View Full Version : Liquid level controls

06-01-2013, 06:01 PM
I am putting together a talk on liquid level controls (LLCs). The basic outline will be an overview of LLCs through the ages, ending with some of the latest technologies and what's on the horizon. Here's my basic outline...

Early LLC's
float valves (Phillips, etc)

Later LLC's
float switches

Current LLC's
capacitance probes, optical sensors

New & future
Danfoss wire

The talk is not intended to promote one company or another. It's for RETA education.

My question(s)...

Are there any other LLC's I should be including?

Do I have the chronological order correct?

I'm most fuzzy on technologies before float switches and float valves (if there were any). And if I'm missing any of the new or "on the horizon" technologies. Again, not trying to promote any one technology over the other.

Websites and pictures are a plus. I've been trying to find a picture of an old Magnetrol mercury bulb switch.

Thanks in advance for your help.

06-01-2013, 07:29 PM
Hi jseidel.
what's your timeline on this one?
How soon are you to give the talk?

06-01-2013, 07:35 PM
Another type of measurement is "differential pressure transmitter" which is a lot cheaper to put in.

06-01-2013, 09:20 PM
I remember a level switch basicly being a thermostat with a heating element from Danfoss(?).
Don't know the type and all my old documentation has been thrown away few month ago so can't find a copy.
The principle was that submerged in liquid the bulb would be cooled much more than when not in the liquid.

Also not in your list are the level transmitters based on Archimedes principle of buoyant force exerted on a body immersed in a liquid like the NI1321 from RTK Kornwestheim.

06-01-2013, 10:09 PM
Check out this link, yes it is a danfoss manual.
But does refer to many types of level control.
Albeit modern variants!



07-01-2013, 09:54 AM
This is a brochure about the RTK level transmitter that I mentioned:

07-01-2013, 03:13 PM

might help you?

Check these pictures


08-01-2013, 04:43 AM
Ah...differential pressure transmitter. Good one.

My talk is next week. So I've got some time.

Love the old water switch pic. Thanks chemi-cool.

09-01-2013, 01:04 AM
Weka sealed column with floating ball thingo and prox switches, oil column repeating ammonia level,( ammonia only) danfoss teva and sporlan levelmaster are similar principle, danfoss SV pilot float series with PMFL vavs., Hansen pulse width vavs. And way back a little old man regulating hand expansion valve

12-01-2013, 06:51 AM
Post might be a bit late but we have used Guided Radar level control with good success.

12-01-2013, 10:30 PM
I would not even mention the Danfoss wire devices as they clearly do not work and will soon be superceded by some other device from Danfoss.

30-03-2013, 09:12 PM
Star refrigeration did a nice one (years back), rather than use a proper float control valve / system on the early LPR systems they used a standard danfoss TEV and cut the Bulb off and soldered this into one of the ports on the system (long time so cant remember where) - this then had system pressure either side of the diaphragm and was used like a float from memory, I think there was an orifice or two involved to slug it......

We called it a bas******ed TEV for want of a better expression