Temp sensors for water pipes ... ?

[john1]

Hi,

I would like to put temperature sensors on some of my water pipes.
I want to be able to read temperatures down below freezing,
and up to boiling.

Hoping to run the stuff from a 12v supply.

Any suggestions as to type of sensors ?

John

 

[rjvh]

NTC and PTC will do the job already in combination with comparators to swich something at a certain level

have a look in spects of the LM335 if you need some more accuracy

Robert-Jan

 

[john1]

Cheers rjvh,

LM *35 series.

Thanks, that looks like just what i want.
All i want to do is monitor the temperatures of my water system,
nothing that requires any special accuracy.

As they will be attached directly to the water pipes, the TO-92 plastic
package will probably the one i go for, as i dont fancy any direct connection
to the metal pipes.
Thats the three legged one, like a transistor.

Any idea how much they cost, roughly ?
i will only want half a dozen or so.

Not looking to switch stuff, just monitoring.

John

 

[Marks256]

If you were to buy from Jameco, you're looking at about $0.81 (~£0.5418) each in quantities of 1.
Jameco Electronics ICs & Semiconductors: VARIOUS: LM335AZ-R

i'm sure you can get them cheaper through digikey or another popular supplier.

 

[Leftyretro]

If you were to buy from Jameco, you're looking at about $0.81 (~£0.5418) each in quantities of 1.
Jameco Electronics ICs & Semiconductors: VARIOUS: LM335AZ-R

i'm sure you can get them cheaper through digikey or another popular supplier.

Yea, it will probably cost more for wiring and stuff for a dozen scattered sensors then the sensors themselves. At the refinery I worked at before retiring we were sometimes asked to add a new thermocouple sensor to some equipment and often with the cost of running the wire and conduit and labor (some hundreds of feet in many cases) would end costing $15,000 to add that single new measurement point. That's OK, we would just bump up the price of gas a little and pay for it in no time

Lefty

 

[xanadunow]

Plenty of ICs

There are plenty of ICs around and with varying accuracy, I just checked Farnell at **broken link removed**

I found there also the LM335, altought with rather hefty price tag.

There are choices of analog output through to serial Digital and a duty cycle dependant temperature outputs. There are so many of them, it took me more than an hour to wade through it, but it was an interesting reading.

One good thing about these listings from Farnell is that you can "compare" all of them at an instant, then choose to look at these that suit you application the most.

RS Components would most certainly have an equivalent list.

Even if you do not want to order from them, it is a reasonably good overview of the chips available at the market in the present time.

Regards,
xanadunow

 

[3v0]

Another option is to go with Dallas 1 wire sensors. There can be read by a PC or a micro. A single twisted pair is enough to support 10s of sensors over many feet. They can be read by a micro or a PC via an adaptor PCB to USB or serial. Peter H Anderson has some interesting interface boards.
https://www.phanderson.com/onewire/owc190.html

Also look at TM125 and TM128

3v0