I need ten temperature sensors and so far this is the best I found. Its not ideal for sensing the temperature of gas or liquid in a pipe. The first pic is of the sensor soldered to a piece of strip board so I can solder wires to it. The strip board and solder joints will have heat shrink around it. The second picture is the shape of a small piece of thin copper sheet. The long part will be wrapped around the sensor with the sensor occupying the lower tang and heat shrink-ed to keep it there. Then the larger part will be wrapped around the pipe to effectively get the sensor to the pipe temperature. Then all of it will be wrapped with some insulating material.
And the question: I suspect there is a better way of doing this. Any suggestions? I am open to anything including a different sensor.
Reading the replies I realize I should have presented the application. This is a project to monitor our home HVAC system. There will be one Arduino DUE in a box out by the compressor. It will monitor the Freon pressure in and out of the compressor, the temperature at both places and the temperature out of the condensing coils. It will monitor the temperature of the ambient air and of the exhaust air, and the voltage and current for the compressor and fan. There will be another Arduino Due in the air handler monitor all the stuff there, and monitoring the furnace part. Other than startup current and voltage there is little need for fast response. Yes, I am going overboard with all the sensor points, but I will do that and see what I get.
The Arduino DUE was selected because it has 12 analog inputs built in.
An easy one is the digital DS18B20. Only one Arduino port for the 10 sensors.
They can work with 5volt logic (powered from 5volt) or with 3.3volt logic (powered from 3.3volt (your Due)).
They also come in a 'waterproof' version (stainless tube, with wires attached).
Leo..
TomGeorge:
Hi,
What temperature range?
What is the application?
speed or response ?
sensitivity to change ?
accuracy ?
resolution?
Clamping a sensor on a pipe and then adding insulation will get you temperatures.
The fast changing temperatures can take time to change the pipe temperature
The shroud or housing and epoxy fill of the temperature sensor can slow the signal but adds protection.
Unlike pressure or light, temperature is a very slow process.
The OP has been edited with additional information. And the shape of the copper heat sink should have been vertically reversed to better indicate how it will be fitted on to the sensor.
Reading the replies I realize I should have presented the application. This is a project to monitor our home HVAC system. There will be one Arduino DUE in a box out by the compressor. It will monitor the Freon pressure in and out of the compressor, the temperature at both places and the temperature out of the condensing coils. It will monitor the temperature of the ambient air and of the exhaust air, and the voltage and current for the compressor and fan. There will be another Arduino Due in the air handler monitor all the stuff there, and monitoring the furnace part. Other than startup current and voltage there is little need for fast response. Yes, I am going overboard with all the sensor points, but I will do that and see what I get.
The Arduino DUE was selected because it has 12 analog inputs built in. Yes, the DUE will be damaged by inputs over 3.3 volts. The temperature sensors can operate on 3.3 so not problem there. I will remember that as I wire it up. I need to check the pressure sensors. If needed, I might have to use a voltage divider network. That will require some space and extra wiring. More strip board usage.
From your list, two Due boards is gross overkill. One Nano can do that all.
10 temp sensors ony use one digital pin, and a Nano has 8 analogue pins for current/pressure sensors.
Many current/pressure sensors are 5volt only, and ratiometric, so another reason to use a 5volt board.
Leo..
A few more details.
One board is outside at the compressor/condenser. It monitors the following:
Pressure in to compressor
Pressure out of compressor
Temperature in
Temperature out of compressor, but before condensing coils
Temperature out of condensing coils
Ambient air
Exhaust air
Voltage at the compressor
Current of compressor motor
Current of fan motor.
That is ten analog inputs.
The board at the air handler will monitor
Pressure in from compressor (is there too much pressure loss in the lines)
Pressure out of the evaporator. The thermal expansion valves are now actively controlled rather than a fixed orifice. Is it being controlled correctly?
Freon temperature in
Freon temperature out
Air in from the house
Air out to the house
Suction air pressure
Exhaust air pressure
Air flow sensor in the air to the house
Exhaust air from the gas furnace. Is too much heat going up the chimney in the winter.
Air flow of that exhaust air to determine total BTU count up the chimney.
That is eleven analog inputs for a total of 21. The distance between the two devices is too far for a single device so each will have an Ethernet connection and both will connect to a wireless router so they can be monitored from within the house.
Makes sense to use two boards if there is some distance between.
Still wondering which pressure sensors you're using.
Most analogue ones I know are 5volt only, unless you have industrial 0-10volt or 04-20mA types.
Leo..
The temperature sensor is by Measurement Specialties, model M3021-000005-500PG. It is a 5 volt device so I must drive it from the 5V line and add few resistors as a voltage divider and drop the peak voltage down to 3.3.
The compressor works at up to 400 psi so the sensor must be able to withstand, about, 1000 psi surge. This one is 500 psi rating and 1000 burst so it should be fine.
It is a physically large sensor but I was not able to find anything smaller. The AC installer brazed in a fitting with a Schrader valve and permanently attached the sensor there.
And to be redundant, if anyone has suggestions for better and/or lower cost the temperature and pressure sensors, please post. In particular, the temperature sensors are a bit of a pain.
