Wednesday, January 30, 2013

Preparing the DS18B20 temperature senders

Today I made up simply mounting hardware to allow the One-Wire DS18B20  (or DS18S20, same part but the 18S20 is limited to 9-bit resolution)  based temperature senders to be mounted.  Four of them will go on a tab (Battery, Alternator, Sea Water pump, and Exhaust / water mixer) and one will need to be placed into a 3/8" NPT-F fitting on the heat exchanger of the Kubota engine temperature.

BTW, in case you are wondering- the reason for sensing the Sea Water pump is in case it overheats, say from a stuck impeller or a closed / clogged sea-strainer.  Likewise, if the exhaust / sea water mixing point is more then a few of degrees above the incoming sea water temperature, again something is wrong in the raw water cooling system.

Here you can see the 4 'tab' mounted senders from begging to end..  I took a short length of copper tubing, flattened one end using the Vice Grips.  Then inserting the sender into the other end I again used the Vice Grips to crimp them in.  Will drill holes into them once I decide which size is needed for each application.

Left to Right
Raw Tube, Tube flattened, Tube crimped onto sender, and all shrink-wrapped

Crimping on the flattened tube.

I briefly thought about soldering them, but I am not sure what would happen to the senders them self under a gas torch   Crimping will have to do.  And I made sure to use good shrink wrap, the stuff with self-melting glue inside.

For the Kubota Engine temperature sender I used a 1/4" copper tubing to 3/8" MPT fitting.  There is a flange inside the fitting that needs to be reamed or drilled out to allow for the sender to pass through and get 'into' the cooling water.

Reaming out the flange inside

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