Where in a pipe should I measure temperature?
Where in a pipe should I measure temperature?
(OP)
I need to measure the temperature of a liquid in a pipe. Assume turbulent flow, temperature slightly elevated over ambient.
Is there an accepted standard for the insertion depth into the pipe of a thermometer bulb (or other temp sensor)? What's left of my common sense tells me that any reading near the centre of the pipe will tell me the temp of the bulk of the fluid. But I no longer trust common sense, and there's probably other factors at work here (like maybe the restriction added by the thermowell??
Thanks in advance.
shackney





RE: Where in a pipe should I measure temperature?
1. Find (or create) along the measured line an Elbow. Replace it to a " T " connection. Insert an RTD at the new outlet of the Elbow so it penetrate into the pipe, at the middle of flow with much larger length then a radial installation can get. Normally Temp. element comes wit Thermo well which inlarge the measuring diameter. If the pipe is small (less then an Inch) consider using Temp. Element without a well.
RE: Where in a pipe should I measure temperature?
Building Automation Professional
RE: Where in a pipe should I measure temperature?
If the liquid is near ambient but you need to measure it accurately use an rtd or a thermister. thermocouples start having noise/compensation problems if the millivolts at the sesor are too small.
you did not specify the response time requirement.
RE: Where in a pipe should I measure temperature?
Depends on your application.
If the pipe is large enough to accomodate the TW then it can be placed at the point desired. If the pipe is too small to accept the TW then one may have to insert it into a Tee or expand the pipe as long as one maintains turbulent flow in the expanded section.
As for the restriction: if it was in a pump suction I would investigae further but normally there is no problem. If the flow area is reduced significantly then I would find an equivalent restriction and model it that way. If a Tee has to be used then one may have a significant reduction in the flow area requiring further investigation of the hydraulics.
RE: Where in a pipe should I measure temperature?