Wenzhou EAA Electric Co., Ltd — I/P and E/P Transducers Built To Drop Into Imported Instrument LoopsYueqing City, Wenzhou, Zhejiang, ChinaTel +86 577 65165096[email protected]
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Solution

Valve Actuator Signal Conversion

A pneumatic control valve receives a pneumatic signal to act, and never touches the electrical signal used in industrial control. The field therefore needs a conversion instrument mounted on the valve that takes the electrical signal from the control room and turns it into the gas signal the valve recognises.

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The process

Step By Step

STEP 01Establish the signal
STEP 02Establish the spring
STEP 03Size the flow
  1. Establish the signal4-20 mA, 10-50 mA, 0-60 mA, or 0-5 V, 1-5 V, 1-9 V, 0-10 V. The input decides whether an I/P or an E/P part number is ordered.
  2. Establish the springThe output range must match the actuator spring compression coefficient, or the valve will not travel through its full stroke.
  3. Size the flowA large actuator needs a transducer that passes the air. The T1000 gives 12 to 24 SCFM; the T1500 gives 6.5 to 9.0 SCFM.
  4. Condition the airFit a filter and pressure reducing device at the transducer inlet so the instrument air is constant near 0.14 MPa and free of impurities.
  5. Mount and calibrateMount first, calibrate second. Zero at the bottom of the signal range, span at the top, then check the intermediate points and the dead band.
  6. Record the resultWrite down the dead band and the stem positions at each calibration point. That record is the baseline for the next service.
What you receive

Deliverables

  • A transducer matched to the signal, the spring and the flow
  • The published datasheet for the selected model
  • A documented calibration procedure with instrument list
  • Air preparation guidance for the inlet
Contact

Where To Send It

WhatsApp 0086-158-5856-3760 or email [email protected]. Photographs of the nameplate and the installation are the fastest way to get an accurate answer.

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Models involved

Products This Process Draws On

500AC Electro Pneumatic TransducerControlair Type Transducer

500AC Electro Pneumatic Transducer

500-AC configuration, 4-20 mA in, 3-15 psi out, 180 ohms

View specifications →500ACD Electro Pneumatic TransducerControlair Type Transducer

500ACD Electro Pneumatic Transducer

500-AC range with a plug-in electrical termination

View specifications →500X Electro Pneumatic ConverterControlair Type Transducer

500X Electro Pneumatic Converter

Controlair pattern E/P converter, 0-5 V, 1-9 V and 0-10 V inputs

View specifications →500X Electro Pneumatic TransducerControlair Type Transducer

500X Electro Pneumatic Transducer

Controlair pattern I/P transducer, 4-20 mA in, 3-15 to 3-120 psi out

View specifications →
FAQ

Questions About This Process

Why does the valve not open fully

Usually a selection problem rather than a calibration problem. If the spring compression coefficient is outside the transducer output range, full-open and full-close actions cannot be realised.

Do I need a positioner as well as a transducer

Not always. A transducer produces a clean signal pressure; a positioner forces the stem to a position. On a stiff or badly packed valve the positioner earns its place. On a straightforward loop the transducer is enough.

How steady does the air supply have to be

Steady near 0.14 MPa at the transducer inlet, which is why the filter regulator belongs at the instrument rather than somewhere upstream.

Next step

Begin With A Specification Not A Guess

Send what you have, even if it is only a photograph of a nameplate, and we will tell you what is missing before quoting.

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