm just enjoying the fact that I don't have to return to the account again (my first visit was during the recent snowstorm in Denver and included a 9 hour unplanned layover).  I may need to actually solved the problem down the road but the process  will be rattling around my head until then and I suspect I'll have a more efficient process. Thank you to everyone that responded. 


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Wed Mar 24 2021Reply from Cbet_Matt
Cbet_Matt

Thanks for letting us know your resolution, I wish more people would do that.



Matt

 
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Wed Mar 24 2021Reply from Bob@montaquip
avatar placemark

Yeah absolutely. Proprietary solutions to non proprietary problems ain't right. I'll update down the road if I make it to the source. 


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