About kishore karuppaswamy

Iam Btech having experience in saudi aramco as instrument engineer

LASER LEVEL TRANSMITTERS

LASER LEVEL TRANSMITTER

The laser level transmitter either uses triangulation, time of flight or confocal chromatic working principle

Triangulation

One method for accurately measuring the distance to targets is through the use of laser triangulation sensors. They are so named because the sensor enclosure, the emitted laser and the reflected laser light form a triangle.

The laser beam is projected from the instrument and is reflected from a target surface to a collection lens. This lens is typically located adjacent to the laser emitter. The camera views the measurement range from an angle that varies from 45 to 65 degrees at the centre of the measurement range, depending on the particular model.

Time of flight

This technique uses the time light takes to travel to a target and back, but the time for a single round trip is not measured directly. Instead, the strength of the laser is rapidly varied to produce a signal that changes over time. The time delay is indirectly measured by comparing the signal from the laser with the delayed signal returning from the target.

Confocal chromatic:

This uses use a white light source to accurately measure the distance to surfaces. The essence of our confocal chromatic imaging principle is the accurate detection of colours from light that is reflected back from target surfaces. The white light is focused onto the target surface by a multi-lens optical system. These lenses disperse the light into monochromatic stages (colours) along the measurement axis. A specific distance to the target is assigned to each colour’s wavelength in a factory calibration. Only the wavelength which is exactly focused on the target is used for the measurement. This light reflected from the target surface is transmitted from the probe, through a confocal aperture and onto a spectrometer which detects and processes the spectral changes and calculates distances. These distance measurements are transmitted at high speed via Ethernet communications protocol

.

Some of the laser LT are below

TURBINE FLOW METER

TURBINE FLOW METER

Turbine flowmeters use the mechanical energy of the fluid to rotate a “pinwheel” (rotor) in the flow stream. Blades on the rotor are angled to transform energy from the flow stream into rotational energy. The rotor shaft spins on bearings. When the fluid moves faster, the rotor spins proportionally faster.

Shaft rotation can be sensed mechanically or by detecting the movement of the blades. Blade movement is often detected magnetically, with each blade or embedded piece of metal generating a pulse. Turbine flowmeter sensors are typically located external to the flowing stream to avoid material of construction constraints that would result if wetted sensors were used. When the fluid moves faster, more pulses are generated. The transmitter processes the pulse signal to determine the flow of the fluid. Transmitters and sensing systems are available to sense flow in both the forward and reverse flow directions

Function of Turbine Flow Meter

SOME OF THE TURBINE FLOW METERS ARE AS SHOWN BELOW

ZERO SUPPRESSION AND ELEVATION

ZERO SUPRESSION AND ELEVATION OF LT:

ZERO SUPPRESSION:

Suppose a DP type LT is mounted below the bottom of the tank/HP tapping point through an impulse line and the tank is filled with water for instance, then before the tank reaches a level the transmitter HP side will be filled with water and this will exert a pressure showing some error in level, to correct this error reading in the LT we do a zero suppression. Or simply when a static head transmitter is installed below the zero liquid level, the transmitter gets a +ve error in the level measurement. This error is corrected by a zero suppression kit by putting a +ve LRV value and a URV=LRV+ (span*s.g. of liquid inside vessel)

supression

ZERO ELEVATION:

Suppose a DP type LT is mounted above the bottom of the tank/HP tapping point through an impulse line and the tank is filled with water for instance, then even after the tank reaches a level just below the transmitter HP side, the LT will be experiencing zero pressure and thus a no level reading will be showing in the transmitter, to correct this error we will be using a zero elevation or by filling the HP and LP impulse line with a liquid like silicon or glycol or simply with water for correcting the error. Or simply when a static head transmitter is installed above the zero liquid level, the transmitter gets a –ve error in the level measurement. The error is corrected by a zero elevation kit by putting a –ve LRV value and URV=LRV + (span*s.g. of liquid inside vessel)

Theoretical elevation example

elevation theoretical

here it should be noted that LP pressure is 0 mmwc for calculating both LRV and URV

Practical elevation example:

practical elevation

N.B. FOR CALCULATING THE LRV AND URV OF D.P. TRANSMITTER REFER MY POST BELOW:

https://kishorekaruppaswamy.wordpress.com/2017/01/02/lrv-and-urv-determination-for-d-p-type-level-transmitter/

SMP of a control valve

Standard maintenance procedure of control valve

  • Obtain a hot work or cold work permit as per requirement.

  • Carryout j.s.a/j.h.a/toolbox meeting as applicable

  • Isolate and barricade the area and use proper p.p.e and tools

  • Override if it is connected to any interlock

  • Ensure the control valve is isolated from the process. depressurise the entrapped process fluid by drain points

  • Clean the control valve with dry cotton and ensure the moving parts are free from dust and debris

  • Lubricate the moving part with appropriate grease or lubricant as prescribed by the valve manufacturer

  • If required tighten all the accessories of the valve like positioner, lockup relay, solenoid valve, feedback link, gland nuts etc. do leak checks in pneumatic tubes and actuator

  • Stroke the control valve from hmi/hart/control room in the steps of 25%,50%,75% and 100% both in increasing or decreasing steps

  • Observe the control valve movement in the field and ensure the travel indicator shows the correct opening/closing of the valve on the scale

  • If valve closing/opening/intermediate positions are matching w.r.t signal go to step “a” otherwise follow the steps below

  • Isolate and disconnect the signal cable of the positioner and connect the loop calibrator to the positioner

  • Apply the 4ma And adjust the zero adjustment in the positioner, ensure the valve is at 0%

  • Apply the 20ma And adjust the span adjustment in the positioner, ensure the valve is at 100%

  • Repeat the above two steps and ensure the valve travel once again

  • Disconnect the loop calibrator and restore the positioner signal cable

  • Stroke the control valve from hmi/hart/control room in the steps of 25%,50%,75% and 100% both in increasing or decreasing steps

  • Ensure the control valve feedback in hmi

  • Step “a”—inform the production department about the completion of the job and its taking in line

  • Normalize the override if applicable

  • Close the permit to work

    Servicing of control valve

    • Servicing of control valve is required if it is reported struck, passing or not responding with respect to signal

    • Obtain ptw from production, override if connected to any interlock

    • Major parts of control valve is to be memorized

    • Actuator

      1

    • Body

      2

    • Packing

      3

      • Dismantling of control valve follows steps which can be explained briefly as below

       

      -mark the direction of actuator/bonnet/valve body with permanent marker

      -fix the control valve on a rigid support

      4

      -loosen spanner-nut (yoke nut) and gland nut to remove the actuator connecting body

      5

      -uncouple actuator upper stem from lower valve stem by removing stem connector (coupling nut)[split block with threads matching those on each stem]

      6

    • 7
    • 8

      -separate valve actuator from the body by removing loosened spanner nut (yoke nut)

    • 9
    • -remove the lower stem and plug from the body for servicing by loosening four large studs and service gland packing. Inspect the internal trim parts such as plug, cage, seat ring etc. if found damaged replace with an o.e.m spare parts. Inspect the seat and plug if found scouring rectify by lapping. Replace all gaskets with new one

      123456789

 -remove the (piston) diaphragm and (shaft) upper stem from the actuator by slowly loosening diaphragm hold down bolts (end cap screws)

12

3

4

5

6

7

8

9

9a

9b

-inspect and replace the worn/torn out parts with OEM parts and start reassembling in reverse order

-reassemble the (piston) diaphragm and (shaft) upper stem to the actuator and check the performance by lock up test.

-assemble lower stem and plug arrangement (trim) to the body and tighten the four bolts in bonnet to assemble the bonnet by placing the seat ring gasket first, then seat ring, cage(if applicable) and cage top gasket set (if applicable)

-now insert the lower stem through the yoke and place spanner-nut (yoke nut) in its place

-adjust for full closed condition by putting a wooden block in between the actuator stem and valve stem, and by pressing down the lower stem and actuator to ensure full close condition. Then tighten the spanner nut (yoke nut) & stem connector (coupling nut) and adjust the pointer scale for closed condition, now place the positioner along with feedback link and check for leaks. Lubricate all the moving parts

-perform the bench set confirmation checks of the actuator by applying specified range pressure directly to the actuator

  • restore all the accessories like positioner, feedback link, booster (if applicable),regulator, tubing etc

  • Calibrate the valve as described before.

  • ensure the proper stroke from the control room

  • inform the control room for the completion of the job and the valve taken in line

  • normalize the override if applicable

  • close the PTW

  • record the activities carried out and the spares consumed

  • prepare the check list/calibration sheet for the control valve

Finally I will explain once more dismantling of control valve…

Firstly uncouple actuator from body by removing stem connector (coupling nut)

Secondly remove yoke nut and separate actuator from body

Third remove studs to inspect lower stem, plug and gland packing

Fourth remove end cap screw (hold down bolt) to service the diaphragm, plate, upper stem and spring

Reassemble in the reverse order

Suggestions please….!!!!!!!!!!!!!!!!!!!!!

 

 

 

Safety Integrity Level (SIL)

Safety Integrity Level (SIL) Classification

sil9a

5 Classes of demand ( D)

D0: negligible demand rate; the scenario has not been heard of in industry;

D1: the interval between demands is more than 20 years; the scenario is unlikely to occur during the lifetime of the platform, but has been heard of in industry;

D2: the interval between demands is 4 to 20 years; the scenario is likely to occur during the lifetime of the platform or has already occurred before in the platform;

D3: the interval between demands is 6 months to 4 years; the scenario is likely to occur in the time period between two major stops;

D4: the interval between demands is less than 6 months; the scenario occurs several times per year on the platform

Risk Matrix to Determine Personal SIL Level

sil9b

 

Correction Factor-Injury:

a)Averting the Danger

sil5

b) Exposure Time

sil6

c) Mitigation

sil7

Risk Matrix to Determine Economic SIL Level

sil8

Risk Matrix to Determine Environmental SIL Level:

sil9

Instrument Gland sizes

  • Cable: 1pair x 1.5 mm2 FRLS   11.9 OD 7.3 ID-Gland:  0.5″NPTM   Range 10 to 14

  • Cable: 1pair x 1.5 mm2 FS 13.1 OD 8.5 ID-Gland: 0.5″NPTM Range 14 to 18

  • Cable: 2C x 1.5 mm2 FRLS 11.6 OD 7.3 ID-Gland: 0.5″NPTM Range 10 to 14

  • Cable: 2C x 1.5 mm2 FS 12.8 OD 8.2 ID-Gland: 0.5″NPTM Range 14 to 18

  • Cable: 2C x 2.5 mm2 FRLS 12.4 OD 7.8 ID-Gland: 0.5″NPTM Range 10 to 14

  • Cable: 2C x 2.5 mm2 FS 13.6OD 9.0 ID-Gland: 0.5″NPTM Range 14 to 18

  • Cable: 1T x 1.5 mm2 FRLS 12.3 OD 7.7 ID-Gland: 0.5″NPTM Range 10 to 14

  • Cable: 1P x 1.5 mm2 FRLS 11.9 OD 7.3 ID-Gland: 0.75″ETM Range 10 to 14

  • Cable: 1Px 1.5 mm2 FS 13.1 OD 8.5 ID-Gland: 0.75″ETM Range 14 to 18

  • Cable: 2Cx 1.5 mm2 FRLS 11.6 OD 7.3 ID-Gland: 0.75″ETM Range 10 to 14

  • Cable: 2Cx 1.5 mm2 FS 12.8 OD 8.2 ID-Gland: 0.75″ETM Range 14 to 18

  • Cable: 2Cx 2.5 mm2 FRLS 12.4 OD 7.8 ID-Gland: 0.75″ETM Range 10 to 14

  • Cable: 2Cx 2.5 mm2 FS 13.6 OD 9.0 ID-Gland: 0.75″ETM Range 14 to 18

  • Cable: 1Tx 1.5 mm2 FRLS 13.6 OD 9.0 ID-Gland: 0.75″ETM Range 10 to 14

  • Cable: 10Cx 1.5 mm2 FRLS 18.4 OD 13.1 ID-Gland: 1″ETM Range 18 to 21

  • Cable: 10Cx 1.5 mm2 FS 22.1 OD 15.7 ID-Gland: 1″ETM Range 21 to 24

  • Cable: 10Cx 2.5 mm2 FRLS 19.9 OD 14.6 ID-Gland: 1″ETM Range 21 to 24

  • Cable: 10Px 0.75 mm2 FRLS 23.6 OD 16.8 ID-Gland: 1″ETM Range 24 to 27

  • Cable: 10Px 0.75 mm2 FS 27.9 OD 21.5 ID-Gland: 1.5″ETM Range 30 to 34

  • Cable: 10Tx 0.75 mm2 FRLS 26.6 OD 19.8 ID-Gland: 1.25″ETM Range 27 to 30

  • Cable: 10Tx 1.5 mm2 FRLS 31.3 OD 24.5 ID-Gland: 1.5″ETM Range 30 to 34

  • Cable: 10Tx 1.5 mm2 FS 36.2 OD 29.4 ID-Gland: 2″ETM Range 30 to 37

  • Cable: 20Cx 1.5 mm2 FRLS 21.7 OD 16.2 ID-Gland: 1″ETM Range 21 to 24

  • Cable: 20Cx 1.5 mm2 FS 25.5 OD 19.3 ID-Gland: 1.25″ETM Range 27 to 30

  • Cable: 20Cx 2.5 mm2 FRLS 24.5 OD 18.3 ID-Gland: 1.25″ETM Range 24 to 27

  • Cable: 20Cx 2.5 mm2 FS 27.6 OD 21.4 ID-Gland: 1.25″ETM Range 27to 30

  • Cable: 20Px 0.75 mm2 FRLS 31.1 OD 24.3 ID-Gland: 1.25″ETM Range 30 to 34

  • Cable: 20Px 0.75 mm2 FS 35.6 OD 28.8 ID-Gland: 2″ETM Range 41 to 46

  • Cable: 20Tx 1.5 mm2 FS 52.6 OD 42.2 ID-Gland: 2.5″ETM Range 53 to 61

  • Cable: 40Cx 1.5 mm2 FRLS 28.4 OD 22.0 ID-Gland: 1.25″ETM Range 27 to 30

    Cable: 40Cx 1.5 mm2 FS 32.8 OD 26.4 ID-Gland: 1.5″ETM Range 30 to 37

  • Cable: 40Cx 2.5 mm2 FRLS 31.9 OD 25.3 ID-Gland: 1.5″ETM Range 30 to 34

  • Cable: 40Cx 2.5 mm2 FS 35.7 OD 29.3 ID-Gland: 2″ETM Range 37 to 41

  • Cable: 5Px 0.75 mm2 FRLS 18.0 OD 12.7 ID-Gland: 1″ETM Range 18 to 21

  • Cable: 5Px 0.75 mm2 FS 21.8 OD 15.4 ID-Gland: 1″ETM Range 21 to 24

  • Cable: 5Tx 1.5 mm2 FRLS 24.5 OD 18.1 ID-Gland: 1.25″ETM Range 24 to 27

  • Cable: 5Tx 1.5 mm2 FS 28.3 OD 21.5 ID-Gland: 1.25″ETM Range 27 to 30

  • Cable: 1Px 1.5 mm2 FRLS 11.9 OD 7.3 ID-Gland: 1″NPT Range 10 to 14

  • Cable: K TYPE THERMOCOUPLE COMP  12.5 OD 7.9 ID-Gland: 0.75″ETM Range 10 to 14

    All Cable OD & ID can have + or – 2 in sizes tolerance and cable glands should be stainless steel ,double compression for out door hazardous area ,stainless steel with nickel platingwith neoprene seal neoprene bushing,IP-66 for steel wire armoured cable,complete with locknut,earth tagPVC shroud and nylon entry threads/seal for IP66 ingress protection

    Tolerance is about (+/-)3 %