Flow measurement instrumentation question and answers

5. How do you identify an orifice in the pipeline?

An orifice tab is welded on the orifice plate, which extends out of the line giving an indication of the orifice plate.

6. Why is the orifice tab provided?

The orifice tab is provided due to the following reasons.

·        Indication of an orifice plate in a line.

·        The orifice diameter is marked on it.

·        The material of the orifice plate.

·        The tag no. of the orifice plate.

·        The mark the inlet of an orifice.

7. What is Bernoulli's theorem and where it is applicable?

Bernoulli's theorem states the "total energy of a liquid flowing from one point to other remains constant. It is applicable for non-compressible liquids

8. How do you identify the H.P side or inlet of an orifice plate in line?

The marking is always done H.P. side of the orifice tab, which gives an indication of the H.P  side.

9. How do you calibrate a D. P. transmitter?

The following steps are to be taken which calibrating:

1. Adjust zero of the Xmtrs.

2. Static pressure test: Give equal pressure on both sides of the transmitter.  Zero should not shift. If it is shifting carry out static alignment.

3. Vacuum test: Apply equal vacuum to both the sides. The zero should not shift.

4. Calibration Procedure:

·        Give 20-psi air supply to the transmitter.

·        Vent the L.P. side to atmosphere.

·        Connect output of the Instrument to a standard test gauge. Adjust zero.

5. Apply required pressure to high-pressure side of the transmitter and adjust the span.

6. Adjust zero again if necessary.

10. What is the seal liquid used for filling impulse lines on crude and viscous liquid?

    Glycol.

11.How do you carry out piping for a Different pressure flow transmitter on liquids, Gas and steam services? Why?

13. An operator tells you that flow indication is more? How would you start checking?

·        Flushing the transmitter. Flush both the impulse lines. Adjust the zero by equalizing if necessary. If still the indication is more then.

·        Check L.P. side for choke. If that is clean then.

·        Check the leaks on L.P. side. If not.

·        Calibrate the transmitter.

14. How do you do a zero checks on a D.P. transmitter?

Open the equalizing valve then close one of either H.P. or L.P... The O/P should read zero.

15. How would you do Glycol filling or fill seal liquids in seal pots 7 Draw and explain.

·        The procedure for glycol filling is :

·        Close the primary isolation valves.

·        Open the vent on the seal pots.

·        Drain the use glycol if present.

·        Connect a hand pump on L.P. side while filling the H.P. side with glycol.

·        Keep the equalizer valve open.

·        Keep the L.P. side valve closed.

·        Start pumping and fill glycol.

·        Same repeat for L.P. side by connecting pump to H.P. side, keeping equalizer open and H.P. side isolation valve closed.

·        Close the seal pot vent valves.

·        Close equalizer valve.

·        Open both the primary isolation valves.

16. How do you calculate new factor from new range using old factor and old range?

 Q₁      ? ?P₁                   Q_{1 =} Old flow (factor)

       =                             Q₂ = New flow (factor)

 Q₂      ? ?P₂              ? ?P₁ = Old range

                                  ? ?P₂ = New range

 Q₂ × ? ?P₁   =    Q₁ ×   ? ?P₂

                              Q₁ × ? ?P₂

                 Q₂   =

                                   ? ?P₁    

                               Old factor × ? new range    

   New factor   =   

                                          ? Old range

 Flow measurement instrumentation question and answers UAE.

17. How will you vent air in the D.P. cell? What if seal pots are used?

·        Air is vented by opening the vent plugs on a liquid service transmitter.

·        On services where seal pots are used isolate the primary isolation valves and open the vent valves. Fill the line from the transmitter drain plug with a pump.

18. Why flow is measured in square root?

Flow varies directly as the square root of different pressure F = K square root of AP. Since this flow varies as the square root of differential pressure the pen does not directly indicate flow. The flow can be determined by taking the square root of the pen. Say the pen reads 50% of chart.