Condensate Pot


Thread Starter


Why is the condensate pot called a "pot" and why is it used in steam plant operations?
Normaly condensate pots are installed at the drain position of the steam line. It is larger in diameter of the drain line and blanked with a blind flange at the bottom.The drain line is tapped from the pot leaving approxiamtely 2/3 of its lenth down side so that all the foriegn matters are collected in the pot and cleaned during shutdown of the main line. It is pot like arrangement hence called so.

Condensate pots are used in pressure transmitter lines of the steam the condensate gets collected in the pot and the down straem impulse line the teperature of the steam is not transmitted to the instrument.
It's called a pot, because it resembles one (slightly) I guess.

To keep the live steam from cooking the instrument for example if you had a pressure transmitter on 100# steam mounted above the tapping point the live steam would condense in the instrument, run back into the line and be replaced by fresh steam. Eventually the transmitter would reach 330+¡ãF.

If a pressure transmitter is mounted below the tapping point the steam condenses and is trapped in the impulse line so the transmitter operates at ambient. You don't actually need a condensate pot in this case but for a DP flow you are never sure of the exact level. With a condensate pot the large mass of cooler metal causes the steam to condense quickly and the level is fixed at the point where the condensate runs back into the line. Sometimes you see a 3000# tee used for this purpose. The pot usually has a plug or some other means of pre-filling with water. You will often see a pressure gauge or switch connected to a steam system a loop of pipe "Pigtail Syphon", This is also to prevent live steam getting to the gauge.

Hope this is clear enough.

From what I remember, Condensate Pots were used in steam service for two reasons:

One reason being that a level of condensed water is accumulated inside of the pot (some pots were vertical others horizontal) and maintained a fluid volume for displacement equal to or greater than the volume displacement of the instrument sensing the flow or pressure.

I'm sure many of your remember how large of a displacement some of these instruments were, and today, the displacement of transmitters are also nothing.

The second reason for maintaining a liquid inside of the pot (were also called chambers) was to prevent flashing of the liquid in the sensing line if a sudden temperature change of the steam is made. A dam inside of the pot prevented this flashing effect.

There were several different styles and at various ratings. We would buy these for new applications from, Bailey Instruments or other ASME approved vendors.
The pots are a necessity on differential pressure transmitters measuring steam flow when the transmittersa are mounted below the steam line.

Over a period of tiume, the steam will condense at unequal rates in the sensing lines creating a false steam flow reading. The longer the lines the worser this problem becomes. The rate of fill and amount of fill will change with steam pressure and room temperature.

Ther pots are used to keep the sensing lines full and at an equal level so the DP creatged by the water is always a value of zero.

If the transmitter is mounted above the steam header, this is not an issue as any condensate in the sensor will equalize to the ports on the transmitter which are at an equal height. Anyy additional condensation would attempt to drain back to the header where it becomes steam again.
I'm seeing this issue more