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Highlighting agricultural developments, problems, research, & issues for central coast CA
Tractor in Sunset
Comments:
by Mark Vawter
on September 29, 2019 at 11:48 AM
Very well written instructions for the tensiometer. I was wondering if you had any directions on how to make a connection to a data logger With a 4-20 mA current input? Are there some off the shelf parts that you recommend?
by Michael D Cahn
on September 30, 2019 at 10:37 AM
"Very well written instructions for the tensiometer. I was wondering if you had any directions on how to make a connection to a data logger With a 4-20 mA current input? Are there some off the shelf parts that you recommend? " Mark Vawter  
 
Thanks for your comment Mark,  
 
I use a voltage output pressure transducer (RSU-V)sold by irrometer Inc. to interface the tensiometer with a datalogger. I have been having very good luck with these transducers interms of stability over time and accuracy.  
 
Michael Cahn
by John Clemens
on September 30, 2019 at 5:03 PM
What is unique about the expensive epoxy/hardener you recommend? Since I'm not going to build several hundred tensiometers, I'd like to find a less costly alternate epoxy/hardener combination. Is bonding to the pvc pipe the problem?
by Michael D Cahn
on September 30, 2019 at 5:20 PM
John,  
I understand your concern with buying the expensive epoxy and hardener. It works well and can be use for gluing many tensiometers but has a limited working life time (1 year).  
 
You can try other epoxy products that are suitable for plastic and ceramic. I suggest to experiment with whatever brand that you choose on one tensiometer first. I have used these expoxies in the past but soil moisture corp. cautioned us against the off-the-shelf epoxy products. One problem that we had was that the epoxy did not harden sufficiently and bond well to the pvc.
 
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