Manufacturer suggest 40-50%RH for photography gears.
No... this is not what i said. What I mean is this.
The dryer unit activates when it sense that the humidity has risen above the set-point. But usually the sensor in the dryer unit is quite slow in response. Usually the time taken for temperature to drop is faster than the time taken for humidity to drop, especially since the TS placed the dry cabinet near the air con. further, the hygrometer reacts slower than a thermometer usually.
If you have a digital hygrometer, put it near the air con. You will find that the humidity is quite high actually.
You know why we need humidifier unit (no, not dehumidifier unit, humidifier unit), the unit that use water, create fog or evaporate water into air? It is because humidity inside air cond room is lower. So when you sleep in air cond room, when you wake up, you feel your throat dry. This humidifier unit work by release water into air. This is not new technology. I don't know what kind of air cond you mentioned since your air cond can make humidity high. Maybe new technology .
Have you ever noticed there are water come out from air cond unit? That's the humidity (water in the air) condensed into water. So what happen if 'water in the air' removed from air cond room? The room will be dry than outside (humidity lower).
Yes, you are right, the water condenses from the air con unit. That is because the air has been reduced to a temperature below its saturation point, or in other words, the humidity of the air that leaves the air con is about 16 deg celsius or lower, with a relative humidity of 100%. So water condenses. After leaving the air con, the air is gradually heated up by the surrounding, and the relative humidity slowly drops. So if you happen to place your humidifier near the air con, you find that the moisture you tries to add into the room has condensed back into water before it travels very far.
So when you place the humidity sensor near the air con, you will be measuring a much higher RH (but of course you need to wait some time to see the change if you are using the analogue hygrometer).
Most of the dry cabinets do not have a feedback control. What they do have, is a humidistat that stretches when humidity is high and contracts when the humidity is low (much like a thermostat). Typically, the response of such devices are quite slow. About 30 min as what I have tested.
Got a Akurai dry cabinet from CP a few years back. Was working fine until recently, the RH lvl is hovering around 60 - 70. Without things inside, it can go down to 40-55. Its been like that for about a month already. Don't know what's wrong.
Anyone know how to contact Akurai? Is there a service centre?
"Photography is an austere and blazing poetry of the real" -Ansel Adams
cantaresg and Artosoft, Thanks.
Correct me if i'm wrong. In summary, absolute humidity (AH) is the measure of actual amount of moisture in gases. As for relative humidity (RH), it is the ratio of actual amount of moisture to the maximum moisture capacity of a gases.
cantaresg, please help me to understand. Referring to your table below. I believe first column is the temperature and the second should be the relative humidity. Are you holding the absolute humidity as constant?
Artosoft, for your below statement. Are both countries having the same AH?
But, if you look into internet, the temperature and humidity in Singapore usually around 30degC and humidity >70%RH. And cold country like Australia, said IF 23degC, the humidity is around 50%. Your example shown different way, humidity rise up with the temperature drop.
Yes, in this example, I have assumed that the AH remain constant. In any case, the concepts of AH is more relevant with people who design dry cabinets and dehumidifiers. On the other hand, for everyday users, RH is more important as this is the factor that determines whether fungus grows or other humidity related problems.
Sorry, more question.
- Is dry-cabinet air seal?
- Humidistat detect AH or RH?
- What is/are the diff between analog and digital dry cabinet?
i) Dry cabinet is designed to be air tight, so that moisture don't enter the cabinet easily.
ii) hygrometer measure RH.
iii) If the digital hygrometer provides feedback to the dryer, it is more responsive and accurate than the analogue dry cabinet. Otherwise, the only difference is that the hygrometer display on the digital cabi is more accurate. That's all.
Icy: Do you mean that when you open the door, the hygrometer still reads below 20%, or after the door is closed, the hygrometer reading drops below 20%?
dry cab setting problems again?
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