Answer / carl_ellis

A draft range measurement is typically a gauge pressure
measurement, referenced to atmosphere.

Draft range is very, very low pressure, so DP transmitters
are typically used because they're readily available in
a 'draft' range with the large diaphragms necessary for low
pressure measurements.

The high side is connected to the process with an impulse
tube. The low side is exposed to atmospheric pressure.
Good practice puts a filter, like a scintered pneumatics
filter on the low side, so that dirt doesn't fill the low
side cavity and air movement (wind, passing vehicles) is
buffered and damped to prevent the forces of air movement
on the low side from affecting the draft measurement.

If the impulse line were connected to the low side, the DP
would be negative, a DP subtracts the low side pressure
from the high side pressure (atmosphere minus some positive
pressure = negative pressure). Convention says that draft
range is positive so the impulse connection is to the high
side, to get a positive value.

Tell 'em Carl sent you.

Answer / deepak

Dear Carl,

Cant we use an Absolute pressure transmitter ?

Why do we floating DC in DC system.

0 Answers  

---

How a oxygen sensor & analyzer work at boiler or furnace, whats the principle & science is beyond this,How O2 sensor sence & convert signal & move toward analyzer & analyzer show reading in percent?

2 Answers  

---

what are the use of belew gear in general ??

0 Answers  

---

Difference between ultra sonic flow meter

0 Answers  

---

When LP SURGE happening in compressor

3 Answers   KNPC, KOC,

---

what is different between modbus and serial link? please could anybody give right answer.

2 Answers  

---

I have 475 hart communicator. this is not support any new type of instruments such as tranmitter,fieldvue DVC6200.DVC 200 since i got point out need to upgrade . my questions is how can upgrade new instruments software in my 475 hart communicator. can any answerplease>?

1 Answers  

---

what is three element loop

7 Answers  

---

Any Transmitter Range (Span value) start from 2?

1 Answers   Exxon Mobil,

---

diff between dead wt calibrator n pressue comparator?

4 Answers   Invensys,

---

how to calibrate an error for pressure transmitter, make it easy to understand

2 Answers   Descon,

---

What is surge in compressors? How to detect and control it?

3 Answers   Kharafi National,

---