Wet Steam table.

[jumacao]

If we have saturated steam at 97 % quality. If we are measuring a temperature 2 degrees lower than the saturated temperature. What could cause that? We are measuring the pressure and the temperature.

 

[ash9144]

Measurement errors.

 

[MiketheEngineer]

Or out of whack or non-calibrated instruments

 

[DRWeig]

Agree with ash9144's and MikethEngineer's answers.

What is the accuracy of your temperature sensor/transmitter combination? Thermal effect? What about the pressure transmitter? At what temperature and pressure were they calibrated? What was the accuracy of the calibration standard? Do you have a calibration report?

What pressure/temperature steam are you working with? If 1000°F, being off by 2°F is trivial considering you are working with two sensors that both have error bands.

Is your temperature sensor insertion well insulated the same as the rest of the pipe or vessel? Your sensor probe may be conducting heat to the surroundings. Is the vessel well-insulated? The probe may be radiating to the vessel wall.

Lots of possibilites.

Good on ya,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[chicopee]

Perhaps, altho I doubt it, an erroneous steam table?

 

[rmw]

So if you aren't able to measure you steam temperature accurately, how do you know that the quality is 97%?

rmw

 

[StoneCold]

Did you compensate the pressure measurements for altitude?

 

[Drexl]

Are you sure you have no air or other gases in there at the time of measuring?

 

[EdStainless]

What do the tips of your pressure sensing lines look like?
Zero flow velocity? are you sure that there is never any water in the lines?
This is a sensor issue.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[rmw]

The OP's keyboard seems to have gone dead.

rmw

 

[ports394]

Is there a thermowell involved?

 

[msquared48]

rmw:

I guess the OP is steamed from the comments.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com