WATER DEW-POINT METERS DO NOT WORK in natural gas unless one has an experienced engineer checking it CONTINUOUSLY or when one has a nice clean gas (but there are so few). Glycol, H2S, inhibitors, liquid hydrocarbon, methanol, CO2 and other contaminants cause the problems.

Check the performance of your dehydrator instead!! In case no water comes out of your glycol regenerator then you are not dehydrating.

Metering WET gas with an orifice box with instrument lines coming from the line in horizontal position (some orifice boxes in which orifices can be changed are like that) may result in TOO HIGH READINGS if liquid gathers in the downstream (repeat downstream) instrument line that connects the orifice-box with the pressure differential (DP)-cell. Although one always will try to avoid metering WET gas, sometimes one can not avoid it. The piece of horizontal line leaving the box is the cause. Turning the box X degrees solves the problem (although it does not look pretty) because liquid is drained automatically back into the line. Normal fixed orifices metering gas have connections from the top of the flanges or at an angle and should not give that problem. Drain pots do not help!!! (they must be drained!!)

The (circular) flow chart shown below indicates the pressure differential across the orifice in the orifice box at a constant flow condition between 00 and 10 hours but from then onwards the pressure differential slowly increases at constant flow. This clearly points at the problem as described above and as shown schematically at next page.