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Does any one have any suggestions for a level sensor that would run a 120V solenoid valve?
I am using the Endress & Hauser level switch FTL31. Basically 24VDC so low voltage. I am in two minds whether to go for the Ex version of this level switch.
But referring to your scenario I say the following.... 120VAC is high voltage and is steered clear of. Rather stick to 24VDC for control inputs and valves.
I will be using 24VDC solenoid valves for distilled product.... heads, hearts and tails. In this selection I am using Ex rated solenoid valves. For my condenser water supply I am using again a 24VDC solenoid valve but not Ex rated.
Obvious caution should be used when switching 120v in proximity to potential vapor or high proof liquid.
Simple switches can and will arc.
Better would be to use a similar type of level switch, but have it switch a small sensing current, and use a relay to switch the solenoid.
Pepperl Fuchs make some nice intrinsic barriers which are basically relays that are switched by simple remote switches.
They are built in such a way that any and all voltage are isolated from the switching side, even during malfunction. They pose zero risk of arc or ignition.
You can use a simple magnetic reed float, or double floats if you want to maintain a fill range.
thanks guys ill pass this on to our electrician
Speaking level switches, my temperature transmitters (4-20mA) and level switches arrived today
@richard did you go for vibrating fork level switches?
I have used the special 150 deg C variation.
Why a fill sensor at the bottom of the tank?
That would be a low level switch or low low level switch if it's at the bottom.
It is positioned marginally above heating elements. It is there for absolute final low level detection ..... where the heating elements ultimately become exposed.
The heating elements are interlocked with the level switch. Once low level is detected, the coil for the power supply to heating elements is deactivated.
No concerns about boiling confusing the tuning fork?
No I certainly hope not, especially if they are correctly orientated. The forks are +- 30mm above highest part of the element as well as being furthest away from the element.
The only time I really expect action is when the still is at the lowest and then I am happy because they will fulfil their function and protect the expensive heating elements when they become exposed.
I am using various liquid level sensors in our industry for a long time with no trouble. The support team is really great to help. If you are interested you can visit this website: Liquid Level Sensors @ ICON Process Controls
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