Hell, Is She Leaking Or Not?

The amount of air or let's say the air pressure inside your airgirl is very critical parameter. For perfect performance the air amount has to be tuned up to mililiters. We don't talk about damage of the doll's body now, but about the most pleasant behavior. The perfect value of air amount must hold several hours without change, during one night as minimum, longer duration is better. From this point of view, the problem is any minimal air leak and also influence of temperature and atmospheric air pressure.

Example of barometric pressure prediction - the black line.

Sometimes the airgirl may appear leaky, but it is not. Also, if you try to do some diagnostics to find or identify an air leak, sometimes you have very hard work. It is very difficult to recognize if the air is really leaking or not. The only way to solve is longer time (few days) observation while watching to a barometer and a thermometer. Computerized system with history of measured data or good weather service will help much.

The first problem is the atmospheric or let's say barometric pressure. Your toy will look weaker if the barometric pressure will grow in respect to time when you had inflated your toy. The average barometric pressure at sea level is given as 1013.25 hPa and variation in range 30 hPa around the mean value is normal. In special cases the variation can be several times bigger. The change can be quite fast, 1 hPa per hour is possible. The nice explanation can be found here. Not only airgirls can have headache caused by barometric pressure.

The second matter is the temperature of the air inside your toy. If the toy will stand in constant ambient temperature, it will quickly get the same temperature as surrounding. In the case of exposition from a sun shine or an IR rays from heating, the temperature will grow. The same will work with your body as a source of the heat. If you will take your airgirl into bed, under blanket with you for a longer time than 20 - 30 minutes, you can expect the similar temperature as at your body. The (roughly) 37 degrees is pretty much and you will observe many interesting effects on the air and on the vinyl material. If the toy was not inflated too much, it will not be dangerous for the toy, but it is very pleasant. You will feel a heat reflected from the toy, which is very nice and it make a perfect feel of a live creature next to you.

In our case of very low pressures without any phase changes the air will behave very near to ideal gas. For the influence of temperature we can use simple thing, a Combined Gas Law, dependence between an absolute temperature T, a volume V and a pressure P.

The Combined Gas Law. Relation between the pressure, volume and temperature of the gas.

For simplicity, we will assume the constant pressure. The volume is then interpreted as uncompressed volume, the volume of air, which you will take from atmosphere and put into your toy. This way lets us avoid complex behavior of vinyl. Also, when you inflating your toy, you will know best what every piece of air will do, what is much, what less, ...

Now, we can express special inflatable related parameters which combined both temperature and barometric pressure into one number.

Generic inflatable related coefficient which combined influence of temperature and pressure.

The kname is generic inflatable related coefficient expressed in PROMILE, which says, how much air is over (+) or how much air missing (-) relative to volume of the toy. If you know the volume, you can multiply and you know, how much air has to be added or removed. If you don't know the exact volume of your toy, you can use this number for comparison between times - see the number and know or do.

The expression "name" is used because there can be more variants of k based on generic kname. The P0 and T0 is always the barometric pressure and the air temperature in the time of inflation. The Pa is actual barometric pressure and the Ta is the actual temperature. We can make three variants based on different Ta.

• The kstorage or kstg uses (Ta) to K as room or ambient temperature.
• The klair or kbed uses (Ta) to K as body temperature 37 degrees.
• The koutdoor or kout uses (Ta) to K as outdoor temperature.

Note that T is always absolute temperature in Kelvins and pressure usually in hPa, but there is a relation so there are other pressure units also possible. Promiles are used because of suitable resolution and number format. You can look to our Hannah Matrix computerized system how the history of inflatable related coefficients look. The system is still under development and many updates will be applied in future, but it is interesting, I think.