Thread Starter


dear fellows,

I need to measure level of liquid ammonia in an horizontal cylinder 40 inches diameter, and I have in our stock a standard dp-cell. Has anyone measured this fluid using this method? I know ammonia it´s not easy to measure since it evaporates easily and so on. Any experience?
I measured the ammonia level of the separator drum in a chiller plant, using a E+H Deltatop dp unit, fitted with remote seals. I had to use remote seals, directly attached to the drums, because in my case, i can't assure that the dp legs are filled with condensate, due a slight temperature increase of the tubing legs, makes the ammonia become vapour.

It works well, but a couple of points must be taken into consideration accurately:

-Check if the seals filling fluid is suitable for the process temperature (-20 º C in my case).

-Don't forgot that ammonia density is slightly temperature and pressure dependent.

Good luck.
The vessel's temperature will determine the vapor pressure over the liquid, no?

A DP cell with its low side piped to the upper tank vapor area will compensate for the head pressure of the vapor and provide a head pressure measurement.

But the readings
- are in head pressure in units of water column (typically) and actual level or volume values requires a compensation calculation for density (specific gravity).

- will be very non-linear in a horizontal round tank except at exactly 0, 50 and 100%. There are tables with 9 or 10 (or more) breakpoint values (% FS) that can be used in a look-up table to correct to about ±0.5%
Or just solve for volume in terms of depth and do the math realtime. PLC processors have plenty of muscle now to do that.
Thanks to all

as matter of fact my problem is not to convert level in volume (the dpcell have the intelligence to linearize) but the issue is that I have a standard ddpcell without remote seals, and I am afraid about evaporation of the ammonia on the legs....

My process temp is 5...30ºC, P=10 bar, T ambient = 20...30ºC. So I will appreciate if some of the participants could share bad or good experiences with ammonia and standard dpcell

Again, thanks!