Question { 5242 }

What are the charecterstics of control valve.

Answer

These are flow paterns.
a. Equal percntage
b. Linear
c. Quick opening

The plug and cage is made in such a way that you can get
flow any one of above construction.
Suppose, Valve cage, plugs are Equal percentage, then at
opening of valve of 30 percent, you may get flow of only 6
to 8%
If linear, then flow also 30%,
If quick opening, then flow almost double, about 60%,
It all depends upon process requirements.
Suppose for vent valve, usually quick opening type valves
are used

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Question { 6489 }

how to check electrical health of vibration probe?

Answer

First you know which type of vibration probe you using.
Suppose you using proximity probe. Then check followings:
1. Its resistance, usually Bently Nevada common probes
restance varies from 4.5 ohm to 6 ohms. But if you using
asnother company probe, then see its literature.
2. Also make a graph of vlotage vesus distance of probe,
its behaviour should be linear.
3. If you have vibulator(Vibration source), then check it
with diffewrent vibrations.
aftabmazari@yahoo.com

Question { 5323 }

what is hall effect?where it is use in power plant?

Answer

There are mostly two types of magnetic pickups for speed
measuring.
1. Passive sensor
2. Actice sensor
In active sensor, hall effect is used to get frequency
signal.

Question { Petrofac, 39035 }

what is the procedure to isolate flow a transmitter and
flushing it?

Answer

For DP type flow transmitter, suppose hp side valve No. 1, LP side Valve No.2, and Equalizer Valve No.1,
Close HP.No.1 Valve
Open Equalizer Valve 3. and then close LP side Valve No. 2

Question { Jindal, 18015 }

how to overhaul control valves.what are the proper procedures.

Answer

It is a very lengthy topic. I will try to explain some major point.
1. Mark the parts orientation before dismantling, such as mark at body, bonnet, yoke, pressure chambers casing.
2. Note down the threads upper side and lower side of coupling.
3. Suppose, valve is air to open, open it with direct feeding signal to diaphragm upto 5%.
4. remove the coupling.
5. release load pressure
6. Loose yoke nut and remove yoke from bonnet
7. Remove gland packing nuts,remove gland pusher
8. Dismantle bonnet nuts
9. Remove bonnet from body
10. Remove trim material

Question { 33131 }

what is working principle of presure and temperature guage?

Answer

Both work at pressure but temperature gauge has filled system and its filled liquid expands with the rise of temperature.So that expansion of liquid gives pressure to gauge which is connected via capillary.

Question { 3117 }

IS THEIR ANY AGEING EFFECT ON FLOW NOZZLE, ORIFICE, MANIFOLD,
OR TRANSMITTER ?

Answer

You have mixed many items. Definitely there are aging
effect. As in case of orifice, its internal bore may get
deshape, dent, or pitting. So the same on other items.
Manifolds get start leaking, tranmitter with the passage of
time, may get hunting due to its aging of components.
aftabmazari@yahoo.com

Question { Chevron, 11182 }

suppose in dcs range of a flow transmitter is 10t/hr what
is dp for 50% in 2500mmwc

Answer

your DP will be 1250 mm h2o but if you want what will be flow at 50% then simply 50 under root multiple 10,= about 70%

Question { 6186 }

what is procedure of calibration of remote seal
transmiter, botom to top flanch 850mm, fluid liquid
density .73, transmiter fixed on a fractionation colum,
under vaccume 10mbar

Answer

If you installed the remote seal transmitter at flanges,
then in case empty tank /vessel, the transmitter will
showing -mA. so do the followings:
1. Make transmitter 4 mA in this case(without any pressure,
only lower low leg remote seal pressure acting)
2. Apply 850 x 0.73 =620.5 mm of water to high side of
transmitter flange and set transmitter out put 20 mA.
aftabmazari@yahoo.com

Question { 7793 }

hello dear
i have faced problem in drum level transmitter.
the problem is when i engrize the meter meter shows 100%
but the actual level 40 or something plz suggest me

Answer

It seems that transmitter low side leg is leaking, or low
side is not being fully condensing.
Please chck low leg fittings, connections and if ok. Then
check transmitter high side and low side pressures with the
help of digital pressure gauge. May be transmitter low side
any problem.When you calibrate tranmitter workshop, also
apply pressure to its low side, indication should go down
to confirm that low side is ok.

aftabmazari@yahoo.com

Question { 8817 }

Why we used cage in control valve?

Answer

I agree with Yomama answer, but add one thing more, Cage also controls cavitation and flashing, it routes flow at different angles to avoid flashing and cavitation.

Question { 8817 }

Why we used cage in control valve?

Answer

Cage is used in control valve to control cavitation or to minimize it.
aftabmazari@yahoo.com

Question { 4666 }

I am new in work for 1 of our project we have some instrument
in BOM including Pressure, Temp. and so on, I also noticed
some objects like pressure switch process HOOK UP; which I
don't know what does "HOOK UP" mean here.

Answer

Process hook up means process connections or primary connections.
Means sensing lines,fittings, elbow, nipples etc

Question { Madhu Power, 7381 }

control valve in manual/auto mode huntting checked spring
tention also it is ok.positioner also good condition &
incoming inst air line also constant pr.kindly give us
correct answer?

Answer

Please check following things:
1. To loose gland packing, due to tight packing, valve may hunt.
2.Check leakage from diaphragm.
3.May be seat or plug loose
4. Check cut marks at feed back linkages.

Question { 25937 }

how to calibrate a capillary type level transmitter for a
closed tank in field?
also what is the procedure for commissioning a capillary
level transmitter for a closed tank?

Answer

There are two methods: 1. workshop calibration, 2. field
Calibration.
Suppose you installed transmitter at vessel and want to
calibrate it.Follow following field procedure:
1. Close process side valves of both upper and lower
flanges.
2. Lose upper remote seal from process flange, It should
not get any pressure from process.
3. Remove lower side transmittrer flange from process side
flange. (It will be high side of transmitter)
4. Put your local made calibration flange at transmitter
remote seal and apply pressure.
(This flange must be same level of vessel flange from where
you removed it)
Suppose transmitter range is 0 to 1000 mm of H2O.
5. Apply this supply to your connected flange and take
readings at 0, 250, 500, 750, 1000 mm of H2O.
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