Photos of my plan attached.
I will use the ambient temp and humidity from my radiation shield for the other parameters used to derive WBGT. These are a Hobby Board temperature and humidity = DS18S20 and a Honeywell sensor.
I don’t/can’t want a true wet bulb temperature using a wick as I will never keep the reservoir topped up! I need something that takes zero maintenance.
Tg is measured using this set up :
- Building bracket bent at 45degrees
- Black plastic ball float (about 5inches). This is a prototype using a plastic ball. I also have a copper 6in float to paint black if this prototype is successful. Getting the copper balls is a hassle in New Zealand, this one came from UK. I don’t particularly like it. If you have a better source of metal spheres let me know.
- Short length of uPVC piping (not yet cut to length) to stabilise the ball onto the bracket
- Ball held in place with a cavity wall/plaster board fixing. This will be inserted into the drilled out mounting point of the ball and hopefully expand inside. Just mounting the ball with a bolt does not seem very stable - I get high winds.
- Sensor is a 1 wire DS18S20
- this enters sphere through a cable gland tapped into sphere
- small metal box plus another cable gland provide a coupling between the sensor and the reset of the stations wiring. This means the sensor can be replaced without major rebuild
[li][i]My current unresolved item is how to keep sensor in the middle of the sphere. I am thinking there will be a hollow plastic or metal tube between the metal box through the two cable glands and half way into sphere. The probe will then be slide down this tube from inside the metal box. I have not resolved what to use here. It needs to be UV stable and low diameter, with an ID to take the sensor and firm enough to not sag when it gets very hot inside the sphere. Metal may be the only option but not sure on the conduction implications. I may just sleeve it in plastic over the short distance it is exposed to the atmosphere[/li/
How are you resolving getting the sensor into the center of the sphere ?
