Hi,

I need ur support to point out our current issue with one of orifice plates at Refinery site. It is measuring LPG produced from Overhead of Platformer Stabilizer Column. The issue is unclear for us until this moment;
The orifice was calculated and its transmitter was calibrated for a full range of 222 TPD of LPG for delta pressure of 0.5 barg. The calculation was checked through software and confirmed that the data is suitable for orifice plate with bore size 27 mm. The current issue is; the transmitter of this orifice plate is reading over range "IOP" lively and DP was checked at site to be found 0.7 bar which makes sense for having "IOP" reading at DCS. However, the actual flow based on other downstream transmitters are showing around 70 TPD coming from this line ! and it goes to the sphere as a final destination. So we are sure this flow should be lesser than what the transmitter is showing (>222 TPD) ! The high DP 0.7 bar around this orifice at site is making us without a clue!
We took plenty of actions trying to understand why we have a high DP where; the impulse lines were changed, the transmitter was changed with a new one, a live pressure gauge was installed at site to measure DP around impulse line. With all of these actions, yet the DP is high "~0.7" bar.
What is missed here? Please advise,
I attached the calc sheet for this orifice.

 

1, What is IOP?

2. What is the mechanical gauge measured DP?

 

1, What is IOP?

2. What is the mechanical gauge measured DP?

1- IOP means the measured value is out of scale.
2- it is measuring ~0.7 bar

 

Hi,

I need ur support to point out our current issue with one of orifice plates at Refinery site. It is measuring LPG produced from Overhead of Platformer Stabilizer Column. The issue is unclear for us until this moment;
The orifice was calculated and its transmitter was calibrated for a full range of 222 TPD of LPG for delta pressure of 0.5 barg. The calculation was checked through software and confirmed that the data is suitable for orifice plate with bore size 27 mm. The current issue is; the transmitter of this orifice plate is reading over range "IOP" lively and DP was checked at site to be found 0.7 bar which makes sense for having "IOP" reading at DCS. However, the actual flow based on other downstream transmitters are showing around 70 TPD coming from this line ! and it goes to the sphere as a final destination. So we are sure this flow should be lesser than what the transmitter is showing (>222 TPD) ! The high DP 0.7 bar around this orifice at site is making us without a clue!
We took plenty of actions trying to understand why we have a high DP where; the impulse lines were changed, the transmitter was changed with a new one, a live pressure gauge was installed at site to measure DP around impulse line. With all of these actions, yet the DP is high "~0.7" bar.
What is missed here? Please advise,
I attached the calc sheet for this orifice.

Are you sure of the density at 508 kg/m3?

 

sounds like cavitation is taking place, but given the date of your query, you've likely sorted out your problem by now.