Valtek Electro-pneumatic
Transducers
GENERAL INFORMATION
The following instructions are designed to assist in
installing, operating, calibrating and performing maintenance as required on the Valtek Electro-pneumatic
Transducer. Product users and maintenance personnel
should thoroughly review this bulletin prior to working
on the transducer in conjunction with the Valtek Installation, Operation, Maintenance Instructions for the
appropriate control valve and control valve positioner
being used.
To avoid possible injury to personnel or damage to valve parts, WARNING and CAUTION
notes must be strictly adhered to. Modifying
this product, substituting nonfactory parts, or
using maintenance procedures other than outlined could drastically affect performance, be
hazardous to personnel and equipment, and
may void existing warranties.
The Valtek Electro-pneumatic (I/P) Transducer may be
mounted directly to the control valve, or mounted
remotely from the valve in any position. A two-inch pipe
mounting bracket is available from the factory.
The (I/P) transducer is Factory Mutual approved and
intrinsically safe for Class I, II, III, Division 1, Groups C,
D, E, F and G, when installed with the appropriate
energy limiting safety barriers. The unit is also explosion-proof for Class I, Division 1, Groups B, C and D;
dust-ignition proof for Class II, Division 1, Groups E, F
and G; and suitable for Class III, Division 1, hazardous
locations, indoors.
I/P TRANSDUCER OPERATION
The input current flows through a fixed coil where a
magnetic force is created. The flux lines of the coil are
exposed at a gap, creating a magnetic force proportional to the input current. This force is applied against
the force of a small magnet mounted on the end of a
balance beam. The magnet is positioned in the electromagnetic field, it interacts with the small magnet on the
balance beam, thus repositioning a flapper at the opposite end of balance beam. When energized, this flapper/
balance beam is the only moving part in the system.
The flapper is in close proximity to a nozzle. The nozzle
is supplied with air through a throttle from the output of
a power amplifier that is controlled by the pressure
change in front of the nozzle. The air flowing from the
nozzle forms a restoring force to the force applied to the
magnet. Hence, a linear correspondence of electric
input and pneumatic output signal is achieved.
The zero adjustment is made by twisting the tension bad
to which the balance beam / flapper is mounted.
Range adjustment is performed at the potentiometer
connected with a resistor in parallel to the coil.
INSTALLATION INSTRUCTIONS
The following instructions are designed to assist in the
field installation of Electro-pneumatic Transducers.
The I/P transducer may be mounted directly to the
control valve with a bracket supplied by the customer, or
remotely from the control valve with a two-inch pipe
mounting bracket available from the factory.
Orig. 3/89 Valtek No. 81369
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NOTE: The air supply should conform to ISA standard
S7.3 (a dew point at least 18 F below ambient temperature, particle size below 5 microns, oil content not to
exceel 1 part per million).
line, depressurize the line to atmospheric pressure.
Drain all process fluids and (if caustic of hazardous
material are present) decontaminate the valve.
Failure to do so can cause serious injury.
Control Valve Mounting
To mount the transducer directly to the control valve, a
bracket must be fabricated by the user.
1. Securely attach the bracket to the control valve in a
position that will not interfere with the movements of
either the valve stem, the positioner linkage, or
accessories.
2. Mount the transducer to the bracket using the two
quarter-inch holes that are drilled through the transducer housing. Be certain the 1/8-inch NPT holes
are accessible.
Two-inch Pipe Mounting
To mount the transducer remotely from the control
valve, use the two-inch pipe mounting kit available from
the factory (part number 70691.999).
1. Attach the mounting kit in any position as required
by the user to a two-inch pipe.
2. Mount the transducer to the mounting kit. Be certain
the 1/8-inch NPT holes are accessible.
Air Connections
1. Screw the pipe or tube fittings into the 1/8-inch NPT
holes on either side of the housing.
CAUTION: The supply air pressure must not
exceed 20 psi (+1.5 psi).
2. Be certain there are no air leaks in fittings.
Control Signal (Milliamp) Connections
1. Remove the housing cover.
WARNING: Make sure the area is clear of combustible gasses before removing the cover,
unless the unit has been installed with the appropriate intrinsically safe barriers.
2. Attach signal wiring to the transmitter terminal
block, using caution to attach the positive and
negative wires tot he appropriate terminal.
CALIBRATION
When an electro-pneumatic transducer installed in the
field requires output signal adjustment, refer to Figure
1 and proceed as follows:
CAUTION: If the valve cannot be stroked without
disturbing the process fluid, it may be necessary to
bypass or remove the valve from the line before
calibrating the transducer.
WARNING: Prior to removing the valve from the
Zero and Range Adjustments
1. Remove the housing cover.
WARNING: Make sure area is clear of combustible gases before removing the cover, unless
the unit has been installed with the appropriate
instrinsically safe barriers.
2. Check zero with an air supply of 20 psi connected
and an input signal of 4 mA. Any deviation in the
output signal from 3 psi can be corrected with the
zero adjustment screw.
3. Increase the input signal to 20 mA. Any deviation in
the output from the value of 15 psi can be corrected
with the range potentiometer.
REVERSING SIGNAL
If the signal to the I/P transducer must be reversed,
consult factory for instructions.
CLEANING FLAPPER AND NOZZLE
If the flapper and nozzle become sticky and need to be
cleaned of dirt build-up, refer to Figure 1 and proceed as
follows:
1. Remove the housing cover.
WARNING: Make sure are is clear of combustible gases before removing the cover, unless
the unit has been installed with the appropriate
intrinsically safe barriers.
2. Remove the rectangular cover by loosening center
screw.
3. Using a heavy piece of lint-free-paper soaked in
denatured alcohol, gently lift the flapper and nozzle.
Work paper back and forth until dirt build-up is removed.
CAUTION: Do not lift the flapper more than 1/16inch or it may be damaged.
4. Replace the rectangular and housing covers.
DISASSEMBLING AND REASSEMBLING
BOOSTER SECTION
Disassembling Booster Section
To disassemble the booster section, refer to Figure 2
and proceed as follows:
1. Remove I/P transducer from line.
2. Using a three millimeter hex wrench, remove the
two housing bolts (119).
3. Carefully remove the lower three sections of the
booster assembly.
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Figure 1: I/P Transducer with Housing
and Electronic Module Covers Removed
CAUTION: There are numerous springs and
parts under compression within this section.
Care must be used not to lose these parts.
At this point, the orifices in the booster section may be
cleaned, or a ruptured diaphragm may be replaced.
The orifices may be cleaned by using an air nozzle, or
by inserting an instrument (which is less than .009-inch
in diameter) into the orifices.
Replace a ruptured diaphragm with the same part. (See
Figure 2 for item numbers.)
Reassembling the Booster Section
To reassemble the booster section, refer to Figure 2
and proceed as follows: (Numbers in parenthesis refer
to item numbers; see Figure 2.)
1. Invert the I/P transducer so that is rests on the
round housing cover.
2. Place the first stage feedback spring (110) in the
housing hole.
3. Place the spring button (111) on the first stage feedback spring (110) with the spring guide in the
spring.
4. Place the upper diaphragm (112, with three holes)
on the spring button (111) with the convolution facing down and with the small hole in the diaphragm
over the orifice.
Parts List
101 Cover
102 Cover O-ring
103 Electronic module cover
104 Electronic module
105 Nozzle O-ring
106 Flame arrestor cover
107 Terminal block
108 Arrestor O-ring
109 Transducer base
110 Feedback spring
111 Spring button
112 Upper diaphragm
113 Nozzle block
114 Lower diaphragm
115 Vent block
116 Booster diaphragm
117 Booster spring
118 Connecting block
119 Housing bolt / washer
120 Electronic module cover screw
121 Electronic module mounting screw
122 Terminal block mounting screw
123 Booster poppet
124 Poppet spring
125 Poppet retainer
126 Ground screw
127 Ground clamp
128 Washer
Figure 2: Electro-pneumatic (i/P)
Transducer – Exploded View
30-3
5. Place the nozzle block (113) on the upper diaphragm (112) with the nozzle down, aligning the
hole in the corner with the orifice in the I/P base
(109).
6. Place the lower diaphragm (114, with four holes)
onto the assembly with the convolution facing up,
aligning the four holes appropriately.
7. Place the vent block (115) on the assembly with the
vent hole on the side aligned with the NPT opening.
Be certain the mounting holes and pneumatic passages are aligned.
8. Place the booster diaphragm and vent assembly
(116) on the assembly with the brass vent assembly facing up. Be certain the large holes in the small
pneumatic passages are aligned.
9. Place the large booster spring (117) on the diaphragm and over the brass vent assembly.
10. Place the connection block (118) on the assembly
with the plugged hole facing opposite the electrical
NPT connection.
11. Tighten the entire booster section together with the
two housing bolts (119).
Troubleshooting
Failure Probable Cause Corrective Action
Operation erratic and 1. Loose signal wire connection 1. Tighten signal wire connection
inconsistent 2. Dirt build-up on flapper and nozzle 2. Remove dirt build-up; see "Cleaning
Flapper and Nozzle " section
Won't calibrate to full span 1. Dirt build-up on nozzle and flapper 1. Remove dirt build-up; see "Cleaning
with normal air pressure Flapper and Nozzle" section
2. Air supply pressure too high or low 2. Adjust air supply to 20 psi
Excessive air consumption 1. Ruptured diaphragm 1. Replace diaphragm; see
"Disassembling and Reassembling
Booster" section
2. Housing bolts loose 2. Tighten housing bolts
Transducer does not 1. Plugged orifices 1. Clean orifices; see Disassembling
respond to singnal and Reassembling Booster" secton
2. Shorted or open circuit coil 2. Replace transducer
Flowserve Corporation has established industry leadership in the design and manufacture of its products. When properly selected, this Flowserve product is designed to perform its
intended function safely during its useful life. However, the purchaser or user of Flowserve products should be aware that Flowserve products might be used in numerous applications
under a wide variety of industrial service conditions. Although Flowserve can (and often does) provide general guidelines, it cannot provide specific data and warnings for all possible
applications. The purchaser/user must therefore assume the ultimate responsibility for the proper sizing and selection, installation, operation and maintenance of Flowserve products.
The purchaser/user should read and understand the Installation Operation Maintenance (IOM) instructions included with the product, and train its employees and contractors in the safe
use of Flowserve products in connection with the specific application.
While the information and specifications presented in this literature are believed to be accurate, they are supplied for informative purposes only and should not be considered certified or
as a guarantee of satisfactory results by reliance thereon. Nothing contained herein is to be construed as a warranty or guarantee, express or implied, regarding any matter with respect
to this product. Because Flowserve is continually improving and upgrading its product design, the specifications, dimensions and information contained herein are subject to change
without notice. Should any question arise concerning these provisions, the purchaser/user should contact Flowserve Corporation at any of its worldwide operations or offices.
For more information, contact:
Flowserve and Valtek are registered trademarks of Flowserve Corporation.
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©1998 Flowserve Corporation. Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611
For more information about Flowserve, contact www.flowserve.com or call USA 972 443 6500
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