How To Solve The Problem With Wet Loads
One simple way this can be accomplished is by defining a “load heat up” phase at the beginning of the cycle. The phase would simply function at the dictate of jacket setpoint, chamber drain (or load thermocouple) setpoint and a phase timer. The phase would not advance until the setpoint(s) were achieved and the phase timer elapses, where it would then pass to the Purge (or Pre-Vac in the instance of a vacuum equipped sterilizer).
- Check the quality of your Facility Steam, including possible excessive demands on your boiler.
- Check piping insulation from your steam source, to the autoclave.
- Check the way you package your loads…do not over pack the chamber!
- Check the size and operation of the steam traps, jacket traps, and drain check valves.
- Check for clogged drains and drain ports.
- Check your vacuum drying phase program, settings and operation.
- Check or add a load heat up phase at beginning of cycle.
Another approach, sometimes used in Pharmaceutical applications, might be to add an actual heated air in-bleed phase at the beginning of the cycle. A heat exchanger can be installed to the air in-bleed assembly to enable a combination of vacuum, and air in-bleed pulses that would bring the product up to temperature more quickly, reducing the condensate formation at the beginning of the cycle. While a heat exchanger is not absolutely necessary, it may prove useful for particularly large chambers or dense loads. As an alternative to the heat exchanger, you might wish to consider simply increasing the jacket temperature setpoint, as long as it does not interfere with maintaining the temperature uniformity within the chamber during the sterilize dwell phase. A word of caution, merely increasing the jacket temperature could result in a “super-heating” of the steam in the case that your condensate issue is not particularly bad, so use this strategy cautiously.}
There are some unique approaches that can be causes, or solutions, to the condensate formation issue.
Charge Rate Control- Many autoclaves are not equipped with a proportional control valve, or the necessary control system capability, to control the “ramp up” or “charge” rate of steam injection during the cycle. If a chamber does not have some means (valving configuration, type of steam control valve, or software limitations…) to control the rate that steam is added to the chamber, the result could be a flooding of the chamber with steam that results in instant condensate formation. If the steam injection were to be ramped up more slowly, the amount of steam (and subsequent condensate) can be more easily controlled.
Filter Sterilization- Many pharmaceutical-grade autoclaves are fitted with an air in-bleed filter casing that can be sterilized “in situ” (in place). Some more popular manufacturers of autoclaves will sterilize this filter during each cycle, other’s make this a unique cycle that is only run when requested. In many cases, the former design does not come with an isolation valve for the filter, while the latter includes an isolation valve as well as a condensate bleed valve. The latter approach is superior in our opinion because a) it reduces the wear on the filter element, resulting in a much longer life-time/lower running cost and b) prevents repeatedly saturating the filter with steam, which would result in excessive moisture being brought into the chamber at the completion of the cycle. To that end, you may wish to look how your current system is configured. }
There are many causes for condensate formation, in fact, condensing of steam is essential in heat transfer (and hence sterilization) but too much condensate is detrimental. If you are experiencing such problems, try some of the above.