Tue Aug 20 2019

Pressure test failure

When running diagnostics we are getting, "Pressure test failed: multiple errors occurred". Performed a leak test by measuring chamber pressure drop over 10 minute interval, and it is within spec as per the service troubleshooting guide. What should we test or look for next?

   RE: Sterilizers/Autoclaves Report Post
Thu Aug 22 2019Reply from Amscopolaris
Amscopolaris

run empty without load, Usually fails if loads are wet or paper content is high

1 Check the vacuum compressor
2 Check the door seals
3 check the valves


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Fri Aug 23 2019Reply from mfolson
avatar placemark

Thanks for the suggestions. The unit does not fail during sterilization cycle. However, we receive this error when running the system diagnostic tests.

I checked and cleaned all the seals in the pump system, the vaporizer manifold, and the door seal. The compressor is pulling vacuum. During the vacuum test the diagnostics are showing a chamber pressure leak rate of 6.0 Pa/sec, and a vaporizer pressure leak rate of 93.6 Pa/sec. I'm still unsure why we are getting the pressure test failure notification.


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Mon Aug 26 2019Reply from Cipher
Cipher

You reported 6.0 Pa/sec for the Chamber Leak Back Test and 39.6 Pa/sec for the Vaporizer Leak Back rate. If you convert this to mTorr/min, it will calculate to:

  • 36 Pa/min = 2,700 mTorr/min for Chamber Leak Back Test rate - Max Allowable is 25 mTorr/min or less
  • 2,376 Pa/min= 17,281 mTorr/min for Vaporizer Leak Back Test rate – Max allowable is 500 mTorr/min or less

With the rates reported, you would be well out of max allowable, and thus the failure messages. If you meant Pa/min, you still would be out of allowable limits for the Chamber Leak Back Test rate at 45 mTorr/min.

Can you verify you readings? - Cipher


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Mon Aug 26 2019Reply from mfolson
avatar placemark

The readings are correct at 6.0 Pa/sec and 93.6 Pa/sec. At least this is what the automated diagnostics are reporting.

I performed a manual leak test according to the Sterrad NX Service Guide, where you measure the pressure change over a 10 minute interval. Using this method I saw a chamber pressure leak rate of 10.2 mTorr/min which falls below the 25mTorr/min limit. Does this suggest an error with the pressure sensors themselves?

I've run a few cycles with chemical and bio-indicators -- both show that the cycle is being sufficiently sterilized even with the errors. 


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Tue Aug 27 2019Reply from Cipher
Cipher

You can try zeroing the pressure transducers - don;t know if will help any.  Wjy didi you run diagnostics If the unit wasn't failing during normal cycle?  If you ran the Chamber Leak Back Test and Vaporizer Leak Back Test as part of your PM and they passed, you should be okay with that portion of the integrity of the vacuum system.


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Wed Aug 28 2019Reply from mfolson
avatar placemark

This is a used unit that is new to us. We ran the diagnostics as a benchmark to see if anything was amiss that was not immediately obvious. I've re-run the chamber and vaporizer leak back tests by pulling a vacuum, turning off the pump, and measuring pressures over 10, 15, and 20 minute intervals. The maximum chamber leak I saw was 15.6 mTorr/min, and the max vaporizer leak was 14.1 mTorr/min. These numbers suggest the systems are working correctly, yes?

I'll try zeroing the pressure transducers to see if this helps.


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