8 replies to this topic

[Dr. N00b]

Ok, so I am considering getting a used Cominox Stericlave 18 B (2011 model) (PDF File) for the lab I am currently setting up.

 

However, I cannot tell whether or not it has a liquid cycle function, and the seller who has used it is his dental clinic does not know either as this is a type of cycle he never uses.

 

I am worried that if I buy this I will end up with an autoclave that will overboil liquids and have only limited functionality for me...

 

All I know is - "Type B" cycle is supposed to cover "all objects". I got that little piece of information from here btw, if anyone wonders...

 

Any and all feedback is greatly appreciated.

 

Sincerely, N00b.

[Dr. N00b]

Does anyone have an example of a cheap autoclave that can handle liquids? And I am not talking about one of those portable pots with screw-on lid.

[El Crazy Xabi]

Those benchtop autoclaves rarely have a liquid cycle, and if they don't specify... don't expect it. We bought a Siltex Pratika S20 mid-late 2011 and it can handle liquids with the proper setup in the configurable programs. All depends on your budget.

 

It has pre-set cycles for wrapped and unwrapped objects at both 121 and 134° C, the later considered the fast cycle. It even has a prions cycle, we never use it though

[Dr. N00b]

Those benchtop autoclaves rarely have a liquid cycle, and if they don't specify... don't expect it. We bought a Siltex Pratika S20 mid-late 2011 and it can handle liquids with the proper setup in the configurable programs. All depends on your budget.

 

It has pre-set cycles for wrapped and unwrapped objects at both 121 and 134° C, the later considered the fast cycle. It even has a prions cycle, we never use it though

 

Thanks for answering. I was beginning to lose hope.

 

Anyhow, I have the oportunity to buy the above mentioned autoclave for 1k USD. Which is actually twice my budget, but still... Those autoclaves are extremely expensive, so I need to strike the best deals I can get.

 

I've checked out the one you mentioned. There is one on e-bay listed at a small fortune. Needless to say - I will not be buying one.

 

That being said though, is there any way I can use a "ordinary" autoclave for liquid if I take care to keep the liquid level in the flask low enough so it wont boil over when it releases the pressure? Or is there some other form of complication I am not aware of?

 

From what I understand, the liquid cycle differs from other cycles only in that it releases the pressure more slowly - thus avoiding any boilovers. Correct?

 

Sincerely, N00b.

[Dr. N00b]

Oh, I found a more detail insutrction manual ("Special Program" is on Page 33). I wonder - it has a programable setting, but I dont know if the function I need to program is present.

What exactly did you change in your Autoclave cycle setting El Crazy?

If I can mimic your programming in this particular autoclave, I am pretty much saved.

 

Edit: I see I can program the Temperature, Duration, Number of peaks, and drying time. Maximum time for drying is 30 minutes. Is there some parameter you are using with your Siltex that I dont have on mine?

 

Sincerely, N00b.

Edited by Dr. N00b, 18 June 2015 - 05:50 AM.

[El Crazy Xabi]

If it has a special program you'll probably be able to use liquids. Let me check my config and I tell you

 

 

EDIT: In the one we have, we can set the initial vacuum before the injection of the steam in the chamber. It's set at 400. We only use one peak

Lower as much as possible the drying time. This is the most important difference, the longer, more volume you will lose and the higher will be the alteration of the medium composition.

 

Another thing is that you usually only should fill the bottles with about 75-80% of their nominal volume. e.g. for a 1 L Schott bottle, 750-800 mL medium

 

 

The time will be dependant on the volume of liquid. This is part of our SWP based on manufacturers indication. It seems that the pre-vacuum makes the content to remain relatively cool compared to the chamber walls, that's why you have to carefully consider the penetration time (time it takes the innermost part of the liquid to reach the sterilising temp)

 

This cycle has been set up specifically for liquids. The maximum drying time for liquids is 5 mins (less if possible). And the maximum sterilisation temperature for liquids is 121°C.

However, you will need to vary the penetration time and temperature depending on the volume used. The penetration times suggested by manufacturer:

 

• Volume Used / Penetration Time / Penetration Temp / Sterilisation Time / Sterilisation Temp

• Test tubes / 2mins / 121°C / 15 mins / 121°C
• 250mL bottles / 9mins / 123°C / 15 mins / 121°C
• 1L bottles / 25mins / 125°C / 15 mins / 121°C

Therefore, total holding time will be 17, 24 and 40 mins for test tubes, 250 mL and 1L bottles, respectively.

Please note – these numbers are a guide only. You will need to test liquid temperature using a thermocouple to guarantee sterilisation temperatures have been reached. See trainers for more assistance with this.

Edited by El Crazy Xabi, 18 June 2015 - 11:21 PM.

[mdfenko]

From what I understand, the liquid cycle differs from other cycles only in that it releases the pressure more slowly - thus avoiding any boilovers. Correct?

 

not just to prevent boilover, also prevents flashing into steam. reducing volume to avoid boilover won't prevent flash. remember, you are heating the liquid to above the boiling point.

[Dr. N00b]

Thanks for that little bit of info mdfenko.

 

This is really gold El Crazy... truly.

 

So I guess the key here is drying time? According to the user manual I can set that to 0.

The initial vacuum before letting in the steam though, is that of any particular importance? Because it seems that that is the only thing I cannot program.

 

Sincerely, N00b.

[El Crazy Xabi]

So I guess the key here is drying time? According to the user manual I can set that to 0.

The initial vacuum before letting in the steam though, is that of any particular importance? Because it seems that that is the only thing I cannot program.

 

Sincerely, N00b.

 

Yeah, reducing the drying time is the most important point. At that stage the autoclave stops heating but makes vacuum... and the temperature does not drop that fast in a sealed chamber. And with superheated aqueous liquids.... well ... what I said before. Indeed, many of these benchtop autoclaves have standalone drying cycles where it heats up a bit 60-80° C (I don't remember well, but it's below 100° C for sure) and with a continuous use of the vacuum dries the stuff inside. I guess this is more designed to dry surgical tools and similar

Edited by El Crazy Xabi, 21 June 2015 - 06:35 PM.