Answer / sridhar

if the flow must be maintained in process line, we can use
the double acting control valve. for example,if there is a
purging system for any process control,even if the signal
fails and air fails, the valve should be in same poistion
to maintain the flow in the pipe line for process safety.

Answer / carl_ellis

Part of your problem is your terminology.

Valves are chunks of machined metal and elastomers, valves
are not single action or double action, the actuator that
moves the valve stem is.

So your Google search should be for double action actuator,
which will provide you an answer.

Carl Ellis
Measure First

Answer / afroz

I need answer

How can i copy program (parameter) from mm440 (V.F.D.) by using BOP?

0 Answers  

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1- Explain about HPM 2- What is the FSC and explain the configuration of FSC 3- explain the complete loop of vibration, how it works (field to control room) 4- What is the use of proxymitter? 5- During job your partner effected with H2S then what you have to do. 6- what type of gland packing uses when valve glind is leaking.

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i want to know the interview format fot gail, instrumentation. pls answer me in habib.sami1003@gmail.com

0 Answers  

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The process variables that need to monitored and controlled are ________, ________, _________ and

1 Answers  

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Explain the thermocouple and RTD?

1 Answers  

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Control valve Flow characteristic. How the equal percentege curve form?

5 Answers  

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Explain types of valves?

0 Answers  

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Q1: Consider part of a control loop, which excludes the transmitter, consisting of a process, a controller and a control valve which may be represented by two dead times of 0.5 min each and three exponential lags of 0.8 min., 1.0 min. and 1.5 min. respectively. We wish to express this system as an overall first order plus dead time (FOPLD) model ie gain, time constant and process dead time. (We will see later that this is often done, to simplify controller tuning). For this exercise, gain is considered to be 1.0. (A) If the transmitter is a flow transmitter whose behaviour can be described by a dead time of 0.2 min. and an exponential lag of 0.5 min. in terms of the overall dead time and overall first order lag how can the system behaviour be approximated ? Overall dead time = Overall time constant = (B) If the transmitter is a temperature transmitter with a temperature sensor in a protecting well whose behaviour can be described by a dead time of 0.7 min. and an exponential lag of 15 min. how can the overall system behaviour be approximated now? Overall dead time = Overall time constant =

0 Answers  

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few questions on RS 232,1 question on relationship of impedance and turns ratio, many questions on flowmeters

0 Answers   Monnet,

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Can I calibrate the Electromagnetic Flow Meter on line and How.

0 Answers   SEWA,

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tell how to calibrate a magnetic flow tx, vortex flow tx,dp flow tx,nozzle flow tx and venturi flow tx?

2 Answers   TATA,

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Gas equation

0 Answers   CCIE,

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