I think my QSI may need a drying out. The instructions say there is a removable dessicant capsule under the hatch but requires 500F for 4-5 hours to dry it out. That seems rather hot, much hotter than a domestic fan oven.
Does anyone have experience of rejuvinating it or replacing one?
i have an SBIG STT-8300M with a removable desiccant plug and i think their instructions call for 4 hours @ 350F. having said that, at least in the US, it’s not uncommon to be able to set your oven to 500F.
IMHO it would probably be fine as long as you can get into the 400F range. if there’s a washer or gasket on the plug don’t forget to remove it before you bake the plug!
Hi Chris,
can you find out which drying agent is used by QSI?
A common drying agent is silica gel (colorless, amorphous silicon dioxide). This is marketed in form of pellets of an diameter of about 4 mm, either uncolored, or colored with an indicator (a dye) which is changing its color when the drying capacity is exhausted. The regeneration of silicagel is a temperature dependant equilibrium process and is performed at temperatures above 100 °C, i.e. it is very slow at 100 °C and more rapidly at elevated temperatures. The suggested temperature range for the regeneration is 150 - 175 °C (= 300 - 350 °F). However, at this temperature the indicator (if present) is decomposed irreversibly. So for silica gel containing an indicator, a temperature range of 120 - 140 °C (= 250 - 285 °F) is suggested in order to preserve the function of the indicator.
I’d be surprised if they used a different drying agent. Anyway a regeneration temperature of 500 °F (= 260 °C) appears very high.
The general procedure for the regeneration of a drying agent is as follows: set the oven to recirculation air and the desired temperature, fill the drying agent to a baking tray. The duration needed for a complete regeneration depends on the fill depth (this is not relevant with very small amounts of the drying agent). After completed regeneration it is important to fill the hot drying agent into a suited vessel and let it cool down, preferably with air exclusion in order to prevent an early re-charging with air moisture. When cooled down on the tray, the drying agent will be partly re-charged by air moisture which will confine the capacity of the regenerated drying agent.
See:
Fundamentals of the regeneration of silica gel
Regeneration von Silikagel im haushaltsüblichen Ofen
Bernd
Thanks Bernd - yes I found some similar advice on Wiki. I’ll ask Atik what they use. The instructions say it is in a pierced brass capsule, so having heated it, I was going to quickly wrap it in foil while it cools down and pop it back in as quickly as possible.
I am curious what drying agent they are using. (Can’t imagine that it is NOT silica gel.) Let me know if they respond.
Bernd
Atik said 220C would be sufficient but did not specify the material.
A better drying agent is molecular sieve. I think that needs up to 450 F to regenerate. The normal grade for drying is 4A.
Regards, Hugh
Hugh - just did a google search - QSI have a microsieve one - looks like Atik just assumed it was standard silica gel.
Ive regenerated mine twice since I bought the camera many years ago. Followed the instructions on the QSI website. When I was done with the oven I removed the brass capsule and put in in a small glass jar with a lid to let it cool to ambient temp before reinstalling it in the camera. Both regens were successful in removing the dew issue I experienced prior to regeneration.
thanks Peter, good to know. Hopefully my fan oven will be just hot enough
Just plonked it in the oven and cooking it at max temperature. Filling the house with burnt pizza fumes. Wife complaining. Pointed out I could buy two cookers for the price of a QSI. Bad move.
Well, it seems to have worked. Promised to buy another oven before I bought another CCD. Ho hum.
Wives just don’t get us when we are on a mission.