Ancient Artifacts-Air Conditioning

[friartuck]

Hi Folks

Has anybody got any experience on providing satisfactory environments for ancient artifacts. I understand that some of thes ewill be clothes and others old books.

The space conditions will I assume need to be conditioned to strict limits of temperature and humidity with a limit on the amount of fresh air and also special filtration may be needed.

What type of system is most appropriate?

Will a simple split AC unit suffice or will I need a ducted unit with heating, cooling , and hum, de-hum control plus Carbon filters.

Any assitance from anyone that has done one of these would be appreciated.

Are there any specialist AC suppliers that can provide a suitable unit?

Are there upper and lower limits of control. If so, what?




Friar Tuck of Sherwood

 

[quark]

Munters have done some exercises for museums and have excellant case studies. Munters' dehumidification handbook is a good source for it. You can get it from

http://www.munters.com.

I have it with me and I can help if you have any specific issues. I have no experience with your type of work but have been using desiccant dehumidifiers for stringent condition as I work in pharmaceuticals where the RH requirement is as low as 15% at 22+/-2⁰C.

Regards,

 

[imok2]

"will I need a ducted unit with heating, cooling , and hum, de-hum control plus Carbon filters".

Yes, If you intend to keep these materials in good condition

Art Galleries, Libraries,General Musiums and Archives:
All reading and retrieval rooms, rooms for storing stable collections,
especially if mechanically medium to high vulnerability.
Set Points: 50% rh (or historic annual average for permanent collections)
Temperature set between 59 and 77°F
Note: Rooms intended for loan exhibitions must handle set point specified in loan agreement, typically 50% rh, 70°F, but sometimes 55% or 60% rh.

 

[25362]

Not being involved with AC my interpretation of the heading was to highlight evaporative cooling as done in ancient Egypt to cool water and wine in porous clay pots.

Nature examples include panting dogs, gaping crocodiles, trees' self-cooling, and sweating athletes among many others.

BTW, a pot-in-pot invention by Muhammed Bah Abba, consisting of one clay pot inside another with wet sand in between, upper openings covered with a cloth, serves to cool fruits and vegetables kept in the inner pot, to below 20^oC.
This and similar arrangements are being extensively used in Africa, Asia and South America.

Sorry for the digression.

 

[MintJulep]

Interesting article in a recent ASHRAE Journal regardng HVAC in several buildings of the Smithsonian Institute.

 

[quark]

Moisture is dangerous and is to be avoided always. Microbes are very famous for their suspended animation particularly in the form of spores and they come to life in the presence of moisture. It was already prooved that wall paintings in Pyramids and Caves of Ajanta and Ellora were victims of the micro organism with in 50 years of their exposure.

Case studies indicate a DBT of 80F and RH of 30% are optimum for preservation of paper and cloth items. There is a decrease of 8% in moisture holding capacity from 60% RH to 30% RH.

Regards,

 

[Whoops]

"...will I need a ducted unit with heating, cooling , and hum, de-hum control plus Carbon filters."
I think you will.

I'd be thinking along the lines of an AHU with chilled water cooling and dehum, LTHW reheat, a humidifier and BMS control. Better control of cooling & de-hum can be achieved with CHW than with a DX system.

30% Rh might be OK for paper or cloth, but is too low for wooden artefacts. The wood and glue will shrink as the moisture content drops. The glued joints may separate or the timber may crack. I think a uniform 50%Rh is recommended. As mentioned by others, the wood becomes more prone to insect or fungal damage if the moisture content is too high. There must be something relevant in the CIBSE or ASHRAE guides, or the British Standards.

 

[pennpoint]

friartuck
May I suggest that you look at ASHRAE Handbook HVAC Applications, 2003, Chapter 21, Relating to; Museums, Libraries,and Archives.
The chapter chocked full of all kinds of information.
e.g.; Temperature limitations, classes of storage, humidity ranges, types and classes of structures and display cases.
Plus, types and examples of conditioning equipment.

Good Luck
pennpoint