Wind Effects on Draft DP Transmitters


Thread Starter


We have 5 frame 5 GE turbines which have exhaust plenum back pressure transmitters (2 out of 3 voting). The LP leg is exposed to ambient pressure. During windy conditions, which is nearly always, these are fluctuating and causing nuisance alarms in the DCS.

I seem to recall in the past there was a device that can be installed on the LP connection to "exclude" the wind. I think it was an off the shelf item, but I can't remember from where (it was years ago). From the web I can only find a Yokogawa manual that refers to a wind-excluding pot (cylinder with a base plate).

Does anyone know the name of this device and where I can order from, or at least a picture or drawing of what a shop fabricated wind excluding pot should look like? Thanks in advance!

Curt Wuollet

I should think any kind of vessel with only a small orifice would average the ambient pressure. The bothersome part is that the wind <b>is</b> part of the draft at any given moment. In other words, if my draft varies from day to day because of the wind direction, that really <b>is</b> the draft and careful consideration should be given to overriding the effects. Perhaps due to the physical setup, short term variation is not important, but I would consider very carefully why they alarm on draft out of limits or consult with the folks who do understand the implications if I didn't. It's good to keep things going in the right direction.

I saw a combination of a metallic scintered filter directly connected to the low side port (called an exhaust muffler, used to muffle exhaust from ports on solenoid valves, comes on a 1/4" NPT nipple), along with the foam that covers newscasters' microphones on draft range DP's on a large furnace.

The guy who installed them said that the combination seems to break up the force of moving air and stabilized the effects of drafts on the reference side.

For outdoor service, an vented enclosure to keep the rain off would be needed.